[Greenbuilding] The dynamic R-value scam...

[Nick Pine]

"John Straube" <jfstraub at civmail.uwaterloo.ca>

>There is a thermal benefit in heating season in cold weather, even if 
>the temperature rises above 40 or 50F.

"Especially if," no? It doesn't help much if it's always colder 
outdoors.

>This is due to the fact that interior-coupled thermal mass can store 
>the bursts of solar energy (or interior gains in office buildings) that 
>would otherwise be wasted.  Basically, I am talking about passive solar 
>heating mass, which does not have to be in the enclosure, but could be 
>in the interior partitions floor, etc.

Then again, thermal mass can limit the depth and energy-savings of night 
thermostat setbacks, and getting a burst of solar energy into a mass is 
hard to do without overheating a house, if it has a small surface or 
it's inside a wall behind foam insulation. On an average December day, 
an ideal overnight mass might "charge" in warmer solar house air for 
about 6 hours and "discharge" to cooler house air for about 18 hours, 
with comfortably small air-mass temperature differences.

Nick