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Insulation and air tightness standards
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adam2
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PostPosted: Tue Dec 26, 2017 2:05 pm    Post subject: Insulation and air tightness standards Reply with quote

Demand always reduces over the holiday season, but this year the reduction has been greater than expected due to mild weather reducing heating demand and windy weather reducing gas burnt for electricity production.

There is also a slow, steady, ongoing reduction in demand for domestic heating due to increasing insulation in new build homes, the trend towards smaller homes, and improved efficiency of domestic boilers.

This post and those following have been split from the long running thread about gas supplies, storage, and potential shortages.

The original thread may be found here

http://www.powerswitch.org.uk/forum/viewtopic.php?p=288906#288906
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Last edited by adam2 on Sat Jan 20, 2018 4:48 pm; edited 3 times in total
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kenneal - lagger
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PostPosted: Tue Dec 26, 2017 6:15 pm    Post subject: Reply with quote

I wouldn't have said that there is any increase in the efficiency of new homes Adam. Yes, they are slightly more efficient than the homes of ten or twenty years ago but they are increasing in numbers and not many of the older homes are being knocked down. If you had said that people are having to be more economical with their heating because of lower disposable incomes I would have agreed. This, I think, is where the energy reduction is coming from although economising on energy use is a good thing.
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vtsnowedin



Joined: 07 Jan 2011
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Location: New England ,Chelsea Vermont

PostPosted: Tue Dec 26, 2017 8:20 pm    Post subject: Reply with quote

kenneal - lagger wrote:
I wouldn't have said that there is any increase in the efficiency of new homes Adam. Yes, they are slightly more efficient than the homes of ten or twenty years ago but they are increasing in numbers and not many of the older homes are being knocked down. If you had said that people are having to be more economical with their heating because of lower disposable incomes I would have agreed. This, I think, is where the energy reduction is coming from although economising on energy use is a good thing.

Only slightly more efficient over twenty years?
Here in the USA codes have been updated quite a bit in that time driven by the cost of heating oil and propane. They revise the codes every three years.
They are up to R49 for ceilings (14 inches of fiberglass) and R25 in the exterior walls. R30 for floors and R 15 for basement walls.
There are also codes for maximum amount of window area (20%) and ducting and leakage elimination requirements for penetration points.
New construction has to be certified by the builder and any variations disclosed to buyers. Remodeling must bring the remodeled section of a home up to code if at all practical unless the home is historic.
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cubes



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PostPosted: Tue Dec 26, 2017 10:21 pm    Post subject: Reply with quote

vtsnowedin wrote:
New construction has to be certified by the builder and any variations disclosed to buyers.


This sort of self-regulation is where things usually go wrong imo. Yes, they can't go really far below regulations but corners can and are cut in areas where it's hard to check.
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woodburner



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PostPosted: Tue Dec 26, 2017 10:32 pm    Post subject: Reply with quote

Some corners should be cut. It is ridiculous to have most of the draughts (distributed ventilation) sealed up to save heat at the expense of air changes. If an approach like masonry heaters, or rocket mass heaters were used, comfort could be maintained without having to raise the temperature of a whole space. Lack of ventilation is not healthy.
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vtsnowedin



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PostPosted: Tue Dec 26, 2017 10:52 pm    Post subject: Reply with quote

woodburner wrote:
Some corners should be cut. It is ridiculous to have most of the draughts (distributed ventilation) sealed up to save heat at the expense of air changes. If an approach like masonry heaters, or rocket mass heaters were used, comfort could be maintained without having to raise the temperature of a whole space. Lack of ventilation is not healthy.

A very good point. If you have an eight inch pipe to a chimney venting a solid fuel burner you need to have an equivalent amount of drafts coming in freely to feed it or it won't work properly. The supper tight homes I've seen built in the area (12 inch thick walls, 30 inches in the attic) pipe cold air in directly to the stove/ furnace and have a heat exchanger in the ventilation system which robs the heat from the stale air being vented out to warm the incoming fresh air.
These homes use as little as one third of the fuel the same sized house built to 1985 standards consumes.
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kenneal - lagger
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PostPosted: Wed Dec 27, 2017 12:54 pm    Post subject: Reply with quote

woodburner wrote:
Some corners should be cut. It is ridiculous to have most of the draughts (distributed ventilation) sealed up to save heat at the expense of air changes. If an approach like masonry heaters, or rocket mass heaters were used, comfort could be maintained without having to raise the temperature of a whole space. Lack of ventilation is not healthy.


If there is a howling gale blowing and you have a leaky house you can't control the amount of air that comes in through those leaks. You can't control the size of the leak. If you have an airtight house you can always open a window if you like a howling gale blowing through on a cold day. To deliberately build a leaky house because you like some ventilation is just crazy! If you're stupid or lazy enough not to open a window if the house gets stuffy then perhaps natural selection should take its course.

The whole idea of a masonry stove or rocket mass heater is for the stove to heat the whole space evenly. They won't function well in a leaky house because the low level of heat they give off would be wafted away by the draughts.
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woodburner



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PostPosted: Wed Dec 27, 2017 1:14 pm    Post subject: Reply with quote

Quote:
If you're stupid or lazy enough not to open a window if the house gets stuffy then perhaps natural selection should take its course.


A statement which indicates a lack of understanding of human behaviour. This attitude will not solve any problems.
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vtsnowedin



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PostPosted: Wed Dec 27, 2017 2:21 pm    Post subject: Reply with quote

Yes no one goes about building a house with deliberate leaks in it. but you can't just go about willy nilly and seal up a house without considering proper air flows for both the living occupants and the oxygen consuming appliances. An adult human consumes about 550 liters of pure oxygen each day. With the 25% efficiency of the human lung and the 20% oxygen content of fresh air that means eleven cubic meters of stale air needs to be vented out of a house each day for each adult human inside it.
One story goes that a home owner had done a energy saving retrofit on his house but was then getting severe head aches each morning. One day as he opened the front door he heard the wood stove whoosh to life from it's smouldering state as the fresh air coming in the door reached it.
Pipe added to let the stove breath and no more head aches.
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kenneal - lagger
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PostPosted: Wed Jan 17, 2018 1:32 pm    Post subject: Reply with quote

vtsnowedin wrote:
...... One story goes that a home owner had done a energy saving retrofit on his house but was then getting severe head aches each morning. One day as he opened the front door he heard the wood stove whoosh to life from it's smouldering state as the fresh air coming in the door reached it.
Pipe added to let the stove breath and no more head aches.


That only emphasises the need for properly designed systems. It is not an argument for a leaky house which is what some would argue from that experience.
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vtsnowedin



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PostPosted: Thu Jan 18, 2018 1:18 am    Post subject: Reply with quote

kenneal - lagger wrote:
vtsnowedin wrote:
...... One story goes that a home owner had done a energy saving retrofit on his house but was then getting severe head aches each morning. One day as he opened the front door he heard the wood stove whoosh to life from it's smouldering state as the fresh air coming in the door reached it.
Pipe added to let the stove breath and no more head aches.


That only emphasises the need for properly designed systems. It is not an argument for a leaky house which is what some would argue from that experience.
I consider it a cautionary tale. The point being to not just apply energy saving materials without considering ventilation and heath requirements. Of course a properly designed system would deal with those issues but how does the first time buyer or renovator know that his contractor knows what they are doing in this regard?
It is a question that needs asking and competent answers given before any contract is signed.
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kenneal - lagger
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PostPosted: Thu Jan 18, 2018 3:39 pm    Post subject: Reply with quote

vtsnowedin wrote:
..... Of course a properly designed system would deal with those issues but how does the first time buyer or renovator know that his contractor knows what they are doing in this regard?
It is a question that needs asking and competent answers given before any contract is signed.


I agree there but there is a problem. Normally you would say "go to a properly qualified person, an architect, say," but the problem is most building professionals haven't kept up to date with the latest science in building design. This is especially true in the architectural profession where the knowledge of sustainable/low energy design is woefully lacking, even among many young architects just coming out of University.

Low energy design is only just making its way into architectural schools and many new architects are only taught about it on a post graduate course when it should be at the foundation of any design process: you can't just make any old design green, as I am asked to do on many occasions. The knowledge among older building services engineers can also be sketchy.

I know this because I have had a keen interest in low energy design for 45 years but the average man in the street doen't even know that there are questions to be asked let alone which questions to ask.

These comments are about the UK but I suspect that it might be true of the US as well from some of the US based building programs that I have seen on the TV. It would seem to me that the levels of insulation applied to new build in Alaska are about the same as our Building Regulations requirement in the UK and we think it's cold if the temperature gets to 0C (32F).
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woodburner



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PostPosted: Thu Jan 18, 2018 6:37 pm    Post subject: Reply with quote

Quote:
I agree there but there is a problem. Normally you would say "go to a properly qualified person, an architect, say," but the problem is most building professionals haven't kept up to date with the latest science in building design. This is especially true in the architectural profession where the knowledge of sustainable/low energy design is woefully lacking, even among many young architects just coming out of University.


Latest doesn’t always mean best. I don’t see the perception of sustainable and low energy meaning anything given the appalling crap that is making up most of the current domestic building. It would be mare accurately described as a shed in a plastic bag with a brick facade. How long will they last? Unlikely to be as long as some of the houses built in the middle ages which are still standing, and despite their age are in many cases quite reasonable places to live.
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oobers



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PostPosted: Thu Jan 18, 2018 7:15 pm    Post subject: Reply with quote

A friend involved with building air tightness once told me that most of the new build housing with PIR boards inserted in the cavities are nowhere near meeting the regulations as no attempt is made to close the gaps between boards. It does make you wonder how many houses given a decent energy rating based on hypothetical build standards are actually very poor.
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cubes



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PostPosted: Thu Jan 18, 2018 11:07 pm    Post subject: Reply with quote

That's always going to be the case with a basic tick-box exercise though. No reason to spend more money doing it properly if you can get a tick in that box cheaper.
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