re: advice sought on passive solar design
16 feb 2003
>> this might work better if
>> a) the outer section has greater temp extremes than the inner one, and
>> b) the "slab" is vertical, since winter sun has a low elevation and the
>> plants might like to grow in the soil floor, and
>> c) the mass wall contains water vs masonry, with 2-3x more specific
>> heat by volume and a higher thermal conductance...
>i'm looking at gaining from solar while at the same time staying comfortable
>for people and also be esthetically pleasing. in my opinion, 55 gallon drums
>are not esthetically pleasing...
la di dah... perhaps you'd prefer a solera, a nice wooden cabinet with
a glass front and lots of horizontal bottles of sherry on wine racks.
>nor is 32 degrees f very comfortable for people (or plants).
smart people would go back into the warm living space at night.
>the idea is to allow the sunroom/greenhouse to heat up fairly quickly
>and to somehow get that heat into the rest of the house - fans, vents,
>or even tubing in the cement slab.
lots of mass on the cold ground, where the sun hardly shines in the winter.
>then allow the sunroom to cool (within reason) at night so that the
>temperature differential with the outside is reduced.
a square foot of r1 glazing with 90% solar xmsn might collect 0.9x1000
= 900 btu and lose 6h(80-34)/r1 = 276 on an average january day in phila
for a 62% solar collection efficiency. keeping the sunspace 32 f at night
increases the loss by about 78 btu and reduces the efficiency to 55%.
at 70 f for 24 hours, it's a net loser: 24h(70-30)/r1 = 960 goes out.
>the design allows the sunroom to be separated at night with pull out
>barrier or we can simply use insulated blinds to increase the r factor
>of the windows.
la di dah...