re: oversized collector and storage.
5 feb 2004
niels lyck wrote:
>"ben simons" skrev i en meddelelse
>> hat muhammad's radio geschrieben:
>> > basically i am asking can one collect heat from the summer and store
>> > it for the fall and winter?
>in not-very-sunny denmark, in 1979, recently deceased solar pioneer alfred
>jakobsen built his house on top of/including a basement, a 300 m3 water
>filled heat reservoir.
...150m x 2m, or a 22 foot cube :-)
>the 150 m2 south facing side of his 45 deg.
>slope-roof consisted of primitive solar collectors. mediocre insulation and
>all, he managed to solar heat his house 100%, reaching its all-year low of
>29 deg c mid-february. his rule of thumb: floor area = collector area.
>living space (m3) = water storage space.
nice simple rules...
>given recent developments in collector efficiency, highly insulated walls
>and windows etc., collector area and storage volume presumably can be
>reduced - especially if you accept shorter periods where e.g a wood stove
>does the job.
a large enough multifamily building might be even simpler, with no solar
collection, just internal heat gains spread around with a hydronic floor
loop. googling on russian apartment heating, i found out moscow walls are
typically 14" of concrete, about r3, with no other insulation, and 10% of
the floorspace is poorly-caulked double pane windows which residents seal
up with newspapers etc in october and unseal in the spring. energy has
long been underpriced and district heating is poorly managed, with little
incentive to conserve. how big would a building with r20 walls and no air
leakage or windows have to be to stay 70 f indoors on a 30 f day, if each
family used 600 kwh/month and occupied 2,000 ft^2 of floorspace?
googling on swedish air leakage, i found a 1999 uk report that mentioned the
world's tightest voluntary standard, canada's ideas (post r2000) 0.15 m^3/h
per m^2 of envelope, tested at 50 pa, which translates into a natural air
leakage of about 2.5 cfm, or 0.008 ach for a 2400 ft^2 1-story house :-)