Energy Efficiency

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Better Use of Energy

A  home awarded 3.5 to 5 stars by the Nationwide House Energy Rating Scheme (NatHERS) can save up to 80% on heating and cooling.  Because of the obvious environmental benefits, national schemes, such as Energy Smart Homes, have been set up to encourage good design and provide examples of what can be achieved.  Many local councils support these ideals and require new homes to follow energy efficiency guidelines or passive solar designs.

New homes, however, represent only a small proportion of our housing stock, so there is an even greater need to retrofit existing homes to improve their efficiency. It is estimated that only 20% of all residential buildings in Australia have both wall and ceiling insulation. A further 42% have ceiling insulation only. The remaining 38% have neither (AGO 1999). Even in Armidale with its colder winters, the Armidale City Planner reported that 47% of new houses built in Armidale in 1992 had no roof insulation and 67% no wall insulation, apart from reflective foil. Less than 10% had adequate north-facing glass and thermal mass.

Go to 'Benefits of Energy Efficiency'
Where heat leaks out

42% through the ceiling

24% through the walls

12% through unblocked chimneys and draughts around doors and windows

12% through windows

10% through the floor


Installing adequate insulation is the easiest and most cost effective way to improve overall energy efficiency, because heating and/or cooling account for the greatest amount energy use in our homes.  Installing insulation in the roof space of  existing homes is generally a simple cost-effective operation.  In other countries such as the UK, householders often also install cavity wall insulation.  The process involves drilling holes in the outer wall to inject either foam or rockwool into the cavity.  It is also possible to install insulating wall batts in weatherboard houses.

Heat loss through windows can be reduced by sealing gaps, and using curtains, window quilts, or insulating window shutters to keep heat in at night. However as the house becomes more airtight, greater attention has to be paid to indoor air quality. One possibilty to to use solar air collectors to pre-heat ventilation air, and supplement the existing space heating system.

Residential Energy Use
Total residential energy use in Australia in 1999 was estimated to be 377 petajoules (PJ) (units). The main source of energy was electricity (43%), followed by gas (31%), then wood (21%).  Petroleum, mainly LPG, accounted for 5% (AGO 1999, 2001).

Electricity was used mainly for applicances (59%) and water heating (28%); 5% of electricity consumption was for cooking and 5% for space heating/cooling. The fridge accounted for the highest electricity consumption of electric applicances (14.5% of total electricity consumption), followed by lighting (10%). It is interesting to note that standby power, that is small amounts of power drawn by many modern appliances for electronic controls even when the appliance is not being used, was estimated to be 6% of total electricity consumption.

Gas was predominantly used for space heating (60%) and water heating (35%), with 5% for cooking.  Space heating and cooling was responsible for 43% of total residential energy use, with nearly 49% of the energy provided by wood burning, and 43% by gas.

The Sustainable Energy Development Authority (S.E.D.A.) has a 12 step guide to making your home energy efficient and greenhouse friendly. For example, they estimate that installing ceiling insulation can save you more than $4,000 and 40 tonnes of greenhouse gas over the lifetime of your home. A solar water heater can save 65% of the energy required to heat your hot water, and can qualify for a $500 discount.

Discovering more about energy, where is comes from, how much it costs financially and environmentally, and how we use it, can be interesting school projects - for example, Watt Watchers, and Kids Crusade For Less Energy, featured on Channel 9's ACA, 29 Nov 2001.

Green and Clever - Your Home in the 21st Century
- demonstrates how the latest environmental solutions are being applied to conventional housing, leading to "huge savings for home owners and the environment".

Two community based projects to provide assistance for retrofitting local housing (in New Zealand, any similar here?):-
Opotiki home energy improvement scheme
Community Energy Action provides access to household energy efficiency measures for people on low incomes.
(I think these links are no longer valid.)

Benefits from Energy Efficiency

As well as saving money, improving the energy efficiency of your home and switching to cleaner more efficient sources of energy reduces greenhouse gas emissions and air pollution.

Greenhouse Gas Emissions
Carbon Dioxide (CO2) is the principal greenhouse gas associated with global warming, see Turning Down The Heat.  Also important are methane (CH4), with a global warming potential of 21 relative to CO2, and nitrous oxide (N2O) which has a global warming potential of 310.

Australia has the highest per capita emissions of greenhouse gas among industialised nations (Australia Institute, 2001). According to the Australian Greenhouse Office inventory, Australia produced 458.2 million tonnes net of greenhouse gas in 1999 (latest available figures).

At the household level, Australia's seven million homes are responsible for the production of more than 50 million tonnes of greenhouse gases every year - almost 12% of the total net greenhouse emissions in 1999 - (not considering private motor vehicle use, which amounts to another 42 million tonnes).

The biggest contribution comes from electricity consumption, nearly 46 million tonnes in 1999, or nearly 84% of the total from residential energy use. Roughly 1 kilogram of greenhouse gas is emitted for every 3.5 MJ of energy consumed - thats the amount of energy used by a 1 KW electric radiator in just under 1 hour. (The notable exception is Tasmania where most electricity is generated using hydro power.)

Gas use in the home was responsible for just under 11% of the total greenhouse gas emissions from residential energy use.

Greenhouse gas emissions from wood heating are usually treated differently to greenhouse gas emissions from fossil fuels. Burning wood emits about as much CO2 as burning coal per unit of energy produced - about 89 kg/GJ, and 70% more than natural gas - 52kg/GJ (units). However, biomass is part of the carbon cycle, and growing biomass absorbs CO2 from the atmosphere. Therefore, CO2 emissions from biomass need to be considered within the overall context of biomass change. In the Australian National Greenhouse Gas Inventory, only the non-CO2 greenhouse gases are reported in the the net greenhouse contribution from biomass burning. The CO2 emissions are accounted for in the 'change in biomass' component of the inventory. In the table below, under greenhouse gas emissions from domestic woodheating, 'Actual' refers to the total estimated emissions (including CO2), and 'Net' refers to only the non-CO2 component. There is considerable variation in the estimates of the emissions of non-CO2 greenhouse gases, especially methane (Edgerton, 1986).  Methane emissions depend on the type of heater, ie open fireplace or woodstove, and the method of burning; a low burn-rate with low levels of oxygen produces greater emissions of methane. According to the National Greenhouse Inventory (1999) methane accounts for 94% of non-CO2 greenhouse gas emissions from woodheating, the rest is nitrous oxide. Carbon monoxide (CO) emissions are not included in the total, although it has an important indirect effect on greenhouse gas formation, its global warming potential is not yet fully quantified (IPCC, 2001).

Residental Energy Use and Greenhouse Gas Emissions
  Electricity Gas Petroleum Wood
Energy Use PetaJoules  161.0    116.1    19.3    81.3   
MegaTonnes CO2 equivalent
45.7    5.9    1.2   
Actual: 9.1
Net: 1.8

Further information on greenhouse gases, the effect on global warming, and some steps to reduce greenhouse gas emissions, can be read in Global Warming - Cool It!

Air Pollution
Particulates (PM10), and especially fine particles (PM2.5) are now recognised as the major cause of adverse health effects from air pollution (Schwartz 1996). Particulates are created in fuel combustion processes, including driving motor vehicles (diesel fueled vehicles are the worst contributors) and electricity production. Over the greater Sydney region, including Newcastle and Wollongong, electricity generation is responsible for 15% of total annual PM10 emissions (see table). Natural gas produces very little particulate emissions.

One of the largest sources of fine particles from individual use is burning wood in fireplaces and woodheaters. Particulate emissions from wood burning depend on the type of heater, ie open fireplace or woodstove, and the method of burning; a low burn-rate produces greater emissions.

Although less than 20% of households use woodheating as their main source of heating, smoke from domestic wood burning is estimated to account for 35% up to 50% of total suspended particles in Sydney air in winter (State of the Environment Report 2000). A significant factor is that woodheater emissions are concentrated in residential areas.  Recent research (Morgan 1998) has linked fine particle concentrations with an increase in daily mortality of 400 deaths per year in Sydney. Long term effects are probably several times greater (Brunekreef 1997).

Other important air pollution emissions relating to energy production and use include:

Particles, ozone, and nitrogen dioxide measurements form the main indicators of air quality in the EPA's Regional Pollution Index.

Air Pollution Emissions Sydney, Newcastle, Wollongong Region
National Pollutant Inventory, 2000-2001
  Electricity Production Domestic Solid Fuel Burning All Sources
PM10 2,700        3,100        18,000       
Carbon Monoxide 2,800        31,000        1,000,000       
Oxides of Nitrogen 51,000        390        180,000       
Sulphur Dioxide 67,000        72        97,000       
Total Volatile Organic Compounds 4        12,000        150,000       
Polycyclic Aromatic Hydrocarbons -        72        120       
Benzene -        290        3,900       

Non-CO2 Emissions from Residential Energy Use
Australian National Greenhouse Inventory 1999
  Methane Nitrous Oxides Oxides of Nitrogen Carbon Monoxide Non-methane Volatile Organic Compounds Sulphur Dioxide
Electricity Generation1 1,008    492    125,718    12,071    2,284    116,836   
Petroleum 2 1,950    10    1,100    64,600    17,130    -   
Gas 190    10    4,500    1,900    360    -   
Wood 81,190    330    6,800    597,700    192,520    -   
1 Assuming residential energy use consumes 26.6% of total public electricity generation
2 Non-CO2 emissions from petroleum are mainly caused by lawn-mowers.

Calculate your household energy use greenhouse gas and air pollution profile.
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Page created on Thursday, 9 August 2001.

Created by  Solar Armidale Project