For the last four weeks I have focused on good home design for winter warmth. From an eco design perspective, good design is passive. Put another way, eco design enables systems to operate as much as possible on natural energy flows rather than on supplemental power such as electricity or gas, and supplemental equipment such as motors, fans or heaters.
Last week I described a great example of passive solar design in Ladakh, India, where homes, offices and schools are being built to be heated entirely by the sun at elevations of 3,000 to 4,000 metres in the trans-Himalaya mountain ranges. If you did not see that article last week, go back and have a look. Or do a Google search for “SECMOL Ladakh” to learn more about the amazing organisation I worked with in 2006.
At the opposite end of the spectrum, eco design thinking can be used for passive cooling in warm climates or during hot summers. A good example of this is the Queenslander home design in Australia. The basic elements of a Queenslander are these: it is built on tall piles so it can catch cross breezes; it has wide covered porches to exclude the summer sun; it has vents in the gable ends to allow cross ventilation through the roof cavity.
I’ve been told that the long piles holding up a Queenslander also come in handy during the periodic severe flooding in the region. Along the same lines, a couple of years ago I saw entire neighbourhoods in Myrtle Beach, South Carolina, USA that had been rebuilt after a hurricane with three metre piles. It looked like all the homes in the entire coastal zone were on stilts. This suggestion has been made for the homes in Wanganui that were flooded last month. But I digress.
Passive cooling through cross ventilation can be used effectively in Palmerston North when summer temperatures get uncomfortably warm. But another strategy to keep cool in summer is to top up your ceiling insulation. In the same way that insulation slows the flow of warmth upward when you are heating your home, it slows the flow of warmth downward from an overheated roof cavity during hot weather. The effect is the same as the vents at the gable ends of the Queenslander but the strategy applied is completely different. Both cases are examples of passive design, and ideally the best home design would plan for a super insulated ceiling and adequate roof ventilation.
Warm in winter, cool in summer, like all homes should be.