[Strawbale] Radiative heat losses

[dfugler at cmhc-schl.gc.ca]

David,

I do not see radiative heat losses as being a significant factor in terms 
of heating loads in well-insulated houses. So I ignore them. I have yet to 
see foil-covered products as being particularly useful, although there was 
some research showing foil radiant barriers as reducing cooling loads in 
Florida houses some years back. Those houses probably had poor attic 
insulation and the air conditioning system within the attic space, so the 
utility of radiant barriers there does not necessarily translate to their 
usefulness in typical houses in colder climates.

There is a movement to design and build "net-zero energy" houses, where 
the total house energy consumption is matched or exceeded by the energy 
produced through solar thermal or solar photovoltaic. CMHC has one such 
program with its EQuilibrium housing demonstration 
(http://www.cmhc.ca/en/co/maho/yohoyohe/heho/eqho/index.cfm). In order to 
avoid the excessive purchase of costly energy generation equipment (e.g. 
PV), these houses are really well insulated (better than straw bale) and 
are very airtight, so that their heating loads are extraordinarily low. 
There are no radiant heat loss counter-measures in these technically 
advanced houses. Good insulation and airtightness are all that are 
required for efficient envelopes. 

Don Fugler
CMHC Policy and Research