Living sustainably

Buildings

Energy use in the Australian residential sector 1986-2020

Department of the Environment, Water, Heritage and the Arts, 2008

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Main report

Appendix A-H

Executive Summary

Climate change is recognised as one of the greatest challenges facing Australia, and the world today. The consumption of energy in the residential sector is a significant contributor to Australia’s stationary energy greenhouse gas emissions. It is therefore imperative that detailed and accurate quantification of energy consumption is used as a basis for the development of climate change response strategies.

Commissioned by the Australian Government, Energy Use in the Australian Residential Sector: 1986-2020 is the second national baseline study on residential energy use. The first study was published in 1999 and provided a quantitative foundation for the development of greenhouse response measures. The reports were produced on behalf of the Australian Government by energy planning and policy consultants Energy Efficient Strategies Pty Ltd (EES). The study includes private residential dwellings, both those that are separate, such as single detached family homes, or attached, such as townhouses and apartments. Energy consumption estimates were made assuming a basecase scenario or ‘Business as Usual’ (BAU). This scenario incorporates the impact of Australian energy policy programs in place or finalised by mid 2007.

For the project, the consultants developed a bottom-up enduse model that tracked energy consumption at a state level from 1986 to 2005 with projections to 2020. This end-use model includes complex stock models of each major end-use, covering ownership, technical attributes and usage patterns. The model separately tracked four main categories of end use; space conditioning, water heaters, cooking products and appliances. In addition, the four main fuel types of electricity, mains (natural) gas, LPG and wood were also tracked. The energy contribution of solar water heating to total water heating energy requirements is explicitly estimated in this study. In all, nearly 60 different end-use and fuel combinations were separately modelled for each state and territory.

Main findings

Between 1990 and 2020 the number of occupied residential households is forecast to increase from six million to almost 10 million, an increase of 61%. Over the same period, total residential floor area is set to rise from 685 million square metres to almost 1682 million square metres, an increase of 145%.

The study estimated that the residential sector energy consumption in 1990 was about 299 petajoules (PJ) (electricity, gas, LPG and wood) and that by 2008 this had grown to about 402 PJ and is projected to increase to 467 PJ by 2020 under the current trends. This represents a 56% increase in residential sector energy consumption over the period 1990 to 2020. This increase coincides with a continuing trend towards an increased proportion of the total residential energy demand being met by electricity (which currently has a high greenhouse gas intensity) and a decrease in the use of wood (with a low greenhouse gas intensity). Although this study does not calculate the greenhouse emissions, it is likely that this predicted growth in energy use in the residential sector will result in a significant growth in greenhouse gas emissions.

Since 1990 the average energy consumption per Australian household has remained relatively constant apart from the influence of year-to-year climatic and weather variations that impact significantly on space conditioning energy demand. Projecting forward to 2020 there is expected to be about a 6% decline in energy consumption per household compared to 1990 levels. This decline is achieved despite expected increases in service delivery to households, particularly in terms of increases in the average size of houses and the types of space conditioning equipment and in a diverse range of appliance types, such as larger, more power-intensive televisions and an increase in standby energy consumption, lighting, computers and other home entertainment. The decline in energy consumption per household is primarily being driven by existing and planned energy programs designed to improve energy efficiency of appliances and the building shell.

The trend in per person residential energy consumption shows a steady but modest increase from 17 gigajoules (GJ) per person in 1990 to 20 GJ per person in 2020, or approximately a 20% increase over the study period. This increase in energy consumption per person is partly being driven by a decline in the number of persons per household, as there are some forms of fixed energy consumption that are associated with each household.

Trends by fuel type

The contribution of electricity to total residential energy consumption is predicted to increase from 46% in 1990 to 53% in 2020. Natural gas consumption is also expected to increase from 30% of total energy consumption in 1990 to 37% in 2020, while wood is predicted to decease from 21% to only 8% over the same period. LPG use will remain relatively unchanged and is expected to contribute to 2% of energy use in 2020.

Trends by end use

Growth in electrical appliance energy consumption was the largest among major end-uses and was estimated to increase from 70.5 PJ in 1990 to 169.4 PJ in 2020, which represents an increase of 4.7% per annum. By 2020 energy use by electrical appliances is forecast to almost match space heating as the largest single energy end use in the average Australian household. Energy demand for space heating is forecast to continue to rise from 126.2 PJ in 1990 to 173.9 PJ in 2020, but at a slower rate in comparison to appliances (1.3% average growth per annum, 1990 to 2020). Water heating is the only major energy use predicted to decline over the study period, principally as a result of various energy programs undertaken by Commonwealth and State/Territory Governments. After plateauing in 2002 at 92.4 PJ water heating energy use is expected to decline slowly to 83.5 PJ by 2020. The key drivers for changes in water heating energy are an increase in the share of gas and solar technologies with a corresponding decrease in electric storage hot water together with some additional impact from electric water heater mininmum energy performance standards (MEPS) in 1999. The gradually declining demand for hot water has also resulted from an increase in waterefficient appliances such as front-loading washing machines and low-flow shower heads combined with a decline in the number of people per household.

Of all the major end uses, space cooling is forecast to show the most rapid growth over the study period with an average growth of 16.1% per annum. This growth comes off a very low energy base of 3 PJ in 1990, so even with this high rate of growth, in total energy terms, by 2020 energy consumption for space cooling is only 17.7 PJ, or 4% of total residential energy consumption in that year. However, despite its low contribution to total energy consumption, space cooling is an end use that attracts considerable political and policy attention due to its very poor load factor and the potential to create major problems for the electricity generation, transmission and distribution systems on peak summer days.

Trends in building shell efficiency

Analysis of the building approval data has revealed that the average size of new dwellings is increasing rapidly. From 1986 to 2020 the total floor area of residential dwellings is expected to increase by 280% while the number of households is only projected to increase by 177% over the same period.

The national trend for building shell energy efficiency (ie total potential space conditioning load per square metre of floor area), shows a modest but steady improvement over the study period, down from 280 megajoules (MJ) per square metre (m2) to approximately 200 MJ/m2. This improvement is being driven by policy initiatives that commenced in Victoria and the ACT in the 1990s and by 2005 had expanded to include all states through the Building Code of Australia (BCA). Unfortunately, the improvement in building shell efficiency over the study period has been outpaced by the rate of increase in average floor area. This has occurred to the extent that the potential space conditioning load is estimated to have increased from about 30 GJ to 35 GJ per household per annum from 1986 to 2005.

Emerging trends

Space conditioning

Energy demand for heating and cooling is projected to increase despite the introduction of minimum building shell performance standards in all jurisdictions. The main factors driving this trend are:

The study also found some evidence to suggest that emerging trends in the climate have been subtly limiting the growth in heating loads and accelerating the growth in cooling loads in all parts of Australia except the tropical north.

Water heating

In 1990 water heater usage accounted for approximately 84 PJ, this is estimated to have peaked at approximately 92 PJ in 2002 but is projected to slowly decline to 84 PJ by 2020, despite an increase in household numbers. The most significant trend over the study period for water heater energy use is the shift away from resistive electric heating (primarily storage systems) towards natural gas or combinations of solar with gas or electric boosting.

Increased natural gas use has coincided with the expansion of the natural gas network, which is growing steadily, but still only covers 46% of Australian households (in 2005). Instantaneous gas units have also gained favour because of their compact size and their capacity to provide a continuous flow of hot water. Solar water heating systems have also gained popularity over recent years (although the installed base was relatively small up to 2003 with a national average of about 4%). This increasing trend is being driven largely by initiatives at the state level. Some of these schemes are also boosting the stock of heat pump solar water heaters, which may become more significant over time as the capital costs are likely to fall.

The application of MEPS, existing and emerging state and BCA requirements mandating the use of lower greenhouse intensive technologies (GWA 2007), and the various incentive schemes designed to encourage greater use of solar and heat pump technologies all combine to result in an overall downward trend in total energy consumption for water heaters from 2002 to 2020.

Refrigerators and freezers

Refrigerator and freezer energy use grew slowly at the start of the study period but has been in decline since 2004. In 1986 refrigerators and freezers usage combined accounted for approximately 26 PJ and by 2020 this is projected to have decreased to approximately 24 PJ. This decrease is predicted to occur despite an increase in total stock (refrigerators and freezers) from approximately 10 million units in 1986 to an estimated 17 million units by 2020 (70% increase).

Since the early 1990s the average energy consumption of new refrigerators and freezers has improved significantly, with a 40% reduction from 1993 to 2006 (EES 2006). These improvements have been driven by both the energy labelling program and by the introduction of MEPS requirements in 1999 followed by more stringent levels in 2005. The 2005 MEPS levels will continue to place downward pressure on energy growth for these products over the study period.

IT equipment

Energy use of personal computers, laptops, monitors and miscellaneous Information Technology (IT) equipment has been growing rapidly since the start of the study period. In 1986, energy use of IT equipment was negligible; this was estimated to have increased to nearly 8 PJ by 2005 and is projected to continue to rise to almost 15 PJ by 2020. The main drivers for the increase in energy consumption have been:

Hours of use have almost doubled since the early 1990s from approximately 500 hours per annum to more than 900 hours per annum. This is projected to continue to rise to approximately 1200 hours per annum by 2020. There is a large potential for energy management of these products to reduce energy consumption.

Entertainment (games, set-top boxes and televisions)

Games consoles, set-top boxes and television (TV) energy use have been growing significantly in recent years. In particular, television energy use has been growing steadily since the start of the study period but is now projected to grow more rapidly over the remainder of the study period. In 1986 TV usage accounted for approximately 3 PJ and in 2005 was estimated to have increased to approximately 12 PJ and is projected to exceed 45 PJ by 2020 (without the introduction of MEPS and energy labelling.

The main drivers for the projected rapid increase in energy consumption are as follows:

Lighting

Lighting energy use had shown steady and relatively strong growth since the start of the study period but is expected to decline from 2010 to 2015 then begin to rise again for the remainder of the study period. In 1986 lighting energy usage was approximately 13 PJ and by 2005 this is estimated to have increased to nearly 25 PJ with a peak of just over 27 PJ in 2010. Following a dip in energy consumption post-2010, consumption is projected to rise again to approximately 25 PJ by 2020.

Apart from the growth in the number of households and the increase in floor areas of those households, the main drivers influencing the general upward trend in lighting energy consumption are:

Areas for further research

The study identified a paucity of end-use data for residential energy use in Australia, particularly in regional areas. Some of the appliance energy consumption estimates used in this study rely on research that is 15 years old or, alternatively, on work undertaken in New Zealand.

Further research is recommended in a number of areas, including:

Energy use cover

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