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Housing and Lifestyle: Energy efficiency in the home
Although the proportion of energy directly consumed in the home is relatively small (8% of the energy consumed in Australia in 1998-99), all energy saved helps reduce greenhouse gas emissions. An energy efficient household can make substantial financial savings compared with an energy inefficient household, with the main benefits coming from insulation and solar water heating.2 In addition to financial savings, insulation and energy efficient design initiatives can also improve the physical comfort of a home. Most households that had installed insulation did so to improve comfort (87%) or reduce energy costs (9%), rather than to save energy (2%).3
Despite homes becoming more energy efficient, Australians are using increasing amounts of energy in the home: 20GJ per person in 1999 compared with 18GJ per person in 1980. Current residential energy efficiency measures are projected to only slow the rate at which our residential energy consumption increases.4 Increasing per capita energy consumption in the home may be related to the trend towards smaller households with larger houses5 (see Australian Social Trends 1998, Smaller households, larger dwellings). Another factor may be the increasing standard of material wellbeing enjoyed by most Australians, reflected in the plethora of electrical appliances on shop shelves.
The need to reduce greenhouse gas emissions has led to policies directed at increasing energy efficiency in new residential housing. Currently, the Australian Greenhouse Office and the Australian Building Codes Board are working together to incorporate principles of energy efficiency into the building code.6
In Victoria, the Australian Capital Territory and in some New South Wales councils, mandatory energy efficiency regulations have been introduced. These regulations are often based around awarding 'stars' to homes that meet specific energy efficiency requirements and specifying a minimum star level for new homes. In the Australian Capital Territory all homes offered for sale must advertise their officially determined energy efficiency star rating.7 However, the overall level of energy efficiency in Australian homes will be slow to increase because new houses make up a small proportion of the housing stock.
The greatest energy savings can be made when a house is designed and built specifically to be energy efficient. The most important design factors are the construction materials used, the building's design and orientation relative to the sun, and the inclusion of insulation and high performance glazing. These factors reduce the energy costs of maintaining a comfortable home throughout the year. However, most of Australia's housing stock predates concern about energy efficient design and cannot be improved without modifications.
In 1999, 56% of Australian dwellings were sited such that they received winter sunlight into their main living area. Because of the difference in climate between the north and south of Australia, dwellings in the southern States were more likely to be sited to receive winter sunshine. Tasmania (77%), the Australian Capital Territory (71%), and Victoria (64%) all had a markedly higher than average proportion of dwellings receiving winter sunlight in their living area. The Northern Territory had the smallest proportion (31%), reflecting the need to exclude the sun's heat to reduce energy usage in cooling even in the winter months.
Insulation can help maintain a comfortable inside temperature in both hot and cold climates. On a typical brick veneer house, ceiling insulation can save about 25% of heating costs, and wall insulation a further 14%.8
In 1999, nearly half of Australian dwellings had no insulation (46%), although that proportion had declined slightly from 48% in 1994. Although medium and high density dwellings were more likely not to have insulation (63% and 85% respectively), 38% of separate houses did not have insulation. Again, climate had an influence. Dwellings in Queensland and the Northern Territory had the highest proportion with no insulation (67% and 55% respectively). New South Wales (52%) also had an above average proportion with no insulation. Among households that had no insulation, cost was most commonly cited as the main reason for not having insulation (27%), and climate was the next most frequent reason (16%).
Dwellings with roof insulation were more common in the south. The highest proportion was in the Australian Capital Territory where three-quarters of dwellings had roof insulation. Above average proportions were also reported in Victoria, South Australia (both 70%), Tasmania (62%) and Western Australia (57%). A similar pattern prevailed among the 14% of dwellings with wall insulation.
Source: Environmental Issues: People's Views and Practices, March 1999, (ABS cat. no. 4602.0).
The choice of fittings such as water and space heating, and curtains and blinds, is generally made near the time of construction and then changed only infrequently. Water and space heating are usually the largest consumers of energy in a house, accounting for about 27% and 42% respectively of an average household energy bill.8 Consequently, the type of water and space heating used in a dwelling has a considerable influence on energy costs and associated greenhouse gas emissions.
Natural gas is considered to be environmentally preferable to electricity as it produces less greenhouse gas emissions when burnt than a comparable unit of electrical energy generated by burning coal. However, because the majority (60% in 1999) of hot water services are electric and nearly all homes have a hot water service, water heating was responsible for about 28% of greenhouse emissions attributable to homes in 1998. Space heating and cooling were estimated to produce about 15% of greenhouse emissions attributable to energy consumption in homes.4
In 1999, 35% of homes had gas hot water heating, a similar proportion to 1994 (34%). Geographical differences probably reflect the availability of reticulated gas at the time of installation. For example, Tasmania had a very low proportion of dwellings with a gas hot water service since there is no reticulated natural gas supply there. The above average proportion in Victorian (65%), Western Australian (56%) and South Australian (47%) dwellings reflects the long-established gas supply network in the capital cities of these States.
Solar water heating also reduces a household's contribution to greenhouse gas emissions - albeit at a high capital cost. Some State Governments offer one-off subsidies to assist households to buy solar water heaters. For example, some councils in New South Wales offer a $500 rebate on solar hot water heaters.10 Although only 5% of dwellings in Australia had solar water heaters in 1999, the proportion varied from 44% in the Northern Territory and 20% in Western Australia, to 1% in Victoria and Tasmania. The investment in a solar water heater is recovered faster in the north, where the sun remains quite high even in winter.10
Between 1994 and 1999, among dwellings that had space heating, the proportion of dwellings that had gas space heating increased from 38% to 41%. Geographical differences between States may relate to both climate and the time over which a reticulated gas supply has been available. Cold areas such as Victoria and the Australian Capital Territory had high proportions of dwellings with gas space heating (72% and 52% respectively of dwellings with heating). Western Australia also had an above average proportion of 47% of dwellings with gas space heating. Again, Tasmania had a low proportion, reflecting the lack of reticulated natural gas supply.
Reverse cycle air-conditioners can heat and cool. Their alternative name, heat pumps, describes their function of moving heat from one space to another. They are more energy efficient than other types of electrical heater because electricity is only consumed to transfer heat from the air outside to the air inside. Among Australian dwellings with space heating, 9% had a reverse cycle air conditioner. The States that had an above average proportion - South Australia (19%), New South Wales and Queensland (both 12%) - can have hot summers, suggesting they were primarily purchased for cooling rather than heating.
Heat can be lost by conduction, or gained by transmission and conduction through glass windows. Depending on the area of glass, about 6% of heating costs can be saved by insulating windows with pelmeted curtains or blinds.8 In summer, outside blinds and awnings help keep sunshine out of rooms. Nearly a third of Australian dwellings had outside blinds or shutters. They were most common on Victorian and South Australian dwellings (both 40%) and least common on Tasmanian dwellings (8%).
About a quarter of Australian dwellings had box pelmet curtains or blinds. Victorian and Tasmanian dwellings had above average proportions (33% and 28% respectively) and the Northern Territory was well below average (13%). These differences reflect climatic regions but may also be influenced by fashions trending towards pelmetless curtains in newer dwellings.
A study commissioned by the Australian Greenhouse Office estimated that 52% of greenhouse gas emissions attributable to the residential sector were due to electrical appliances.4 In 1999, nearly all dwellings had a refrigerator, and most had a washing machine (95%). Both are seen as essential appliances. Less common were clothes dryers (53%) and dishwashers (30%). These appliances, which were once luxury items, have become more common in Australian homes. Separate freezers, which were in 45% of households in 1994, have become less common, with 40% of households in 1999 reporting owning one (see Australian Social Trends 2001, Household amenities).
The proportion of households with a dishwasher increased from 25% to 30% between 1994 and 1999. The proportion ofhouseholds with a dishwasher that reported using it everyday also increased, from 32% in 1994 to 35% in 1999.
Front loading washing machines generally use less water and electricity than top loading machines. In 1999, among households that had a washing machine, 7% had a front loader. Another way to decrease energy consumption and associated costs when washing clothing is to use cold water rather than hot water. Among households with washing machines, nearly two-thirds (64%) used cold water to wash their clothes: an increase from 61% in 1994.
While hanging clothes outside to dry is the most energy efficient option, just over half of households had a clothes dryer. However, the majority (71%) of these households used them only occasionally or depending on the weather. One in five households with a dryer used it at least once a fortnight, a decrease from almost one in four in 1994.
Most major household appliances on sale are required to display an energy rating, expressed in stars, to indicate the amount of energy they are likely to consume in a year of average use compared with similar products (for more information see <URL:http:/www.energyrating.gov.au>). However, purchasers did not place a high priority on this facility. Only 34% of households that had purchased major appliances in the past year had considered the energy star rating - the most common consideration was cost (59%).
1 Commonwealth Scientific and Industrial Research Organisation (CSIRO) 1996, Climate change scenarios for the Australian region, Climate Impact Group, CSIRO Division of Atmospheric Research, Melbourne.
2 Australian Consumers' Association 1997. How to save the earth and your money, Choice, April 1997.
3 Australian Bureau of Statistics 2000, Survey of Environmental Issues: People's Views and Practices, 1999, cat. no. 4602.0, ABS, Canberra.
4 Australian Greenhouse Office 1999, Australian Residential Building Sector Greenhouse Gas Emissions 1990-2010: Executive summary report 1999, Canberra.
5 Ironmonger, D.S., Aitken, C.K., and Erbas, B. 1994, Economies of scale of energy use in adult-only households, Research paper No. 438, Department of Economics, The University of Melbourne, Melbourne.
6 Australian Building Codes Board and Australian Greenhouse Office 2001, Energy Efficiency in Buildings, Directions Report, Australian Building Codes Board, Canberra.
7 Bennett, B. 1999, 'Green housing', Ecos, No. 101 October-December 1999, pp. 25-29, CSIRO Publishing, Melbourne.
8 Ballinger, J., Prasad, D. and Rudder, D. 1997, Energy Efficient Australian Housing, National Solar Architecture Research Unit, University of NSW, AGPS, Canberra.
9 Sustainable Energy Development Authority NSW 2001, Trends in Green Power Customer Numbers (as of July 2001)
URL:http://www.greenpower.com.au/download.shtml> (accessed 6 August 2001).
10 Australian Consumer Association 1999. Hot water from the sun and air, Choice, December 1999.