As I write this on 1st March 2007, the sun is streaming in our South-facing windows, the inside temperature is 19.3 degrees C and the outside in the shade is 7.6 C. There is no other heat in the house and hasn’t been for the past three days. We had to use a 400 watt heater (4 x 100w light bulbs) for two hours then.

Passive Build Works
In October 2006 we moved into one of Scandinavian Home’s Passive Houses. (See The Local Planet Issue 6, page 36 for details).
The orientation is due South where most of the windows are and the front door is on the North. The orientation is most important and apart from the insulation and draught-proofing of the structure, it contributes most to the comfort of the house. When the sun is shining, like now, the temperature rises 1 degree celsius every hour.

We do not have a heat pump and we feel that for the amount of extra heat we need for this type of house there is no need for the extra cost of putting one in. For now I am concentrating on space-heating so we have kept a record of the outside and inside temperatures to give us some idea how well the passive standard of insulation etc., works. These are the results:

The ambient temp for most of the period was 19/21 degrees with some dips during wet and cold days to 17.5/18C and on sunny days midday was around 23/24C. The temperature over the period ranged from a low of 14 degrees centigrade to a high of over 25 - the 14 was registered only twice and one of these times, was after the house was unoccupied for three weeks. The high of 25 for 2 times (one of these was when we had about twenty-five people in on 26th December and at 11 o’clock that night all the windows and doors had to be opened to cool the place – we don’t know how hot it would have got!

We have a small electric halogen heater which we bought for €19.95. It has three heat settings; rated at 400w, 800w and 1200w. We have only used the 800w for about twelve hours, and 400w for about fifty hours in all since October. That works out at under €10 for four months space-heating. 50 units at 16c (800x12=9600+ 400x50=4000). Even if I am underestimating this by 100/200%, I think it’s OK!

Some Comments on the Difference Between Living in a “Conventional” House:
We have lived in three very different ones since the 1960s. The most striking thing I think is the fact that the temperature is so even throughout the house day and night. Now we are definitely spending very little money on space heating and best of all there are no oil or gas bills. Gone are the days of lugging coal, turf and timber for the stoves, back boiler, etc. Gone too, is the chore of cleaning out the ash and having it blowing into my face when taking it out and gone is the heap of ash in the corner of the garden. O.K. so the pure wood ash went on the fruit bushes - but the other stuff...? The ash also used to add to the general dust around the house. This has been much reduced. Some people ask do I miss the open fire. NO, NO, NO! We have had a variety of open fires, stoves, back- boilers over the years, and also had oil and gas central heating. When I look back on it, while we had the oil or gas heating we really did not use the fire much anyway. Over the months of December, January, February and part of March, when it was really cold, windy and wet I did light it. The fire did help to heat up the main chimney breast and this helped to heat the whole house but so much of the heat went up the open chimney. The fact is no matter how much you spend, heating a house with holes in the roof (i.e. chimneys) you end up heating the outside with at least 50% of your fuel (gas/oil and solid) and that is probably a conservative figure.

We will have a more complete idea of how the house works after a year’s occupation but so far it exceeds our expectations to the point that we can’t understand why all houses are not built to this standard. The cost of space heating, no matter what kind is used, is going up all the time. Insulation is relatively cheap and once installed is a fixed cost as against the running cost for fuel. The average annual cost for space-heating is approximately €1,500. €10,000 spent on insulation/draught proof windows etc. could easily reduce this by half and with careful planning a lot more.