John Elliott wrote:It has to get really hot before it is a negative in the summer. I mean like Death Valley hot, where it only cools down into the 90s on hot summer nights. If that is the case and the temperature averaged over the course of the day is over 100, then yes, thermal mass is a negative because your air conditioning will be working double duty to cool all that thermal mass down.

How many cooling degree days do you run in the summer where you are?

John Elliott wrote:Did you generate that from the BizEE degree days page? Degree days are (degrees over the set point)x(number of days). For instance, that 608 for August tells me that since August has 31 days, the monthly average temperature is about 20 degrees higher than the set point you picked. That is a load on the A/C system, but it doesn't sound too bad.

My experience has been with concrete block buildings, a high thermal mass, but not nearly as much as adobe. In the low desert of California and Arizona, daytime summer temps are always over 100F, sometimes over 110, but they seem to radiate the heat away at night and are comfortable without the air conditioning running all night. It's only when the temps start hitting 120F that the A/C seems to get overwhelmed and runs all night.

Brian Knight wrote:I think interior mass walls would help reduce your cooling costs by a measurable amount.. but probably barely. I doubt that the saved energy would payback the increased costs to do so and the walls will be more difficult to clean compared to a more traditional smoother wall. Subtract the lost interior floor space from your costs per square foot and it seems like a pretty tough deal to me.