Energy-efficient windows

[Leif]

I don't know about anyone else trying to read this thread, but my brain is beginning to glaze over...

[HansV]

Beginning?

[stuck]

So how does this sound: UV light is absorbed by glass and the glass becomes warmer, and the glass then radiates IR to the room (heating the air and then the walls and fittings)?

No, when glass absorbs UV the heating effect will be minimal.

Double-glazing seems not to be effective at heating a room at all, as much as preventing room-heat escaping to the outside air.

Correct, double glazing is not supposed to heat a room, it merely slows heat loss from a room.

(1) Glass houses (green houses as in Holland Tulips) must be using solar radiation to boost heat during the day, and using that trapped heat to offset fuel costs.

All greenhouses, anywhere, get hot when the sun shines because the solar energy that passes through the glass is absorbed by what's inside the greenhouse, mainly the air inside it. That warms the air but the warm air is trapped, it can't escape, unless you open the door / a window.

(3) Why in mid-winter is my room shooting up to 20 or 22c on a sunny day?

Your room is acting like a greenhouse. Sunlight can pass through the glass, the sunlight warms the air but the air can't pass through the glass, it's trapped in your room.

My goal remains to replace the draughty sliding panes with air-tight casement windows, so the project goes ahead!

Yes, replacing old loose fitting windows with modern good quality double glazed units is a good plan, because you'll be sealing off the escape routes for the air that's either been warmed by the sun or your heating system.

Ken

[BobH]

I might be mistaken (again), but I think there are windows now that have wood frames that are coated with plastic to reduce the high costs of maintaining paint and to prevent damage to the wood. I think both Andersen and Pella sell such products in the US. Don't know about the GWN.

[Graeme]

.... Don't know about the GWN.

Global Wrestling Network?

Greenwich Winter Night shelter?

[HansV]

Graeme's Winter Nights?

Great White North (a nickname for Canada)

[GeoffW]

Greaves' Window Network?

[StuartR]

Geoff W's nonsense?

[GeoffW]

No, because that would have to be GWBS.

[StuartR]

[ChrisGreaves]

Geoff W's nonsense?

Close enough Stuart.
You got the name wrong, but you get the cigar anyway!
Cheers
Chris

[ChrisGreaves]

"Heat loss through your windows is predominantly caused by radiation through your glazing, while air leakage is another big contributor, especially from windows with poor insulation. "
I think that this is possibly true in general, but lying in bed (February 2019) and feeling a draught of cold air across your face throughout the night suggested to me that extremely leaky windows was my main cause of heat loss. Those persistent (i.e. 36 hours) 100Km/hour northerly winds are effective air pumps.
This was confirmed when the Newfoundland Housing Corporation sent a technician around. He closed all doors and windows, sealed the outside door with a flexible barrier, then attached a giant air pump to suck air out of the house. Waited one minute, then pressed a button on a controller, and back at the office typed it all up. Windows was high on his list, and I got the grant. Which later was withdrawn because I couldn't find a contractor.

First: the walls are well insulated
Second: the walls are well insulated (no that's not a typo, it's emphasis)
Third: The loft is well insulated
Fourth: see 'Third'
Fifth: No outside door opens directly to the outside, there would have to be an enclosed porch between it and the big bad cold world, so that you can close the door from the house before you open the one to the outside and vice versa when entering the house.
Sixth: the windows are triple glazed windows and are completely draft proof
Seventh: there are thick curtains that can be drawn over the windows as soon as the sunsets

With the utmost respect, if you lived where I lived - in this house - you would be more aware of the speed at which the winds pump outside air into the house. The house, when I arrived, had a huge wood stove in the living-room, a larger oil stove in the kitchen, and a furnace designed for a trailer-home, that pumped the hot air into the crawl-space below the house where it cooled off and arrived for the first 60 seconds as forced sub-zero air that had been sitting in the un-insulated ducts under the house. Which, of course, pumped warm air out of the house, replacing it with freezing air, which of course told the thermostat to keep the furnace on ...

The habits fifty years ago were to chop down trees and burn kerosene for heat. (My good friend David goes through a 53-foot flatbed of wood each year; spends four days non-stop chain-sawing it into one-foot lengths, then splitting those with a hydraulic splutter; it is how he was raised). I got rid of the wood stove and oil stove ($800 for the only time I filled the tank) and gained more living space and installed two baseboard heaters that year, four the next.

I understand the general advice from members here and from the web, but I have to work on this house, and no other.
In short, I would give the same general advice that you do, but in this house, the gales that I could feel coming through the front door were tangible.

I'd expect more glass, even if it is triple glazed, to make your house colder.

Again, I see your point, and by going from 13,000 sq in to 52,000 sq in of glass I am possibly losing four times as much heat (energy) through radiation. But I suspect ( I have not measured) that by going to crank-and-lever windows I am gaining ten to twenty times that much energy savings just by having air-tight windows, instead of sliding windows with a ½ centimetre gap.
My secondary objective is, of course, more light. The only south-facing window is the 2'x3' thing in my bedroom. Each of the other small rooms has a stingy 2'x3' window, set some 48" above the floor level.

Now I value all the advice from this topic and from a fellow in Lethbridge and from my neighbours.
It is time, as the late Doctor Robert Northcote used to say, to "cut code", so this morning I ordered eight multi-unit 72"x48" double-glazed windows. For those who delight in decoding esoteric terminology:-

20220429_02 [800x600].png

And for the fiscally frugal, my original estimate has dropped from $26,304 to $13,153 as a result of solid paper-and-pencil work and being ignorant, but smart enough to keep asking questions. And valuing the responses!
Cheers, and many, many thanks to all
Chris

[ChrisGreaves]

I was wrong in most of my beliefs about Windows. This post from "stuck" got me unstuck.

A quick update:
bedroom: South-facing window installed, east window postponed to next year
study: South and west facing windows installed.
guest-room: West window installed, north-facing postponed.

On September 14th my diary contains "At 1600 the study was at 26c and the bedroom at 25c. I have turned down those two thermostats to 16c.".
Previous years, that small window in the bedroom helped me to get to 21/22, mid-winter. We are in autumn here, so this is not a fair comparison, but it is encouraging.

The study & bedroom heaters are on and set to 18c. bedtime (9pm) and the thermostat shows 24c in the bedroom. I believe that during the day much heat energy has been pumped into the fabric of the room (walls, ceiling, bed frame and so on), and is being released during the night. In the morning (6am) the heater is not on, so yesterday's heat is reducing my heating energy use to zero.
I think.

I have decided to rid myself of the blackcurrant canes along the south side of the house and using the twelve panes of small windows to implement a form of solar heater, pumping heat by water to a reservoir under the bed. This project appeals to me because it should use NO external energy, which means I must beat the freezing-pipes problem with heat generated from solar energy - in mid-winter.

I am basking in each evening's thought that "Maybe I should open my windows to cool the bedroom down a bit ...".

Cheers, Chris

[ChrisGreaves]

I was wrong in most of my beliefs about Windows. This post from "stuck" got me unstuck.Subject: Meeting software

...Going with energy efficient windows really made a difference in our house, cutting our utility bill by more than half when combined with an up to date AC system.

Here we are in the coldest months of the year.

Feb	Max	Min
1	-4.6	-13.6
2	-6.8	-10.2
3	3.1	-9.6
4	-6.7	-14.9
5	-0.7	-7.4
6	2	-5.5

The first six days of February brought serious cold. I curtailed my trips to the shops. Today, February the seventh, has a bitterly cold wind driving from the North, so the -7c feels like -16c.

I had problems with Muskrat Falls frying three thermostats, and felt that my house was unnaturally cold. My estimated monthly average has risen above $300 for the first time in my four years in the house.

Now I am of the opinion that the advice of losing heat through windows is correct; The study is especially slow to warm up each morning, and it is the only room (to date) that sports two 6’x4’ windows, basically forty-eight square feet through which heat can escape,

The time has come to purchase a slew of curtain rods and drapes, drapes that come just down to the window sills, and see if that has an effect on my heating bills.

Millions of people can’t be wrong.

With all that, I really do enjoy the grand views outside the house while I am trapped indoors. The large windows were purchased for the views, not for the heat efficiency. Well, apart from eliminating drafts.

Cheers, Chris

[ChrisGreaves]

Untitled.png

My ELECTRICAL energy usage since February 2019. For the remainder of that winter I had inefficient oil-heating for the house.
My first full winter I was all-electric, with a 500w heater in the tiny bedroom and 1000w in the living-room. Essentially I lived in a two-room cabin.
The next winter I had six baseboard heaters installed, the highest being 2500w in the kitchen,
The third winter I was less afraid of financial ruin and enjoyed programming the thermostats.
This winter (right-hand side, incomplete mountain) has seen my running thirty-day average go over $300.
I am now contemplating rummaging through my collection of old heaters in the shed and replacing the 500W in this study with a 1000w.

I remain convinced that my uncurtained 48 square feet of window in the study is my main culprit in heat loss. Time to buy curtain rods and curtains.
Cheers, Chris