Passive solar design lets the sun and the shape of your house do some of the heating for you, and the biggest decisions cost little or nothing if you make them before building.
The basic idea
The book calls facing a home towards the sun the most cost-effective energy-efficiency method. In the Northern Hemisphere that means a south-facing home (north-facing in the Southern Hemisphere). It describes this passive solar design as something that can reduce heating requirements, and it says the natural temperature regulation costs nothing in itself.
Winter sun in, summer sun out
- A south-facing home captures low winter sunlight and naturally warms the interior.
- A deep roof overhang on the sunny side shades the windows in summer, when the sun is higher.
Insulation does the rest
The book says heat loss is a major issue off-grid and advises investing in insulation, because a well-insulated home with a good energy system will outperform a poorly insulated one. Passive solar gain is only useful if the warmth stays in.
Decide early
Orientation, window placement and overhangs are cheap to get right on paper and expensive to fix after the walls are up. When you evaluate land, check that the site allows the orientation you want and has a clear sky on the sunny side, the same exposure you need for solar panels. Then fit the layout and your systems to it.
Questions to ask on your plan
- Which side faces the sun, and is it free of trees and hills?
- How big are the windows on that side, and how will they be shaded in summer?
- How well insulated are the walls, roof and floor?
- Does the layout put the rooms you use most on the warm side?
The book covers orientation, insulation and layout in the Choosing Your First Off-Grid Home guide. For the full walk-through, Off Grid Survival for Beginners puts it alongside energy, water and food.