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Living Lightly column

Sustainable House

By Ted and Glenda Minty, Minty’s Binderee Grove House

Living in a galvanized iron shack for 25 years with hot summers and brisk winters gives one time for reflection. Glenda and I realized it’s relatively easy to keep warm in winter as we have access to firewood, but keeping comfortable in summer, that’s a whole other thing.

Keeping the heat out of your house in summer requires a combination of reflective, insulated exterior surfaces, shady trees with deciduous vines for walls and pergolas, a large thermal mass inside the building with excellent night cross-flow ventilation.

Ceiling fans throughout are a must. But for those extreme still, hot, humid nights, lacking a cooling breeze you need a reverse cycle A/C. Our moderate sized A/C runs off our solar during the day, keeping the house cool with minimal cost to us as we turn it off at day’s end, shutting  the house up to keep to the cool in!

Nightly, cool air slides past our house site, so we knew that a house with a large thermal mass and cross flow ventilation would take advantage of this 20 degree plus temperature difference. We chose rammed earth as it has a large thermal mass as well as being low maintenance, healthy, durable and is great to look at.

The open plan living not only helps with cross flow ventilation but reduces waste space as traffic areas can be multi -purpose.  Remember, the exit point for the air needs to be bigger than the entry to maximize air flow.

So most summer evenings we get a cool breeze that  enters open louvre windows, flows past the rammed earth walls and polished concrete floor, to flow out through the open sliding doors, taking with it heat that the building has gained during the day.

Many mass produced houses fail to incorporate good passive design, having very small window openings and lots of walls to impede cross flow ventilation. The lack of eaves, poor orientation and absence of landscaping shade lead to occupiers spending a lot of money trying to be comfortable.   With research and advice anyone can improve the thermal performance of their home, but if you are building it is best to incorporate good passive design from the beginning.

Check out a Sustainable House near you to start living more comfortably.