Energy Efficiency
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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

Insulation

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

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).

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:

• Polycyclic Aromatic Hydrocarbons (PAH) - a group of over 100 different chemicals that are formed during the incomplete burning of coal, oil and gas, wood, rubbish, and other organic material. The less efficient the burning process, the more PAHs are given off. PAHs can affect the eyes, kidneys, and liver, and some may cause cancer (in particular benzo(alpha)pyrene). Smoke from wood burning heaters and fireplaces is responsible for 60% of PAH in the Sydney, Newcastle, Wollongong region (excluding motor vehicles?) (see table). Other sources of PAHs are industrial smoke, forest fires, lawn mowers, tobacco smoke, and barbeques.
• Carbon Monoxide (CO) an odourless toxic gas, CO reduces the blood's ability to supply oxygen to body tissues. Small amounts in the air can stress the heart and reduce ability to exercise. Large amounts of CO are produced from woodheating, but the main source is motor vehicle exhausts.
• Sulphur Dioxide (SO₂) The majority of SO2 from the combustion of fuels containing sulphur, mainly coal used for electricity generation (see table). Sulfur dioxide can affect the upper respiratory tract, acting as an irritant and producing symptoms of coughing, wheezing, shortness of breath and reduced lung function. Like particles, higher concentrations in the air have been associated with increased mortality and hospital admissions for respiratory disease.
• Nitrogen Dioxide (NO₂) a brown coloured gas, which is a serious respiratory irritant. NO₂ can cause inflammation of the respiratory system and is associated with increased incidence of respiratory illness. NO₂ also reduces ability to fight infection. Indoors, unhealthy concentrations of NO₂ can build up from the use of unflued gas fires (Environment Australia, 2001).
  Motor vehicles are responsible for two-thirds of NO2 in the Sydney region, while electricity generation accounts for 28%. Together with NO, NO₂ is a major component in development of the photo-chemical smog observed in summer.
• Volatile organic compounds (VOCs) are a group of easily evaporated organic compounds that occur in petrol, paints, and solvents, and are produced during combustion processes. They include formaldehydes and benzene. VOCs irritates eyes and lungs, and some may be carcinogenic. VOCs react with NO₂ and NO in sunlight to form ozone, or photo-chemical smog. Main source of VOCs is from motor vehicle petrol tanks and exhausts, and solvents, but woodheating is also a significant source (see table).

Air Pollution Emissions Sydney, Newcastle, Wollongong Region
National Pollutant Inventory, 2000-2001

	Electricity Production	Domestic Solid Fuel Burning	All Sources
	(tonnes)
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
	(tonnes)
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.