DIY pasive solar heating designs

[Stephen Tashiro]

Are there designs for DIY passive solar collectors that don't introduce unfiltered air into the house? - some sort of filter or heat exchange arrangement?

What does one do with a DIY passive solar collector in summer? If the air flow is turned off then can the collector function as a shade? Or will the temperature inside the collector in summer cause damage -- or perhaps a fire?

The "screen" type of collector looks simplest to build and, according to https://www.builditsolar.com/Experimental/AirColTesting/Index.htm, it's effective.

[Adam Herman]

you are circulating inside air, you could put a filter over the input, it will reduce the amount of dust going in and coming out, but will reduce your air flow as well.

turn the fan off, you could put a solid white cover over it.

technically passive solar uses no fans, fans make it an active collector.

you could use an air to air heat exchanger, but it will reduce your efficiency by a large amount.

[roger wiegand]

Passive solar has gotten a lot easier with modern construction, insulation, and air sealing techniques. You can get a lot done without big masses of stone for heat sinks simply by not letting the heat escape the conditioned interior. We designed with large south/west facing windows with deciduous trees and vines on pergolas to provide shade in the summer. Our furnace seldom runs during sunny days in the winter time (on 40 degree days it tends to get too warm inside), and the well-insulated and sealed house holds the heat pretty well until bedtime. According to our utility company we use about 25-30% as much gas as our neighbors with similar sized houses. That's just with very good insulation and air sealing, a moderate effort to site for passive solar, and a couple of big, high quality windows.

Deciduous trees are by far the easiest approach to moderating solar gain in the summer.

[Roger Nair]

A very effective method of passive solar is to have the right overhang above windows on the south side. Properly designed, the technique will shade the windows throughout the summer and allow full sun in the winter. Know your latitude and the seasonal fluctuation of the earth's surface angle to the sun are your principal variables.

[Perry Hilbert Jr]

there was an article in Mother earth news about 12 years ago about solar water panels that let warm water into a radiator when warm and when the water cooled shut the flow off. It worked on the very marginal expansion of water due to heat. no switches no powered circulators etc. As water heated and rose, it would flow inside and down through a radiator and back out to the collector which was a thin panel on the exterior wall about 6 ft high. The expansion of the water due to heat only lifted the water a few millimeters above the overflow into the radiator inside. the circulation operated through natural convection of water warming in the outside panel and cooling in the inside radiator. It seemed like a really good idea but required a pretty good level installation to work. Of course it would require anitifreeze in the north.