Building with 'thermal mass'. Are the claims bogus?

[CalG]

GalG,

"Air conditioners are inefficient dehumidifiers. But they help!"

I would say I agree if the temp is not the issue. As you know, sizing AC equipment is important. Oversized equipment leaves a damp but cold room. Undersized and it runs all day but can't get the home cool.

Due to our mass, temperature is not the issue. Often, By opening windows at night we can keep it cool.To control the humidity, we have a whole house dehumidifier. It's an AprilAir and can removed 96 pints a day. We set the AC to 75 but set the humidity to 45%. The 75 deg at 45% feels much better to us than 72 deg at 70%.

The whole house dehumidifier is really is nice is when in the Spring and Fall when clearly no heat/cooling is required. The mass is holding the temp in a comfortable range but damp Indiana days get's old. Now is a good example. Our heat has not kicked on for quite some time. But it has been raining alot and the dehumidifier has been cycling a bit.

For my needs, The added heat from the running dehumidifier is a welcome addition to the walk-out basement. Cold and humid makes for a useless space.

Well, It can be used for growing mold on seldom used domestic articles, and for casting a rusty surface finish over precision machine tools ;-)

 

[westcliffe01]

Trying to do passive solar with lightweight construction materials is an exercise in futility. Without mass the room will quickly overheat from the solar gain, and will also rapidly cool once the sun sets. Anyone who has spent time in a tent in the desert has experienced how this works...

If you do not regularly have sun during winter, or if you have extremely humid summer conditions, then high mass may not be for you. I know that there has been a lot of experimentation with "earthtubes" to "condition" air brought in from outside, but I think the systems I have seen were too simplistic and have poor heat exchange. If one was able to use groundwater run through a conventional air/liquid heat exchanger it would probably work a lot better. Imagine pulling hot summer air through a heat exchanger through which 55F ground water was circulated. One would condense out most of the moisture and it would certainly be at a comfortable temperature for conditioning the living space.

Certainly, in MI, drilling a shallow well is a lot more predictable/reliable compared to dry places like Colorado, where a well might have to be 550 ft deep and cost #25k to drill, in addition to the $3500 state permit.

 

[TnAndy]

Paddy

This statement is a popular "misconception" regarding conventional A/C operation.
"
During the Summer, due to the flywheel effect, the AC often runs late at night. This is fine because it's the coolest time of the day. So you can imagine an AC unit cooling a home to 74 deg with an ambient air of 70-72 deg outside is nearly no load. "

The "no load" condition does NOT APPLY to the operation of a compressor type A/C unit.

Whenever the compressor is running, the full motor amperage for operation is drawn. The "work" being done is compressing the refrigerant, not moving heat.

The "savings" comes from the possibility that the A/C will run for less time.

So when the A/C turns on in the middle of the night, It costs the same per operational hour as it does when the outdoor air temperature is 104.

Just a point of clarity

Your home is so open and spacious. Very nice!

INVERTER-driven compressors do vary in the amount of refrigerant flow and power use. I think that is how they get SEER ratings up to 26. That is how my Mitsubishi mini split unit works.