Divorce and the environment

DIVORCE is not just heart-breaking -- it's bad for the environment. When a couple or family separates, they create two households where there used to be one.

Suddenly, the same number of people are using twice the number of hot water systems, two refrigerators, two kitchens, two heaters and two air-conditioners. If there are kids, then sometimes each child inherits two bedrooms instead of one.

It's like a mini-fiscal expansion: separation puts upward pressure on the rental market and is a boom for suppliers of furnishings and electrical goods like Harvey Norman and Bing Lee. But it's a much less efficient way to live.

A four-person family that breaks up will generate around 43 per cent more garbage than they did when they were together. They will use up to 34 per cent more water and up to 70 per cent more energy, depending on the type of new dwellings being occupied.

It's not a trivial problem. Around 40 per cent of marriages will end in divorce. If governments want to improve environmental performance, maybe they should start recruiting marriage counsellors.

Divorce is only one of a number of evolving social changes making Australian households less sustainable. The number of people living in each Australian household has been falling steadily since before federation.

Late last century, there were around five people living in each household. By the 1960s, it was fewer than four people and by 1990 it was fewer than three. In its latest projections, the Australian Bureau of Statistics estimates that households will be approaching two people by 2026.

This decline is the result not only of family break-ups but other social drivers, such as more couples deciding not to have children, more people not getting married and baby boomers living longer.

As a result, the number of households is expected to increase by up to 47 per cent between 2001 and 2026, while the population will only increase by 25 per cent.

As bookshops fill their shelves with handy eco-guides on how to switch to more efficient lighting and appliances, the savings are dwarfed by these social and structural trends in the way we live.

The biggest determinant of the total energy used by Australian households, the waste generated and even the amount of water used is the number of people who live in each household.

No one took much notice of a remarkable new study on household energy use released by the Department of Environment, Water, Heritage and the Arts in June. They soon will.

The DEWHA study found that despite the advent of airconditioners and plasma-screen TVs, the average energy consumption of each Australian household is not expected to change significantly. From 1990 to 2020, household energy demand will increase by 56 per cent, but mainly because the number of Australian households will increase by 61 per cent.

The report noted the rise of wood-burning stoves and water beds in the 1980s, and their subsequent decline. It predicts increased energy demand to be offset by a range of efficiency programs, including better insulation, more gas and solar hot water, and more efficient appliances.

When it comes to the number of people in each home, small is not beautiful. In 2004, a detailed audit of household waste in Canberra found that the rate of waste generated per person decreased by 30 per cent for each extra person in the household. Similar household audits by Yarra Valley Water in 2003 found a similar relationship for water use, tapering off after three or more people. It's more efficient to live with other people and share the economies of scale in lighting, heating, cooking and watering the lawn.

Similar estimates can be made of per capita energy use by combining surveys of household time use with data contained in the DEWHA report.

Despite the numbers of people per household falling steadily over the past century, the physical size of each household continues to increase.

According to the DEWHA report, the average area per household has increased from 113sqm metres in 1990 to 145sqm in 2007 and is projected to increase to more than 170sqm by 2020.

This growth is being driven in part by renovation of the existing stock of dwellings, but mainly by the strong financial incentives that exist for new home builders to maximise the size of their house.

The principal place of residence is exempt from capital gains tax and it's the main personal investment for most Australian households.

The value of this asset is increased by maximising the numbers of bedrooms, bathrooms or car spaces.

While not diminishing the ongoing role of micro-efficiency improvements in Australian households, the DEWHA report reveals the breadth of policy thinking needed to address environmental challenges.

Ignoring these macro social factors threatens to negate any hard-won improvements made by government initiatives or enthusiasts.

Perhaps planners should think beyond more efficient building to encouraging more efficient societies: share-houses for baby boomers, the return of the granny-flat or other systems that can at least arrest if not reverse the inefficient demographic trend that unwittingly consumes us.

Australian Business.