What we mean when we say “Sustainable Housing”
This is part of our Design and the Environment Series. I acknowledge that I have a lot to learn in this area and I’m simply putting forward my understanding and what I’ve discovered from reputable sources. If you disagree with anything you read or want to correct me, please contact me via email. You can reach me at brad@guidearchitects.com.au
It’s a bit hard to pin down and clearly define what sustainable housing actually means. There are lots of different ways to view it – do we mean economically, socially or environmentally sustainable? In this series, we’re keeping within the framework of environmentally sustainable. In relation to environmental sustainability I’m going to work through the lens of “design that reduces our carbon footprint”. Let’s put that in some context.
Australia, through the Paris Climate Agreement has committed to doing its part to help keep global temperatures from rising 2 degrees or less by the end of the century. So far global temperatures are up about 1 degree this century and if we continue on a business-as-usual path, temperatures are on track to rise by about 3 to 3.5 degrees.
The Federal Government has committed to a reduction in emissions by 28% by 2030 and, along with most states, has a target of net zero by 2050. As far as I can tell, WA has only committed to matching the federal and unlike other states, doesn’t have its own targets.
While we are moving towards decarbonising the grid and offsetting carbon, these are expected to take a while yet. Although they are likely to become a bigger part of our strategy to get to Net Zero in the future, where we can limit consumption we should. This means, reducing energy demand in our current and future buildings.
How does building design relate to Net Zero
The built environment (this just means buildings) makes up a large percentage of our current emissions. In total, about 40% - that’s a huge percentage, so the built environment has been a key area of focus to help lowe emissions.
There are two key things to keep an eye on when it comes to emissions in the built environment. First, of that 40% about 65% are operating emissions. This means carbon emissions related to heating and cooling a building. Another 17% is made up of embodied energy – the energy used in creating the bricks, steel or glass to get to site.
Carbon Emissions in the Built Environment (Based on data from “A carbon Positive Roadmap for the built environment, GBCA")
Heating and Cooling Emissions
First, there is a very strong correlation between the way a building is designed and the heating and cooling load required to maintain comfortable temperature. Basically, how much does it cost (both in dollars and carbon) to heat the building during winter and cool the building during summer.
Embodied Energy
The second factor is embodied energy. New construction materials make up about 12% of global emissions. Embodied energy is the total amount of energy it takes to source, mine, process and transport a certain material to site so that it can be used in a building. For example iron ore has to be mined, that ore has to be transported (usually from the Pilbara to China) where it is processed in a high energy intensive process. It is then shipped back to Perth to be used on site. This has a very large amount of embodied energy. Contrast this with timber, which has to be forested and processed, but in itself is a carbon store - I’ve written more about our slow movement towards large structural timber buildings and embodied energy.
What does that mean for clients and architects?
So you as a client, and we as architects have a choice in how we design our buildings (which impact running cost of energy) and what we construct them out of (embodied energy).
At the area of the market we work at, a lot of things come back to budget. We won’t (yet) dive into whether certain materials are more expensive to build from, but we can say, that in the long run there is an economic benefit to you the owner in designing buildings that use less energy. Exactly how much of a benefit, I can’t yet say, but I can tell you which elements of the building design limit the heating and cooling load. In our next article we’ll go into that.
This is sourced from the Australian Institute of Architects Series on Net Zero.