Design Strategy in Detail

Why is technical specification important? Design

As aforementioned, maintenance is an integral part when connecting architecture/ built infrastructure to health of occupants. The key to successful performance of healthardware and enduring hardware to reduce maintenance requirements is technical specification.

Technical specification is the detailed investigation and instruction to builders of particular parts or hardware and how they work within the design or system. This can be proprietary from manufacturers who specialise in particular products, or it can be custom design and detailed by the architect or designer.

When choosing a specification for an item or system, it should be individually tailored to the function and performance expectation of the item. For example, specifying materiality for an indoor fan, will not be the same materiality for an outdoor water tank.

When evaluating which specification product to choose, the four largest considerations are: materiality, quality, cost and performance. The next few pages will focus in great detail of why certain specifications were made to suit the Mt Liebig climate, the desired performance, the product life/durability and expected costs (including maintenance, and upfront costs).

Some generic construction notes:

- All fixings and systems to be installed to manufacturers written instructions

- All construction to be installed to current BCA, NCC and Asutralian Standards

- All metal sheet cladding to be of a colour suited to solar absorbance level 0.48 and under

- All proprietary systems to be installed to manufacturer written instructions

- Contractors to install systems to relevant Healthabitat recommended Housing for Health guidelines were applicable

- All systems warranties to be collected by contractor for handover to relevant authorities post-construction

Window Systems

As aforementioned, Healthabitat found in their studies that one of the first items to fail and have a great effect on the thermal performancing of housing is the windows. Maintence to existing windows should be top priority if the project is bound by cost, as enabling ventilation is key to improvindg the cooling of a house. Furthermore, windows are integral to offering security, weather protection, dust protection, and light into space - all of which have an effect on a tenant health.

Design considerations:

When exmaining what maintenance may need to be performed on a window system, the following items should be checked:

- window track - caulking

- glass - handles/hardware

- rust - locks

-flashings - flyscreens

If any of these items are damaged they should be fixed to enable correct funcitioning of existing windows. These repairs should be carried out as per the Healthabitat methodology.

Improvements on existing windows can be added with the following:

- low-e film

- thermal break strips

However, if a window requires replacing, a casement window system is suggested as an alternative. Whilst this system is difficult to cost due to custom design, it has minimal moving parts, requires non-specialised skill to replaces key components such as hinges, and maximises ventilation. All windows should be made of powdercoated aluminium, and be installed with thermal break strips, flyscreen, flashing and caulking to make the windows air tight.

Windows also provide security and safety from the elements, as well as reduce the effects of dust within a house.

Door Systems

Another targeted system intrinsically tied to cooling performance of housing is door systems maintenance. Door maintenance or upgrades provide security, weather sealing, and cross-ventilation if fitted with flyscreens.

Design considerations:

When exmaining what maintenance may need to be performed on a door system, the following items should be checked:

- hinges - architrave

- leaf - handles/hardware

- locks - weatherseals

- caulking - flyscreens

If any of these items are damaged they should be fixed to enable correct funcitioning of existing windows. These repairs should be carried out as per the Healthabitat methodology.

Improvements on existing doors can be added with the following:

- upgrade of door hadrware to prevent handle breakages

- thermal break strips

- steel kickplates

- replace the leaf (assumed existing solid core) with fibreglass leaf if required

Doors are intrinsically linked to the health outcomes of tenants within these houses, and specifically to allowing cross-ventilation through the building. Maintaining hardware, flyscreens and opeation of the doors is top priority. If the door leaf requires replacement, a fibreglass door is much more durable to occupancy use, UV radiation, and provides better thermal comfort than a solid core or hollow core door. The durability can be increased through applying a steel kickplate, and correct door hardware. This project recommends Assa Abloy TESA AISI 316c or equivalent, due to its corrsion resistance, hidden screwes, high quality material, and recoil spring protected resin cartridge.

Active Cooling Maintenance

As discussed, active cooling maintenance in arid remote areas such as those in the Northern Territory is no longer a luxury, but a nescessity. These systems are extremely important when days exceed 40C for long periods of time with no reprieve - especially for young childeren, elderly or those with medical conditions.

Design considerations:

Active cooling systems such as evaporative coolers, also known as ‘swampies’ are useful within arid environments as they humidify the air and use a fan to blow damp cool air into a house - which is one of the most effective physiological ways of cooling the body.

However, the maintenance of these systems can be difficult due to the ‘hard water’ found in these areas, which often come from bore systems underground. This calcifies the cooling pads at a quicker rate than a water main or rainwater supply. The recommended solution to this would be to install a rainwater tank on the property, to use some of the water to reduce the degredation of the cooling pads. However, if this is unavaliable, then investigation into water softeners could reduce the effects of bore water on these systems.

When examining these systems for maintenance, the following items should be assessed, and if required replaced:

- Pads - Pump

- Filter - Water softener

- Float valve - Bleed off fitting

- Motor pully and belt tension

- fan

Active cooling systems not only help improve the thermal comfort of a house, but can also reduce the negative effects of overcrowding. By supplying a cooling system that can be utilised in many rooms of the house, there is less risk of a room becoming overcrowded because it has an artificial cooling unit.

Window shading system

Window shading has been proven to be more effective when applied on the external face of a wall, as it prevents heat from entering the building. The optimum shading system is one which prevents summer heat into the building, whilst allowing winter sun - to allow for building cooling in summer and warming in winter.

One of the most proven and effective shading systems are louvre systems - which can come in fixed blades, or in operable louvre systems that range in price and come in a large range of materials.

When applying this to an arid environment, the largest problem with operable louvres is the complexity of moving parts, and the dust - as dust can cause significant corrosion.

This project proposes a manually operated louvre system, which can be changed seasonally which will minimise amount of moving parts which will improve maintenance and cost, whilst also allowing optimised response to the environment. The louvres are made from powdercoated aluminium, and fixed with simple nuts and bolts clamping the louvre to the frame. These can be applied to any window on the house, with a thermal break seperating it between blockworkto stop heat transference.

The louvre angles have been calculated to respond to site-specific solar angles to maximise cooling and heating throughout the year.

For the Mt Liebig area, calculating the depth of required eaves for shading of window systems, the angle of the sun requires eaves of 2.5m to allow for full shading, and as such eaves in this area are not an option. It is recommended that verandahs be used instead.

Window shading systems help reduce temperature, but also help reduce access for dust to enter a house.

Ceiling Insulation

The existing condition of many of these houses located in the Northern Territory are assumed to have a lightweight truss roof system with the metal roof sheeting directly fixed to the trusses. Whilst it is widely known that applying reflective roof blankets to the underside of metal roof sheeting to improve thermal efficiency of a house, this is not possible as a retrofitting solution without the removal of the roof sheeting.

Thefore, the proposed insulation should be applied to the ceiling of the house. As outlined in the National Construction Code, insulation for roofs within these areas is recommended at an R-value of 4.6.

For ease of installation and performance of the ceiling insulation, glasswool is readily avaliable ceiling insulation, and can be retrofitted into the existing ceiling cavity without skilled labour. Glasswool insulation is composed of recycled glass, limestone and soda ash which is converted into fbres and manufactured into rolls. It is non-combustible, resistant to rot and corrosion and has very low moisture absorption and low thermal conductivity.

An example of a proposed glasswool insulation that meets a R5.0 value is Knauf Earthwool Ceiling Batt. It has a 50 year warranty, compression packed for more product per pack, odourless, safe to handle and install. The material code is 2437543, and is 210mm thick. Each pack covers 5.5m2 of area. Each pack is $88.

It is recommended that this product or an equivalent is used.

Ceiling insulation helps to create a thermal envelope, which prevents heat from entering the house, and therefore makes it cooler during hot periods. Ceiling insulation can also reduce the effects of overcrowding, as it can create a consistent thermal comfort throughout the home.

The alternative is that as walls become hot with the passing of the sun, people will tend to move to cooler rooms in the house. If overcrowding is an issue, than ceiling insulation will reduce the impact of overcrowding due to thermal comfort and solar heat gain.

Ceiling fans

As argued, maximising ventilation in an environment below 35 degrees celcius provides the greatest cooling effect with minimal cost, and without the need for artificial cooling systems.

Ceiling fans were investigated for this project in both outdoor and indoor use - however due to the dust in the arid environment of the Northern Territory, the motor system is too delicate to withstand outdoor systems and would result in costly maintenance.

The ideal indoor ceiling fan should have 3-5 blades at 12-15 degree pitch to maximise airflow. These fans should be mounted above 2100mm from finished floor level for safety. The size and number of fana should be suited to the size of the room. 48” or smaller fans should be in rooms smaller than 3m x 3m. Rooms between 3m x 3m and 4m x 4m should be sized between 48” - 56”. Rooms larger than 4m x 4m should have fans larger than 56”. The operation of the ceiling fans should be able to have different speeds to allow for user comfort, and be of a durable material - typically a white powdercoat metal fan with corrosion resistant paint is sought after. Fans with a DC motor use 70% less energy than those with an AC motor and should be considered.

An example of a specified ceiling fan is the 360 Fans DEL56MW, Delta 56” (142cm) Matte White 3 blade DC ceiling fan. This fan is avaliable from Bunnings, and has a 3 year warranty, 6 speed remote control with summer and winter reverse modes. The material is polymer moulded blades, which are quieter than metal blades, corrosion proof, UV stabalised, easy to maintain, weather resistant and is long wearing.

Ceiling fans through providing proven effectiveness and reducing indoor temperature, creating cooling effects, and reduce energy insecurity - their consistent placement throughout a home can reduce the effects of overcrowding by increasing ventilation.

Roof Solar Absorpance

Solar heat transference happens at a greater rate with darker colours, especially when they’re on materials that have a high heat transference such as metal.

An easy way to reflect heat and heat transference is to have a light roof colour, which will help reflect solar head gain.

If the existing roof colour is not light, then painting the roof a lighter colour will help reduce the solar heat gain.

When looking at Colourbond colours and roof metal sheeting, solar absorpance levels are considered on new builds to aid with the thermal enevelope. It is recommended that a roof solar absorpance level (SA) of no higher than 0.745.

If choosing a paint colour, it is important to keep a similar solar absorpance level in mind - and this should be specified by the paint supplier.

When painting an existing metal roof sheeting it is important that it is cleaned and prepared correctly so the paint will be applied in a way that is durable, and low maintenance. It should be scoured and left with a slightly abraded finish so the new paint will bond with the metal roof. Then a primer with anti-corrosive properties should be painted on the roof. Once this has dried, then two coats of colour are applied.

Note:

All new metal sheeting products to be of a solar absorpance level of 0.48 or less

Solar roof absorpance levels can reduce the effects of solar heat gain into a ceiling cavity, and therefore reinforces the thermal envelope which aids in cooling the building. This can make a home more livable, and as such can reduce overcrowding of tenants seeking alternative housing which may have a lighter roof colour, or a better thermal envelope.

Verandahs

Verandahs are one of Australia’s greatest home features when analysing cooling methods within a hot envrionement. The verandah creates many solutions to the problem of hot houses through the following:

- They create shaded outdoor living areas, therefore reducing the effects of overcrowding within the home

- Verandahs in remote communities are often used for alternative (or in some cases preferred) sleeping and cooking facilities

- Verandahs enable a better connection to community and country through enagement to the surrounding environment

- Verandahs provide shading to walls and window openings if installed at the correct length, which can reduce thermal mass heating of masonry walls, and double as a window shading device which reduces solar heat gain through glass.

- Verandahs can be fitted with gutters and downpipes to harvest rainwater which can be used as an integrated system for shade planting or washing etc.

- Verandah construction is simple and cost effective for the amount of benefit it can provide a household. It also very durable and has been a proven method of house cooling in the Australian envrionement.

Whilst being the most expensive phase of the proposed kit-of-parts, the verandah is a long term durable investment which has one of the largest effects to the household, with low maintenance and upkeep.

As described above, verandahs can reduce overcrowding, improve the thermal comfort of a house, improve nurtition by creating outdoor cooking facilities, and provide a method of rainwater collection to utilise for washing clothes or people.

Veneer Wall

Similar to window shading systems, providing a heat barrier on the external face of walls can help reduce the heat transference into the building. This system has been designed to be applied to the external face of existing blockwork buildings - both undercover and exposed.

The undercover option can add reflective insulation to the underside to create a greater resistance to heat transference. It is important that the veneer wall has both flashing, capping and storm mould to protect the metal sheeting from corrosion. The top hats should be attached to the blockwork wall with a layer of thermal break strips between to ensure that heat transference does not occur.

These veneer walls should be applied to elevations which are exposed to direct sunlight, or exposed to a heat sources to mitigate radiant heat transfer.

The veneer walls reduce heating effects on external house walls by creating an external ventilated and insulated wall, which protects the wall of the house. It is important to note that this method is most effective on walls completely exposed to sunlight, or to be applied where existing verandahs or eaves do not shade the entire wall of a house - and can be applied at appropriate heights to reduce the heating effect on these walls.

Veneer walls reduce temperature, and also can reduce the effects of overcrowding by minimising the effects of solar heat gain on masonry walls, creating a negative thermal mass heating effect which can cause people to seek other parts of the house that have better thermal comfort.

Half Wall

Half walls provide many uses to tenants in arid environments. They are usefule to semi-enclose verandah spaces to aid with cooling, dust reduction and creating indoor-outdoor spaces for living.

These walls are particularly useful when investigating cooling methods as it can help overcrowding by making outdoor spaces more livable through shading and insulating - but they also create an extra barrier to key walls on a house that could be subject to direct sunlight.

These walls can be fitted inbetween existing columns on verandah structures, or they can be added as part of the verandah extension.

It is important that these walls do not exceed 1m in height, as it could become a privacy concern by reducing visual amenity - but can still be used by someone if they were sitting on the ground.

Gates can be added to prevent animals entering the verandah space which can improved these areas if being used for outdoor cooking or sleeping.

The half wall has been designed to be able to be hosed down for cleaning purposes, and to be resistant to vermin.

Similar to the effects of the veneer wall and verandah, the half wall provides shading and enclosing of outdoor areas which can cool down the slabs and surrounding walls, improving the thermal comfort of these areas. This therefore can help reduce the effects of overcrowding by creating cooler outdoor living envrionments. The half wall also aids with dust reduction, by creating a barrier between outdoor and indoor areas.

Solar & Solar Hot Water

A significant reason to failing cooling methods within remote arid environments is inaccessablity to energy - typically due to pre-paid metering systems, and during peak heat waves, active cooling systems drain energy resources.

As aforementioned this not only effects tenants health in regard to heat, but also causing them to choose between food, cooling, and medication. This leads to extreme adverse effects on health and wellbeing of tenants due to energy insecurity.

A climactic condition of remote communities in Australia is long dry period of full sunlight. Whilst creating a problem of hot houses, it also opens an opportunity for energy collection through solar.

Whilst solar panels in general are a great energy saving device and are kind to the environment, they can have a high upfront cost. This project prioritises hot water solar heating. 70% of electricity costs within a home is from heating and cooling, with 21% of that being hot water energy.

When specifying solar hot water systems, choosing one with frost protection, roof mounted, with electric booster - these systems require no electronics or pumps and therefore are easier to maintain. Heat pump (air sourced solar) systems have zero running costs and are 70% cheaper than gas or electric hot water heating.

Another important consideration is knowing how much hot water the household uses. Typically a household of 5-6 users 348L of hot water a day in an efficient home, and 692L in a non-efficient home. This must be calculated to ensure that the specified system will meet household needs.

Solar and solar hot water indirectly help the cooling of a house by reducing the impact of energy insecurity and the cost of running artificial cooling systems. This can also reduce overcrowding, as when power is shut off, people tend to move to housing which has power and facilities.