Metateps

Other factors come into play when trying to solarize a home. Basically the rule of thumb is to keep it simple and keep it small. Here are some important points to bear in mind:

Large structures are harder to heat than small structures.

An east-west axis (90 degrees to true south) allows the longer side of the structure to be exposed to the sun. That's where the big windows should be. North- and east-facing glass can lose a lot of heat in the winter, and west-facing glass can cause overheating in summer, so they should be few and small. (Use overhangs over the windows to protect the interior from too much summer sun. A 2-foot overhang is usually enough.) If possible, burrow into a south-facing slope and build the structure with its north side buried in the berm. This is called earth sheltering. Thermal mass inside collects heat in the winter and stays relatively cool in the summer, which helps prevent overheating. The thermal mass should be widely dispersed inside so it warms the whole structure. Narrow rectangular masses help heat multiple rooms independently without fans or ducts, and they help block the sun from the interior surface of the east and west walls.

Insulate the structure. Exceed the insulation levels required by code. Protect insulation from moisture, as moisture decreases thermal resistance. It is especially harmful to cellulose and fiberglass insulation. Vapor barriers on walls may help some, but moisture usually attacks through penetrations like loose fittings around doors, windows, roofs, or through small holes in the walls. Be sure to comprehensively caulk and flash these penetrations. Baft insulation should not be compressed and should be flush against framing. Liquid foam products make an airtight seal and repel water. Insulated windows are important on the east-, north-, and west-facing walls. Cover windows at night with insulated shades or rigid thermal shutters.

Consider radiant barriers on the roof. Internal ventilation is important to spread the heat evenly.

Build structures that are as airtight as possible. Seal penetrations to prevent infiltration of cold air and exfiltration of heat in the winter, and infiltration of warm air and exfiltration of cold air in the summer. A sealed entryway (sometimes called an airlock) prevents air from rushing in and out when the main structure's doorway is opened. Earth sheltering also reduces in- and exfiltration, and it reduces heat loss to exterior wall space and roofs. It also provides a thermal blanket around the structure that helps keep it warm in winter and cool in summer.

Keep some sun-free areas in the structure. If it gets too hot, they'll provide some relief.

Maintain a source of backup heat, such as a propane heater, woodstove, or low-watt electric space heater.