More on curtains and their insulating effect

[Terry Fields]

Fairly ordinary situation in the lounge, with a 6' x 6' double-glazed patio door at one end, installed to give a 6" recess; the curtain rail is screwed into the lintel above the door leaving said gap between curtains and door. The curtains are eyletted, and are made of fairly thin material, partly to ensure than when drawn back they hang in a narrow vertical bunch giving maximum light through the window.

SWMBO and I had the idea of instead of lining said curtains and spoiling the 'drape', of hanging another curtain in the recess, using thin material and a removable sprung curtain rod. The idea was to use the two air-gaps formed to provide better insulation rather than just making the curtains thicker. Off we went to the local haberdashers, and decided on some thin curtain lining - not the 'thermal' or heavy stuff; cost about £15 as SWMBO already had rod, tape, rings, and cotton to hand.

She knocked up the new curtains in an afternoon, ensuring that gaps at the top and bottom were minimal when hung, and there was enough for a slight overlap in the centre.

So, last night I put wireless weather-station sensors outside the patio door, between the new curtains and the door, and the lounge side of the original curtains, and waited for everything to equilibrate.

Final readings in degC were: lounge 23.5, curtain sensor 10.1, outside -0.1.

It is clear from these figures that the temperature drop across the two curtains at 12.4 degC was greater than that across the patio door at 10.2 degC, meaning the insulating effect of the two curtains and two air-gaps was greater than that of the door. Subjectively the lounge felt more even in temperature.

One thing to try is to repeat the experiment without drawing the new curtains, to see what the temperature drops are, but it seems reasonably clear that the investment of the £15 was well worth it, and the idea of using air as the insulating medium was successful.

It should be noted that the central heating system is controlled by a thermostat in the hall, which was on its usual setting. The lounge temperature at 23.5 degC was probably 1 degC above 'normal', as I aim for 22.5 in the evenings, and might represent a gain due to lower heat losses through the patio door.

[Grimly Curmudgeon]

Do you lounge around in shorts and t-shirts in there? It's winter man, show some solidarity with the otters.

[Dave Liquorice]

B-) Those are the sort of temperatures were I melt... Mid twenties is the start of the "too hot to do anything" range. Living room currently

18C, it's not yet warmed up from the overnight low of about 16C, the stat is set for 18.5C during the day and 20 for the late afternoon/evening.

[Terry Fields]

Sod the otters....I lounge around in T-shirt and jogging bottoms.

These days I feel the cold, and the lounge got to 23.5 degC because of the extra curtain lining, the heat input being set by the thermostat in the hall (which was not affected by the change). Normally the lounge temp is 22.5, the lowest temp at which SWMBO complains and gets out her horse blanket.

I'm just old enough to remember the winter of 1947, in an uninsulated 1930s house - I had ice on the inside of my bedroom window. I have every respect for those who run their lounges at 16 or

18 degC, but if I did that I'd go to bed feeling like a block of ice and simply wouldn't warm up, even if I wore heavy clothes and a woolly hat for the evening.

Annual gas consumption here (4-bed detached with two occupants[1]) is 17500 kWh which includes DHW (estimated at 5000 kWh).

[1] One of the occupants believes that switches only have an ON position, and thermostats have only a MAX setting :-( No names...no pack drill...

[Percy]

On Fri, 7 Dec 2012, "Terry Fields" writ:

I lived and worked in Sweden for some years and it was common for the temperature to be set at 17 24/7 in the winter. Normal indoor wear was what some people wear outside over here!

[Grimly Curmudgeon]

house - I had ice on the inside of

I was 7 in the winter of '63 and ice on the bedroom window was a feature for a few winters. I just accepted that as being normal and though I was glad of the spring coming it was with a sense of loss that no more pavement slides and snow-sledging would happen. Anyway, I hate the cold now and the same ice-on-the-window scenario would have me reaching for the kindling. A room temp of 23.5 is a bit much, though.

[polygonum]

Last night our living room was 17.5 - and we discussed that it felt quite toasty warm. In fact, hitting 20 is a rarity - and almost invariably either a mistake or because my elderly mother is here.

[Terry Fields]

I remember that - the snow was so deep and so prolonged that only bikers could get to the coffee bar.

Snow on the ground for about 70 days, IIRC.

Ah, well, in this house we've got the dreaded dry-lined walls that have no heat content at all. Although rooms warm up very quickly they also cool down very quickly too. It is a completely different kettle of fish to having plaster over masonry that holds the heat and lets it back into the room. I guess the radiant heat from the dry lining goes two ways: into the room and into the cavity, the latter of which is never returned :-(

ISTR that humans radiate about 400W of heat and receive 330, the difference of

70W being made up from burning food. If the dry-lined walls aren't returning so much radiation, then the rooms will 'feel cold' and the temperature needs to be jacked up to cut down on the internal food-burning demand. Perhaps a case of 'being green' that never was thought through.

[SteveW]

Well I do wear a short sleeved tee-shirt outside nearly all the time. I did surrender to wearing a long sleeved one while working outside for eight hours at a stretch in the middle of winter, with snow on the ground.

I could save a fortune if my wife didn't object to anything lower than

20.5 in the living room!

SteveW

[Grimly Curmudgeon]

70W being made up from

the rooms will 'feel cold' and the

demand. Perhaps a case of 'being

Well, I re-discovered the 'Fisherman Effect' whereby if you plunge your hands into ice-cold water, remove them and let them warm up naturally, your finger circulation improves dramatically and you can work in the same ice-cold water for hours, like the trawlermen.

Makes me wonder if it could work with the whole body; of course, it would draw on reserves much more than just fingers and hands would, so probably not recommended for anyone not in the best of health, but look at all those elderly Scanwegians who jump into frozen ponds and have been doing it every winter for decades.

[polygonum]

of 70W being made up from

the rooms will 'feel cold' and the

demand. Perhaps a case of 'being

Babies have brown adipose tissue (BAT) which allows thermogenesis without shivering. More recently it has been shown that at least some adults also have enough to be significant - and/or other tissue that behaves in a similar fashion.

It seems entirely feasible that those who expose themselves to the cold are more likely to retain enough BAT to be useful.

When Darwin was on the Beagle off South America, the natives of what is now Patagonia seemed to be able easily to swim in freezing seas. Their apparent uncaring attitude towards cold seemed to astonish even the sailors who must have been pretty tough folk by our current day standards. I wonder whether they retained BAT - possibly due to their genes rather than cold exposure?