Phase-change materials in a heating climate, Zone 6B
Pat_Kiernan
| Posted in Green Products and Materials on
I’m hoping to break ground Spring 2016 on a Pretty Good (or better) House in Carbondale, CO (climate zone 6B).The site has excellent solar for winter heating and broad diurnal swings for summer cooling. It would seem that PCM would be a great technical solution, but I haven’t seen any compelling case studies. Has anyone seen good research on the use of phase-change materials (PCM) in a heating climate?
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Replies
Pat,
I've read several phase-change materials reports over the years, and most of them involved a lot of hype. I've never seen an application that made sense to me.
It's certainly true that these materials only make sense if you are willing to tolerate a fairly wide range of indoor temperatures -- the old passive solar approach of putting on a sweater in the morning and peeling down to your shorts and T-shirt in the afternoon.
http://info.ornl.gov/sites/publications/files/Pub41752.pdf
The research is one thing, finding a commercially available product is another.
The lignin in massive wood buildings (12" log houses) has phase change characteristics in relevant temperature zones, but it's pretty squishy. Still, it give log structures a much higher "apparent thermal mass" than simple models of the thermal mass of wood would imply.
But either way, it's "in the noise" from a home design point of view. Inattention to air sealing could easily swamp any phase change material benefit in the less-than-laboratory setting of a real and occupied house.
Martin,
Thanks for your reply. The Rocky Mountain Institute (Amory Lovins) is installing BioPCM in their new Innovation Center just up the road in Basalt. They are designing for a temperature range of 64 to 84 degrees F. Individuals can adjust for personal comfort with office chairs that have low-wattage heating and cooling capability.
Dana,
Thanks for your post. I wonder what the melt/freeze temps are of the lignin in massive wood structures, and whether they are consistently in the right zones to be beneficial. I hadn't heard about the lignin factor before. I finally got around to reading the ORNL report you referenced. It doesn't seem like PCM is quite ready for my application.