Compact housing against risks of overheating in London

Compact housing against risks of overheating in London

University of Westminster College of Design, Creative and Digital Industries School of Architecture and Cities MSc Architecture and Environmental Design 2018/19 Sem 2&3 Thesis Project Module Hamza Alhalabi September 2019

Abstract: Throughout the history of man, Architecture was the shelter to protect people from their surroundings and provide thermal comfort for living. The requirements of thermal comfort have changed throughout the last 50 years due to climate change, when the risk of overheating started to arise. However, measures for the dominant cold climate are still more considered than the changing climate in the last two decades, where UK Building regulations implemented measures to reduce energy consumption in dwellings by reducing air permeability and increasing insulation. The approach of reducing energy consumption in the winter has led us, in many cases, to forget about the risk of overheating in summer, and this is the main focus of this paper.

This paper consists of three sections. The first section examines how overheating can occur in dwellings by showing how different internal and external heat-gain sources, combined with poor building fabric, can cause thermal discomfort for its occupants. In addition, it shows that compactness and over insulating a dwelling leads to overheating.

The second section is a study done on a shoebox through Dynamic Thermal Simulation (edsl TAS), testing the risk of overheating in compact houses. The aim of this study is to generalise basic standards for different parameters to reduce the risk of overheating on hot summer days of the current climate and to adapt better with the climate in 2050. The shoebox is designed to represent a typical one bedroom flat with parameters that represent compactness. The methodology followed is to change specific parameters and ventilation strategies in order to improve the thermal comfort, and make the flat passes CIBSE TM59 assessment methodology. The findings of this study show that high insulation and airtightness should not be substituted with poor ones. In fact, changing parameters like ceiling height and improving natural ventilation strategies with controlling the aperture air flow to floor percentage can eliminate the risk of overheating.

In the third section, the findings of the shoebox experiment are applied on a real residential project designed by Architype practice. Aiming to pass the same TM59 assessment on free run system only, and to cancel the need for mechanical ventilation, which is supposed to be implemented in the building by the designers.

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Abstract:

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Acknowledgement

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Introduction Chapter 1 - Theoretical background Literature review

Thermal comfort and adaptive comfort

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Overheating in dwellings

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Climate change and heatwaves

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London Climate and future predictions

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Climate change - London 2050

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Intensification in London

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Evolution of UK building regulations

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Problem definition

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research questions and hypotheses

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Assessment methodologies.

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Heating and ventilation systems 03-01

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Passive House Planning Package (PHPP)

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Standard Assessment Procedure (SAP)

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CIBSE Guide A

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CIBSE TM52:

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TM59:

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Natural ventilation strategies for homes

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Windows types and controls

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Conclusion

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Chapter 2 - Analytical work - Shoe BOX Analytical work - Shoe BOX

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Introduction

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Variable Parameters

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Model specifications

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Strategies and steps of the study

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Overheating assessment

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South shoebox - 2020

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South shoebox - 2050

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North Shoebox - 2020

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North Shoebox - 2050

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East Shoebox - 2020

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East Shoebox - 2050

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West Shoebox - 2020

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West Shoebox - 2050

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Research outcome and applicability Chapter 3 - Application of findings - RUSS Project Application of findings - RUSS Project

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Introduction

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Methodology

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Model specifications and Current parameters

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Flat EW ( East West )

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Flat NS ( North South)

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Table 3.3.2 - dimensions and total area of flat NS

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Flat EWs (East West Single sided)

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Overheating assessment

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Simulation results

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Findings

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Chapter 4 - Conclusion Conclusion

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Final outcomes

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A critique of TM59

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Limitations of the study

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References

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Bibliography

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Table of images

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Programs

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Appendix Authorship Declaration Form (Form CA1)

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Acknowledgement This dissertation came up after very hard efforts behind the scenes that taught me alot and gave me life experience to deal with prolonged stress exposure with the presence of other life difficulties. The help and support from Rosa Schiano-phan will never be forgotten. She knew how to balance between understanding my difficulties and at the same time, pushing for improvement and for what has to be done. I would sincerely thank as well Kartikya for his major influence on the final outcome of this thesis and for trying to widen up the research with more depth in details to make the dissertation more interesting. As I want to thank him for consisting his private time for doing so with not even a minor complaint about that. Thanks for the rest of the team and for Joan Valejo who suggested one of the basic sections of the research. And Amedeo for providing guidance that had, with no doubt, influenced the direction of the research.

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Introduction Thermal comfort is a basic need for the health and wellbeing of the occupants that formed the architecture in different zones around the world. This can be seen in the traditional buildings of south Spain that have elements like courtyards and parameters like high ceilings, and high thermal mass as a response to the hot climate of its location, with the aim to cool the indoor dry bulb temperature. The same drive for thermal comfort shaped a different architecture in cold cities, which led some parameters to be generalized like small window openings and hipped roofs or even the very seldom availability of external shading elements like in the UK. However, the question is how can these buildings respond to climate change? Will the Igloo or the mud house still have the same function that they are meant to have?

Due to greenhouse gases (GHG) and other factors, including phenomena like the Urban Heat Island, the climate is never like before. The climate is changing significantly, resulting in a much warmer planet. An increase of 0.8 °C above pre-industrial levels in global temperature is already happening. and an expectation of global mean surface temperature of up to 5.4°C might occur by the end of the current century (Maslin, 2014).

The reliance on air conditioning and central heating systems has impacted the form of new buildings and has made them less responsive to their environment. The fully glazed towers in the Middle East are a prime example of this. However, the rising awareness in developed countries about greenhouse gases and how mechanical cooling or heating, which used to provide comfort for occupants, have at the same time had a massive impact in increasing greenhouse gases, has resulted in a response to mitigate the reliance on them.

In the last two decades, UK Building regulations implemented measures to reduce energy consumption in dwellings by reducing energy losses through the building fabric. And that is mainly by reducing air permeability and increasing insulation. Since 2002, building regulations obliged new dwellings to achieve a minimum airtightness of 10m³/(hr.m²) at 50 Pa(DTLR, 2002). Later on, the code of sustainable homes implemented in 2007 led the new homes built by public finance to follow codes aiming to reduce the energy loads by 25% less than the lowest standards provided in AD L1A 2006 (NHBC Foundation, 2012).

The approach toward compactness in order to reduce energy consumption in winter has led, in some cases, to less focus on how the building will function in summer time. These buildings are exposed to a higher risk of overheating, not only during hot summers like the infamous summer of 2003, but also in dealing with the regular internal heat gains during an average summer, where some cases are exposed to high occupancy ratios and internal appliances that radiate heat, which the building fabric is not capable to disperse. This is the main focus for this paper and study conducted.

Problem statement: The approach towards more and more compact houses at a time when the climate is changing towards a warmer one in London is preventing the building’s internal temperature to drop down when the outdoor DBT is lower than the internal space temperature.

Dissertation purpose: The purpose of this dissertation is to find the links between over insulated and airtight dwellings, and overheating on the other side. The dissertation not only aims to examine this issue, but also aims to define the generalised parameters to be followed as rules of thumb in order to design new dwellings with lower risks of overheating, without the need for mechanical ventilation or any mechanical cooling. Furthermore, this paper will examine how the buildings of London should evolve and adapt with the changing climate towards the year 2050.

Collaboration: This thesis is conducted in collaboration with Architype practice, as they have the same interest in the topic. Part of the research is to analyse a project of their design (RUSS), and improve it to reduce the overheating risks.

Research question: ● How can highly insulated and airtight dwellings lead to overheating in houses? ● Can we generalize standard parameters and strategies to reduce annual overheating hours in dwellings for each orientation? ● How will London architecture fabric evolve towards 2050?

Hypothesis: ● High insulation and isolation in dwellings is maintaining the internal heat gains inside the dwellings, resulting in overheating. ● More codes and overheating assessments are going to be created due to significant climate change.

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Methodology and tools: In order to answer the thesis questions a 3D shoebox was designed representing a typical compact one bedroom flat. The design is created through Dynamic Thermal Simulation software (edsl TAS). The methodology is to define the standard and changing parameters linked with overheating. The standard parameters are like walls and slab U-values, while the changing parameters are like glass to floor ratio, Windows G-value, etc. An assessment methodology for overheating is picked to assess the shoebox against overheating with the aim to make the shoebox pass the criterias of TM59 by changing the parameters that suits each 1 on the 4 main orientations and by using different natural cooling strategies. This is after finalizing the generalized standards for each orientation.

higher thermal mass facing the internal spaces will become a priority to absorb heat during the day and release it at night, doing what’s called ‘.night cooling’ or ‘purge ventilation’.

The second section of the analytical work begins by assessing three different flats with different orientation and natural ventilation strategies in RUSS project. By realizing the risks of overheating in the flats, improvements are applied based on the findings from the shoebox study, aiming to eliminate the need for the HRV systems planned to be used in the project.

The final outcomes of this paper is a clear guidelines for designers to follow for new dwellings. And in the cases of assessing an overheating house, looking for the guidelines can help to detect the parameters causing the issue.

However, following standardised parameters is not always applicable as seen in the 3rd chapter when applying findings on RUSS project. The project shows that more severe scenarios can occur due to security and safety controls. Whereas, each building has different difficulties and circumstances that can expose it to higher risks of overheating.

Summary of results: The shoebox study shows that having more leaky houses cannot be the way to tackle overheating. This is because the heating loads in winter are increasing significantly when changing airtightness from 3 to 7m³/(hr.m²).

Therefore increasing ceiling to floor heights to a minimum 280cm and using the type of windows with bigger aperture in order to increase air exchange during the cool hours have helped significantly in reducing the overheating hours. A strategy of double windows, instead of one, in the bedroom has improved air movement in and out of the space during the night hours while the internal doors are closed and the ventilation is totally single-sided.

In RUSS project, using the parameters designed by the designers (Architype), the three chosen flats did not pass the tm59 criteria. Further improvements were required to reduce overheating hours. increasing the windows throw length from 20 to 30cm in living rooms has had a good impact, letting the living rooms pass criteria 1. While, on the other hand, the bedrooms facing West were still overheating even though louvers were used on a low level close to the floor. However, the overheating hours were reduced to reach 41 hrs annually in the worse performing bedroom out of 32 as a benchmark.

The best scenario achieved on the south facing orientation has minor adjustments to adapt with East or West orientations that are represented in adding extra vertical shading to the horizontal ones, and By changing the timing of the blinds to start earlier on the East and later on the West orientation.

Improving the building fabric to deal with 2050 weather has required further improvement on the window types, which required using low louvers to penetrate cool air while preventing solar gain. In addition, the need for

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Chapter 1 - Theoretical background

(energistuk.co.uk, 2017)

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1. Literature review 1.1.Thermal comfort and adaptive comfort The physiology of our human body requires it to keep our core temperature stable in order to stay healthy. Our body has different strategies in order to preserve a core temperature of 37°C, like sweating to cool itself down evaporatively and shivering as a response to cold stress exposure (Nicol et al., 2012). The less the body has to do to keep itself stable, the more comfortable thermally we usually are. From that point, the American Society of Heating, Refrigerating and Air-Conditioning Engineers defines thermal comfort as ‘’that condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation’’(ASHRAE, 2010).

Thermal comfort is mainly affected by physical parameters linked with the environment of the perceiver, which are: (Dry bulb temperature - mean radiant temperature relative humidity and air velocity). These parameters combined with personal factors consisting of the metabolic heat production, which is related to the activity of the person and type of clothing, are colorated directly with the thermal comfort of the person (Cibse, 2006).

Adaptive comfort: Our bodies are naturally flexible and can adapt to different environmental conditions. This adaptation is not only by the body’s physiological response, but also by the conscious choices we make to deal with warm or cold weather. This is represented by our choice of summer clothing whether inside or outside the house, in comparison to winter clothing. The activities we make helps us adapt as well. For instance, people tend to reduce their activity to slow down their metabolic rate when they are feeling hot. Cibse Guide A has suggestions for office building users when the temperature goes above 25°C. Despite the fact that we all have the same core temperature, thermal satisfaction always varies from one person to another, due to many different factors. To understand the thermal comfort perceived by individuals there are two main scales that can be used to represent human comfort numerically. The ASHRAE comfort scale and Bedford comfort scale (FIG 1). These scales are the main tool used in conducting comfort surveys. The Bedford scale ranges from 1 to 7 while ASHRAE ranges from -3 to +3.

figure 1.1.1 (Nicol et al., 2012) (p13) It is hard to fix a generalised temperature range that keeps all occupants feeling comfortable, especially in their homes. The average room temperature standards have increased in the UK since 1970 due to the availability of central heating systems. The average temperature went from 12°C to 18°C nowadays (ovoenergy, no date) Ovoenergy, online). The World Health Organization (WHO) recommends for the average home temperature to be between 18-22°C for the safety of its occupants (World Health Organization, 2007). For offices, the Australian standard is widely used, and this standard recommends 21-24°C for offices.

However, using this range as a guide for active heating or cooling causes high energy demand. Furthermore, surveys show a relation between the outdoor temperature and the indoor temperature in forming the thermal satisfaction or dissatisfaction of the building occupants.

As a result, the British Council for Offices 2010 upgraded its recommendation for office temperature to become 24 ± 2K instead of 22 ± 2K in the summer (Nicol et al., 2012).

More widely, ASHRAE and EN 15251 have designed adaptive comfort charts that can increase the comfort limits significantly and decrease the temperature difference between the indoor and outdoor, which helped with reducing energy loads whether for heating or cooling purposes when a fixed thermostat is used. It also added more flexibility for the designers and their aim to achieve thermal comfort targets for the occupants on free-running buildings.

Predicted Mean Vote (PMV) The PMV is a methodology usually used for mechanically ventilated or cooled buildings in order to predict the number of people that would feel dissatisfied thermally based on the ASHRAE comfort scale (figure 6). It considers 6 physiological parameters of the huge studied samples in

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the surveys (DBT, radiant T, relative humidity, air speed, clothing and metabolic rate) (Nicol et al., 2012). The PMV method includes another factor which is the predicted percentage of people dissatisfied, considered for the people voting Âą2 or Âą3 in ASHRAE scale. Reaching 0 PMV has a minimum unsatisfied percentage which is 5%.

ISO uses the PMV method in order to classify the buildings between A, B and C.

categories for the buildings, its categories are unlike the ISO, which categorizes the buildings as a high or low standard. It categorizes buildings as a different types of buildings ( I ,II ,III ), aiming to encourage more adaptability with the outdoor conditions to mitigate the energy demand and accept higher or lower temperature levels.

Figure 1.1.3 - ASHRAE Adaptive comfort and acceptable operative temperatures in freerunning buildings (Nicol et al., 2012) Figure 1.1.2 - Predicted Mean Vote method (PMV) (ASHRAE, 2010) ASHRAE 55 A different methodology was adapted by ASHRAE 55 to go beyond the mechanically ventilated buildings and cover the free running ones, which relies on natural ventilation coming in from the windows. The main difference is that ASHRAE and the Europian Standard EN 15251 mainly consider the psychological factors rather than only the physiological ones. However, this method still relies on PMV as a base to predict the percentage of people feeling comfort based on the outdoor mean temperature of the month. The ASHRAE method contains two limits of comfort for the temperature to be contained within.

Achieving mean temperature within the first range predicts 90% of the occupants to be satisfied. Crossing the first range into the second one can predict 80% of people to be satisfied. The second range is the last range, and exceeding it means that the temperature of the space is not suitable and needs to either be raised or lowered (the psychrometric chart can help find the best way to improve comfort considering relative humidity).

This method has the same guidelines of the international ASHRAE 55, however it is more specialised in the European region. Its PMV results rely on big surveys conducted by the European SCATs project on five European countries at the same period of time. The EN15251 contains three ranges of comfort rather than two, and although the methodology classifies three

Figure 1.1.4 - Acceptable comfort ranges by EN15251 in free running spaces (Nicol et al., 2012) In the end, PMV methods and adaptive methods cannot always be precise, and conducting surveys in different projects can have considerably different results. Some surveys conducted in other places already showed different results and percentages of satisfied occupants (Nicol et al., 2012). The advantage in the residential sector is that the occupants have higher range of adaptability because they are free to wear and control their activity.

On the other hand, this advantage is usually not available in workspaces or schools. Nevertheless, the Japanese Cool Biz programme has given a great example for adaptive comfort to increase the limits of accepted temperatures in workplaces by reducing the clothing insulation rates in summer. Having high range of adaptive options can help the occupants’ satisfaction if not physiologically, psychologically.

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1.2.Overheating in dwellings What is overheating?

There is no such consensus on one definition for overheating, especially in dwellings, however, it’s generally defined by CIBSE as: “That state of mind that expresses dissatisfaction with the environment caused by prolonged high temperatures” (CIBSE, 2015) Overheating causes in micro scale: The feeling of dissatisfaction from high temperature can either be related to an over exposure to heat gains or to building design or fabric. In internal spaces like dwellings, there are two groups of heat gains. Internal heat gains are all the heat sources generated from inside the building.

These sources can be the electrical appliances like the PC or the TV, the cooker, artificial lighting, boilers etc. The heat generator could also be th​e occupants themselves.

As explained previously, human activity affects the metabolic rate and therefore, increases the heat generated by the person. Additionally, it increases the possibility of feeling overheated.

The other heat sources group is external heat sources, which is represented mainly by solar gains. The microclimate environment is also considered an external heat source, where the nearby traffic or factory could generate heat that penetrates to the building. To summarise, the external heat sources are the external dry bulb temperature and the solar radiation (figure 1.2.1).

appliances or impose some limitations for the user.

Designing a building that creates shading on itself describes how it can be responsible for overheating.

Internally the materials and the insulation has a high contribution on isolating the indoor spaces from the external DBT. Glazing sizes and window designs have a significant relation with the solar radiation. Finally, ventilation strategies are part of the building design which can control the fresh air penetrating to the building that can force the hot air outside.

In conclusion, overheating happens either when the internal heat could not be extracted mechanically or passively to the outdoor which has a lower temperature; or when the building fabric is incapable of preventing the external heat sources penetrating into the cooler building spaces. In worse cases, both scenarios can happen. For instance; if a building is highly insulated thermally high U-values for the external walls and windows, and with low numbers of air-permeability through building fabric, added to an intermediate exposure to solar radiation, and a high occupancy ratios. Cases like this can be a disaster even if the external temperatures are not extreme. The final result of such a case can overtake the risk of discomfort to become a risk on health or even cause deaths, especially among old people or young children.

1.3.Climate change and heatwaves

Figure 1.2.1 - Illustration of the heat sources that can expose dwellings for overheating (Zero Carbon, 2015)

The dominant weather conditions around the earth have distinct characteristics which have shaped different climate conditions in different zones without humans directly impacting the climate, until the invention of the steam engine in the industrial revolution in the second half of the 18th century. This period was linked with a significant increase in fossil fuels and carbon dioxide (IPCC, ) and other greenhouse gases (GHG). Because the earth has a connected Ecosystem, this increase in GHG started resulting in rapid change in temperature and caused what is called Global Warming (figure 1.3.1)

Building design and building fabric is the third and most important factor that decides whether the building will overheat (there are different criteria for assessing overheating that will be discussed later). The design of the building is responsible for eliminating the external heat sources. However, it is not necessarily capable of eliminating internal heat sources because it is driven by the occupant’s behaviour. This is particularly the case in the domestic sector, unlike office buildings where to some extent the designer can choose the desired type of

Fig 1.3.1 - the graph shows peaks of CO2 concentrations throughout the history till now (Davies & Company, 2000)

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An increase of 0.8°C above pre-industrial levels in global temperature is already happening, and an expectation of global mean surface temperature of up to 5.4°C might occur by the end of the current century (Maslin, 2014).

The increase of GHG is not only causing an average warmer temperatures, but also resulting in excess heat waves which increase fatalities related to overheating and moreover spikes the pollution levels which will again increase deaths caused by cancer and other pollution-related diseases.

Heatwaves: The infamous 2003 heatwave that hit the European continent was responsible for over 19,490 deaths only during the months of June to September, 12 times higher than the typical numbers of deaths during the same period (Stone, 2012). That great numbers of deaths mainly happened because the city’s buildings were not prepared to deal with the severe hot weather. For example, all the houses in the UK are equipped with central heating system because the temperature is usually below 20°C, while all the houses in Gulf countries like Kuwait are equipped with central cooling systems.

Therefore, the current and predicted climate scenarios must affect the current and future buildings in the UK and especially in dense cities like London, to deal with warmer weather. That is more applicable to cities rather than rural areas thanks to the urban heat island effect that can create additional heat source hitting the city centre.

Figure 1.3.2 - beaches well crowded with people as a result of the heatwave (theguardian, 2018) 1976 records the second hottest summer average temperature in the UK where the DBT reached 35.6°C. It is considered to be the summer with the worst drought (BBC, 2017). However, 2003 is considered more intense, while 1976 is considered as a prolonged period of sustained warmth (CIBSE, TM49, 2014). The inductive methodology and current climate warns us of worse future conditions. Instead of having a heatwave once every 100 years, we are in danger of having a heatwave once every 2 years by 2050, and the 2003 summer to be considered as a cool summer by the 2070s (Nicol et al., 2012).

Urban heat island: On the other hand, other factors and a phenomenon like the urban heat island (figure 1.3.3), plays a part in climate change, where the change in land surfaces like having asphalt instead of vegetation, added to the intensity of the buildings. Transportations and population increased the surface temperature and the overall emissions which caused imbalance and abnormal temperature spikes.

Urban heat island can be responsible for a temperature difference between the urban and rural areas of up to 10°C by the mid-morning in during the summer (KIM, 1992).

That is why studying the risk of overheating using data from weather stations located in rural areas can be misleading when applied to study the building performance in an urban area.

Figure 1.3.3 - the effect of urban heat island in increasing the temperature differences between the city and the countryside (​coolparramatta.com.au. ​)

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1.4.London Climate and future predictions

heat waves. The DBT in London reached 34 °C on the 26th of July at 14:50 (timeanddate.com, no date).

Current climate: Located in the Northern hemisphere, more precisely on latitude 51.5°N, London city, the capital of England and the UK has a temperate oceanic climate. The highest DBT occurs usually within July and August, scoring 22.4°C as a mean average temperature based on the current climate data (​Meteonorm, ​2017). The outdoor average DBT is less than the comfort zone most of the year, and it goes within the European EN 15251 adaptive comfort scale, barely during the period of (June-August) (Figure 1.4.1).

The meteorological simulations of the future climate show a slight increase in average temperature in London 2050 (figure 1.4.3). However, looking for average data can be tricky, as the maximum DBT in 2050 is expected to be 31.9°C in July, while the highest in the same month of 2017 is 28.9°C (​Meteonorm, ​2017) &(​Meteonorm, ​2050).

This data is considering normal weather conditions, and in fact, not considering heat waves that are going to occur more frequently as previously mentioned.

Figure 1.4.1 - climate & adaptive comfort data of London 2017 (​Meteonorm, ​2017)

Figure 1.4.3 - climate & adaptive comfort data of London 2050 (​Meteonorm, ​2050)

The climate data of central London shows that the city suffers cold stress most of the year with no heat pressure normally during the summer. Apparently, The reduction in its DBT can be related to one of the main features of London’s climate, and here we mean the overcast sky.

Clouds cover the sky of the city for most of the year resulting in up to 68% cloudy sky in July (figure 1.4.2) (Meteonorm, 2017).

Figure 1.4.2 - The frequency of sky types in London based on weather data of 2017 (​Meteonorm, ​2017))

Climate change - London 2050 Like the rest of the world, London is going to be exposed to a climate changed as a result of global warming. The consequences of climate change is already being seen in the current weather. In 2018, the residents of London experienced six weeks of warm spells that can be compared to the ones that occurred in 2003 and 1976

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Figure 1.4.4 - population density in London 2011 in relation to land area (James Gleeson, 2013)

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1.5.Intensification in London

1.6.Evolution of UK building regulations History summary of Building Regs.: The idea of Building Regulation originated after the Great Fire of London in 1666, which led to the formation of the first Building Construction Legislation 1667 in London. It introduced restrictions to limit the chances of fire in the construction industry. It took the government 200 years to upgrade the act with the first Public Health Act in 1875, which focused on ensuring the health and safety of the occupants. Revisions happened later on to the act, until finally the first set of Building Regulation Standards was obtained in 1965 (east cambridgeshire district council, ) East Cambridgeshire District Council, ).

Figure 1.5.1 - population intensity based on land area in England (Wikipedia contributors, ) The population all over the world is growing massively.

We are now 7.7 billion based on (​Current World Population  ​2019). People tend to live in cities more than rural areas due to factors like services and job opportunities, etc. According to Census, London had a population of 8.17 million in 2011, while it was 7.17 million in 2001. The population is still growing and expected to grow not less than another one million by 2021 (world population review,2019). This growth has burdened the residential sector, leading to an intensification in residential houses and an increase in occupants profile. Most of the traditional houses are being refurbished and split into smaller flats, or at least occupied by a higher number of occupants with the same house areas. Therefore, it has contributed to lower living standards with regard to the spatial or thermal comforts that occupants need. The high intensity of occupants significantly increases internal heat gains, whether it is because of the energy emitted by the human body or by increased pressure by occupants due to activities like cooking and hot water usage.

During this period, an important change occurred to households in the UK regarding heating systems and energy consumption. Because the dominant climate in London is considered cold, the need to achieve thermal comfort is higher during the winter rather than summer.

Having severe winter with poor heating systems leads to excess deaths, especially for old people and young children. Therefore, there was a massive spike in the use of central heating systems since the 1970 where only 30% of households in the UK were supported by central heating systems that relied on fossil fuels. By 1980 this number almost doubled, reaching 59%, and continued to grow until 95% of the UK houses were equipped with central heating by 2005. This number was almost the same until 2019. The statistics are done by the Office for National Statistics (UK), 2019 (figure 1.6.1).

Fig 1.6.1 - This major change in the availability of central heating systems contributes to a higher reliance on fossil fuel, especially natural gas consumption. (Office for National Statistics, (UK), 2019)

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Most of the houses in the UK relies on gas as a fuel for heating internal spaces, in addition to cooking and hot water. National statistics show that gas consumption went from 8,922 (ktoe) in 1970, to 31,806 in 2000 (figure 1.6.2) (National statistics, 2019). An interesting statistic shows that the domestic sector is considered as the most responsive to change in outdoor temperature (figure 1.6.3)

standards provided in AD L1A 2006 (NHBC Foundation, 2012). The implementation of sustainable code has resulted in most buildings achieving air permeability between 5 and 6 m³/(hr.m²) at 50 Pa, (figure 1.6.4) and some were even below 5 m³/(hr.m²) at 50 Pa.

Figure 1.6.4 the predicted and achieved air permeability in dwellings around the 2006 (NHBC Foundation, 2012) Fig 1.6.2 - high pressure on gas as an energy source after the 1970 (National statistics, 2019)

Figure 1.6.3 - The graph shows direct links between outdoor temperature and energy consumption in dwellings (National statistics, 2019) Approved document 1984 came into effect at the end of 1985. However, a response to the high energy demand in dwellings did not show up until the approved document in 2002, when building regulations started enforcing a minimum standard for new dwellings airtightness were cannot exceed 10m³/(hr.m²) at 50 Pa (DTLR, 2002). There was no increase in the requirements of more airtight buildings until now (NBS, 2013). Nevertheless, the code of sustainable homes implemented in 2007 which was meant to reduce carbon emissions in the UK led the new homes built by public finance to follow the codes aiming to reduce energy loads by 25% less than the lowest

Architectural practices are going for more and more compact designs with the aim of limiting energy consumption. Some practices follow criteria like Passivhous which is based on the concept of closing the envelope of the building to the maximum to achieve energy targets. The criteria of Passivehous require airtightness of ≤ 0.6 h −1 at 50 Pa.(Gonzalo and Vallentin, 2016). This means, as described in Passivhaus Primer: Airtightness Guide (McLeod et al., 2014), that in passive house certified buildings, there is a whole size of 5 pence each 5m² of the building envelope. While, in contrast, UK building regulations allow a whole size of 20 pence every 1m² of the building envelope.

The latest updates for the last approved documents 2010 was made in 2016. The approved documents now assure the minimum standards for health and safety, energy efficiency and even sustainability. Still, there is not enough legislation that deals with overheating and maximum temperature limits in dwellings. The only legislation in the UK comes from health and safety which instruct occupants to leave schools or workspaces under certain indoor temperatures (Nicol et al., 2012). The expectation for future updates is to respond to the overheating issue that was a result of compactness in the private sector by setting up standards and controls.

Global warming is constantly moving, and climate change is happening anyway, whether it follows the best or worst predicted scenarios. Adaptations for buildings is a necessity to face higher temperatures. Not necessarily by paying the consequences of consuming more energy, but by imposing higher standards to cool down the houses in

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hot summers and to make the building fabric balanced between summer and winter.

1.7.Problem definition Compact in the building fabric prevents houses from breathing and keeps the indoor temperature higher than the outdoor.

Figure 1.7.1 - new houses are smaller and very highly insulated and airtight

1.8.research questions and hypotheses 1. How can highly insulated and airtight dwellings lead to overheating in compact houses?

2. How will new houses respond to excessive heat waves and to the 2050s predicted climate 3. What is the best module for each orientation of a compact house to reduce the risk of overheating

to be described briefly because they are not specialised in dwellings and won’t be adopted in this research.

Precedents: Zero Carbon Hub organization have a lot of research about overheating. In one of the reports published on 2015 (Zero Carbon, 2015). A comparison was made in details. However, due to the date of the publication, it doesn’t cover the new version of CIBSE guide A, or even the adopted methodology in this paper (CIBSE TM59).

Another inspiration about overheating assessment methodologies is a report done by Passivhaus trust (Passivhaus trust, 2016)), where they mention some of the assessments methods. But they focus more on the passive house assessment method which this paper will cover as it includes all building pench marks for passivhaus certification. The paper covers as well factors linked with overheating like glazing ratios, but the heat loss from hot water pipes.

1.9.1.Heating and ventilation systems 03-01 (Specialised ventilation for healthcare premises)

Hypothesis​: ● High insulation and isolation in dwellings is maintaining the internal heat gains inside the dwellings resulting overheating. ● More codes and overheating assessments are going to be created due to significant climate change.

1.9.Assessment methodologies.

Assessment methods for overheating are meant to add another layer to the adaptive and PMV methods for thermal comfort by setting limits of temperature that the occupants can tolerate without causing health issues.

Due to the cold weather, there is not enough legislation for tackling overheating especially at homes from the governmental regulations. Which made other private environmental organisations to suggest methodologies and limits. CIBSE is the main pioneer in assessing overheating. And many other standards follows its guidelines. For instance, BREEAM refers to the CIBSE guide A and CIBSE TM59 in BREEAM new construction (BREEAM, 2014). Apart from CIBSE, there are other methodologies for overheating assessment that are going

Figure 1.9.1.1 (Department of Health, 2007) Healthcare buildings In its assessment for service requirements, it requires thermal modeling to be undertaken to guarantee that the DBT of patient areas do not exceed 28°C for more than 50hours during the entire year. There is no upper limit of the temperature that cannot be exceeded. In the end the criteria refers to CIBSE guide A, for comfort temperature (Department of Health, 2007).

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1.9.2.Passive House Planning Package (PHPP)

1.9.3.Standard Assessment Procedure (SAP)

Figure 1.9.2.1 (Passive house, no date) Healthcare and Dwellings PHPP is a dynamic tool by the passive house institute made for studying energy balance and for planning efficient buildings and refurbishments. The tool can study different aspects regarding energy and comfort, and it gives the frequency of overheating hours during summer.

The criteria for both residential and other buildings is the same. The DBT shouldn’t exceed 25°C for more than 10% of occupied hours. Which equals 876 hours/year. 10 15% is considered poor, while when the percentage exceeds 15%, the building or the space is classified as ‘Catastrophic’ (table 1.9.2.1). The The tool calculates a limit of 3K swing in temperature, however, this is not mandatory for the certification (Passivhaus trust, 2016).

Figure 1.9.3.1 - Standard Assessment Procedure (BRE, 2012) SAP is an assessment methodology for dwellings developed by the Building Research Establishment (BRE), and adopted by the UK government. Its main purpose is to provide assessment for energy performance.

Overheating is not greatly considered in the assessment.

However, in the appendix p (table p2), there are some guidelines for the Likelihood of high internal temperature during hot weather. When the temperature is greater or equals 23.5°C during the period June till August, the likelihood is high (table 1.9.3.1)(BRE, 2012).

Table 1.9.3.1 - thresholds for likelihood of high internal temperatures (BRE, 2012) Table 1.9.2.1 summer comfort scale (Passivhaus trust, 2016)

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1.9.4.CIBSE Guide A

Table 1.9.4.1 - Previous overheating benchmarks(Cibse, 2006)

Figure - 1.9.4.1 (Butcher and Craig, 2015) Guide A is considered one of the most important environmental guidelines in the UK. many assessment methods whether governmental or other organisations like BREAM refers to its guidelines. For overheating assessment, the 8th edition of cibse Guide A recommends that internal temperatures for both mechanically and naturally ventilated buildings shouldn’t exceed 26°C (schools and shops require lower Δt) for more than 3% of annual occupied hours. It’s worth mentioning that in CIBSE guide A 2006, the standards were slightly different (table 1.9.4.1), requiring a benchmark 28°C but for only 1% of annual occupied hours in living rooms, and 26°C for bedrooms with the same percentage of frequency (Zero Carbon, 2015). Setting these thresholds are based on the PMV data of EN 15251 where the acceptable PMV for the building type II is ± 0.5. This threshold is applied for dwellings, offices, public spaces and classrooms.

Kindergartens and shops have a slightly lower limits (table 1.9.4.2) (Butcher and Craig, 2015)

Table 1.9.4.2 - Last update of Benchmarks for guide A (Butcher and Craig, 2015)

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1.9.5.CIBSE TM52:

1.9.6.TM59:

Figure 1.9.5.1 (CIBSE, TM52, 2013)

Figure 1.9.6.1 (Cibse, TM59, 2017)

TM52 is a more advanced methodology came into the public in 2013. It is a specialised methodology for assessing overheating in European dwellings using adaptive comfort methods similar to the ones used in guide A (EN 15251), it relies on PMV index, but with more details. The assessments of TM52 has 3 criterias. Passing 2 of them is mandatory to pass the assessment and not to consider the building as overheated. Which covers the exceedence of the threshold by a specific percentage, and the severity of the temperature during one day. It also sets up an absolute upper limit of the mean operative temperature that the space shouldn’t reach at anytime.

1. Δt < upper comfort for max 3% - during summer (May - Sep) occupied hrs 2. Peak Daily Weighted Δt ≤ 6 within a day (The weighting factor WF is calculated by summing up how many hours the temperature is exceeding the limit and by how many degrees.)

3. Δt < Upper limit Where the operative temperature cannot exceed a specified upper absolute limit defined based on the outdoor temperature.

The last methodology that came to the industry is the TM59 which has been published in 2017, and that’s why it’s used in this research to assess the analysed buildings.

The assessment is considered the most strict one from all the previously mentioned assessment methodologies whether by CIBSE or by other standards. TM59 is an evolution the TM52. it’s unlike TM52, specialised only in dwellings. However, it adopts parts of its criteria with some additional guidelines and conditions that suites residential buildings only (Cibse, 2017).

Some of the following guidelines explained are meant to insure that the assessed dwellings are under reasonable conditions of ventilation and strategies, and at the same time, are exposed to hot weather conditions that are likely to happen more often thanks to the global warming.

Summer files: The guidelines require using the Design summer years of 2020s high emissions 50 percentile scenario, generated by the most appropriate meteorological station, for the thermal analyses. To pass the assessment, the building has to pass criterion A and B under the conditions of 3 different summer design files (DSY1, DSY2, DSY3).

DSY1 is considered as a moderately warm summer file representing the conditions of the heatwave occurred in

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1989. It represents the least severe summer file in comparison to DSY2 and DSY3.

DSY2 is considered as a short intense warm spell, representing the severe conditions of 2003.

DSY3 is considered as a less intense warm spell but for prolonged exposure. (CIBSE, 2014) Windows and doors openings It’s advised that the windows must open when the indoor DBT exceeds 22°C. And restrictions for security should be considered. The doors of the corridors and rooms should be open during the day time to improve air movement.

However, the bedroom doors must be closed during bed hours which are 22:00 - 7:00.

so 33 or more hours above 26°C will be recorded as a fail).‘’(Cibse, TM59, 2017, p5) For mechanically ventilated homes: There are a fixed temperature criteria which requires the same criteria of CIBSE guide A (Butcher and Craig, 2015), which is that the ( all occupied rooms operative temperature cannot exceed 26°C for more than 3% of the annual occupied hours).

Summary for all assessments is illustrated in the next table 1.9.6.1, showing a comparison between all thresholds and requirements. For other detailed comparisons, look (Antonietta Canta, no date) and (Passivhaus trust, 2016)

Air speed within the space shouldn’t exceed 0.1 m/s unless ceiling fans are used.

Blinds and shading External shading and blinds can be considered only if included in the design. However, the blinds must not interfere with the windows opening where it can restrict the opening area and reduce airflow in reality.

Pipework and heat loss The heat loss from pipeworks ,HIU and heatmaintinance should be considered if available in the assessed space. A guideline for the heat loss from pipes based on the pipes size is provided in the same book (Cibse, 2017),p5). The pipeworks are mainly considered in communal areas like corridors. Although it’s not mandatory to pass the corridors in the assessment, the corridors temperature shouldn’t exceed 28°C for more than 3% of the annual hours. Else, it should be identified in the report as a risk.

Compliance with the criteria for naturally ventilated homes: Criteria 1 ​- ‘‘For living rooms, kitchens and bedrooms: the number of hours during which DT is greater than or equal to one degree (K) during the period May to September inclusive shall not be more than 3 percent of occupied hours. (CIBSE TM52 Criterion 1: Hours of exceedance)’’ (Cibse, 2017), p5) Criteria 2 - ‘’For bedrooms only: to guarantee comfort during sleeping hours the operative temperature in the bedroom from 10 pm to 7 am shall not exceed 26 °C for more than 1% of annual hours. (Note: 1% of the annual hours between 22:00 and 07:00 for bedrooms is 32 hours,

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Standard

Building type

Threshold

Duration of time

Max Duration of exposure

Departme nt of health (03-01)

Healthcare

DBT 28°C

All year

50 hours = 0.57%

Passive House (PHPP)

All buildings

DBT 25°C

All year

10% annual hours

(SAP)

residential

DBT 23.5°C

jun-Aug

unspecified

CIBSE guide A 2006

CIBSE guide A 2015

CIBSE TM52

CIBSE TM59

Dwellings

criteria

1- (Living room)

Δt 28°C

2- (bedrooms)

Δt 26°C

offices classrooms

Δt 28°C

residential offices Public spaces classrooms

Δt 26°C

kindergarten

Δt 25.5°C

shops

Δt 25°C

Residential and commercial

Residential (Free running)

Residential (Mechanic vent)

All year 1% annual occupied hours

All year

3% annual occupied hours

1

Δt > upper comfort limit

2

Weighted Δt ≤ 6

3

Δt > Upper limit

1- (BedroomsLiving rm Kitchen)

Δt > upper comfort limit

May-Sep

3% occupied hours

2- (bedrooms)

Δt 26°C

All year bed hours (22:00-07:00)

1% annual occupied hours

1- BedroomsLiving rm Kitchen)

Δt 26°C

All year

3% annual occupied hours

3% occupied hours May-Sep

Within 1 day 0% occupied hours

Table 1.9.6.1 - Summary of the most critical assessment methods benchmarks for overheating

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1.10.Natural ventilation strategies for homes Natural ventilation is the main strategy by man to reach thermal comfort inside a space. It mainly rely on using windows to allow air to penetrate and in some other cases using louvers to allow air only and blocking the solar radiation at the same time. However, using windows in random sizes can result undesired temperatures to occur.

Thus, there must be an understanding for the main strategies and how to improve the air exchange by wind force and thermal buoyancy to maximize the benefit of natural ventilation.

The simplest strategies of natural ventilation that is usually used in dwellings is the si​ngle sided ventilation, where the bedroom or living room has a view on one of the streets surrounding the building (figure 1.10.1) Its recommended that the room depth not to exceed 2.5 times the floor to ceiling height, to not lose the force driven by the turbulence happening inside the room. And this means, the higher the room ceiling is, the more depth of the room can be. Thus, ceiling height is a major factor to improve the single sided ventilation. Incases that the guideline if width to height cannot be achieved, it’s advised to use a ceiling fan to improve air movement.

The other mechanism that could be used for room with the same case is using buoyancy force, which happens by using the difference in temperature between the internal space and the external air to drive the air exchange (figure 1.10.2) (Rennie and Parand, 1998)​. Stack ventilation is usually used in buildings like offices or that has multiple stories. Because the bigger distance between the intel and the outlet, the higher the temperature difference is. Using chimney exposed to solar radiation is an idol to improve ​Δt​, added to the wind force which increases in higher levels. Based on the same physics, it’s recommended in single sided ventilation when using double windows to set a height between them of 1.5 M (Yang and Clements-Croome, 2012), (Irving et al., 2005) The final and most effective strategy is the cross ventilation. An inlet and outlet is needed like in the single sided double windows strategy. However, the cross ventilation requires the inlet to face another side of the room, and the air movement is mainly on reliance on

wind driven force (figure 1.10.3). This strategy allows more flexibility for the depth of the room to reach up to the double of that used for single sided ventilation. In addition it allows higher levels of air exchange and therefore, it’s one of a better way to reduce the risks of overheating by penetrating cool air to substitute hot air inside the space.

Dwellings can benefit from all of these strategies in London based on the requirement of each room in different buildings. Double storey houses can benefit highly from stack ventilation, while small flats which face one orientation can increase its chances for discharging heat by using a smaller effect of stack ventilation added to the wind driven air exchange. The analytical section includes simulations that prove the quality if such techniques.

Figure 1.10.1 - single aspect ventilation depth and height guidelines

Figure 1.10.2 - double windows activate stack effect

figure 1.10.3 - cross ventilation (Rennie and Parand, 1998)

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1.11.Windows types and controls

Figure 1.11. 1 variety of classic windows used in london dwellings (honestlywtf.com, no date) There is a need to study the difference in window types due to the huge influence they have on the amount of air penetrating into the space, and overall, the air exchange (ach) between the inside and outside. Sash windows are widely seen used in Victorian houses and other classic houses types in the UK. they are more effective in regard to open window area and the discharge coefficient if compared to the top hung windows. However many dwelling and offices designers tend to use top hung windows thanks to the security and safety they offer. But they sacrifice a better natural ventilation opportunities.

2-Casement window (side hung) This window is widely used in countries that need big openable window area to allow air exchange, thanks to its ability in most cases to open 90°. The discharge coefficient of this window which is 0.62 (look table 12) allows it to reduce air resistance.

There are 6 main window types as referred in (Irving et al., 2005). Each opens differently.

1- Top hung/ Bottom hung This type of window can be opened 10 to 90° degree, allowing 0 to 100% openable area. In most of the cases these windows don’t open to that extent. Building regulations allow max of 55cm (​Architype, ​) for the throw length. The big advantage in this window is that it works well with actuators to automated with smart systems. even though the actuators usually have li​mits for the throw length unless high specifications are requested.

4-Sash window (sliding window) To allow controlled clean openable area, sash windows are idol. Where the user is able to open it partly or fully in most cases if it’s sliding to the side rather than to the top because of gravity limitation.

3-Tilt and turn For more complexity and control they allow the user adaptive comfort to decide which way and how much is the needed openings.

5-Pivot window (Vertical / Horizontal) Vertical and horizontal pivot are suitable to give the maximum amount of openable area featuring the ability to split the window into an inlet and an outlet, which can offer a better air exchange and less air resistance.

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The horizontal pivot allows the window to improve the stack ventilation opportunities. The only issue with these windows is that they can interfere with regular blinds.

Thus, interpane blinds can be more convenient. However, they are less popular to be used for home windows.

6- louver Louvers best to be used where natural ventilation is needed without the desire of having solar radiation. They can be used as well for positions that are restricted by regulations or security reasons.

4. Sash window (sliding window)

Window types (Irving et al., 2005)

1.Top hung/ Bottom hung 5. Vertical pivot

2. Casement window (side hung)

6. Horizontal pivot

7. Louver 3. Tilt and turn

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Discharge coefficient: Having a window openable pane area of 2m² doesn’t mean the airflow through the window is going to be with the cover the same area. Discharge coefficient is a main factor to calculate the effective aperture of the window which will define the amount of air going in and out through the window. And it basically relies on The window’s calculated openable area (Pane area for sash windows), and the opening angle (for hinged windows). A top hung window with 90° opening angle has a discharge coefficient of 0.62 (table 1.11.1) (Karl Terpager Andersen, no date). So if the pane area is 1m². The effective aperture (A​eff​) would be 0.62m². And to calculate if the Aeff is enough for a convenient ach. It’s recommended to calculate effective aperture area to room-floor area (Aeff:Afl). There is not enough guidance for this ratio for homes in literature, However, window masters recommend a minimum of 4% in offices with single sided ventilation. And 1.5% if cross or stack ventilation applied (Window master, no date). The analytical part, chapter 2 will try to give guidelines for minimum window effective aperture area to floor area. Further details about calculations of effective aperture and windows openable area is included in (appendix 6.1)

Table 1.11.1 - discharge coefficient based on angles (Karl Terpager Andersen, no date) Understanding window types and the discharge coefficient controlled by their opening angle is a guidance for choosing the most suitable window or combination of windows to achieve an efficient natural ventilation.

However, it’s not the only factor that will decide the final air exchange. Restrictions like the sill, blinds and

accessories, or throw length restrictions for security and safety can always interfere.

Windows actuators: The windows in most of the dwellings are controlled by the adaptive method. The occupants would open or close the windows based on their own physio or psychological need. However. The occupants knowledge about when and how much to open the windows might be misleading and can increase the risk of overheating as to increase energy consumption as well. For instance, when the heatwave occur, the regular response could be to fully open the windows to provide fresh air while the indoor temperature is still lower than the outdoors. Normal people would not know how thermal mass would work and how to use night ventilation. And even if they do.

They could mistakenly forget the window open before leaving. And in winter cases as well. Windows could be opened more than needed and cause energy loss that will increase the bill and has its fingerprint because of the fossil fuel being as number 1 source of energy for heating.

To control windows to be automated responding to the environmental function and occupant’s comfort, actuators can be installed for openable windows and for out of reach roof windows, and they are linked with smart systems. However, they still can be controlled manually and remotely by the occupant. There are many actuators providers in the markets. And they are sometimes limited to reach a maximum lengths. Actuators are usually best to be used with top or bottom hung windows. Window master is a famous provider in the industry for actuators.

The following is a brief about the actuator types and their maximum reach (window master, 2018)

Figure 1.11.1 ‘’Bottom hung inward windows or top hung outward openings in the facade’’ (Window master, no date) 1. Chain ACTUATOR​S (figure 1.11.1) and (figure 1.11.2) It’s the most popular actuator in the industry. It can open up to 1000 mm. It’s worth mentioning that the manual control function faster than the auto​matic. And furthermore, responding to health and safety measures they run the fastest.

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1.12.Conclusion

Figure 1.11.2 - chain actuator 2. Door actuators (figure 1.11.3) Up to 90 degrees. These actuators are used for side hung windows and doors.

Figure 1.11.3 door actuator

3. Spindle actuators (figure 1.11.4). Suitable more for roof openings, where as they are more convenient for smoke and comfort ventilation.

Up to 1000 mm. More suitable for roof openings

Climate change is the main factor that led to the prolonged thermal dissatisfaction in dwellings. Adaptive comfort offered a big margin for the buildings to comply with warmer weather without the need for mechanical cooling. However, assessing building performance in winter with partly neglecting the compliance with heat waves conditions will with no doubt, lead to health problems for occupants with different age ranges. Dealing with overheating must must be considered during the building design through environmental guidelines and building parameters. And using natural ventilation strategies must be the main approach rather than mechanical ventilation, especially in dwellings where there is a big opportunity for adaptive comfort behaviours.

Assessment methodologies are meant to predict how the building will perform based on the available data simulated by computer softwares, and using weather files that are generated by meteorological centres. Thus, the buildings can perform differently under warmer or cooler unusual years as (Passivhaus trust, 2016) refers to one of their certified buildings. They mention that in 2014 it overheated of annual hours while the simulations resulted 0% exceedance, and they relate this to the heatwave which occurred that summer (Passivhaus trust, 2016). Climate change is resulting in more unpredictable conditions than usual. Therefore, using the assessments will not guarantee total thermal comfort for occupants, but at least it will mitigate the risks of overheating.

Figure 1.11.4 - spindle actuator

Figure 1.11.5 Louver actuators

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Chapter 2 - Analytical work Shoe BOX

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2. Analytical work - Shoe BOX 2.1.Introduction Due to dynamic thermal simulations, predicting overheating became much easier. It can help avoiding the need of retrofitting the new homes to adapt to the future climate. As it usually include most of the physics available in real life. Therefore, the capability of testing different designs and the impact of the smallest change on the building performance became a player in the evolution of environmental Architecture.

Benefiting from what the technology offers, and aiming to understand the basic parameters linked with overheating in compact housing, and how is it possible to improve London dwellings design against the risks of overheating.

A shoe box is designed using the dynamic thermal simulation software (EDSL Tas). the shoebox is designed to represent a typical compact 1bed flat which has a very high insulation and airtightness.

Methodology a) Design Compact 1 bed flat with basic parameters on TAS ● Using parameters from different compact houses and other references b) Test the shoebox against overheating on 4 different orientations with different variables ● Using an overheating assessment methodology c) Define the most effective parameters on overheating d) Define the best possible module for each orientation e) Improve the design to suit 2050 predicted climate Expected outcome a) Illustrating all the aspects known so far that may cause overheating in dwellings in London. b) Define possible passive environmental strategies that can help mitigating the risk of overheating. c) Better understanding, with evidence about the relation between very airtight and insulated building fabric, and the risk of overheating. d) To highlight the pros and cons of the RUSS project design to be taken into consideration for future projects.

Assessment method CIBSE TM59 is the assessment method used. As it is the most recent and almost the only methodology known by the time of this research specialised in dwellings.

Additional aspect for choosing it, is that it’s connected with Tas by a wizard which offer a full CIBSE TM59 report for the simulated files, and also, a user profile by CIBSE TM59 is included where it can be used to be added for the occupied rooms to define a reasonable internal heat gains by the user and by the equipments. (note: the TM59 occupancy profile is all day). The wizard includes as well the heat loss from pipeworks to the spaces. For more details see in chapter 1 / 1.8.6.TM59.

2.2.Variable Parameters Although simulations can predict overheating. Basic design parameters can give a strong expectation about how the building will perform. Compactness for energy saving and thermal comfort in winter as explained before that can lead to overheating. There are many parameters that can define compactness that can be the leader to the increase in indoor temperature.

The main parameter is the ​U-value​. Whether for walls and ceilings, or for window. U-value of the external walls is responsible for the speed of heat exchange by conduction, and convection, between the indoor and outdoor. Same is considered for windows. Usually a lower U-value for windows would change the window’s type between single, double or triple. Nevertheless, in the study we will consider these values rather than specifying the glazing layers. The U-value standards are used from 2 sources, the first parameter 0.8 W/(m²·°C) is referred by (​Architype, )​ . The second one 1.2 is taken as a good double glazing standard (Designing Buildings Wiki, no date) Airtightness ​is another parameter and is a main parameter in compact housing that led to this thesis, due to the fact that the more airtight is the building, the less air exchange with the outdoors will happen (if the windows openable area is the same). For airtightness the lowest used is going to be 7m³/(hr.m²) as a regular building complying with building regulations. A higher standard of airtightness is 5m³/(hr.m²) which represents a middle level between the good practice standard and the best practice which is used as the highest airtightness standard in this study 3m³/(hr.m²), based on the HOUSING ENERGY EFFICIENCY BEST PRACTICE PROGRAMME (BRE and EST, 2003)

30

The G-value is not necessary linked with compactness because it’s related to solar radiation which is usually welcome to heat the homes in winters. But due to its ability to reduce the solar heat gain, 0.3 , 0.5 and 0.7 are used as variables in the study. The standards are inspired as well from Architype’s project assessed in this paper.in addition to manufacturers and online references (train energy, no date).

Floor to ceiling ​height is a parameter considered, thanks to the principles for natural ventilation that was mentioned in the literature review part, which explains that a higher ceiling is needed to increase air flow. On the other hand, it’s totally linked with compactness as a lower volume of the space would need less energy for heating.

In addition, the building regs doesn’t have guidance for the lowest floor to ceiling height, and many architects advise to go minimum for 220 cm , and others use 240 , 260 or higher (onaverage, no date).

The type of window used might not have a strong impact as long as it will which the required ratio.

Shading External and external shadings are clearly important parameters for more control on solar gains.

The showbox will be tested with and without each of the external and internal shading. The external shading will change based on the orientation of the facade. While the use of internal blinds is going to vary based on the window type. Furthermore, the timing of the blinds will be influenced by the orientation as well.

The rest of the parameters are more of a strategies rather than parameters, related to to natural ventilation. Like changing window types, and location on the wall, opening internal doors, etc.. the usage of thermal mass is another cooling strategy used to study its effect against future london climate. Different materials are tested to reach the best performance with the least environmental fingerprint.

Glass to floor ratio is another factor that can enhance daylighting but on the other hand, it increases solar gains.

Different ratios were used in the study. The minimum ratio is 15%, which can be usually enough for a bedroom which require less daylight than living rooms. However, building regulations don’t require any standards for window to floor ratio. It only recommends for building extensions not to use much less than 20% for better daylight (NBS, 2013). (note: daylight studied are not considered, only 15% is considered as the minimum possible).

Effective aperture to floor ratio (A​eff:​A​fl​) At the first stages of the research, only window to floor ratio were considered. And that was less detailed layer and not really helpful enough to understand how air change is happening and how to control it. And that’s because in reality, windows openable area will vary based on the window type and openable area. And directly affected by the discharge coefficient as well.

Furthermore, measuring the (A​eff:​Af​ l​) will help give a base more applicable general standard that can be used as a guide for new homes. Where when the (A​eff:​Af​ l​) is defined.

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Variable Parameter

Basic

Variable1

Variable2

infiltration m³/(hr.m²)

3

5

7

Windows U-Value W/(m²·°C)

1.2

0.8

____

Windows G-Value

0.7

0.5

0.3

shading

No

External

Blinds

glass / F

20%

15%

_____

Floor to Ceiling (cm)

240

280

300

Aeff:Afl

1 - 4%

4-8%

8-12%

Thermal mass

Single block

Double block

Brick

Table 2.2.1 - variable parameters chosen to be implemented in the shoebox study where needed.

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2.3.Model specifications The analysed shoe box as mentioned before is a 1bed flat representing a compact house. The flat has a rectangular shape covering an area of 39m² (6.5x6). It has one facade only which is on the shorter side (6m). It consists of an entrance with a small corridor that opens onto 3 doors (bathroom, living room/kitchen, bedroom). The bedroom is a double bedroom 2.85x4.55m. And the living room has a width of 3.15m and a length of 4.7m, the rest of the length (1.85) is for the open kitchen (​Figure 2.3.1)​.

To guarantee the shoebox model is more realistic, flats from both sides were added to the model. In addition to upper and lower floors, which locate the studied flat on the 2nd floor of the 5 floors building ​(Figure 2.3.2) with flats on both sides separated by a long corridor. This will add more complexity of heat transfer between the flats themselves and the corridors.

Figure 2.3.2 - The location of the analysed shoebox on the facade, showing adjacent flats from 4 side

Figure 2.3.1 - The architectural plan of the shoebox consisting of 5 spaces.

1- Bedroom 2- Living room 3- Kitchen 4- corridor 5- Bathroom

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2.4.Strategies and steps of the study The following strategies tare created to test how the flat will respond to extreme compactness with restricted ventilation. And see how the building will perform in hot summer, and to how extent overheating can occur in these cases. Then improvement based on the parameters and other strategies explained before, will be added to the model one by the other (table 2.4.1). The aim is to pass all CIBSE TM59 criterias.

The methodology for adding the parameters is to first: eliminate external heat sources from solar gain and outdoor DBT. then internal measures will be added to mitigate the internal heat and improve ventilation strategies. This will be all applied first in the south facing flat. Reaching the best south scenario will be the base scenario for North orientation where adjustments will be made to reach the best suitable North scenario, and so on. The next steps will be improving the design to better perform against 2050 hot weather file.

Steps: strategy

parameter

NOTE

1

glass / F 15%

bed room only

2

external shading

3

Blinds 1

4

blinds 2

on openable windows

5

Window U-value 0.8

6

G-Value 0.5

7

Floor-Ceiling(280cm)

8

Open Doors

9 10

on fixed windows only

Internal doors during day Effective aperture:floor 4-8%

Improve window design

Limiting external loads

Internal measures

upper & lower

11

G-Value 0.3

12

Floor-Ceiling(300cm)

13

Thermal mass

14

Effective aperture:floor 8-12%

for 2050 if needed

Further improvements

Table 22 - steps of improving parameters and strategies to improve the shoebox performance against overheating

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2.5.Overheating assessment 2.5.1.South shoebox - 2020 The first section of the study is simulating the shoebox with south orientation and with basic parameters using design summer year file, London weather centre 2003, 2020 high 50% (DSY2 2020). Based on TM59. the maximum exceedable hours of the kitchen and living room is 59 hours of summer occupied hours, while it is 110 hours in the bedroom during the day time. While the maximum excedable hours in the night for bedrooms equals 32 hours of annual occupied hours (see table 2.5.1.3).

Parameter

Basic infiltration m³/(hr.m²)

3

External walls U-Value W/(m²·°C)

0.2

Windows U-Value W/(m²·°C)

1.2

Windows G-Value

0.7

shading

No

glass / F

20%

Floor to Ceiling (cm)

240

Aeff:Afl

1% Bedroom - 2.7% Living+kitchen

Window type

Top hung Opening 30° living rm & 15° bedroom

Table 2.5.1.1 - The basic model parameters for the first scenario in south Shoebox Note: heat from pipes is considered as 14 Watts assuming a good design of hot water system. (2m pipes going through the open kitchen with diameter 8mm).

35

Aperture function applied đ?&#x2018;&#x201C;x Doors Window Table 2.5.1.2 - Doors and windows opening function First Simulations results The first results show severe overheating in all rooms. All rooms exceeded crâ&#x20AC;&#x2039;iteria 1 (hours exceeding comfort range) by high percentage (figure 2.5.1.1). And the criteria 2 which is the hours that the operative temperature exceeding 26°C from 22:00 - 07:00 in the bedroom, is also exceeded severely (figure 2.5.1.1) and (table 2.5.1.3).

Assumed closed Open when Î&#x201D;t 20-22 -- external temp. Cut offÂ

Zone NameÂ

Max. Exceeda ble HoursÂ

Criterio n 1: #Hours Exceedi ng Comfor t RangeÂ

Max Excee dable Night HoursÂ

Criterion Resul 2: t Number of Night Hours Exceeding 26 °C for Bedrooms .Â

Bed RoomÂ

110Â

553Â

32Â

571Â

FailÂ

Kitche nÂ

59Â

125Â

N/AÂ

N/AÂ

FailÂ

Living 59 RoomÂ

212Â

N/AÂ

N/AÂ

FailÂ

Table 2.5.1.3 - Overheating hours and max excedable threshold

Figure 2.5.1.1 - Criteria 1: hours of overheating in bedroom - living room - Kitchen - Under basic scenario conditions

Figure 2.5.1.2 = Criteria 2: hours of overheating in bedroom Under basic scenario conditions

Analysing results: To understand what is going on inside the flat. An analysis for an overheating week (6/Aug - Aug,13) is made on the living room. The graph (figure 2.5.1.3) shows that although the external DBT is going down during the night, the internal temperature is contributing slowly and rarely going under it. it seems like the high insulation of the external walls and the strict airtightness is reducing the thermal exchange between the space and the outdoor temperature resulting overheating in the space. Another main factor can be seen as well is the amount of air exchange whether through windows or infiltration. The air exchange (ach) is not high enough to purge the heat preserved inside the space, especially with the current infiltration. Having an airtightness of 3â&#x20AC;&#x2039;mÂł/(hr.m²) has resulted almost 0.25 air exchange per hour. All the data provided can explain how compactness can lead to overheating without even having any extreme internal heat loads. In the next steps we will try to improve the performance of the shoebox by changing the parameters related to the compactness.

Another graph is made for the same duration to understand what are the highest sources of heat, whether from internal or external heat sources (see figure 2.5.1.3).

36

Figure 2.5.1.3 - The graph is showing the internal and external temperature of the living room in addition to the air exchange, during the period (6/Aug - Aug,13)

Airtightness​:

Increasing air permeability by setting the air tightness to 7m³/(hr.m²) to improve air exchange and reduce overheating hours was effective. And reduced the overheating hours in the bedroom cr1 from 553 hrs to 448 (more than 100 hours). It didn’t have as significant improvement in to the other spaces (Figure 2.5.1.4) and (Figure 2.5.1.5).

Figure 2.5.1.3 - significant increase in new homes insulation and airtightness

Figure 2.5.1.4 - Criteria 1: hours of overheating in bedroom - living room - Kitchen - With airtightness 7m³/(hr.m²)

Figure 2.5.1.5 - Criteria 2: hours of overheating in bedroom under airtightness 7m³/(hr.m²)

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For the main aim of the Architects which led them improve airtightness in order to reduce energy consumption. Annual heating loads comparison is made between the basic scenario and this one which included making the building fabric more leaky by reducing the airtightness standard to only cover building regulations rather than going for best practice ​(​Figure 2.5.1.6​)​.

Making the building more leaky resulted an increase of 13% of the annual heating loads per area. And this is while the building is too compact with restricted windows openings. This 13% could make a high margin of energy wastage for bigger flats or projects. Especially if there is less restriction in windows aperture.

Thus, this change in airtightness by making the building fabric leakier is not going to be considered in the next stage. We will have another perspective on it. Airtightness is not only reducing energy consumption. It’s also improving the control of the building performance, especially for ventilation. In addition, high infiltration can be negative under prolonged heatwave conditions. when the outdoor temperature is considerably higher than the indoor temperature, the need to close windows and preserve the lower temperature inside rather than allowing heat exchange. This will reduce the chances of the inner space temperature to increase. Therefore, The other path that is going to be followed to mitigate overheating is by improving natural ventilation strategies, and instead of allowing uncontrolled air exchange to occur,improving air exchange is going to be by changing the windows type and openable area.

Figure 2.5.1.6 - Comparison between heating loads if the airtightness 3m³/(hr.m²) and 7m³/(hr.m²). It shows an increase of 13% of the annual heating loads per meter The loads breakdown (Figure 2.5.1.7) is a guide for the next stages and improvement methodologies. The solar gains are responsible for most of the heat loads in the flat. The second highest source is the heat coming from equipments. Therefore, the way towards providing thermal comfort inside the spaces is going to be first by, eliminating external heat gains, mainly solar radiation.

Especially that the building is already isolated from heat that can come through convection thanks to the strict airtightness, and from conduction, thanks to the high insulation of the external walls.

Figure 2.5.1.7 - heatloads breakdown: it shows the major internal and external heating loads in the living room on ​Aug 6.

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Glass:floor ratio

External shading

Figure 2.5.1.8 - basic bedroom windows - glass:floor 20% Reducing glass to floor ratio is step 1 to control solar gain.

The amendment of the glass ratio is only done in the model on the bedroom, due to the results which showed that itâ&#x20AC;&#x2122;s under higher risks of overheating. Furthermore, even if the daylight is not considered as a main aspect in this study, bedrooms usually require less daylight factor.

Reducing the glass to floor ratio in the bedroom has decreased the overheating hours in criteria 1 by 47% compared to the basic scenario. (figure 2.5.1.9 and figure 2.5.1.10)

Figure 2.5.1.11 - bedroom window with external shading External shading in dwellings is something unusual in london. However, as a response to global warming and the previous analytical graphs, a need for external shading imposes itself. something unusual in residential buildings.

Because this shoebox has south orientation, the external shading added, is only horizontal, With depth of 50cm.

There is no need to add fins. This shading can be an upper floor balcony, or a movable shading device that can be open in summer and down in the winter.

The benefit of using external shading is with no doubt very considerable as it can be seen from the graphs (figure 2.5.1.12) and see (figure 2.5.1.13) for the bedroom overheating hours against criteria 2.

Figure 2.5.1.9 - Criteria 1: improvement in overheating hours by using 15% glass:floor

Figure 2.5.1.10 - Criteria 2: less overheating hours in the bedroom when using 15% glass:floor

Figure 2.5.1.12 - Criteria 1: overheating hours in bedroom, kitchen, and living room

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Figure 2.5.1.13 - Criteria 2: overheating hours in the bedroom , night hours Blinds Using blinds is widely used in homes, in london mainly for privacy , since the sky is overcasting most of the time in the regular London climate. The increasing risks of overheating is going to give the blinds a priority to be used in homes. As explained before; blinds can interfere with the windows opening and restrict air movement.

Therefore, and mainly, the blinds at this simulation were considered fully open from 7am till 7pm on fixed windows. On the other hand, and because window type considered here is the top hung, blinds on openable windows are considered 50% open only (2.5.1.14â&#x20AC;&#x2039;). Else, the other strategy that could be used is using interpane blinds. But for more realistic measure, they are considered 50% anyway, due to the need for daylight during occupancy times.

Shutting down the blinds during daytime has decreased 33 hours of the annual overheating hours in the living room, and 50 hours for criteria 2 in the bedroom.

However, the only room that passed the first criteria is the kitchen, achieving 47 overheating hours out of 59 benchmark.

Figure 2.5.1.14 - limiting solar radiation using external shading and blinds.

Figure 2.5.1.15 - Criteria 1: passing the criteria in the kitchen blinds

Figure 2.5.1.16 - Criteria 2: Overheating hours in the bedroom , is 50 hours less after using blinds

40

Windows U-value

In spite of that the U-value of the exterior walls is considered very low (0.23 W/(m²·°C) ), there is a need to see how decreasing the U.value of the windows would affect thermal comfort in the spaces.

The graphs (figure2.5.1.17 and figure2.5.1.18) shows an increase in overheating hours in all the rooms as a result of insulating the building fabric moreover. This explains more how compactness can lead to overheating.

Decreasing the U-value of the glass is slowing down the heat exchange with the outdoor more than needed, which is not reducing the ability of the space to cool down when the external temperature is lower than the indoor.

The glass on fixed windows will be more of a problem than the openable one. Improving ventilation is the way followed to decrease indoor temperature, nevertheless, it could be not enough sometimes if the heat loads preserved inside are very high, especially when having high user profile loads.

Usually, in the market, to improve U-value or G-value of the windows, the window type can change from single to double or triple glazing. However, for the sake of academic research, we are going to deal with U-value and G-value as a non necessarily linked factors. Thus, and because this change in the parameter was found not helpful, it’s going to be ignored. And the process of improving parameters will step over it.

Figure 2.5.1.17 - Criteria 1: increased overheating hours using lower U-value for glazing

Figure 2.5.1.18 - Criteria 2: increasing overheating hours in the bedroom because of increased compactness

G-value The most important window’s specifications are the U-value and the G-value in regard of heat exchange whether by convection, conduction and radiation. To preceed mitigating external heat sources, windows G-value was reduced from 0.7 to 0.5.

Reducing G-value had the third most effective parameter so far on overheating compared to the previous improvements. In criteria 1, It reduced the overheating hours of the bedroom 99 hours and the living room 74 hours and the kitchen for 32 hours from the last conditions (from setting up blinds), (see figure 2.5.1.20 and figure 2.5.1.21). This is the first parameter improvement that led to pass criteria 1 by a good margin in all the rooms.

Figure ​2.5.1.19 (​greenbuilding.saint-gobain.com. ​no date)

41

Figure â&#x20AC;&#x2039;2.5.1.20 - Criteria 1: passing overheating hours all rooms

Figure 2.5.1.22 - floor to ceiling height

Figure â&#x20AC;&#x2039;2.5.1.21 - Criteria 2: high effectiveness in reducing overheating hours in the bedroom using lower G-value Floor - Ceiling height Even though, controlling external radiation by the previous measures had led to pass criteria one in all the rooms, the second criteria which only applies on bedroom is still extremely overheating. A need for further improvement is high. The first internal parameter to change aiming to improve natural ventilation is the floor to ceiling height. It is increased from 240 cm to 280.

Figure 2.5.1.23 - criteria 1: further decrease in overheating hours

Increasing ceiling height reduced 41 overheating hours (Figure 2.5.1.24). And thatâ&#x20AC;&#x2122;s thanks to the previously explained fact, that increasing ceiling height will improve air exchange and will allow air to reach deeper distance throughout the single sided room when relying on single sided or even cross ventilation (see figure 1.10.2: Natural ventilation strategies for homes).

Figure 2.5.1.24 - Criteria 2: Overheating hours in the bedroom

42

Opening Doors Internal doors in the previous simulations were closed all the time. The next step is allowing the door’s aperture to open in the summer for 90 degrees during the daytime and to close only on bed time (22:00 - 07:00),whereas to close during winter. And this strategy is applied following TM59 guidelines which require bedrooms door to close over the night.

Figure 2.5.1.27 - Criteria 2: Overheating hours in the bedroom Aperture : floor ratio The next step is increasing airflow through the windows.

Previous windows in basic scenarios were restricted and opening only for 30 degrees for the livingroom and kitchen windows providing 2.72% effective aperture to floor ratio, and 15 degree for the bedroom, providing 1% (A​eff:​Af​ l​). The new living room window aperture is opening for 33 degrees resulting a wi​ndow throw of 57cm and an (A​eff:​Af​ l​) of 3.4%. For the bedroom the factor is increased by the double to become 2%(A​eff:​Af​ l​) (Figure 2.5.1.29). For more details about the calculations see appendix 6.1

Figure 2.5.1.25 - The affect of opening doors on natural ventilation strategy Although the doors are open only during the day, overheating hours were reduced to 136, which is 10 hours less (Figure 2.5.1.27). And this is thanks to the improved purge ventilation that the flat became exposed to when using openings in 2 rooms even though they are facing the same side of the facade (figure 2.5.1.25).

Figure 2.5.1.26 - Criteria 1: Overheating hours near 0

Figure 2.5.1.28 - Living rooms 2 parallel windows opening to supply sufficient air

Figure 2.5.1.29 - Bedroom window new throw opening to supply 2% (A​eff:​A​fl​)

43

Air exchange has increased considerably resulting less overheating hours for the bedroom. However, the number of overheating hours is still more than double the benchmark of criteria 2 (â&#x20AC;&#x2039;Figure 2.5.1.31).

The type 2 windows has had a slight effect on the temperature, resulting 2hours from the previous overheating hours to pass criteria 2.

Figure 2.5.1.30 - Criteria 1: Overheating hours near 0 Figure 2.5.1.32 - improving ceiling height added to the use of double opening improved internal temperature

Figure 2.5.1.31 - Criteria 2: Overheating hours in the bedroom Double windows (type 2).

The literature review has shown that using different strategies of natural ventilation can improve the natural cooling.

Therefore, another design was made for the bedroomâ&#x20AC;&#x2122;s windows with the same size of the previous ones. The strategy is using double windows instead of one to use the buoyancy to force air movement in and out of the space.

Figure 2.5.1.33 - Criteria 1: Overheating hours near 0

Figure 2.5.1.34 - Criteria 2: Overheating hours in the bedroom is slightly reduced

44

Windows with louver (type 3)

The ventilation will be driven more by the buoyancy. The lover will open added to the already opened main side hinged window, resulting enhanced air movement where the cold air is going to enter from the louver and the hot air extracted from the upper window.

Using the louver has resulted a full compliance with criteria 2 of TM59 assessment method, reaching just the exact maximum allowed number of hours exceeding 32°C.

Figure 2.5.1.35 - bedroom window with lower louver Because the previous windows type and opening aperture were not enough to improve purge ventilation in the night for the bedroom, another design with louver is proposed. The main window type is changed from top hung to tilt and turn (side and bottom hung) adding more flexibility to the user to fully open it when needed. In addition, under the fixed window, a louver is designed with the same width of the main window but with height of 45cm. The big window itself will allow 6%(A​eff:​Af​ l​) added to about 1.5% (A​eff:​Af​ l​) from the louver, resulting total 7.5%.

Summing up the ventilation strategy: 1. During the day, when the indoor temperature is over 20°C and lower than the outdoor temperature, the living room and kitchen windows will open resulting 2.4 %(A​eff:​Af​ l​), and the bedroom main window will open as well causing up to 6%(A​eff:​Af​ l​). Thanks to the opened doors, this will work roughly like cross ventilation where the air exchange will be improved by the wind force which will cause it to inter from one room and exit from the other one.

2. During the night, the doors will be closed. Therefore, the bedroom will work as isolated single sided room.

Figure 2.5.1.36 - Criteria 1: Overheating hours near 0

Figure 2.5.1.37 - Criteria 2: passing the criteria with just reaching the threshold 32hrs

45

Figure 2.5.1.38 - criteria 2: graph summarizing the improvement progress in the bedroom by changing different parameters and strategies.

Figure 2.5.1.39 - Final outcome of the Southshoebox illustrated, using high ceiling , external shading , window with lower louver, etc.

46

2.5.1.1.South shoebox - 2050 Running the same best scenario under DSY2 2050 hot weather conditions is with no doubt challenging, and expected to cause overheating. Especially because the bedroom in had barely passed the criteria under DSY2 2020.

Further improvements are definitely required. The aim here is not to pass the assessment method, especially that the assessment methodology doesnâ&#x20AC;&#x2122;t require to pass any 2050 files. Itâ&#x20AC;&#x2122;s more likely that different criterias are going to be developed to be more appropriate for future summer files.

1. G-value 0.3 2. Floor to ceiling height = 300cm 3. Thermal mass a. Remove plaster & use 150mm exposed block b. Double layers of block 150 with cavity c. Using exposed thick brick for internal walls and the inner face of the external walls, thickness 210mm 4. Balcony with door to open instead of the windows.

A comparison is made showing the results of all the steps on overheating happening in the bedroom, since the best scenario of 2020, is passing criteria 1 of all the spaces.

While on the other hand, the starting point for criteria 2 was almost doubled compared to the 2020 results.

Steps of improvement.

Figure 2.5.1.1.1 - showing process of improvement in overheating hours in the bedroom based on criteria 2 and under the conditions of DSY2 2050.

47

Figure 2.5.1.1.2 - image illustrating parameters of south shoebox to tolerate 2050 hot weather conditions. Major changes are the use of thermal mass. And balcony to increase ventilation ratios

48

2.5.2.North Shoebox - 2020 Testing the same parameters of the South shoebox on North orientation led the flat to pass with high margin. This made us reduce one of 2 standards applied for controlling external solar radiation. And thatâ&#x20AC;&#x2122;s due to the low solar radiation exposure from North orientation.

Basically there is no need for any external shading to pass the criteria against 2020 hot weather files. In addition,

there are 2 extra options of parameters that vary in terms of cost and daylight needs. Keeping the bedroom glass to floor ratio on 15% and Increasing G-value to 0.7 can reduce the expenses of the glass. But on the other hand, we can increase glazing ratio to 20% (see results 2.5.2.1) as in the basic scenario of the southern shoebox, and keeping the G-value on 0.5. This will improve daylighting and offer better skyview factor. The freedom is left to the designer.

Figure 2.5.2.1 - Criteria: passing criteria with 0 overheating hours in all assessed spaces

Figure 2.5.2.2 - Criteria 2: passing the criteria in the bedroom

Figure 2.5.2.3 - Final outcome of the North Shoebox illustrating mainly the use for larger windows 20% glass:floor, with no need for external shading

49

2.5.2.1.North Shoebox - 2050 Same as what previously was done on the northern shoebox, less standards were required here compared to other orientations.

The same materials specifications are used. And there is still no need to use any external shading Elements. The major improvements are using higher thermal mass as the ones used for the south 2050 shoebox. The second improvement is made on windows. Louvers needed to be used to improve air exchange. Although itâ&#x20AC;&#x2122;s not required to pass the criteria on 2050, the Northern shoebox complies with both criterias (figure 2.5.2.1.1).

Figure 2.5.2.1.1 - criteria 2: passing 2050

Figure 2.5.2.1.2 - illustrations for Northern parameters that can be fit against 2050 weather conditions

50

2.5.3.East Shoebox - 2020 In order to adjust the shoebox to perform well in East orientation, The main change to be must be dealing the the change of solar azimuth and vertical angles. East orientation in London requires to deal lower angles of the sun which is moving up towards the South. Therefore, for best external shading, the fins should be located on the left basically, and from the top to maximise solar shading. Another measure to be

improved, is to allow blinds earlier in the morning and turning them off at midday were they wonâ&#x20AC;&#x2122;t have a considerable benefit on solar gain. Simulations show a full compliance with both criterias (figure 2.5.3.1 and figure 2.5.3.2). The number of overheating hours in the bedroom is exactly like the one in the south shoebox scenario.

Figure 2.5.3.1 - Criteria 1: all spaces passing

Figure 2.5.3.2 - Criteria 2: passing by just the max allowance

Figure 2.5.3.3 - East shoebox with main feature of having top and left fins for external shading

51

2.5.3.1.East Shoebox - 2050 As in 2020, vertical and horizontal external shading are a must for 2050, in addition, the same change in material by using Brick is applied. Increasing ceiling height and having a bigger aperture for air exchange had its impact making the bedroom close from passing criteria 2 (figure 2.5.3.1.1), were already criteria 1 is fully passing.

Figure 2.5.3.1.1 - Criteria 2: very close to achieve passing the criteria

Figure 2.5.3.1.2 - 3d illustration for the parameters used for East shoebox to deal with future climate of 2050

52

2.5.4.West Shoebox - 2020 The same specifications of the East Shoebox were used to simulate the West Shoebox. The only changes made are to mirror the vertical shading to be on the right side of the window. In addition, blinds were made to start 12:00 to 19:00.

Surprisingly the bedroom didnâ&#x20AC;&#x2122;t comply with criteria 2 (figure 2.5.4.2). However, itâ&#x20AC;&#x2122;s only exceeding by one hour reaching 33 hours. Checking the frequency of hours exceeding the criteria shows that they exceed sometimes by just less than half a degree K (Figure 2.5.4.4)

Figure 2.5.4.1 - Criteria 1: passing with no difficulty

Figure 2.5.4.2- Criteria 2: exceeding the benchmark by 1 hour only

Figure 2.5.4.3 - Eastern shoebox with different external shading requirements

53

Figure 2.5.4.4 - shows that 2 overheating hours during the Aug,7 are slightly exceeding the benchmark

54

.

2.5.4.1.West Shoebox - 2050 No improvements were made additional to what was made for 2050. Same 2 major changes, Thermal mass and fully openable doors for ventilation.

The overheating hours exceeding criteria 2 donâ&#x20AC;&#x2122;t have a big margin, but slightly higher than the East shoebox against same weather conditions DSY2 2050. (figure 2.5.4.1.1)

Figure 2.5.4.1.1 - criteria 2- scoring the worse

Figure 2.5.4.1.2 - 3d illustration for the parameters used for West shoebox to deal with future climate of 2050

55

2.6.Research outcome and applicability The shoebox analytical study had shown how compact houses that uses high insulation and airtightness standards , with lack of appropriate purge ventilation put the space in high risks of overheating. ● Increasing air-permeability is not the best solution in terms of energy and heat control through building fabric. ● High air exchange ratio is needed to compensate slow heat transfer through building fabric, when the outdoor temperature drops lower than the indoor (usually during the night), which offer an opportunity for purging the heat from inside the spaces. And later on, when the outdoor DBT rises up, the building fabric should work as an isolation from the outdoors and preserve cooler operative temperatures offering comfort for the occupants. ● Decreasing window’s U-value is going to increase the risks. ● There is no one parameter alone that can be responsible for overheating like (airtightness).

Overheating happens due to the availability of different parameters together at the same time.

Generalised standards are taken from the study for each orientation are going to be illustrated in tables (table 2.6.1). If the objectives of the design are not going beyond 2020 climate, the following parameters should be followed as a guide line.

If the design has a futuristic view, it should follow the guidelines summarized in table 2.6.2

56

Final comparison between all orientations 2020

Parameter

South

North

East

West

External shading

Horizontal top

Non

Top + Left

Top + Right

Blinds

South 7am - 5pm

Non

7am - 12pm

12am - 7pm

glass / F

living room - 20% bedroom - 15%

living room - 20% bedroom - 20%

living room - 20% bedroom - 15%

living room - 20% bedroom - 15%

Bedroom 7-8%

Bedroom 5-6%

Bedroom 7-8%

Bedroom 7-8%

Aeff:Af

Window type

Living+kitchen Living+kitchen Living+kitchen Living+kitchen 2-4% 2-4% 2-4% 2-4% Tilt and Turn + Louver

Tilt and Turn + Louver

Tilt and Turn

infiltration m³/(hr.m²)

3

External Timber walls U-value W/(m²·°C)

0.117

Windows U-Value W/(m²·°C)

1.2

Windows G-Value

0.5

Floor to Ceiling (cm)

280

Tilt and Turn + Louver

Table 2.6.1 - final outcomes for parameters suitable for each orientation under conditions of ​2020

57

Future adaptation parameters Parameter

South

External shading Horizontal top

Blinds

glass / F

Aeff:Afl

Window type

South 7am - 5pm

North

East

West

Non

Top + Left

Top + Right

Non

7am - 12pm

12am - 7pm

living room - 20% living room - 20% living room - 20% living room - 20% bedroom - 19% bedroom - 15% bedroom - 19% bedroom - 19% Bedroom 10-12%

Bedroom 7-8%

Bedroom 10-12%

Bedroom 10-12%

Living+kitchen 2-4%

Living+kitchen 2-4%

Living+kitchen 2-4%

Living+kitchen 2-4%

Balcony door

Tilt and Turn + Louver

Balcony door

infiltration m³/(hr.m²)

3

External Timber walls U-value W/(m²·°C)

0.117

Windows U-Value W/(m²·°C)

1.2

Windows G-Value

0.3

Floor to Ceiling (cm)

300

Thermal mass

Double layer of Brick 210mm

Balcony door

Table 2.6.2 - final outcomes for parameters suitable for each orientation under conditions of ​2050

58

59

Chapter 3 - Application of findings - RUSS Project

60

3. Application of findings - RUSS Project

3.1.Introduction ● ● ● ●

Residential project for the Rural Urban Synthesis Society (RUSS).

Project’s title ‘’CHURCH GROVE PROJECT’’ Designed by Architype Co-designing concept

The case study is a residential project for the Rural Urban Synthesis Society (RUSS). the project’s title is ‘’CHURCH GROVE PROJECT’’ located in South London in Lewisham on a river side. And designed by Architype. It is a residential project that aims to provide environmentally friendly houses for the Lewisham residents, for an affordable price. The concept behind the design is co-designing, where the future occupants of the building, participate in the design process. In this regard, Architype has provided variety of design modules and given the freedom to the future occupants to choose their idol future house design. In addition, a variety of personalized adjustments were also given to the occupants like doing customisation of the main entrance facades and the door color finishes.

Figure 3.1.1 - visualisation from the southern external corridors in the ‘’CHURCH GROVE PROJECT’’ client : RUSS / Designer: Architype

Because the project construction didn’t start by this time, the analysis of the building performance is going to be conducted using dynamic simulation tools only. The project consists of different flat sizes with different designs. Starting from 1 bed, and ending with 4 bed flats.(see figure 3.3.1 ). Some of the flats are oriented East to West, and others, North to South. The natural ventilation strategy varies as well based on the occupants chosen design; some flats benefit from cross ventilations, and others have single sided ventilation. Moreover, all the flats benefit from big windows to allow sufficient daylight in, but the South and East windows are shaded with external walkways that was designed mainly for the purpose of allowing social interaction between the occupants.

Summary of the main project features: ● To follow passive house standards ● Triple glazing ● Timber construction ● South & East shading ● (corridors) ● Different flat sizes and designs ● Different orientation ● Heat recovery system MVHR

Fig 3.1.2 - Ground floor plan ‘’CHURCH GROVE PROJECT’’ client : RUSS / Designer: Architype

The project is designed to meet with passive house standards. However, it will not be certified from passive house. Being a new residential building that is meant to comply with passive house standards gives a good opportunity to study the building performance in hot weather and the risk of overheating.

61

3.2.Methodology 1) Choose 3 flats with different properties. ● Orientation (North-South or East-West). ● Natural ventilation strategy (Single sided vent. or Cross vent.).

2) Compare the flats using environmental dynamic simulation tool (TAS) and assessing them against TM59 3) First conclusion ● Defining the flat with highest risk of overheating 4) Applying findings from SHOE BOX 5) Final conclusion and recommendations to reduce the risk of overheating without the need for mech ventilation.

Figure 3.2.1 - 3D perspective - RUSS project (​Architype, )​

3.3.Model specifications and Current parameters

Figure 3.3.1 - 2nd floor plan of RUSS project. Showing the 3 chosen flats to be assessed.

1- flat (EW) referring to East West orientation 2- flat (NS) referring to North South orientation 3- flat (EWs) referring to East West orientation with Single sided ventilation for all rooms

62

Flat EW ( East West )

Figure 3.3.2 - One bed Flat (EW) - located in the second floor (​Architype, )​

Flat EW Dimensions (m) Area (sq.m)

6.15

Living +kitchen

9

55.35

________ 36.7

Bedroom

3.90

3.36

13.10

Table 3.3.1 - dimensions and total area of flat EW

63

Flat NS ( North South)

Figure 3.3.3 - One bed flat (NS) - located in the second floor (​Architype, )​

Flat NS Dimensions (m) Area (sq.m)

6.2

Living +kitchen

8.8

54.56

_______ 37.4

Bedroom

3.90

3.54 13.82

Table 3.3.2 - dimensions and total area of flat NS

64

Flat EWs (East West Single sided)

Figure 3.3.4 - One bed flat EWs - located in the second floor (​Architype, ​)

Flat NS Dimensions (m) Area (sq.m)

6.2

Living +kitchen

8.8

54.56

_______ 37.4

Bedroom

3.90

3.54 13.82

Table 3.3.3 - dimensions and total area of flat EWs

65

3.4. Overheating assessment

They are considered as minimum as possible

Building parameters: The designers (Architype) has considered most of the parameters for the entire building (table 3.4.1).

Therefore, the information that was available were used to simulate the flats as a basic scenario with no improvements added. Only some basic assumed parameters were added, like using blinds and doors functions.

Unconsidered factors: ●Surrounding vegetation (simulation limitation) ●Heat loss from hot water pipes (lack of details info)

Parameter

Assessment method: As in the Shoebox, TM59 is the overheating assessment method for RUSS project. The weather file used is similar as well, DSY2 2020 (London weather centre, 2003, 2020 high 50%) Assumptions: Flat ( EWs ) has a higher risk of overheating due to the single sided ventilation.

Source

Basic

Air permeability (ach)

Architype

0.6

Floor-Slab U-value W/(m²·°C)

Architype

0.137

External Timber walls U-value W/(m²·°C)

Architype

0.117

Windows U-Value W/(m²·°C)

Architype

0.8

Windows G-Value

Architype

0.5

Shading

assumed

Blinds + External (South +East)

glass / F

Architype

Varies around 26%

Floor to Ceiling (cm)

Architype

255

Table 3.4.1 - flats basic specifications and parameters used for the simulation. (follow the rest of the table next page)

66

Aeff:Af

Based on windows throw

1.25% Bedroom - 1.8% Living+kitchen

Window type

Architype

Top hung 200 mm throw restricted

Table 3.4.1 - flats basic specifications and parameters used for the basic scenario Aperture function applied Doors Window Table 3.4.2 - Doors and windows function for basic scenario

Open during the day only Open when Δt 20-22 -- external temp. Cut off

3.4.1.Simulation results The simulations show a slight overheating in criteria one on the living room of flat EW. which wasn’t expected due to the opportunity for cross ventilation between the living room windows facing East and the open kitchen windows on the other side (​figure​ 3.4.1.1).

On the other hand, all bedrooms are overheating in the night based on criteria 2 (table 3.4.1.2). The highest overheating room is as well, the one located in flat EW, which faces West.

Figure 3.4.1.1 - Criteria 1 - overheating assessing flat EW, NS, and EWs

Figure 3.4.1.2 - Criteria 2 - bedrooms overheating assessing flat EW, NS, and EWs

Figure 3.4.1.3 - 3rd floor plan for flat EW - which show the direct exposure to the sun

67

Investigating the causes: By checking the loads from solar radiatiâ&#x20AC;&#x2039;on (figure 3.4.1.4), we realize that flat EW has the highest solar gains compared to the others. From analysing the hours when the solar gain is intense, we can see that most of it coming from the East and the South. And that can be explained by looking to the plan of the 3rd floor (figure 3.4.1.3) that illustrates how this flat is exposed to 3 orientations and moreover, there is no external shading applied like in the rest of flats. From the 3rd floor plan (figure 3.4.1.5), it shows that flat EWâ&#x20AC;&#x2122;s ceiling is in fact a roof. Exposed directly to solar radiation.

Figure 3.4.1.4 - Aug,10 solar radiation comparison between flat EW - NS - EWs

Figure 3.4.1.5 - Loads breakdown for flat EW. Aug,10

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Improving the design: Applying the findings from the shoebox can result in major changes in the design, especially regarding the living room-kitchen glazing:floor ratio, or increasing the very low air permeability (0.6 ach). In addition, there are some security restrictions that won’t allow to increase the living room windows to more than 30cm. Thus. To improve the performance of the building, some applicable proposals were made, that will keep the general outlines of the architectural design (table 3.4.1.1).

Parameter & strategies Windows throw opening living room

living room - 300 mm Bedroom - up to 90°

Window effective aperture

7.5% Bedroom 3.5% Living+kitchen

Glass / Floor

Bedroom windows

Table 3.4.1.1 performance

bed room 26% >>> 15%

Tilt and turn + lower Louver

- parameters to improve flats summer

Simulation results: A massive drop in temperature and overheating in all the flats and all room. All living room kitchen spaces and bedrooms, passed criteria 1 (Figure3.4.1.6). However, only flat NS passed both criterias (figure 3.4.1.7).

Figure 3.4.1.7- Criteria 2 - bedrooms overheating assessing flat EW, NS, and EWs Although the bedrooms of 2 flats couldn’t pass criteria 2, under free running ventilation, the building designers (as mentioned before) are already using MVHR system which is more likely to overcome the overheating hours. The limitations of TAS, couldn’t allow simulating such a system to confirm this assumption. Moreover, the building site is designed with lots of vegetation that can cool down the micro climate temperature, and enhance the building performance in the summer.

3.5.Findings ● Risks of overheating varies from building to building and even from flat to another in the same building. ● Topfloor dwellings are with higher risk of overheating due to the direct exposure to the sun all day. ● Facing multiple orientations is beneficial for cross ventilation, however, it increases the duration and intensity of solar radiation exposure. Thus, external shading is a must to minimise it and benefit from a better natural ventilation strategies. ● Windows opening limitations can be a serious cause for low air exchange and would let the natural ventilation strategy down with very low benefit to purge the heat outdoors, especially in cases of compact designs.

Figure 3.4.1.6 - Criteria 1 - overheating assessing flat EW, NS, and EWs.

69

70

Chapter 4 - Conclusion

71

4.Conclusion 4.1.Final outcomes Adaptive Climate change is happening anyway, and the predicted future scenarios are a warning for the architecture industry and building regulations to be prepared for if wishing to avoid crises in building that were designed to deal with previous weather conditions. Which will result in increased fatalities and health issues related to overheating.

Thanks to the PMV method and adaptive comfort of ASHRAE and En 15251, a good margin is offered for the designers to comply with, rather than having a fixed benchmarks of comfort. However, and because there is no consensus about the definition of overheating, assessment methodologies vary with their criterias. Even a leader organisation in environmental design like CIBSE, requires different benchmarks and criterias in 3 of their guide books that were published within 11 years.

Assessment methods should be a basic guideline for designers. However, even if the building passed in the simulations, it still may overheat due to the unexpected real life factors or climate conditions that can change within short periods. Rather than the micro climate factors that are more exposed to change after the buildings are constructed.

Identifying parameters linked with compactness had shown through simulations how they all together can lead to overheating. The shoebox analysis has shown that every orientation requires different parameters standards. In fact, it showed as well that the western orientation have even more difficulty to pass the criteria of TM59. the Southern orientation was much easier to control the solar radiation which is responsible for most of the external heat gains inside the flats. And thatâ&#x20AC;&#x2122;s by only adding horizontal top shading element, while in the west facade an additional vertical shading to the right side is needed. Whereas for the East orientation, but with locating the vertical shading to the left. There is no difficulty for the North facing bedroom to pass overheating assessment as there is very low solar radiation. Thus, there is no need for any external or internal shading except for privacy if needed. The use of ventilation strategies showed a great improvement in air exchange and purging the heat outdoors. Opening internal doors allowed the air movement between the rooms which made the ventilation strategy work almost

like cross ventilation, and that helped with reaching almost 0 overheating hours. But following the guidelines of CIBSE which require closing the doors during the night, has imposed further improvements for the ventilation strategy during the night in the bedroom which was overheating the most. Using casement window with lower louvers improved the single sided ventilation considerably, Especially when combined with high ceiling of minimum 280cm. Whereas using 7-8% effective aperture to floor ratio is a main factor to insure enough air exchange. And thatâ&#x20AC;&#x2122;s because calculating the windows to floor ratio wonâ&#x20AC;&#x2122;t give any precise info about the air exchange due to the difference in performance between different types of windows and different openable areas.

Designing dwellings for 2050 will require extra parameters like using high thermal mass that can absorb heat during the hot hours of the day and release it at night. Nevertheless, this strategy needs a convenient natural ventilation during the night, or else it will cause undesirable results. Therefore, using balconies with door is a good strategy to insure enough air exchange to be provided. Using the thermal mass when then building is exposed to more than 1 orientation can be tricky and inefficient. The distribution of the high thermal materials should be well studied.

Applying the findings from the shoebox had shown a big improvements in RUSS project. However, the main lesson here that every building has its own challenges to perform well and provide comfort for occupants. Looking for ventilation strategies opportunities is not enough to predict which flat is going to overheat more. The major aspect was solar radiation. When the flat is exposed to solar radiation from the 3 main directions the risks are going to increase with no doubt. And in addition, being located on the top floor will add extra exposure to the sun all day. Therefore, even if the flat has external shadings, more measures should be considered, like increasing ceiling height combined with convenient window strategy like the one proposed (casement window with lower louver). Security and regulations restrictions can contradict with the expected performance. Like limiting the window opening throw to 200mm while it is liable to open for much higher number. Dealing with these restrictions must be considered before the design is over, and substitutions like using louvers should be offered. .

72

4.2.A critique of TM59 Although the TM59 is the latest assessment and most advanced assessment for dwellings by CIBSE, and perhaps in the most advanced and specialised in the entire industry, it’s thought to have some limitations and missing factors in the criteria. The difficulties to comply with its requirements is mainly to pass criteria 2 which is only applicable to the bedrooms.

1.The assessment guidelines require closing the doors during the sleeping hours (22:00 - 07:00). And this is preventing air movement inside the flat and causing an increase in the temperature, in reality, if people are feeling discomfort, the adaptive nature of human beings will make them act upon and open the doors. Even if it will interfere with their privacy in multiple bedroom flats.

The thermal comfort in most cases will have the priority for the occupant. The suggested improvement is to consider opening interior doors under severe conditions during the summer only. From the simulations data, it show that overheating occurs mainly within one week of the summer. An exception could be considered for this week.

reports and surveys done by the NHBC Foundation and Zero carbon hub. Even provided data in person from Architype firm. The biggest limitation of the study was the ability to conduct field work on one of the buildings claimed to overheat due to the very high insulation and airtightness. Inability to conduct the survey was because of lack of access to the buildings and because of time limitation of the thesis final course. The field work investigation could have been done to analyse the issue in real life by environmental tools for an occupied building.

Such a field work, could have supported the dissertation with concrete data and direct evidences about the issue.

The fieldwork could as well, draw attention to other aspects and parameters that may not be considered in the analytical work.

Time is in most cases a major limitation whether for academic research or for professional reports. Due to the short duration of this MSc course (1 year), further research and simulations could have been done. A CFD simulations for the air movement through different windows with different effective aperture can give more understandable results that can support the proposal.

2.Having a fixed benchmark for bedrooms in criteria 2 is as will very stricket measure. Simulations showed many hours barely exceeding 26, and for the criteria they are included in overheating hours. There could be at least another range that allows for a number of hours to exceed 26 by a slight margin.

3.Moreover, the assessment doesn’t consider air movement as a factor that can improve thermal comfort.

Infact, in CIBSE guide A, section 1.5.2.3 (Butcher and Craig, 2015), advise that Δt in bedrooms should not exceed 26°C unless ‘°C unless there is some means to create air movement in the space’. And they refer to ceiling fans as an example. Even the enhanced air movement through double windows can be considered in real life.

4.Occupancy profile is considered all day, which is not the case in real life. There are hours of work, or random hours outdoors. However, it might be seen from another perspective, that it’s the worst possible case.

4.3.Limitations of the study This paper was investigating the risks of compactness in london dwellings, which was placed based on many

73

2080

2080

2050

2050

2020

2020

2050

2080

2020

2020

2050

2080

5.References 5.1.Bibliography Current World Population&nbsp; ​(2019). Available from: https://www.worldometers.info/world-population/ [Accessed27/08/2019 at 17:05]. , 6.0. M ​ acroFlo Opening Types User Guide, ​.

Antonietta Canta (no date). Comparison of Overheating Assessment Methods for a Naturally Ventilated Healthcare Premise in London. ​Arup. ​Available from http://cibse.org.uk/getmedia/50c730a1-b602-49d 5-adac-af9567490b37/02-Antonietta-Canta-Arup.p df.aspx​[Accessed 30/08/2019].

ASHRAE, A. (2010). ​Standard 55-2010:“Thermal Environmental Conditions for Human Occupancy”​.

BBC (2017). What the drought of 1976 looked like as this year's heatwave continues. Available from http://www.bbc.co.uk/newsbeat/article/40358961 /what-the-drought-of-1976-looked-like-as-this-year s-heatwave-continues [Accessed 27/08/2019 at 13:55].

BRE (2012). SAP 2012: The government's standard assessment procedure for energy rating of dwellings.

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BRE and EST (2003). GOOD PRACTICE GUIDE 192:&nbsp;Designing Energy Efficient Multi-Residential Buildings. Available from https://www.cibse.org/getmedia/7ef0dab3-6201-4 650-8cc6-5be057c15047/GPG192-Designing-Ener gy-Efficient-Multi-Residential-Buildings.pdf.aspx [Accessed 02/09/2019 at 22:28].

BREEAM (2016). Overheating in dwellings: guidance document. ​Breeam. ​Available from https://www.bre.co.uk/filelibrary/Briefing%20pape rs/116885-Overheating-Guidance-v3.pdf​[Accessed 13/08/2019 at 18:41].

BREEAM, U.K. (2014). New Construction. ​Breeam UK New Construction Non-Domestic Buildings Technical Manual. A ​ vailable from.

Butcher, K. and Craig, B. (2015). ​Environmental Design: CIBSE Guide A Chartered Institution of Building Services Engineers.

Census Information scheme (2012). 2011 Census first results: London boroughs' populations by age by sex.

Available from https://data.london.gov.uk/census/reports/ [Accessed 24/04/2019 at 15:11].

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CIBSE, T. (2014). Design summer years for London. ​London: The Chartered Institution of Building Services Engineers. A ​ vailable from.

CIBSE, T. (2013). 52: 2013-The limits of thermal comfort: avoiding overheating in European buildings, in. G ​ reat Britain. ​Available from.

Cibse, T. (2017). Design methodology for the assessment of overheating risk in homes. ​The Chartered Institution of Building Services Engineers, London. ​Available from.

Department for communities and local government (2012). Investigation into Overheating in Homes :Analysis of Gaps and Recommendations.

Available from https://assets.publishing.service.gov.uk/governm ent/uploads/system/uploads/attachment_data/fil e/6380/2185799.pdf [Accessed 25/04/2019 at 09:06].

Department for Communities and Local Government: London (2006). Housing Health and Safety Rating System,&nbsp;Guidance for Landlords and Property Related Professionals. Available from https://www.gov.uk/government/publications/hou sing-health-and-safety-rating-system-guidance-forlandlords-and-property-related-professionals​ .

Department of Health (2007). Specialised ventilation for healthcare premises, Part A: Design and validation. ​Health Technical Memorandum HTM 03-01. A ​ vailable from.

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Designing Buildings Wiki (no date). &nbsp;U-values. &nbsp;U-values. ​Available from: https://www.designingbuildings.co.uk/wiki/U-valu es​ [Accessed2/08/2019].

DTLR (2002). Approved document L1: Conservation of fuel and power (2002 Ed.).

Available from https://webarchive.nationalarchives.gov.uk/20141 202124314/https://www.planningportal.gov.uk/up loads/br/BR_PDF_ADL1_2002.pdf [Accessed 25/04/2019 at 09:37]. east cambridgeshire district councilWhat Are The Building Regulations?

Available from https://www.eastcambs.gov.uk/building-control/w hat-are-building-regulations [Accessed 27/08/2019 at 23:44].

Gonzalo, R. and Vallentin, R. (2016). ​Passive House Design: Planning and Design of Energy-efficient Buildings​, 2nd. Institut für internationale Architektur-Dokumentation GmbH & Company KG. Hub, Z.C. (2015). Overheating in homes: The big picture. ​Zero Carbon Hub: London, UK. ​Available from http://www.zerocarbonhub.org/sites/default/files/ resources/reports/ZCH-OverheatingInHomes-The BigPicture-01.1.pdf [Accessed 25/04/2019 at 08:53].

Hub, Z.C. (2016). Solutions to overheating in homes.

Available from http://www.zerocarbonhub.org/sites/default/files/ resources/reports/ZCH-OverheatingEvidenceRevie w.pdf​[Accessed Accessed 25/04/2019 at 09:02].

IPCC​Definition of Terms Used Within the DDC Pages&nbsp; Definition of Terms Used Within the DDC Pages&nbsp; ​Available from: https://www.ipcc-data.org/guidelines/pages/glos sary/glossary_hi.html [Accessed26/08/2019 at 22:53].

Irving, S., Ford, B., Etheridge, D. (2005). Natural ventilation in non-domestic buildings, CIBSE AM10. Available from.

Karl Terpager Andersen (no date). FRICTION AND CONTRACTION BY VENTILATION OPENINGS WITH MOVABLE FLAPS. ​Danish Building and Urban Research. ​Available from ​www.by-og-byg.dk​ .

McLeod, R., Jaggs, M., Cheeseman, B., Tilford, A., Mead, K. (2014). Passivhaus Primer: Airtightness Guide. ​Airtightness and Air Pressure Testing in Accordance with the Passivhaus Standard, BRE, Watford.[Google Scholar]. ​Available from[Accessed 25/04/2019 at 09:34].

Met officeHot spell - August 2003&nbsp; Available from https://www.metoffice.gov.uk/binaries/content/as sets/metofficegovuk/pdf/weather/learn-about/ukpast-events/interesting/2003/hot-spell---august-20 03---met-office.pdf [Accessed 25/04/2019 at 09:12].

National statistics (2019). ​Energy Consumption in the UK (ECUK) 1970 to 2018&nbsp; U ​ K: OGL. NBS (2013). The Building Regulations 2010 Approved Document L1A: Conservation of fuel and power in new dwellings. Available from https://assets.publishing.service.gov.uk/governm ent/uploads/system/uploads/attachment_data/fil e/540326/BR_PDF_AD__L1A__2013_with_2016_a mendments.pdf​ [Accessed 25/04/2019 at 09:36].

NHBC Foundation (2012). Overheating in New Homes: A Review of the Evidence. Available from.

Nicol, F., Humphreys, M., Roaf, S. (2012). ​Adaptive thermal comfort: principles and practice​ Routledge.

Office for National Statistics, (UK) (2019).

Percentage of households with central heating systems in the United Kingdom (UK) from 1970 to 2018. ​Statista. Statista Inc. ​Available from https://www.statista.com/statistics/289137/centr al-heating-in-households-in-the-uk/ [Accessed 27/08/2019 at 22:22]. onaverage (no date). ​Average Height Ceiling&nbsp; Average Height Ceiling&nbsp; ​Available from: https://www.onaverage.co.uk/other-averages/aver age-height-ceiling​[Accessed08/09/2019 at 22:24]. ovoenergy (no date). ​What’s the average room temperature and thermostat setting in the UK? What’s the average room temperature and thermostat setting in the UK? ​Available from: https://www.ovoenergy.com/guides/energy-guide s/average-room-temperature.html [Accessed29/08/2019].

Maslin, M. (2014). ​Climate change: a very short introduction​ OUP Oxford.

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rheating-in-london-such-a-hot-topic/ 08/09/2019 at 23:56].

5.2.Table of images Architype, ​. coolparramatta.com.au. ​Available http://coolparramatta.com.au/about_us [Accessed27/08/2019 at 16:21].

from:

greenbuilding.saint-gobain.com. ​(no date).

Available from: https://www.greenbuilding.saint-gobain.com/certi fication/leed-v4/glass-facade-windows/optimize-e nergy-performance​ .

Meteonorm, ​(2017).

Meteonorm, ​(2050).

ASHRAE, A. (2010). ​Standard 55-2010:“Thermal Environmental Conditions for Human Occupancy”​.

BRE (2012). SAP 2012: The government's standard assessment procedure for energy rating of dwellings.

Available from https://www.gov.uk/guidance/standard-assessme nt-procedure​.

Butcher, K. and Craig, B. (2015). ​Environmental Design: CIBSE Guide A Chartered Institution of Building Services Engineers.

Cibse (2006). Environmental design: CIBSE guide A. ​Building and Environment. ​Available from.

CIBSE, T. (2013). 52: 2013-The limits of thermal comfort: avoiding overheating in European buildings, in. G ​ reat Britain. ​Available from.

Cibse, T. (2017). Design methodology for the assessment of overheating risk in homes. ​The Chartered Institution of Building Services Engineers, London. ​Available from.

Davies & Company (2000). Climate Change: New Antarctic Ice Core Data&nbsp; Available from http://www.daviesand.com/Choices/Precautionar y_Planning/New_Data/ [Accessed 27/08/2019 at 15:11].

Department of Health (2007). Specialised ventilation for healthcare premises, Part A: Design and validation. ​Health Technical Memorandum HTM 03-01. A ​ vailable from. energistuk.co.uk (2017). Why is Summer Overheating in London Such a Hot Topic?

Available from https://www.energistuk.co.uk/why-is-summer-ove

[Accessed

honestlywtf.com (no date). ​Windows Of The World.

Windows Of The World. ​Available from: https://honestlywtf.com/art/windows-of-the-world /​ [Accessed08/09/2019].

Irving, S., Ford, B., Etheridge, D. (2005). Natural ventilation in non-domestic buildings, CIBSE AM10. Available from.

James Gleeson (2013). Dasymetric map of London’s population density, 2011. Available from https://jamesjgleeson.wordpress.com/2013/01/2 3/dasymetric-map-of-londons-population-density-2 011/​ [Accessed 07/09/2019 at 20:26].

National statistics (2019). ​Energy Consumption in the UK (ECUK) 1970 to 2018&nbsp; U ​ K: OGL. NHBC Foundation (2012). Overheating in New Homes: A Review of the Evidence. Available from.

Nicol, F., Humphreys, M., Roaf, S. (2012). ​Adaptive thermal comfort: principles and practice​ Routledge.

Office for National Statistics, (UK) (2019).

Percentage of households with central heating systems in the United Kingdom (UK) from 1970 to 2018. ​Statista. Statista Inc. ​Available from https://www.statista.com/statistics/289137/centr al-heating-in-households-in-the-uk/ [Accessed 27/08/2019 at 22:22].

Rennie, D. and Parand, F. (1998). ​Environmental design guide for naturally ventilated and daylit offices​ Construction Research Communications. theguardian (2018). &nbsp; This article is more than 1 year old Summer 2018 was UK's joint hottest on record, Met Office says.

Available from https://www.theguardian.com/uk-news/2018/sep /03/summer-2018-uk-joint-hottest-on-record-met-o ffice-says​ [Accessed 08/09/2019].

Wikipedia contributors (no date). Demography of England.

Available from https://en.wikipedia.org/w/index.php?title=Demog raphy_of_England&oldid=911561037 [Accessed 7/09/2019 at 19:10].

Window Master (no date). eBook for Architects: Why and how to use natural ventilation in

76

your building design. Available from.

5.3.Programs EDSL TAS, ​(2019).

Meteonorm, ​(2017).

Meteonorm, ​(2050).

Passive house (no date). ​Passive House Planning Package (PHPP). Passive House Planning Package (PHPP). ​Available from: https://passivehouse.com/04_phpp/04_phpp.htm​[ Accessed29/08/2019].

77

6.Appendix 6.1.Windows openable area and effective aperture calculations: Windows type and openable area define how much air will go in and out the space. The effective aperture can be calculated based on the discharge coefficient of each opening. Further complexity is added for the calculations, and that’s because using thermal modelling program EDSL Tas require to take into consideration calculations that the program automatically does. For the windows and doors apertures, TAS will automatically add a minimum discharge coefficient of 0.62. Thus, there was a need to do an equation to consider the right total number.

Key shortcuts (for further illustration) ●The needed effective aperture to input in Tas will be called (TAS eff). ●Window Pane area or structural area, will be referred to as (Str area) ●(A eff) = effective aperture to floor ratio. ●(openable area) is the total calculated area e.g. the rectangle and 2 triangles in the top hung window (figure 6.1.1)

Figure 6.1.1 - illustration of the openable area measured from a bottom hung window.

In cases of the total openable area is more than the window pane area, a factor of one was considered. Which means the openable area equals the pan area. Cause if the number is exceeding the Str area, even with multiplying with discharge coefficient, the final numbers doesn’t seem realistic. A lack of info for these details forced to do many calculations to finally get to this conclusion.

Therefore, back to the Tas equation. Which is mainly coming from : 1. Str area * (Tas eff) * 0.62 = openable area * discharge coefficient 2. Str area * (Tas eff) * 0.62 = A eff 3. TAS eff = ( A eff / pane area * 0.62 ) Example from the shoebox basic simulations (2.1.5. South shoebox - 2020): Window type of the bedroom = top hung Opening angle 15 degree >> discharge coefficient based on (table Table 1.11.1) = 0.18 Str area = 1.23 sq.m Openable are = rectangle area + 2* triangle area = 0.67 _____ TAS eff = (0.67*1.23/1.23* 0.62 ) = ( 0.16 ) So using window with openable area 0.67 will require to input in tas (0.16) And the measure the effective aperture to floor ratio (Aeff:Afl) we divide the resulted Aeff from multiplying to openable area with the discharge coefficient, on the floor area of the room.

Another note needs to be illustrated whole calculating the openable area is, when calculating the triangles and rectangles, window restrictions should be considered (figure 6.1.2).

Figure 6.1.2 (Window master, online)

78

Thro Wind str T str w Rec Tri ow Angl Heig Widt area area coun lengt area area type e ht h (m2) (m2) t h (m2) (m2)

Bed

Top Hung

15

1.35 0.915

1.235 1.235 25 25

Fixed glass

15

1.35 0.915

1.235 25

1

0.3

Ope nabl e Dis area Coef A eff (m2) f (m2)

0.274 0.679 5 0.405 5

0.18

0.122 31

eff area Tas : str A eff apert area : F ure 9.90 %

0.95 %

0.16

0

Table 6.1 - Calculations of basic scenario bedroom window

str Windo area w type Angle Height Width (m2) top hung fixed glass

30

1.05 0.915

T str Rec area Throw area (m2) count length (m2)

0.9607 5 1.9215

Opena eff Tri ble area : Tas Area area Dis A eff str A eff / apertu (m2) (m2) Coeff (m2) area F re

2

0.5

0.54 0.648 0.567

0

1.05

1.83

casem ent

90

1.05

1.2

1.26

1.26

1

Fixed glass

30

0.6

1.2

0.72

0.72

1

Louver

--

0.45

1.2

0.54

0.54

1

0.4575 0.2625 0.72

1.26

0.324

0.38 0.2736

28.48 % 2.72% 0.46

0.62 0.7812

62.00 % 6.07% 1.00

0.62

0.2008 37.20 8 % 1.56% 0.60

Table 6.2 - Calculations for windows of best scenario 2020 south (casement with lower louver)

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6.2.Authorship Declaration Form (Form CA1)

UNIVERSITY OF WESTMINSTER MARYLEBONE CAMPUS

COURSEWORK COVERSHEET FORM CA1

I confirm that I understand what plagiarism is and have read and understood the section on Assessment Offences in the Essential Information for Students. The work that I have submitted is entirely my own (unless authorised group work). Any work from other authors is duly referenced and acknowledged.​ STUDENTS MUST COMPLETE THIS SECTION ONLY IN FULL AND IN CAPITALS

Surname Forename ALHALABI HAMZA

Registration No:

W

Module Title

Thesis Project

Module Code

Assignment No:

1/1

Date Submitted

Markers: Joint Assignments:

1

6

7

0

5

9

7

Course

Word Count N/A

ARCHITECTURE AND ENVIRONMENTAL DESIGN 7AEVD005W.2 02

09

2019

18400

Joint Submission

Architype, .

Current World Population&nbsp; (2019). Available from: https://www.worldometers.info/world-population/

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