Measuring energy efficiency effectivness

the most obvious ways are:

1. Thermal imagers

and

1. air leak testing (which involves sealing up doors) and using a huge fan to suck out air and then measuring pressure difference to then get the leak rate.

While at it , discover the effect , for those like me more concerned about hotter summers than colder winters. What is the effect of blocking the convection within the cavity when the outside skin is heated by the sun. How much heat is vented ertically to the loft , rather than transfered to the inner core with and without insulation?

Yes, that was what I was thinking. So if you know the internal and external surface temperatures, how would you calculate whether that was performing to spec?

Yes, that's for another day - not quite that advanced here :-)

For a given outside temperature, you can calculate how much energy is necessary to maintain a chosen internal temperature, based on the surfaces and their U or R values.

Then put inside a thermostatic electric heater and bring the room up to that chosen temperature (and equilibrate any heavy thermal masses like masonry). When up to temp, record how much energy it takes to keep it at that steady state (over a few hours or more). Compare with the calculated value.

Obviously this is easier on a day when the outside temp doesn't vary too much, and there's not much solar gain or other extra heat. (turn off other electrical loads in the building and vacate it to minimise self-heating)

Theo

The main bonus for my house was the elimination of the astonishing air leakage through the gable end wall into the ends of the joists that ran side to side and then into party wall that was also a cavity wall with holes front and rear to allow a throughput of cold air from the North-facing front through the gap between gnd floor ceiling and upstairs floor, into the party wall cavity and out the holes in the rear wall in the corner where the stack in the corner of the part wall and rear wall was boxed in and hid another missing brick right up under the wall plate.

It was so cold at one point that with the 14Kw Baxi back boiler on full blast and the 6Kw radiant fire on full I couldnot get the house above 16C.

Cavity wall insulation mostly fixed that and lining the insides of the north-facing wall (single hollow block + plastic shiplap and no building paper upstairs) with EPS (1992) and 80mm Celotex (2010) downstairs plus digging out the GF screed and having 70mm celotex bwteen 3x2 battens + hardwood flooring made all the difference.

The big problem is the bit of wall above the south windows that is hidden by the 37 degree overhanging trusses and soffits. This is a single skin up to the wall plate (*) which means heat loss in winter and massive heat gain in summer. Last summer this bit of wall above the window was measuring 35C inside, while the loft temp was 46C.

(*) The cavity wall stops at the top of the upper windows and the asbetos/cement soffits sit on this outer skin and slot into the fascia boards.

Local authority has been upgrading some social housing by adding external insulation about 50mm thick + fibreglass cladding that is rendered, and reroofed them with inset solar PV panels. all paid for by the council tax payers. These properties were built in 1974 with ?50mm cavities anyway so the big question is did they also fill the existing cavity because if not then there is cold air ventilating the gap between the inner leaf and the outer insulation.

well.... thermal conductivity and U values would be a good start:

that sucks! :-)

I'm reaching the conclusion that that's as good as it's going to get. The problem is that it's not measuring actual performance because it relies on given R-values for each of the building components. One of the issues was that poorly installed components (for example, insulation board foil facing removed) affects performance too. I think.

Yup :-)

That doesn't The foil is s cheap vapour barrier, thats all

Granted - not a good example - but they didn't give any examples in the workshop. Just a series of graphs illustrating the relative effectiveness relating to about 10 properties retrofitted to the same standard. The scales went from 'pretty much useless to the point that they might as well of not bothered' to 'pretty much to spec'. I'm just wondering how they came up with such precise estimates.

I'm watching a reroofing across the way - again and as usual, loose fitting insulation board between the rafters.

The one that got me because I didn't realise it at first, is sealing against air movement.

Which is why no one uses rockwool much any more - celotex is easy to seal into a hermetically sealed barrier.

Living as I do in a non cavity wall terraced mid terrace, house, I was wondering what one might be able to do about insulation in such a building. I note that there is a void full of rubble under the downstairs floorboards and yes we do get some draughts from that but then again the wood there needs to have fresh air. I only mentioned it as there was some gov would be advisor suggesting that all such houses should be bulldozed and proper insulated ones put up. I feel that this is rather unlikely to occur and if they do it will be blocks of flats in any case. Brian

I feel the former might be more useful as it would point the finger at the problem areas directly. Brian

Not true. It reflects more than just water vapour

Brian

That was what John Prescotts 'Pathfinder' scheme was all about.

Andrew

or so sellers like to claim.

Pathfinder - yes, it had a lot to answer for in terms of indiscriminate clearance in the name of 'market renewal'. But ever thus really - from the 20s slum clearances.

'Decent Homes' was the most perverse - an agreement between councils and central government to bring council housing up to modern standards (basically, new kitchen and bathroom, central heating, some insulation). OK, a lot of properties were improved. But put huge strain on LA's revenue budgets, and then ended up as RTB-fodder in the process. And a lot were demolished because it couldn't be done economically, and 100,000s privatised to raise finance to do the work.

Brian - similar to my house. For GF drafts, take off the skirting boards and low expansion foam in the gap between the wall and the floor. A more flexible silicone type filler wold be better but the foam works IME. Cheap and easy. Also if possible deal with wall mounted sockets and aerial points etc.

It starts getting expensive and disruptive when you get to walls and opening, though. But a lot is DIYable with no need for craft-like skills. Some advice/guidance on the method is a good idea - to avoid things like cold bridging, and planning in the context of later improvements.

The myth that you can retro-convert Victorian workers terraces to modern standards cheaper than by demolishing them is rampant.

Remedial work on old bu8ildings is impossibly tricky and time consuming. And you ned up with e.g. smaller rooms once you subtract 6" or more on internal insulation and studwork.

And most of the rooms in those terraces were not big enough to sing a cat in anyway.

Half of them front onto the street, which then becomes a parking nightmare.

They are not disabled friendly either.

One of the best developments for social hosing I ever saw was a courtyard, with resident parking, a place for kids to play off-road, surrounded by two storey apartments, with more or less individual staircases. Insulated to the hilt, cheap to run, and rented out at cost by a local housing association.

I had one such house once. I achieved miracles by tacking down hardboard over the flooring, and laying vinyl over that. Ive used the expanding foam trick as well, on this house, when a gap appeared between upper and lower storeys due to wood frame shrinkage. It worked very well .

Wooden floors need underfloor ventilation, but there is no requirement to extend that into the room above!

The problem is the law of unintended consequences. Building regulations are great on new builds, and I utterly endorse them, but when it comes to renovation, sometimes it is not possible to comply: the solution in that case is simply not to renovate.

Which is why, again, sometimes its is simply easier to tear down and rebuild to modern standards.

You get room sizes that are better, light levels that are better, insulation that is better, probably off road parking, a guaranteed electrical installation with enough plugs and sockets and a modern CU, proper disabled access, double or triple glazing, plumbing that works...

It's foil, so it reflects radiant heat. Which is a key part of keeping cool in summer, and a decent chunk of heat losses in winter.

Theo

It might be, if it were in fact subject to any radiation at all, but of course it isn't. Its buried inside the wall. Like having a mirror inside your wall so you can see your reflection Not.

No more ArtStudent™ comments, please