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lisetrise
Registered Users
Posts:1
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| 05/27/2008 11:50 AM |
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hi,
I'm doing research for a website on green building. I'm really impressed with ICF building. I'm also a big fan of passive solar. I'm now doing some more in-depth research, and have a question.
While online this weekend, I came across a site that said traditional ICF (insulation on both sides) will not work with passive solar. The insulation on the inside would keep the cement from absorbing the heat and radiating it through the home, I think it said.
What do you all think of this? Have you built homes both ICF and passive solar? Good idea or not?
I think this builder said Rafstra blocks were ok, or just to use cement blocks.
I would really appreciate some feedback from those of you in this field and really familiar with ICF.
Thanks!
http://www.building-your-green-home.com
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adi43d
Registered Users
Posts:7
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renangle
Registered Users
Posts:77
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| 05/27/2008 12:52 PM |
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lisetrise,
I am not an expert in passive solar, but I will give your question a shot. We worked with a client here in Virginia who was going to build his own house with ICF and go with mostly passive solar. The client is a physicist and one of the smartest people we've ever worked with. Anyway, he built the house with 8" ICF all the way from the foundation to the second floor (yes that's a bit much) , with large windows facing east and smaller ones facing west. He is NOT putting in a HVAC in the house, but he is putting in a device that will take cold air from the basement and trasfer it to the 3rd floor in the summer and take hot air from the attic to the basement during the summer. I think it serves a few purposes, one being circulation of air. The client certainly did his homework and we have yet to hear of any problems.
I would think that ICF would work well for passive solar, because of the R-value, thermal mass, and how tight the house will be. The windows would be the major factor for the passive solar aspect of building. A cement block wall has very little R-vallue, so in the winter you would have issues especially overnight when the sun isn't there to help you. Granted some of this depends on where you are looking to build (Canada, Florida, etc), but ICFs should work better than most other systems in my opinion of course.
renangle |
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Alton
Registered Users
Posts:285
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| 05/27/2008 2:10 PM |
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| Does anyone know of any research comparing the thermal-mass efficiency of ICF walls with T-Mass type of walls. This type of research could probably answer the question as asked. My guess is that T-Mass walls should outperform ICF walls. |
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ReadyToRetire
Registered Users
Posts:185
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| 05/27/2008 4:35 PM |
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Alton,
I'd posted this link over in the general forum. It's a thesis for an MS-ME out of Virginia Tech.: "Investigation of Concrete wall systems for reducing heating and cooling requirements in single family residences." He simulated traditional 2x4 and 2x6 construction and compared it to flat ICF, waffle ICF (the brand he compared did very poorly), and Dow's T-mass. I'd debated emailing it directly to you, but I didn't want to impose.
I found his conclusions reasonable and well explained, but I'm not an expert! (My BS-ME is 35 years old, and I've never practiced.) What was really interesting was his conclusion on where, geographically, thermal mass was an advantage, which did NOT follow my existing understanding. In part, the difference might have been driven by the comparative lack of depth/thickness in ICFs and T-Mass walls when comparred to an adobe home: they responded faster. The second conclusion that I didn't anticipate (but should have) is that -- given a quality wall -- the infiltration at the wall-window, wall-floor, and wall-ceiling joints drive the results. He concluded that, in order of importance, were the walls' infiltration, insulation, and thermal mass.
Anyway, while it's not data from a field test, it is interesting. I'd be interested in your take on his results.
http://scholar.lib.vt.edu/theses/available/etd-10262004-214448/unrestricted/FinalThesis.pdf
VERY respectfully,
Larry
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Alton
Registered Users
Posts:285
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| 05/27/2008 5:41 PM |
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Larry,
The study makes a lot of sense to me. It reinforces what I have been teaching for years. A designer should design a building for the local climate. |
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ReadyToRetire
Registered Users
Posts:185
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| 05/28/2008 2:39 PM |
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Alton,
Thank you for the sanity check -- it makes me much more comfortable with the study.
Very respectfully,
Larry
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