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re: sizing a heating system
21 jun 2000
news  wrote:

>> > article from the times 17th june 2000...

>> > the four-bedroom detached house is so
>> > well insulated that the sun shining
>> > through the windows and into the
>> > conservatory, together with the body heat
>> > of the occupants, keeps it warm in the winter...

>> hard to believe, in the cloudy, cold uk.
>> does it have any backup heating
>> systems? gas logs, coal or woodstoves?
>> a heat pump or electric heaters?

>woodstove. hot water via electrc immersion, but being changed to an
>air-to-water heat pump.

>> how much heating fuel has it actually used since 1993?

>the uk heating season is from october to the end of april, a total of 212
>days.  the autonomous house has a heating season of 76 days and uses approx
>278kg of wood. the early figures are not representative as the house was
>still drying out.

thanks for the digging up this further information. it seemed
too good to be true, but 600 pounds of wood, 1/4 cord? not bad :-)
how many pounds of newspaper, cardboard, etc?
>> with no backup systems or fuel consumption, i'd
>> call it a solar house, but wonder how much heat
>> internal electrical usage contributes.

can you find out the electrical consumption in wintertime?
your posting mentioned that the pvs don't yet make as much
electrical energy as the grid supplies, so this house is
partly electrically heated at the moment. (banking summer
pv energy and using it for a heat pump in wintertime can be
reasonably economical, but that's a different scheme.)

>> and was it comfortable? was it less than 10 c (50 f) indoors
>> for more than a few days per year, requiring lots
>> of traditional english indoor cold tolerance?

>"traditional english indoor cold tolerance", nick have you been
>listening to the ww2 gis?

no. i've been to the uk a dozen times and seen how you live in
those 4 pound b & bs with gas logs and electric and peat fires
and sweaters and no central heating :-) i'm not even sure my auld
family castle (dunvegan on skye) has central heating.

>average living room temps for 1995-96:
>oct: 22.4c
>nov: 18.3c
>dec: 18c
>jan: 17.7c
>feb: 17.7
>mar: 17.5

march was 63.5 f. not bad... was the living room the only one heated?

>as the house dried out further the above temps increased.  it must be
>pointed out that superinsulated houses tend to have lower temperatures
>as cold fronts are eliminated.

i guess you mean they are less draughty and the walls are warmer, so
convectional and radiational cooling of people is less, and the rooms
feel warmer with a lower air temperature than in conventional houses.

>> > the massive brick and concrete construction
>> > stores heat through the long periods when it
>> > is not sunny.
>> for a week or two? that seems unlikely.
>> back of the envelope calcs suggest to me
>> that you'd have to stack it full of bricks
>> indoors to make anything close to that
>> happen. with lots of airspaces between
>> the bricks, very few windows, and
>> airtight hyperinsulated walls.
>the house does not have the mass suggested by lund - the walls would be
>so thick the inside would be like a telephone box.  the mass is moderate.

and those thick walls would have significant thermal resistance
which severely limits their heatflow, unless they were full of holes
for airflow (and dust.) you might suggest that the times print a
retraction, or publish another story about the actual house and
its performance as built, vs as envisioned by its creator :-)

>> a couple of weeks ago, the philadelphia inquirer published
>> a story... that said houses with steel studs had "no air leaks"
>> and "lower utility bills" compared to wood-framed houses...

>cold bridging by steel studs is a problem unless spaced studs are used
>with thick insulation between the studs.

double-studded walls...

>metal framing is only good on the inside of a house. the external walls
>should be of a material that reduces cold bridging. look at a normal
>4x2 stud wall.  about 10% of the outer surface of the wall is stud
>acting as a cold channel from outside to in.

us r1, vs r20 insulation (or r0.004 steel.) steel studs have thinner
conductive paths, but a much larger bulk conductivity than wood. one
option is foamboard on the outside, but you could do that with wood too,
and save more heat. 

>"i" beams should be used with their reduced cold bridging (about half
>of the wood of normal timbers), or spaced studs with insulation between.
>lintels are another big cold bridging problem. spaced lintels over doors
>and windows eliminate cold bridging.

plywood web "z-beams" would be almost as strong, and easy to make.

>> ...though sustainable building is a good idea,
>> it appears to have veered away from energy-efficiency
>> and more toward natural materials and fibers, feng shui, and so on.
>> the [british] ecological design association publishes
>> a slick periodical that recommends calming interiors,
>> incandescent versus fluorescent lights [more natural], and
>> no metal bedsprings, because they interfere with the
>> earth's magnetic field and can cause serious illness...
>nick, you never know. ;-)  was this a wind up?

no, these people are quite serious. their mag is "ecodesign," the
journal of the ecological design association, editor david pearson.
(registered charity no: 1004226, registered office: the british
school, slad road, stroud, glos gl5 1qw england, tel 01453 765575,
fax 01453 759211. email submissions to deputy editor charlie ryrie, the winter 1999 issue has an article titled
"feng shui: ancient wisdom or new age nonsense?" they aren't sure.

>or was it written by those 1000s of people, from all over the world,
>who are now congregating around stone henge for midsummer's night.

you might enquire. is their office surrounded by standing stones?

>some think the stones give off "powers". there are numerous stone
>circles in england, some older than stone henge. "leylines", the
>ancients understood them and mapped them out.  we are only
>just beginning to understand them again.

i recall some on harris and lewis, where many people don't even
seem to know enough to come in out of the rain ("it's just soft.")

>i wonder if car suspension springs screw up the earth's magnetic field?
>mmmmm, is that why la is so screwed up?  all those cars and their springs
>and their pollution? ;-) ;-)

we'd have a different world with people like this in charge.


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