[GSBN] Fwd: Modeling or measuring mass effect of interior plaster

[Art Ludwig/ Oasis]

Speaking of undocumented phenomena, (I haven't been reading all these posts to the bottom, so please forgive me if this was already mentioned) earthen walls functions partially as a phase change material.  In cooling conditions moisture in the wall will change from gas to water, releasing considerable heat per unit of water (more than five times that needed to heat the same quantity of water from 0 to 100°C), whereas in warming conditions the reverse occurs. In other words, a breathable earthen wall will have more temperature moderating effect than one which was sealed against passage of moisture. The magnitude of this effect would be a function of several variables, but I can imagine conditions in which it could be significant. Note that this apart from the moderating effect on room humidity, which would also have an effect on perceived temperature.

Ianto Evans shared with me his evolving view that mass is more important that insulation, based on his observation at Cobville that mass buildings with minimal or no insulation, lots of air infiltration, and minimal heating somehow managed to remain fairly comfortable all winter.

In our climate here I've noticed that buildings with no insulation and earthen walls as thin as 3" behave like mass buildings, particularly one we have that is coupled to uninsulated earth. It's been close to 100° the past few days and this building is still last Saturday's cool temperature inside. 

A practical effect of the apparent disconnect between observed experience and energy calcs in our area is the (so I hear) difficultly of cob buildings to meet title 24 energy compliance, even though they seem to require the least mechanical intervention to maintain comfort in reality land…


On May 13, 2013, at 9:49 AM, John Swearingen <jswearingen at skillful-means.com> wrote:

> Another undocumented phenomenon would be the "Hypothalamus Effect", the tendency for people to put on a sweater in response to slow cooling, rather than rushing to turn on the heat in the face of a more abrupt drop in temperature. They they go to bed without having called for heat, saving some Btu's along the way..
> 
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