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

[John Straube]

Apparently I was misunderstood. 
It does not matter if the temperature is -50 or +40. Thermal mass on the interior increases the fraction of solar energy that enters the building that can be used to offset heating.

It is true that when one sets back a thermostat, the temperature will drop more slowly in a thermal mass house than one with no thermal mass. For special occupancies (if people are leaving for quite some time or if the temp during sleeping hours is allowed to drop to something very low, like 50 F) this could be a problem.

For most people, who want to avoid the temperature exceeding 78 during sunny days and not drop below 65 at night, interior thermal mass is just the ticket.


Nick Pine wrote:
> "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 
> 
> 
> _______________________________________________
> Greenbuilding email list
>      Environmentally-preferable design, construction, building elements
> List info: http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
> List email: Greenbuilding at listserv.repp.org
> Managed by BuildingGreen, Inc. http://www.buildinggreen.com
>       publisher of Environmental Building News and GreenSpec
> Hosted and archived by REPP / CREST http://www.crest.org
> To get on the list:
>   http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>   or mailto:greenbuilding-request at listserv.repp.org?subject=unsubscribe
> To get off the list:
>   http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>   or mailto:greenbuilding-request at listserv.repp.org?subject=unsubscribe
> 
> 
> 
> 
> 

-- 
Dr John Straube, P.Eng.
Associate Professor
Dept of Civil Engineering & School of Architecture
University of Waterloo
Waterloo, ON Canada