november 29, 2011 03:40pm

To heat or to bake?

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We gave in on November 23rd last week and took our central heating system out of its box.

This will be our third winter in the house and it is still not obvious when to start heating. Unlike a conventional house the indoor temperature changes only very gradually. With such a mild autumn we could easily drift along while getting used to the slowly falling indoor temperatures.

The amount of heating required is so low that it's tempting just to make an extra loaf of bread and bake a few potatoes (instead of boiling them). I tried this, but now I'm having to eat too much bread because I did not syncronise with Shirley who bought the usual 2 loaves as well.

With no conventional built-in heating system we do need to make sure the temperature of the building fabric does not drop too low. I've been keeping a closer eye on the 40+ tons of internal thermal mass this year. I only have one fixed monitoring point, in the heart of one of the earth block walls. This is not data-logged yet and I would really like to monitor at least two other points (one in the ground floor slate).

However, I'm now fairly sure that if the core temperature of the thermal mass drops below 21°C, and there is no great prospect of significant solar gains, then we need to use additional heating.

At least in our PH, using the air temperature alone to determine when to heat is misguided.

Posted By: MarkTiramani

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