Sept 6, 2015: Sustainable House Day



The Greeny Flat will be open again this year for Sustainable House Day on September 13 between 10am and 4pm. We had about 80 people come to see the Greeny Flat during last year’s Sustainable House Day(s) and we received a lot of very positive feedback. If you came last year you might like to come back and hear about our experience of living in the place for the last year and a half. The Greeny Flat has surpassed our expectations on almost all levels. We’re particularly proud of the facts that in our first full year of operation we: exported to the electricity grid nearly three-and-a-half times as much power as we imported from it; used about and-and-a-half times more tank water than town water; and had a total running cost for the year of $311.

If you couldn’t make it last year, here’s your chance to come and experience a small, affordable, comfortable, healthy, energy positive, low-maintenance, fire-resistant, water-efficient, elderly-friendly infill house. There are also a few other Sustainable House Day projects in our area. One is the Southern Highlands Welcome Centre in Mittagong which has recently undergone a sustainability upgrade incorporating energy efficiency, renewable energy and even a brand new electric car charging station. I haven’t had the tour of the upgraded facility yet so I’m hoping to find a few minutes on Sunday to head over there and see what they’re up to.

Another project in our area is one I have been to and written about in a previous Newsletter. Called ‘The Keep‘ it is a wonderful project that incorporates natural and sustainable buildings with renewable energy, permaculture gardens, aquaculture, animal husbandry, herbal medicine, and an incredible food forest. I strongly encourage anyone with an interest in sustainability, self-sufficiency, food growing and community building to take this opportunity for a visit. You’ll be glad you did.

In nearby Bowral, the Four Seasons Community Garden will also be open on the day. It’s another one I haven’t been to yet myself but it sounds like a great place to learn about all things relating to organic gardening. The only bad thing about opening the Greeny Flat for the day is that it means we can’t go around and visit all the other inspiring projects that are on offer. Anyway we hope to see you here on Sunday. If you live in a different region, chances are there are projects open in your area which you can search for on the Sustainable House Day website.

Passive House, Active Owner

There’s an old saying in Passive Solar Design circles… ‘A passive house requires an active owner’. What this means is that, in order to get the greatest benefit from a passive solar designed house, the occupants need to operate the house in a logical and consistent way. For example, during the summer, the way we keep the Greeny Flat cool is by opening the windows and blinds at night to let cool air flow through the house. This lowers the temperature of the thermal mass in the concrete floor. During the day, we close all the windows and blinds to keep the heat out and the thermal mass helps to keep the interior nice and cool. As ‘active owners’ it’s up to us to remember to open and close the windows and blinds in the mornings and evenings.

In the winter time we keep the windows closed all the time. We open the insulating blinds during the day to let the sun pour in and warm the thermal mass of the floor and close the blinds at night to help keep the heat in the house. By opening and closing the blinds at the appropriate times we were able to keep the interior relatively comfortable through our whole first winter with almost no additional heating (apart from a very small radiator we used once or twice in the bedroom). The graph below shows the difference between the indoor and outdoor temperatures during the last winter when we were here to operate the house correctly.


This winter was a different story, we just got back from a six-week trip, during which time the Greeny Flat was empty and no-one was here to operate the blinds. As you can see from the second graph below, this meant that

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