OPERATIONAL MANUAL for SHADING DEVICES + WINDOWS FO R O F F I C E B U I L D I N G S I N C L I M AT E ZO N E 5 A
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CARNEGIE MELLON UNIVERSITY | CENTER FOR BUILDING PERFORMANCE & DIAGNOSTICS
CONTENTS 1. Introduction / Scope of Work 7 2. Background / Research Description 8 2.1. Solar shading devices 8 2.2. Windows 9 3. Index 11 4. Recommendations: Blinds 13 4.1. Manual Controls 13 4.1.1. Cooling Season 14 4.1.2. Heating Season 16 4.2. Automated Controls 19 4.2.1. Cooling Season 20 4.2.1.1. South East 20 4.2.1.2. South West 21 4.2.1.3. West 22 4.2.1.4. East 23 4.2.2. Heating Season 24 4.2.2.1. South East 24 4.2.2.2. South West 25 4.2.2.3. West 26 4.2.2.4. East 27 4.3. Energy Savings 28 4.3.1. Cooling Season Savings 28 4.3.2. Heating Season Savings 28 4.3.3. Annual Savings 29 4.4. Additional Benefits 30 5. Recommendations: Windows 33 5.1. Manual Controls 33 5.2. Automated Controls 35 5.3. Cooling Season 36 5.4. Swing Season 37 5.5. Heating Season 38 5.4. Energy Savings 40 5.4.1. Cooling Season Savings 40 5.4.2. Swing Season Savings 40 5.4.3. Heating Season Savings 40 5.4.4. Annual Savings 40 5.5. Additional Benefits 41 6. Conclusion 43 7. Appendix 44 3
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INTRODUCTION SCOPE of WORK The building sector has a major share in consuming world’s nonrenewable resources and contributes significantly to the greenhouse gas emissions and climate change. Within the USA, the building sector has a 39% share in total energy consumption (Selkowitz, 2009).This conjecture was verified by the McKinsey & Company 2007 report and it stands in direct contrast with the popular belief about the transportation & other industry sectors being the major contributors. In the USA, 71% of the electricity is consumed in lighting, heating and cooling the buildings. Commercial buildings alone are responsible for 19% of the total energy consumption (Selkowitz, 2009). These staggering numbers suggest that there is an utmost urgency for the buildings to go on an energy diet. To add to this dilemma, a very large percentage of commercial buildings are highly glazed for aesthetics and transparency. The designers aim to provide maximum outside view and access to nature and insist that such glazed buildings would significantly reduce the lighting loads offset by natural day light. Although conceptually the idea is functional, numbers suggest otherwise. While the lighting loads continue to be very high, issues such as visual discomfort due to glare and more global issues such as urban heat island are raising concerns among the environmentalists. The main reason for this gap between the concepts and reality is the lack of effective passive and active design strategies application to optimize the daylight and solar heat gain. The facade, the skin of the building, is the point of maximum thermal exchange between the indoor built environment and the exterior, therefore having a great potential for energy saving. The benefits of dynamic layered facades as compared to static facades and their integration with lighting and thermal control systems are being explored rigorously. Along with the overall energy use benefits, a large body of research has indicated the additional advantages of dynamic facades such as occupant health & comfort and increased productivity. Europe has experienced several structures built over the last decade that have adopted this technology with proven results showing a reduction in energy consumption. Along with reduced energy consumption, the indoor acoustic quality and aesthetics of the structures have also seen improvement. The building stock in the US too has few examples that have used the layered facade strategy but the application needs to be more wide spread like in Europe. Studies show that the main reason for less aggressive use of these strategies in USA is lack of field tested results, little or no documentation regarding the commercially available products and systems, no third party post occupancy evaluation quantifying the energy benefits and little awareness amongst clients and occupants with respect to return of investments and triple bottom line analysis (Selkowitz S., Aschehoug O., Lee E., 2003) (Lee E., Selkowitz S., Bazjanac V., Kohler C., 2002) (Zelena K., Perepelitza M., Lehrer D., 2011). The Center for Building Performance and Diagnostics of Carnegie Mellon University has conducted a series of field experiments for windows and solar shading devices (limited to internal & external venetian blinds) in order to propose guidelines for optimum operation. The studies aimed at quantifying the potential energy and cost savings and create a set of operational guidelines for office buildings. This manual presents the set of guidelines and communicates them in a way that are easily applicable by facilities managers and business owners. 5
BACKGROUND RESEARCH DESCRIPTION 2.1
Shading Devices
The study for the shading systems included an overview of various types of solar shading devices and focus on analyzing the potential of external and internal dynamic venetian blinds. The proposal included a literature review to justify the need for this research topic followed by an investigation of commercially available high performance products. It then encompassed generation of detailed case studies matrix of the existing or upcoming building projects (national & international best practices) where those products are used and show significantly positive results. The main focus of this research was to generate quantitative data highlighting the energy savings potential through field experiments and simulation done as a part of a DOE funded research Energy Efficient Buildings (EEB) Hub. Finally, the literature review confirmed the importance of this strategy with respect to improvement in indoor environmental quality, occupant health and productivity.
Methodology of research
The main purpose of the research was to quantify the energy savings with the help of solar shading devices and access the improvement in indoor environmental quality at the same time. The primary goal was to quantify the thermal and daylighting benefits of solar shading devices (limited to internal and external venetian blinds) by conducting field experiments to encourage a wide spread application of this strategy in the USA. The analysis specifically included the effects of deployment of different slats angles of these blinds in different orientations and according to seasonal and daily variations to reduce heating, cooling and lighting loads while maintaining the desired day light intensity and thermal and visual comfort standards as prescribed by ASHRAE 55 2010 and IESNA 2011. The experiment results are specific to open plan commercial offices and climate zone 5. The experiments were not performed in a controlled environment and therefore it can be said that the results are conservative figures. Second aim of the research was to identify the high performance products currently available in the market and generate a detailed case studies matrix of the existing or upcoming buildings where those products are installed successfully showing significantly positive results. Last but not the least; the research goal was to confirm the importance of this strategy with respect to improvement in indoor environmental quality, occupant health and productivity through the literature review. Through the above strategies, conclusions have been made for optimal daily operation of shading devices in office buildings for cooling, heating and swing seasons. These conclusions suggest different operation for the different facades of the building based on orientation. Hence, this manual intents to provide facility managers with useful guidelines for operation for blinds based on the facade orientation, the season and the time of the day.
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2.1
Windows
For the windows operation research, again different scenarios were investigated for the cooling and swing season, in order to explore the optimum solution for natural ventilation based on the daily weather forecast. Different experiments were realized in the Intelligent Workplace, the living laboratory of the Center for Building Performance and Diagnostics, and human comfort was documented through voting. As a supporting tool, simulations were realized in TRNSYS. The research goal was dual; the main objective was to create guidelines for windows operation based on the current weather conditions, in order to ventilate naturally office spaces without compromising the human comfort. Natural ventilation and night precooling can lead to energy savings, however there might be negative impact on human comfort due to temperature change, wind and rain. The suggested recommendations aim to balance the positive impact of natural ventilation on the energy consumption of an office building without jeopardizing the human comfort and productivity of the employees. Within the same scope of work, the research tried to create guidelines for space precooling during the night, based on the hourly weather forecast.
EXPERIMENT SIMULATION ‘07
EXPERIMENT SIMULATION
EXPERIMENT SIMULATION
EXPERIMENT SIMULATION
EXPERIMENT SIMULATION
EXPERIMENT SIMULATION
Figure 1- Locations of research for shading operation
Figure 2- Locations of research for windows/natural ventilation
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INDEX TERMS, SYMBOLS AND ABBREVIATIONS Abbreviation
Meaning
Unit
IT L OT ORH R SR Tdp WS
Indoor Temperature Luminance Outdoor Temperature Outdoor Relative Humidity Rain Solar Radiation Dewpoint Temperature Wind Speed
°F Lux °F % In/h Nm °F mph
Symbol
Meaning
Category
Open window
Windows
2
Closed window
Windows
3
Open blinds
Shading
4
Blinds 0° (horizontal)
Shading
5
Blinds 45°
Shading
6
Blinds 90° (closed)
Shading
1 2 3 4 5 6 7 8
1 .
9
10
manual control
BLINDS
SUMMER [COOLING SEASON]
Is it too warm or too cold in your office? Do you keep the blinds always closed to avoid glare issues and you cannot see outside? Is your office overheated in the morning when you arrive at work in the summer? The following simple recommendations will help you improve your office conditions and save energy! Just figure out the orientation of your office, pick the current season and follow three easy steps for morning, afternoon and night!
pick your office orientation:
pick the season:
SE
SW
cooling season
3 steps: 1
W
E
heating season
2
3
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BLINDS manual control
COOLING SEASON SOUTH EAST ORIENTATION
+
morning
+
afternoon
+
night
On summer mornings, when you arrive at the office please close your blinds (0o) to avoid overheating your office. No one wants to feel sweaty when they just arrived at work!
On summer afternoons, when you come back from your lunch break, change your blinds to 45o. Let the natural light in the space and enjoy the view out of your window!
Work is almost done! You are about to leave the office and enjoy a nice summer night. Do not forget to open up your blinds before doing so. Tomorrow your office will feel cooler!
SOUTH WEST ORIENTATION
12
+
morning
+
afternoon
+
night
On summer mornings, when you arrive at the office please put your blinds at 45o. You will let sunlight in without overheating your space. Also you will be able to enjoy the view outside while you are working!
On summer afternoons, the sun my penetrate your blinds and create glare issues on your screen or desk. To avoid that, when you come back from your lunch break, close your blinds (0o).
Work is almost done! You are about to leave the office and enjoy a nice summer night. Do not forget to open up your blinds before doing so. Tomorrow your office will feel cooler!
COOLING
WEST ORIENTATION SEASON
+
morning
+
afternoon
+
night
On summer mornings, when you arrive at the office please put your blinds at 45o. You will let sunlight in without overheating your space. Also you will be able to enjoy the view outside while you are working!
On summer afternoons, the sun my penetrate your blinds and create glare issues on your screen or desk. To avoid that, when you come back from your lunch break, close your blinds (0o).
Work is almost done! You are about to leave the office and enjoy a nice summer night. Do not forget to open up your blinds before doing so. Tomorrow your office will feel cooler!
EAST ORIENTATION
+?
morning
+?
afternoon
+?
night 13
16
automated control
BLINDS
Are you a commercial facility manager and you want to advance your building’s performance? Does your office building consume a lot of energy and your employees are uncomfortable? Do you receive complaints about overheated or cold spaces and poor natural light? If you are installing or already have an automated control system for the blinds in the occupied spaces of your building, set it up with the following recommendations. You will see reduction in your energy consumption pattern and positive shift in the employees’ productivity and comfort!
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BLINDS automated control
COOLING SEASON SOUTH EAST ORIENTATION
IF
morning
afternoon
night
o
OT< 65 SR> 400 L> 500 o
65 <OT<75 SR< 400 L< 500
o
BLINDS: 90
o
BLINDS: 0
o
o
BLINDS: 0 or open
o
BLINDS: 0
o
OT> 65 SR> 400 L> 500 o
OT< 65 or OT> 75 SR< 400 L< 500 o
o
BLINDS: 45
o
BLINDS: 90
BLINDS: 90
o
o
BLINDS: 45
o
o
55 <OT<70 IT>SETPOINT
BLINDS: open
o
OT< 55 or o OT> 70 IT<SETPOINT
o
BLINDS: 90
o
OT< 65 SR> 400 L> 500 o
65 <OT<75 SR< 400 L< 500
BLINDS: open
BLINDS: open
o
o
BLINDS: 0 or open
o
BLINDS: 0
o
OT> 65 SR> 400 L> 500 o
OT> 75 or OT<65 SR< 400 L< 500 o
o
BLINDS: 90
o
BLINDS: 90
BLINDS: 90
o
o
BLINDS: 90
o
o
55 <OT<70 IT>SETPOINT
BLINDS: open
o
OT< 55 or o OT> 70 IT<SETPOINT 18
o
BLINDS: 90
COOLING
SOUTH WEST ORIENTATION SEASON
IF
morning
afternoon
night
o
OT> 65 SR> 400 L> 500 o
o
BLINDS: 45 o
55 <OT<70 IT>SETPOINT
BLINDS: open
o
OT< 55 or o OT> 70 IT<SETPOINT
o
BLINDS: 90
o
OT> 65 SR> 400 L> 500 o
o
BLINDS: 90 o
55 <OT<70 IT>SETPOINT
BLINDS: open
o
OT< 55 or o OT> 70 IT<SETPOINT
o
BLINDS: 90
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30
manual control
WINDOWS
Is it too warm and stuffy in your office? Do you feel sleep or tired because the CO2 levels are too high in your space? Do you want to open your window but you do not know what your companyâ&#x20AC;&#x2122;s policy is? Well, your company supports operable windows by the employees in order to improve their comfort and save energy! During the day you will receive an informational notification on your smart phone by your company with the appropriate recommendation of opening or closing your window. The recommendations are based on temperature, relative humidity, rain, wind and CO2 levels in your office. Most important of all, especially during the summer, do not forget to check your application before you leave! We run a 16 hour forecast for you and let you know if you can open your windows during the night, so that your office is cooler when you come back the next morning!
iF >68o F <75% <6 mph no rain OPEN YOUR WINDOWS
the COMFORTapp
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32
automated control
WINDOWS
Are you a commercial facility manager and you want to advance your buildingâ&#x20AC;&#x2122;s performance? Does your office building consume a lot of energy and your employees are uncomfortable? Do you receive complaints about overheated and stuffy spaces? Are your employees feeling tired or sleepy due to high levels of CO2 in the office? If you believe that operable windows in office spaces are important we are here to support you! If you are installing or already have an automated control system for windows in the occupied spaces of your building, set it up with the following recommendations. You will see reduction in your energy consumption pattern and positive shift in the employeesâ&#x20AC;&#x2122; productivity and comfort!
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WINDOWS automated control
COOLING SEASON
IF
morning
night
IT<68°F, Cooling needed IT>68°F, Cooling Needed OT<59°F or OT>79°F IT>68°F, Cooling Needed 59°F<OT<79°F Wind Speed>6mph or Rain>1 in/h IT>68°F, Cooling Needed 59°F<OT<79°F Wind Speed<6mph or Rain<1 in/h ORH>75% or OTdp>Mul Tdp-5 IT<68°F, No Cooling needed CO2>1000 ppm IT>68°F, No Cooling needed OT<59°F or OT>79°F CO2>1000 ppm IT>68°F, No Cooling needed 59°F<OT<79°F Wind Speed>6mph or Rain>1 in/h CO2>1000 ppm IT>68°F, No Cooling needed 59°F<OT<79°F Wind Speed<6mph or Rain<1 in/h ORH>75% or OTdp>Mul Tdp-5 CO2>1000 ppm IT<68°F, No Cooling needed CO2<1000 ppm IT>68°F, No Cooling needed OT<59°F or OT>79°F CO2<1000 ppm IT>68°F, No Cooling needed 59°F<OT<79°F Wind Speed>6mph or Rain>1 in/h CO2<1000 ppm IT>68°F, No Cooling needed 59°F<OT<79°F Wind Speed<6mph or Rain<1 in/h ORH>75% or OTdp>Mul Tdp-5 CO2<1000 ppm
SEMCO ON: Dehumidification
SEMCO ON: Dehumidification
SEMCO ON: Dedicated Outside Air Mode
SEMCO ON: Dedicated Outside Air Mode
SEMCO OFF
SEMCO OFF
SEMCO OFF
SEMCO OFF
IT>68°F 59°F<OT<79°F Wind Speed<6mph and Rain<1 in/h ORH<75% and OTdp<Mul Tdp-5
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SWING SEASON
IF IT<73°F CO2>1000 ppm IT>73°F OT>IT or OT>(IT - 15°F) CO2>1000 ppm IT>73°F OT<IT or OT<(IT - 15°F) Wind Speed>6mph or Rain>0.5 in/h CO2>1000 ppm IT>73°F OT<IT or OT<(IT - 15°F) Wind Speed<6mph or Rain<0.5 in/h ORH>80% (IT - OT) < 7°F CO2>1000 ppm IT<73°F CO2<1000 ppm IT>73°F OT>IT or OT>(IT - 15°F) CO2<1000 ppm IT>73°F OT<IT or OT<(IT - 15°F) Wind Speed>6mph or Rain>0.5 in/h CO2<1000 ppm IT>73°F OT<IT or OT<(IT - 15°F) Wind Speed<6mph or Rain<0.5 in/h ORH>80% (IT - OT) < 7°F CO2<1000 ppm IT>73°F OT<IT or OT<(IT - 15°F) Wind Speed<6mph or Rain<0.5 in/h ORH<80% (IT - OT)> 7°F
morning
night
SEMCO ON: Dedicated Outside Air Mode
SEMCO OFF
SEMCO OFF
SEMCO OFF
SEMCO OFF
SEMCO OFF
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