Jake":2fs4rvhb said:
How does the 21C come about? Interested because I'd find that uncomfortable especially at night - is there a way of 'setting' that at less with more air changes,reducing solar gain or something?
Good point Jake.......and sorry I didn't get to answer this last night....
Sleeping temperatures first:
In the summer, there is no problem. We aren't trying to preserve heat in the house in summer, so bedroom windows are open at night, and we benefit from sleeping in a cool draught.
In the middle of winter there is no problem, as the house is at a constant and comfortable temperature, and if the heating has been on, upstairs temperatures lag behind downstairs temperatures by a couple of hours.....and that one degree of difference makes bed-time temperatures quite pleasant.
The one time of the year when it can be a bit of a nuisance is the period that has just ended ......September/ October......when we close all the windows for the last time for the year, gain quite a lot of heat from the south-facing conservatory, and are looking to get the house as warm as possible before the onset of winter to delay the start of the heating season. Night-time temperatures of 22 are then possible, and we simply swap to a lighter weight duvet.
Now, you ask "why 21 degrees?
Well, the whole point of this house is to trap "waste" heat. The fridge and oven are pretty much enough between them to heat the house through the winter. Lights don't contibute much as they are mostly low-energy bulbs........but the computer makes a steady contribution.......as do our bodies. A normal adult gives off about a kilowatt of heat energy just walking around the house.....even the dog contributes. The conservatory is designed to maximise solar gain.......and we control whether that heat is let into the house (spring and autumn) or released to the outside air (summer). Trap all this heat well enough and most of the year the house is around 21 degrees. This is comfortable for sitting around in (and I work at home, so sit around in it all the time), yet not excessive for night-time, as discussed earlier.
A point that arises from all of the above is that our windows are permanently closed for about 7 months of the year. This is only possible because we have a ventilation system with heat-recovery. This sounds grand, but is basically a fan in a box with a whole lot of ducting and, critically, a heat exchanger.
This means that we have a constant supply of fresh air, at a controllable rate, which is pre-warmed by the waste heat from the extracted "stale" air. You have to learn that "fresh air" doesn't necessarily mean "cool air". This constant air-change means that the house is always fresh, there is never any condensation (get out of a hot shower in the middle of winter and the mirror isn't misted up.........you can shave straight away), there are no dog smells or cooking smells. The triple-glazing has no condensation (let alone ice!!!!) on it in the morning. This system also helps move the heat around the house, so all of the house is the same temperature...........go into the spare bedroom in the middle of the night in the middle of winter and it is the same temperature as the lounge.
This house has only 9 inches of insulation in the external walls, compared with the 12 I built into the house next door, but crucially, it has dense concrete blocks for the inner skin of the walls, bumping up the thermal mass available for storing warmth (and, incidentally "coolth" in the summer, when the house is pleasantly cool on even the hottest days). There is also 500mm of loft insulation in both houses.
I do whitter on, don't I?
Mike
