Cugel wrote: ↑8 Feb 2023, 12:44pm
The passive heating elements of the hoose are not the full set, consisting of: large windows that gain some radiant heat from the sun; plus between-the-skins wall & roof insulation that tends to keep heat in the house for a long time and also prevent too much solar gain via the roof and sun-facing walls in summer.
In all events, it's very noticeable that even in cold (currently 5 degree C) outside temperatures, the ground source heat pump doesn't come on if the sun is shining brightly.
Cugel
A way of storing all that free solar radiation is one of the best ways of improving our carbon footprint - often nothing more than good design. As we move to high levels of in-wall insulation, this inhibits solar energy stored in the structure from steadily warming internal spaces long into the evening, something I've noticed on sunny Spring days having come from thick stone walls to a modern build.
We need to somehow maximise the energy coming in through glass (I mentioned friends' solar wall inside a greenhouse on the sunny side of their house), and/or use the energy to heat water which can be used to warm a large mass such as a floor slab, even at this time of year. I'm considering solar water heating mounted vertically on a South-facing wall, designed to make the most of the sun when it's lower in the sky, it could easily be plumbed in to the heated floor slab, or for houses with radiators, into a heat storage tank to be pumped through radiators in the evening.
Thinking is evolving all the time, I see this page https://www.westcoastgreen.com/passive-solar-design/ suggests that wall insulation isn't always recommended for those which face the equator - I would like to see some data for a house with 3 insulated and 1 solid wall.