... winter? with PASSIVE ANNUAL HEAT STORAGE of course! Passive Annual Heat Storage takes solar energy out of the dark ages Passive Annual Heat Storage, Improving the Design of Earth Shelters ©1983 ... simple: The sun heats the house, and the house heats the earth when the sun isn't out, the earth heats the house Although the physics of underground heat flow is complex, Passive Annual Heat Storage ... in the earth the first working example of annual heat storage improving the earth shelter how passive annual heat storage works cost Chapter PASSIVE ANNUAL HEAT STORAGE developing passive annual...