The most important factors in designing a sustainable house
None of this is cutting edge, and I’m sure if you’ve spent any time looking at sustainable house design you’re going to know most of this. However, after talking about the importance reducing heating and cooling loads in the housing, talking about how to do this feels like a logical next step.
Part of my mission in this series is to be a better practitioner of architecture and sustainable housing design. I’ve been doing it for close to a decade so I’ve got a good ‘hunch’ about what works, however, what’s been missing for me is a clear idea of the impact of each design decision. This article, which is based on my understanding of the Australian Institute of Architects Net Zero series, starts to look at the measurable impacts of good sustainable house design by placing them in a hierarchy of results.
One final disclaimer is that this is written for Perth’s Mediterranean climate. Much of this will be similar to other climates, but because all of our work is based in Perth, we’ve got a special interest in this climate.
So, what are the most important factors?
Orientation
When designing for a climate like ours, orientation in relation to North is numero uno. Its’ by far the most important factor in designing sustainable houses for Perth. This is because the sun's path is predominantly from the north, allowing north-facing spaces to harness consistent natural sunlight for optimal warmth in winter while utilizing design elements like eaves to provide shade and prevent overheating in the scorching summers, striking a balance that significantly enhances energy efficiency and indoor comfort
Refers to the way a building is positioned in relation to the sun's path.
Correct orientation ensures living spaces receive sunlight when needed, like warmth in winter and shade in summer.
For instance, in many climates, north-facing windows can capture winter sun, while minimizing unwanted solar gain in summer.
Compact cubes reduce the amount of wall exposed to the elements, making it a more sustainable approach.
Form Factor
Relates to the shape and size of your building.
A compact form (like a square or circle) reduces the surface area exposed to the elements, meaning less heat is lost or gained. Think of how a compact object stays warmer/cooler longer than a stretched-out one.
Massing and Shading
Massing: Refers to the bulk or volume of the building. Proper massing can distribute heat evenly throughout the building.
Heat transfers more readily through windows than walls. Take a look through our Definitions article for some more explanation, but for now, a low ratio of window to wall is better than a high ratio. About 30% means a significant reduction in heat transfer while still allowing opportunities for natural light and cross ventilation
Window to Wall Ratio: It's about finding a balance between having enough windows for light and views while avoiding excessive heat loss/gain. Large windows might offer great views but can compromise on thermal comfort if not properly managed.
Strategic shading lowers the temperature around a wall and window and therefore helps to reduce heat transfer
Shading: Means using elements like eaves, awnings, or trees to block excess sunlight. This can keep your home cooler in summer.
Window Performance
Not all windows are made equal! The way a window is constructed can greatly influence the comfort of your home.
Important aspects include the U-Value (insulation effectiveness) and SHGC (how much solar heat it lets in). Good windows can keep warmth in during winter and block out heat during summer.
Double glazing is always often asked about. Consider, it will cost between 30-50% more than single glazing. What is the payoff? To be honest, I don’t know yet, but this series is looking to explore this.
This is part of our Sustainable Design Series. I acknowledge that while I have a lot of experience in designing buildings, I am not an expert in carbon reduction. I am trying to be proactive and learn more about it so that I can be a more sustainable architect. I have sourced these facts from reputable sources. If you disagree with anything I’ve written and you want to correct me, please email me at brad@guidearchitects.com.au