[Greenbuilding] Replacement foam insulation for greenhouses

[Nick Pine]

Tiny cold bubbles (1/16 inch at a 50 F mean temp) can be as good as 
fiberglass.

>>One wonders if they include some method of storing heat for long periods 
>>of time?

Overnight, at best, I think.

>>The proponents behind this are claiming that the greenhouse will use as
>>little as 5% the energy an equivalent greenhouse without the insulation
>>would use for heating and cooling.
>>Does this work?

Yes. This all goes back to a Swedish patent around 1960, with more recent
work by John Groh at U Arizona and Otho Wells at U New Hampshire.
After some expensive and unsuccessful experiments with (solarroof father?)
Richard Nelson, Bill Sturm built a 10,000 ft^2 tomato greenhouse in Calgary
and measured an 82% propane savings with vs without bubbles on alternate
minus 20 F nights. He got a patent, and further development work was done
for Venlo greenhouses by Bill Quist in Toronto.

Bill Sturm's system was simple, with a 2" holey pipe in a 10% SLS detergent
solution in a 100' trough on the ground on each side of a double wall poly 
film
greenhouse. At dusk, a shop vac would make bubbles with about 1000X
the solution volume. When the bubbles got up to the air return at the ridge,
they would push on a screen that pushed on a microswitch that turned off
the vac, and the process would run again about an hour later, when the
bubbles began to subside from the ridge. During the day, the plastic films
were inflated with air.

Greenhouses need dehumidification as well as heat, since green plants can
evaporate about 1 pound of water per square foot on a sunny winter day.
This doesn't solve that problem.

Nick