The built environment and climate change

'Embodied energy' is the total energy used to manufacture and transport an item or material. Some materials have high embodied energy (i.e. they take more energy to produce), while others have naturally low embodied energy. ‘Total embodied energy' includes the estimated energy used during the operational lifespan of a material or product until it is no longer useful, and is subsequently discarded or recycled.

The evolution of the built environment is an important component of the overall strategy to address the greenhouse, water, waste and pollution challenges we currently face. The construction and maintenance of the built environment uses a lot of materials and products that can have a damaging impact on the wider natural environment, particularly by creating greenhouse gas emissions from coal-fired electricity. How much energy is used and how much embodied energy the resulting product has depends on factors such as what material sources and production processes were used, whether the product is reusable or recyclable and how far it has travelled.

Around 25% of Australia's total greenhouse gas emissions are a result of energy used by buildings. Commercial buildings alone are responsible for 10% of greenhouse emissions and this figure is growing at almost 2% per annum. Around 40% of Australia's waste results from construction and demolition activities, yet most of these discarded materials are ideal for re-use or recycling.


How does the way we build cause greenhouse emissions?

The majority of modern construction methods use a lot of new materials and require large amounts of energy and water. Australians have also made home renovations a national pastime. A typical home is renovated every five-to-seven years, with most or all of the demolished materials discarded for new products and materials.

The process creates two sources of greenhouse gas emissions:

  1. Emissions from construction. The embodied energy of a development is not occupant-dependent; the emissions are built into the materials used to construct and furnish the home, with this only occurring when you build or renovate (apart from maintenance).
  2. Emissions from operational use. Operational energy consumption depends on all of the occupants of the completed building, and how they interact with it on a daily basis. Operational energy accumulates over time and can be reduced, such as with an efficiency retrofit and smart energy use.

Research by the CSIRO has found that the average household contains about 1,000 GJ of energy embodied in the materials used in its construction. This is equivalent to about 15 years of normal operational energy use. For a house that lasts one hundred years, this is over 10% of the energy used in its life.


Effects of climate change

In the future, not only will energy and water become more expensive, but materials that use a lot of energy and water will also cost much more. 

A primary challenge is to build homes and buildings that are naturally more resilient and able to withstand climatic extremes while using much less energy and water to run. This means designing buildings that work with (not despite) climate and using materials to stabilise and maintain comfortable indoor temperatures and air quality.

The other challenge will be to use building materials that are more sustainable: renewable, re-used, recyclable and low in pollutants.