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Comment by cr0sh | Hacker News Reader

> With this design, there have been 3 icky-hot days so far this year, when there was no wind and the night did not get very cool.

As you noted, this used to be a fairly standard design for homes in some areas.

Perhaps a "whole house attic fan" could help on those marginal days?

The same thing happens here in Arizona; the proper way they should be building houses here would probably be a monolithic dome with most of the home set below grade - although caliche would make that difficult in some areas (and it would be expensive regardless). The next best thing would probably be rammed earth with 2-3 foot thick walls.

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Modern insulation is really good - much better than you get with rammed earth. Rammed earth isn't a particularly good insulator, it just has really high thermal mass, so once it heats up (and out here, it will heat up), it will continue leaking heat into the interior of your structure for quite a long time. Thermal mass doesn't prevent heat transmission, it just delays it.

The biggest heat transmission problem in most construction isn't the walls, it's the windows. The amount of heat transmission you get via glass - even high-performance triple-pane glass - is significantly higher than heat transmission through the rest of the structure. Your walls are going to be R20+, your attic insulation will be R35+. Your best windows are going to be equivalent to R6 or so, with the median windows being significantly lower.

Main energy gain happens because of the radiation.

I think that the best combination is high thermal mass structure followed by the insulation inside. This way the heat is not easily transmitted to the inside and the thermal mass can cool off to the outside during the night.

Of course when the heat finally does get inside then it is trapped because the house will act like a thermos and only way of cooling would be the by circulation of cold air.

Problem of windows can be solved by outside blinds (or shutters but blinds are better) and IR reflective coating.

There's newer double/triple pane windows that have blinds built in which are nice

Are you aware of anyone using eutectic salts in the walls in the desert? I remember reading an article from the 70s about it and it seemed well suited for desert environments where there's a large temperature swing from day to night. They would absorb heat in the day keeping the house cool and release it at night keeping it warm. If I remember correctly, the difficulty was finding salts that worked on the right temp range

I'm not sure why you're getting downvoted? I was in Tucson in the summer in a rammed earth house (about 2-3 feet thick as you mention) and it was comfortably cool inside. The whole house had very large eaves, as well [1]

[1] I don't recall the other design details that made it so cool in temperature, but it was all analog/natural (i.e. no AC)

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