FEATURE ARTICLE: HEATING AND COOLING


INTRODUCTION

Heating and cooling can account for more than 40% of a household's annual energy consumption. How people choose to heat and cool their homes therefore has great impact on their energy use and greenhouse gas emissions. The energy usage of household appliances may vary for a variety of reasons. Some of these factors include the type of appliance, the frequency of use, the period of use, and whether the appliance is new or old. The numbers and types of heaters and coolers in dwellings can also give some indication of the amount of energy used in heating and cooling. Examining the change over time in heating and cooling systems may indicate whether households are moving towards more environmentally friendly methods.

This article looks at household heating and cooling, examining the numbers and types of heaters and coolers used in South Australian households. It also examines reasons why households across Australia have chosen particular types of heaters for their dwelling. This article uses data from Environmental Issues: Energy Use and Conservation, March 2008 (cat.no. 4602.0.55.001), covering the period between June 1994 and March 2008.


HEATERS

In March 2008, 91% of South Australian dwellings had a heater, compared with 77% of dwellings across Australia. Of these dwellings in both South Australia and Australia, around two-thirds had only one heater in use and nearly one quarter had two.

Between 1999 and 2008, the proportion of South Australian households with more than one heater declined from 38% to 31%. This decrease may have been partly due to an increasing tendency for households to install heating systems, such as ducted systems, that can heat the whole dwelling, reducing the need for separate heaters.

TYPES OF HEATERS

Reverse cycle and gas heating generate considerably less greenhouse gas emissions than electric heaters (DEWHA 2008). Between March 2005 and March 2008, the proportion of households using a reverse cycle unit as their main heater increased from 28% to 37%, but gas experienced a small decrease from 36% to 33%. There were decreases in the proportions of households using electric or wood heaters.

FACTORS IN HEATING CHOICES

In the Energy Use and Conservation survey, householders who were responsible for installing the main heater in their dwelling were asked the main reason for their choice. In a separate question relating to household appliances, households that had replaced or bought an appliance in the past 12 months were asked the factors they considered before making their purchase. These data are only available for Australia as a whole, but may give an indication of the considerations for South Australian households in choosing heaters.

In 2008, comfort and convenience was clearly the main reason why Australian households selected their main type of heating. Though comfort and convenience was nominated as the main reason a particular heater was chosen by 39% of households across Australia (for all heater types), 47% of households with reverse cycle heating stated this reason. Using less energy was more likely to be a reason considered by households with gas heaters (17% compared to 12% for all heater types), while those with wood heaters were more likely to state saving on energy bills as their reason (24% compared to 14% for all heater types).

MAIN REASON FOR CHOICE OF MAIN HEATER, Australia - March 2008
	Electric	Gas	Reverse Cycle	Wood	All types(a)
	%	%	%	%	%
Comfort/convenience	44.7	31.6	46.8	29.1	38.7
Cost price	24.7	21.1	18.0	17.0	20.5
Save on energy bills	np	20.1	8.5	23.6	14.0
Use less energy	5.2	16.9	13.5	10.5	12.4
Other	np	10.4	13.2	19.8	14.5
np not available for publication but included in totals where applicable, unless otherwise indicated
(a) Includes oil heaters

In March 2002, 56% of households across Australia stated that they considered cost price when replacing or purchasing any heating appliance in the previous 12 months. The energy star rating was the next most common factor, considered by 32% of households. Between March 2002 and March 2008 the proportion of households across Australia that considered cost price when replacing or buying a heater declined from 56% to 40%, in contrast to a small increase from 32% to 35% in the proportion of households over the same period who considered the energy star rating. In March 2008 only 7% of households across Australia thought that environmental considerations were an important factor to consider when replacing or purchasing a heater, down from 11% in March 2002.

COOLERS

Between March 1999 and March 2008 the proportion of South Australian dwellings with a cooler (an air conditioner or evaporative cooler) in use increased from 54% to 85%, while the proportion of dwellings across Australia with a cooler in use increased from 35% to 66%.

TYPES OF COOLERS

There has been a decrease in the proportion of dwellings with their main cooler set in a wall or window in South Australia, in contrast to an increase in both ducted and split system coolers. The proportion of South Australian dwellings with units set in a wall or window decreased from 68% to 30% between March 1999 and March 2008. Conversely the percentage of South Australian dwellings with ducted systems rose from 28% to 45% over the same period. The proportion of dwellings with split system units has more than doubled from March 2002 to March 2008, rising from 11% to 23%. The proportion of South Australian dwellings with a portable cooling unit as the main source of cooling remained below 5% from March 1999 to March 2008.

SYSTEMS OF COOLING

The proportion of South Australian households with an evaporative system as their main cooler declined from 36% in March 1999 to 26% in March 2008. Conversely reverse cycle or heat pump systems were the main coolers in 35% of dwellings in March 1999 and this increased to 59% in March 2008. In conditions of low humidity evaporative cooling systems can use one-quarter of the electricity required by refrigerated systems (ABS 2006).

CONCLUSION

Data from Environmental Issues: Energy Use and Conservation gives some insight into the way South Australians heat their homes. Since March 2005, households have tended towards gas and reverse-cycle systems for their main heater, and away from electric and wood heating. Data for Australia as a whole shows that environmental considerations rank low among factors considered in heating choices, with comfort and convenience the most commonly stated factor considered.

The proportion of South Australian households with a cooler in use has increased since June 1994, which suggests more energy is being used to cool homes. Over this time, the popularity of reverse cycle coolers has increased, while the proportion of refrigerated coolers has declined. This period has also seen an increase in the proportion of households with split system and ducted coolers and a move away from portable coolers or those set in a wall or window.


LIST OF REFERENCES

ABS (Australian Bureau of Statistics) 2006, Australian Social Trends, 2006, (cat. no. 4102.0), ABS, Canberra

ABS 2008, Environmental Issues: Energy Use and Conservation, March 2008, (cat.no. 4602.0.55.001), ABS, Canberra

DEWHA (Department of the Environment Water Heritage and the Arts) 2008, Global Warming Cool It - Home Heating and Cooling, viewed 2 April 2009 <http://www.environment.gov.au/settlements/gwci/heat.html>