Comments on: Stop Settling For Stratification

By: Todd Collins

Todd Collins — Fri, 18 Sep 2020 20:02:57 +0000

In reply to dave brach. Dave, I consider you a very knowledgeable person and your feedback is valued for certain. That said like with a virus, there is attacking symptoms once a person has it and there is prevention or staying safe from getting it. The prevention part of stratification is a high-performance envelope with lots of insulation and low thermal bridging to reduce that delta-T between interior surfaces and the ambient air. And the attacking symptoms component of fixing the issue once you have it is related to circulating the ambient air with a CERV for example to even out the temperatures. It has been our understanding from the Passive House training that a high performance building envelope reduces stratification because you have few sources of convection currents due that that interior surface temp to ambient air temp delta-T. If we have this part of the building science wrong, we would be delighted to say that we had it wrong in an upcoming blog.

By: dave brach

dave brach — Thu, 10 Sep 2020 16:29:37 +0000

sorry, not trying to be a know-it-all…. actually when I initially read the email and clicked to read the blog, I was fully expecting the blog post to be about the recirculation function on the CERV.

By: dave brach

dave brach — Thu, 10 Sep 2020 15:00:14 +0000

good windows, insulation and air tightness do not combat stratification. Maybe they combat drafts, but not stratification. Case in point: my water heater is DESIGNED to stratify as much as possible, and it is airtight, highly insulated etc. Of course water is not air but you get the point. In my experience the only thing that decreases stratification is air movement, either natural convective, or most typically, predictably, and effectively with fans and ducts (or possibly ceiling fans). And by the way you need more air movement than you think, especially in a multi story house with close rooms