The housing sector in Victoria is a major energy and resource user. There is growing concern over climate change we need to be more committed to the reduction of greenhouse gas emissions, sectors such as housing need to have more sustainability in the future.
Australian housing industry builds around 145,000 new homes every year adding to the housing stock of 7.8 million dwellings. The housing type in Australia is mostly low density homes which requires increased amount of resource and energy use that is not sustainable.
In the State of Victoria, a 5 star home energy rating standard has been implemented from July 2005. This legislation means every new home constructed from July 2005 has to obtain an energy rating of 5 star for the building occupancy certificate. Plus a rain water tank or a hot water system must be installed. This is a good step towards sustainability in the housing sector.
Australian housing style is mostly low density homes. Low density housing requires large investment such as road networks, water and wastewater networks, gas and electricity, telecommunication etc.
The construction of buildings in Australia, has a massive impact on the environment. impacts include use of land, materials and energy this then turns into greenhouse gas emissions and the production of other waste.
Housing sustainability components include passive solar design, onsite use of solar energy, solar hot water, solar panels, efficient water use, harvesting rainwater on site, grey water recycling, use of landscape and shading to minimize energy usage etc. On the materials and construction side, use of natural and recycled materials, low embodied energy materials and efficient construction techniques are important. A description of main ways to help improve efficiency in Victorian homes:
Insulation is the single most important aspect of good thermal design. The measure of insulation is R value. It is the measure of the product’s resistance to heat transfer and is a guide to its performance as a heat insulator. The higher the R value, the more effective the insulation is in reducing heat flow. To achieve 5 star rating for houses in Melbourne, the minimum recommended R value is R2.5 to R3.0 for ceilings and R1.5 for external walls.
The purpose of thermal mass is to store heat energy when it is daytime and release when it is night thereby reducing the temperature extremes. A concrete slab on ground or masonry walls can act as a thermal mass. Care must be taken so that thermal mass has sufficient solar access during winter otherwise it may actually increase the heating demand.
It is possible to produce 100% of a home’s electricity using solar panels. A major problem is that not necessarily the sun will shine every day or when it is needed most. But in which case the household will still supply the panel grid when electricity is produced in excess and take from the grid when it is needed and the household will be charged for the net amount of electricity used. The cost of solar systems is sometimes costly although currently they usually pay off in 5-6 years’ time.
Double glazed windows
A great portion of heat loss in a house can occur through the windows and it can be prevented by double glazing the windows. Double glazing comprises two panes of glass with a sealed space (about 12 mm of width) between. The space is filled with air or an inert gas with better insulating properties than glass.
Solar hot water system
Water heating accounts for about 30% of energy use in an average household. A solar hot water system can greatly reduce the energy use in a home in Australia and is highly cost-effective than the solar system. Most solar hot water systems use solar collectors or panels to absorb energy from the sun. Water is heated by the sun as it passes through the collectors. It then flows into an insulated storage tank for later use. A solar hot water system should be gas boosted in times of higher demand if gas is available.
Includes low flow fixtures, rainwater collection and grey water reuse. Efficient plumbing fixtures and appliances include AAA rated shower heads, dual flush toilets, water efficient washing machines and dishwashing machines etc. A rainwater tank collects roof runoff and is easy to install and the water may be used for all purposes permitting regulations. A grey water recycle system typically can supply water to subsurface irrigation of the garden.
Waste minimisation and recycling
Waste minimisation can be achieved at construction phase and operation phase. In Australia, approximately, 40% of all waste going to the landfills are building waste. There are private companies who do the recycling of demolished building waste commercially. At the operation stage, separations of recyclables at source your home from other waste to help the local councils in collecting and processing recyclables is important. Local councils generally provide two separate bins for households. In most council in Melbourne, even more bins are provided to facilitate separation of recyclables at source. Organic waste can be composted in a compost bin and used as manure in the garden.
The dwelling I have chosen to inspect is the home I live in currently. It is a 20sqm home roughly two years old. Single story brick home with open living with four bedrooms and two bathrooms. The house contains a split system air conditioner in the main living room with a ducted heating system running throughout the household. Solar panels have also been fitted on the north side of the roof and a water tank for storm water run-off. The house has been built to a 5 star energy rating. The dwelling I believe is quite sustainable as it does have a 5 star energy rating but there are still ways it could be improved to reach a higher sustainability level. The three ways my dwelling could be sustainably improved are through heating and cooling systems, Insulation and shading. Below I have detailed in a little more depth each of the three most beneficial ways for me to increase sustainability not only in my house but other homes too.
Beneficial sustainability measures for my home
Heating & cooling uses very little energy and required to make a well designed house. Heating and cooling account for 38 per cent of household energy use making it the largest energy user in the average home.
There are two types of main heating in a home radiant and convective. Radiant heaters which heat people and objects by direct radiation of heat. Convective heaters warm and then circulate the air in a room. Other forms of heating do include heated floors.
Different types of heating are best in different rooms
- In larger rooms with higher ceilings, a combination of radiant and convective heating is most effective.
- In small rooms, space convective heating is very effective.
- In larger rooms or bathrooms, radiant heating is effective.
Central heating Uses more energy than normal space heating as more of the house is heated. Efficient house with central heating may use less energy overall than an inefficient house with space heating. Several types of central heating are available. Central heating can often heat a whole house whether individual rooms are occupied or empty. Space heating heats the one or two rooms that are in use.
Hydronic systems Hot water is circulated through radiator panels in rooms which provide convective and radiant heat. Hydronic systems are usually gas operated but can be heated by a wood fire heater, solar systems or a heating pump. Low water content systems are more effective as they reduce energy use and cost. It is very important that the water circulation pipes are well insulated and installed for the best results.
Open fireplaces Open fireplaces provide a large radiant heat, but are very inefficient, with up to 90% of the heat energy going up the chimney and into open air. Large amounts of cold air are sent into the room to replace air lost up the chimney. They are the least efficient heating method and produce the highest levels of air pollution.
Electric fixed heaters Reverse cycle heated pumps provide convective heat and are the most energy efficient electric heater. Wall panel convectors use the peak electricity and are expensive to run.
Gas fixed heaters Wall units and floor consoles can provide convective and or radiant heat. They usually contain fans to circulate hot air. Requiring less ventilation and producing fewer condensation problems.
Cooling Helps increase the comfort. The major mechanical cooling are fans, evaporative coolers and air conditioners.
Fans Fans are the first choice when it comes to cooling. With good design and insulation, fans can often provide cooling for all residents in all Australian conditions. They save money and the environment. Fans are the cheapest to run providing they aren’t working 24/7 and have the least greenhouse impact, while air conditioners are expensive to run and produce more greenhouse gas.
Fans cost little to buy and run. They circulate air but do not reduce temperature or humidity. Portable table and floor fans or fixed ceiling and wall models are available. Fans are useful in combination with an air cooling system as the extra air movement provides comfort at higher thermostat settings.
Evaporative coolers The other choice for mechanical cooling is evaporative coolers. They are significantly less effective in climates with high humidity. Operating costs can be low as only the fan uses most of the energy. Evaporation provides the cooling energy. Many units have inefficient fans that consume more energy than it needs to. Evaporative coolers use water on the cooling medium.
Air conditioners If the right comfort cannot be achieved with a good passive design or fans or evaporative cooling then air conditioning should be considered. While normally giving a higher level of comfort, air conditioning consumes more energy and creates more greenhouse gases than fans and efficient cooling systems. Air conditioning can provide comfort in any Australian climate. For efficient air conditioning, the house or room should be sealed and well insulated with bulk insulation. Windows must also be shaded and closed to minimise the summer sun. Purchase costs are higher than evaporative coolers. Efficiency varies between units and models.
Shading Reduces summer temperatures improves comfort and saves energy. Shading can block up to 90 percent of heat. The following concepts are ways shading helps improve sustainability throughout the house.
Shading of glassto reduce unwanted heat gain is critical. Unprotected glass is often the greatest source of unwanted heat gain in a home. Most cost effective way to shade the property. Shading of walland roof surfaces is important to reduce summer heat gain, particularly if they are dark coloured and/or heavyweight. Deep verandas,balconies or pergolas can be used to shade east and west elevations, but may still admit very low summer sun. Use in combination with planting the filter out un wanted sun. Drought tolerant plantsinstead of paving where possible, try to plant tall plants to keep the temperature of the ground and surrounding surfaces lower in summer. Skylights need to be protected with blinds or louvers. This is crucial as roof glazing receives almost twice as much heat as an unprotected west facing window. GlazingSuch as solar films and tinted glass may be used as shading. They can exclude up to 60 percent of the heat compared to plain glass.
Insulation Acts as a barrier to heat flow and is needed to keep your home warm in winter and cool in summer. An insulated and well made home will provide comfort, cutting cooling and heating bills by half. This can reduce greenhouse gas emissions. Insulation can be added to existing buildings with varying effectiveness and cost depending on the construction type and where the insulation is being placed. Ceilings and suspended floors with easy access are relatively simple to insulate post construction. Insulation board can be laid beneath floor finishes if there is no under floor access.
Insulation can be added to existing buildings but is not very cost effective with varying effectiveness and cost depending on the construction type and where the insulation is being placed. Ceilings and suspended floors with easy access are relatively simple to insulate after construction. Insulation board can be laid beneath floor finishes if there is no under-floor access. Walls and roofs are the hardest to insulate after construction, as the internal or external lining must be removed. A good time to insulate walls is during recladding or replastering.
Housing sustainability in Australia can be achieved progressively. The 5 star standard introduced in Victoria was a major step in this direction. If this standard is successfully incorporated in the national Building Code of Australia (BCA), this will be a huge steptowards housing sustainability in Australia. The outcomes achieved from the Ecohome, a five star home, will be useful to the industry and policy makers and will help towards sustainability in the housing sector.