There is so much interest in sustainable buildings and design now, which is a good thing, since buildings account for about 40% of global greenhouse gas emissions. There is a common misconception that buildings need to be plastered in solar panels, or be made of straw bales or recycled tires or other unusual materials to be considered ‘green’.
But there are many simple and common sense design strategies that can make buildings dramatically more sustainable, and I put these under the general category of ‘passive design’. Passive design is making high performance, comfortable buildings using smart design decisions rather than high-tech systems. To use a simple example, when designing a house, you could take any typical house design and add heat pumps or a geo-exchange system to increase the performance and give it some green cred.
But even better would be to design the house so that it was oriented to take in the maximum amount of sun (free energy) on the south side, and insulate it really well and use good quality windows to keep in the heat, so that we might not actually need the high tech heating system at all.
Passive design works with natural systems and forces. For example, we know, at least in this part of the world, that the winter sun is very low in the sky and the summer sun is high in the sky. So we can design buildings that invite in winter sun when we need the warmth, but block the summer sun when it would overheat the building.
The main ingredients of passive design are building orientation, optimized wall to window ratio, increased levels of insulation and air-tightness, high-performance windows, natural ventilation and daylighting. Passive design can be applied to any building type and size and can also be used to inform large scale urban design. As energy prices climb, and as the impacts of global warming increase, we can expect to see a lot more passive design.
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