Insulation report - a bit long

[GMM]

So another gas bill arrived today, giving me a chance to assess the impact of a few minor energy saving measures on the house.

In summary, since the same quarter last year, I have done some draughtproofing (doors and windows), wherever seemed to be running a tangible draught, insulated under the dining room floor (170mm loft insulation from below) and added 40mm PIR to the inside of the panelling under the stairs, which is also the side of the cellar steps.

Local degree days tell me that heating requirements this year have been

89% of last year. A little surprising, as my subjective feeling is that it's been warmer than that, but that's the data, guv. It seems from the data that March was the killer month last year.

Our gas bill says we used almost exactly 2/3 of last year's consumption for the same period, which is a saving of roughly £350 at current rates, so allowing for the degree days, we're about £300 in pocket. Last quarter, I reckoned we had saved around £200 on a similar basis. The total cost of these insulation projects to date is around £150, a pretty clear win all round. Happy days. More importantly than money (really?), the house is now way more comfortable.

There is still plenty of scope to improve on this and the trick is to tackle the energy use without compromising the character of the house, so here's my latest little experiment, in case anyone is interested:

All the external doors are 4-panel. Surface temperatures in the evening (ie heating on and stable, cool outside) are about 2 -3 degrees lower on the panels than the stiles and rails. No shock there.

I took a piece of 6mm ply, 10mm bigger each way than a panel, masked off the appropriate area and built up a layer of canned foam to the depth of the panel (~12mm), then pinned this over one lower panel of a back door. The surface of this is consistently 0.5 - 1 degree warmer than the adjacent stile /rail, and up to 4 degrees warmer than the other panel on the same door (ie a matched control).

That seems like a good result, although I'm wondering if it's going to be worth the effort of following up for such relatively small areas (though there are 3 such doors), as I'll have to trim it up with mouldings to blend the apprearance in, repaint etc etc.

I've no idea how a surface temperature difference relates to a useful outcome here. I do know the panelling under the stairs/side of the cellar steps was 4 degrees below surrounding internal walls and insulating that had a great effect, although it's a much greater area.

Maybe someone has a view?

[harryagain]

Canned foam is not that good an insulator. You would be better to use some form of sheet insulation. Eg celotex or kingspan. Just use the canned foam to fill gaps and as an adhesive. You will need to wet down any enclosed spaces, canned foam needs moisture to make it go off. I have insulated doors with 100mm of insulation

[Michael Chare]

You could read your gas meter weekly this would enable you to see how well the heating load corresponds to degree days.

I dip my oil tank weekly when I put the rubbish out. This enable me to see how my consumption fluctuates. Of course I have the additional problem of having to order replenishments.

[GMM]

I guess my statistical training would tell me that it gives a clearer idea of what's happening if you average over a reasonable period and it's not like I'm going to influence the outcome by onitoring it any more often.

[GMM]

It may not be as good as celotex, but the canned foam was there, in the garage, ready for use on a Sunday afternoon when I had a few minutes to set it up, at almost zero cost. I doubt it would last anywhere near as long, but I doubt its insulating propeties are signficantly different and this was a proof of principle. I have no doubt 100mm PIR would do a fantastic job, in fact a bit more than 50mm, but it would hardly be in keeping with the house and I have a higher authority to answer to on aestethic issues....