How can we build in a more environmentally friendly way, while at the same time making buildings cheaper to run? One way is by using the sun and wind to heat, cool, light, and ventilate them, thus avoiding the use of fossil fuels. This can be done by applying a set of techniques—known as passive solar design, or bioclimatic design—many of which have been used in traditional buildings for centuries. Like, for example, this house in northern Spain with its sheltered, south-facing balcony and porch to catch winter sun while excluding summer heat.
For an average building with an estimated 60- to 120-year lifespan, between 80 and 90% of energy is expended during use, for heating, cooling, ventilation, etc.. Only 10-20% is so-called embodied energy, coming from materials and the construction process. A building that’s carefully designed to minimize energy use will continue to produce savings year after year.
The starting point for passive solar design is to understand the place where you intend to build, and in particular the local climate: temperature, humidity, prevailing winds, and the path the sun takes as it travels across the sky at different times of year.
Once we understand the local context, there are a wide range of design strategies that can be applied to ensure that the building remains comfortable throughout the year with minimal use of fossil fuels. While some of these rely on high-tech solutions like automatic windows or forced air circulation, in this series of posts we’ll be focusing on simple techniques that have stood the test of time.
Some fundamental elements of a passive solar building include:
- Design and orientation of windows to capture solar energy;
- Control elements, like roof overhangs, blinds, curtains, plants and landscaping, to reduce heat loss or gain;
- Thermal mass to maintain steady temperatures;
- Insulation, to make sure the interior stays comfortable despite variations in outside conditions;
- Natural ventilation to keep the air in the building fresh.
In the next few posts we’ll be looking at some of these design techniques in more depth.