GeoffW wrote: ↑25 Apr 2022, 21:56
What about simple convection heat loss?
I reduced that by using 12 wood screws to tack a sheet of Masonite over the ceiling hatch to the attic, after gluing strips of toweling around the sheet to provide a cushioned air barrier! Apart from closing the door there is not a lot else that I can do about convection; the ceiling has about a foot of insulation atop.
In Canberra in winter, which does get cold, but not as cold as in Bonavista, we received good sun during the day. But the windows were very cold to the touch, and at night, they were a major source of heat loss in the room. Windows and doors were very well sealed, with a gap under the door being covered to stop air loss in the one gap. Thick curtains helped stop the heat loss, but I suspect that double glazing would have stopped a great deal of that heat loss. I understand that double glazing can cut heat loss by up to 30%.
I don't mind windows being cold to the touch; when body heat is at 37c and the outside temperature is at 0c or -20c, there will always be a frontier of temperature change somewhere. And we must not confuse "temperature" with "heat movement". Computer-rooms haad air-conditioning ducts which could be at a cool room temperature (to the touch) but channeled frigid air inside the ducts.
I suspect that your hot greenhouse would have become extremely cold after sundown. I wouldn't like your chances of a good night's sleep overnight after a sunny winter's day.
Not at all. I
do have baseboard heaters in each room (now). I am not trying to live without heating; I am trying to reduce the feeling of cold air wafting across my face when I am lying in bed! My maximum average daily electricity use over the past 12 months was $17 (heat, water, cooking, ...) and the minimum was $1. I am looking to reduce the spread of the two figures by reducing the maximum average. It is true that in a 10-day power outage my home will quickly become almost unbearable, but a great deal of heat (in any house) exists as a reservoir of heat in the walls and furniture.
You're talking about allowing for the sun only, which is great, but then you have around 8.5 hours of sun only in mid-winter, and that's only on clear days. So you have to allow for all those non-sunlight hours.
True. But gather ye rosebuds while ye may. I think that maximizing my glass area (13,000 sq in to 52,000 sq in) makes the best use of solar energy; and by trapping, as always, I mean the conversion of short- to long-wavelength electro-magnetic radiation. Remember, those glass-houses (green-houses) work! If the night-time temperature plummeted, those tomato plants would die. How does a glass house stay above freezing? Can it be a reservoir of heat energy, or auxiliary heaters (the equivalent of my baseboard heaters)? If the latter, then glass walls and roofs help to reduce, not eliminate, fuel bills.
I don't think that double glazing stops much of the sunlight warmth at all.
Well, OK, but why do you think that? I think that glazing works
because I can read 22c off the room thermometer. I think that Double-glazing uses the trapped air as a conductive heat barrier; Single glazing suffices for blocking loss through radiation (infra-red waves).
Now I think of it, WA and SA are settling in for total electricty needs through solar cells. Solar cells work in a similar manner: they allow sunlight in (through the glass), but then convert it to another electro-magnetic form and store it somewhere else (in a battery cell as an example).
Being in a cold climate, I assume that houses have good insulation. I suspect that your place in WA would perhaps not have been as well insulated. Houses in Australia, built in a largely warm client, are built to be cool in the heat, and often ignore a colder winter - hence your small windows, and possible not quite adequate insulation - though sometimes they are insulated against heat.
New houses have insulation. This house is from 1955, and while we suppose it has insulated walls, no-one has looked inside yet! Our house in Gawler, and rented houses in Newcastle, Wollongong, and Perth were indeed cold in winter. In Gawler we burned mallee roots in one of the five fireplaces and the interior chimney warmed two rooms! Mind you, that house had 15" limestone walls.
The mining-house in SX had walls and roof of galvanized iron of course, and that meant that in winter-time the night-time temperature was close to the outside temperature.
{later)
... and then I waded through the local news:-
Bonavista Peninsula Farmer Concerned with Lack of Local Food Production
Note the harvested date on the label on the plastic container; 2022-Jan-10.
Then check
the outdoors temperatures surrounding that date.
Assuming the operation is a commercial success, the data suggests that glass houses (either 98% glass; or 50% glass as in my case) are worth pursuing.
Cheers, Chris