Double or single glaze door?

[Peterm1000]

So somehow a question about whether to single or double glaze has got way off topic and now pictures of Jacob in his underpants are being discussed...

I can't believe I am about to agree with Jacob, but I think he is right. Double glazing should be way down the list of energy saving things done in a house. However, I also think he is not answering the original question - should a new door be double glazed to increase energy efficiency or single glazed to improve the way it looks. I also think energy saving is not just about cost saving.

It sounds like the house is not very efficient anyway so the benefit of double glazing it would be very marginal. No one has mentioned the higher likelihood of condensation on a single glazed window but I think I would prefer double glazed for that reason alone.

 

[RogerS]

Doug71

Any chance of a photo showing the wall/windows where this door is to go ? Would I be right in saying that the wall has the single-glazed sash windows in? The ones with the slender glazing bars ?

If the answer is Yes then IMO single glazing with thin glazing bars to match into the existing sash windows is the way to go. Although I agree 100% with MikeG re the rationale for DG.

But, as has been mentioned already, are there external constraints such as Listed Building status, Conservation area issues and even Building Control (I'm not up-to-date re what is notifiable when it comes to replacing doors).

We were in a similar dilemma when it came to replacing the windows in our place. For aesthetic reasons, single glazing with thin glazing bars won out over those horrible Georgian bars stuck like an eyesore in between two panes of a DGU. Thick, too boot.

 

[MikeG.]

...... I don't believe that replacing all the single glazed windows in my 1854 non-cavity walled house with gas fired CH would make financial sense for me(unless I plan to live here for another 55 years)......

Absolutely (unless you factor in the reduced price you'd get for the house from having single glazing, potentially, when it comes to selling). But if all the windows frames were shot and required replacing, then the extra cost of double glazing as compared with single glazing (if indeed there was an extra cost), would be judged against the savings in fuel bills.

-

It's all a bit more subtle than the headline figures make out, too. For instance, south facing efficient windows can be a net contributor of heat to a house.

 

[RogerS]

....
It's all a bit more subtle than the headline figures make out, too. For instance, south facing efficient windows can be a net contributor of heat to a house.

Tell me about it ! I'm sitting here sweating away and thinking just how I can harness all that 'free' heat.

 

[MikeG.]

.....Double glazing should be way down the list of energy saving things done in a house........

No one has suggested otherwise. Jacob is right on this.

 

[MikeG.]

....
It's all a bit more subtle than the headline figures make out, too. For instance, south facing efficient windows can be a net contributor of heat to a house.

Tell me about it ! I'm sitting here sweating away and thinking just how I can harness all that 'free' heat.

Build an inter-seasonal heat store....a super-insulated south facing rock-filled room (possibly a lean-to against an outbuilding/ garage etc) with south facing triple glazing and automated insulated shutters (which close at night). Size this correctly, and then draw your incoming fresh air for your ventilation system through this, and you may well provide enough heat to get through the winter without needing any additional heating in the house.

Or install a Trombe wall.

Or a well located "sun space" with twin thermostats controlling a high level fan drawing the heat into the house when needed.

 

[Jacob]

.... No one has mentioned the higher likelihood of condensation on a single glazed window but I think I would prefer double glazed for that reason alone.

I put back restored single glazed windows in our chapel conversion using the old glass as far as possible. They had condensation channels and drainage (1/2" lead pipes) originally and I replaced them too with timber channels and copper pipe. Also heavily insulated the whole building.
Once everything had dried out there was virtually no condensation at all - just on the coldest days a little pool in one or two of the channels and icicles on the drain pipe ends (10mm copper).
I put this down to the "Passivent" passive ventilation - one in each of the two upstairs bathrooms which stay very dry and air is effectively drawn up there from the whole building. n.b. not draughty at all anywhere.
I'd heard high praise of Passivent before and was sceptical - but it works brilliantly. Not always possible to install it, it depends on the layout
PS Passivent not the only brand there are others similar

 

[Lons]

.....Double glazing should be way down the list of energy saving things done in a house........

No one has suggested otherwise. Jacob is right on this.

Except as you've already hinted Mike the difference in value when / if you sell your house can be considerable. Changes the figures a bit if it's factored into the long term cost calculations and if the market at the time is tight it can make it more difficult to find a buyer.

Right or wrong the general perception is that DG is a desirable feature and this is pushed hard by the TV Do it up and buy at auction progs. My house has a fair number of windows and is double glazed and an estate agent mate told me a few years ago that the difference in value was well in excess of £10 k.

I've been retired a few years but I thought if not a dwelling subject to listed building or conservation area if you replace a door with a completely new one it has to comply with building regs which includes the glazing element. Is that the case with out me going off to research?

 

[OscarG]

I've learned a lot from this thread, fascinating stuff, just been googling Trombe walls.

If I ever win the lottery I'm gonna buy a bit of land and hire Mike to design and build me a super duper house* full of Trombe walls and other cool stuff (hammer)

*except the workshop, I wanna try doing that myself :wink:

 

[RobinBHM]

one of the big disadvantages of modern homes is the fact the insulation is mostly fitted on the warm side, so there is very little building material that acts as a thermal store.

Im not sure how that can affect the cost of energy, I suspect it largely depends on the way a house is used. A retired person will have vastly different heating needs to somebody that works all day and is absent form the home for 10 hours plus a day.

Certainly solar gain is a factor for windows and energy rating of windows has this factored in. However most heat is needed in the winter during the evening -not much solar gain happening then.

But, we build orangeries and customers say the solar gain for daytime use is most noticable, meaning heating is hardly required.

 

[Rorschach]

Certainly could be but it would take big state commitment to R&D. Yanks and ozzies (all that space and sunlight!) severely held back by the oil/coal lobby but the Chinese will do it - they've expanded massively on oil and coal to build an industrial base but are now going renewable big time.

They will have no choice. I hear this week that soon new houses will not be allowed to connect to the gas grid, something I have been expecting for several years now.

The Chinese uses cheap fossil fuels to build up their manufacturing ability and are now using that power to build cheap renewable technology for the home market and for export. With the efficieny increasing and costs falling it won't be long before it will make economic sense for people to put non-subsidised solar panels on their roof and generate their own electricity.
The question then is how best to use that power if you are not on a feed back tariff? If you are not at home during the day then you need a way to store that energy, batteries are still too expensive and inefficient however you could store the energy in the form of heat, use electric immersion heaters to warm an insulated tank of water and then at night you can pump that around the existing radiator system. During the day if heat is needed you can use the solar power to run an air source heat pump, tripling the efficiency of the solar panels.

 

[Lons]

Hmm... The same Chinese who were blamed last year for the release of massive amounts of CFC-11 which they are secretly and illegally using in the production of insulation for the construction industry.
A process banned worldwide since 2010. :roll:

 

[Jacob]

one of the big disadvantages of modern homes is the fact the insulation is mostly fitted on the warm side, so there is very little building material that acts as a thermal store.

Im not sure how that can affect the cost of energy, I suspect it largely depends on the way a house is used. A retired person will have vastly different heating needs to somebody that works all day and is absent form the home for 10 hours plus a day.

Certainly solar gain is a factor for windows and energy rating of windows has this factored in. However most heat is needed in the winter during the evening -not much solar gain happening then.

But, we build orangeries and customers say the solar gain for daytime use is most noticable, meaning heating is hardly required.

Thermal store only makes sense if you have a substantial source of free surplus energy. (e.g. as per  Rorschach's post above re solar panels). If not then zero thermal store with internal surface high insulation is the cheapest way to go. Quickest warm up of air and surfaces, least wasted heating structure.

 

[Jacob]

Hmm... The same Chinese who were blamed last year for the release of massive amounts of CFC-11 which they are secretly and illegally using in the production of insulation for the construction industry.
A process banned worldwide since 2010. :roll:

I think they feel they are entitled to catch up with the worst (USA and Europe) and they are likely to overtake us in renewables.

 

[sammy.se]

Another benefit of DG is sound proofing. That has to be worth some money to some people.

I live in a terraced house, on a road with a small amount of foot and car traffic. The noise, even with DG, annoys me. I wish I had Triple glazing or some sort of better sound proofing.

 

[MikeG.]

.........Thermal store only makes sense if you have a substantial source of free surplus energy. If not then zero thermal store with internal surface high insulation is the cheapest way to go. Quickest warm up of air and surfaces, least wasted heating structure.

Jesus H, Jacob. You don't know when to stop displaying your ignorance, do you.

OK, let me tell you about two houses I built side by side in the 1990s. One was of lightweight construction, double stud, 300mm insulation in the external walls, south facing glazed "sunspace", triple glazed, MVHR system, UFH, lobbies/ porches/ air-locks over all the external doors. It had a suspended timber first floor, and all internal walls were lightweight partitions. The other was built with extruded concrete internal blockwork with 200mm of insulation external to it, a concrete suspended first floor, concrete steps, and brick internal walls.....triple glazed, south facing sun space blah blah.....all the same as the previous house I described. They were in the same orientation, no overshading, and of virtually the same size, and they were monitored for their energy use by 2 different teams, one from a uni, and one by an energy consultancy.

Please tell me which one had the lower heating bills, and which one overheated in the summer. The one with more insulation, or the one with less?

 

[MikeG.]

More.....

Build yourself two boxes in the garden, each 1 metre cubed. Build one of plywood, 100mm Celotex, plywood....all round. Build the other of 100mm cast concrete, with 100mm Celotex externally, with ply cladding. Put a thermostatically controlled 100W incandescent light bulb inside both as a heat source, and monitor the energy use for a year. Report back.

Repeat the above exercise with a south facing window in each. Report back.

Jacob, I've a lot of time for you when you are talking about woodworking, but you are laying the law down here on something you know very little about. I've often thought that amateur woodworkers would do well to argue a bit less with you, and learn a bit more from you......and now I'm suggesting that this applies in reverse to you on this subject. At one stage I had 7 houses in the top ten most energy efficient above-ground buildings in Britain. This is stuff I know a little about, and if I don't know it, I don't google the answer, I refer to academic studies, and to, for instance, Design with Energy by Littler and Thomas, which despite being 30+ years old is still the bible of low energy design.

 

[Jacob]

.........Thermal store only makes sense if you have a substantial source of free surplus energy. If not then zero thermal store with internal surface high insulation is the cheapest way to go. Quickest warm up of air and surfaces, least wasted heating structure.

Jesus H, Jacob. You don't know when to stop displaying your ignorance, do you.

OK, let me tell you about two houses I built side by side in the 1990s. One was of lightweight construction, double stud, 300mm insulation in the external walls, south facing glazed "sunspace", triple glazed, MVHR system, UFH, lobbies/ porches/ air-locks over all the external doors. It had a suspended timber first floor, and all internal walls were lightweight partitions. The other was built with extruded concrete internal blockwork with 200mm of insulation externally, a concrete suspended first floor, concrete steps, and brick internal walls.....triple glazed, south facing sun space blah blah.....all the same as the previous house I described. They were in the same orientation, no overshading, and of virtually the same size, and they were monitored for their energy use by 2 different teams, one from a uni, and one by an energy consultancy.

Please tell me which one had the lower heating bills, and which one overheated in the summer.

Obviously the expensive concrete building would have lower bills - but at what building cost compared to the other? Was it cost effective in terms of saved energy bills? I doubt it.
The overheating of the light weight sounds like design failure to me - inadequate ventilation (opening windows?), blinds, etc. Google 'desert house ventilation' or "passive cooling" :lol: https://www.pinterest.co.uk/mcmayhem33/ ... ntilation/
Re your garden experiment - the lightweight box would be a lot cheaper to make and on a house scale the same cost effective issues would apply.
Basically you can't save much if the heating bills are already low - £1000 p.a. for a typical house, so cost effectiveness is key.
PS I do know a bit about. We did a lot of research into alternatives such as bio mass boilers and thermal stores for our chapel conversion and it all came down to cost effectiveness in the end. Still intending to put solar panels up but haven't got around to it yet
PPS re overheating of your light-weight house; confirmation bias? It confirmed your preferences which distracted you from looking for a design solution?
PPPS Things have changed a lot since Littler & Thomas, concrete is on the non green list nowadays https://www.theguardian.com/cities/2019 ... l-on-earth and the emphasis has shifted enormously to renewable energy generation rather than conservation, thanks to climate change urgency.

 

[RogerS]

..... so cost effectiveness is key.
......

So you've got a house that's going to outlast your lifespan and so the long term energy saving is going to help fix global warming etc but because it's going to cost you money to make it even more energy saving, you're saying 'Sod the planet'. That's what it sounds like to me. Bit hypocritical seeing as how you keep banging on about climate change.

 

[MikeG.]

.......Obviously the expensive concrete building would have lower bills - but at what building cost compared to the other?........

And that, ladies and gentleman, is what moving goalposts look like. We've gone from "thermal mass requires spare energy" or something, to "thermal mass costs more.