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Ready Survival Kits

Off-grid living · US

Shelter that heats itself

Use passive solar design to let the sun heat your home in winter and keep it out in summer, in any climate zone.

By The Ready TeamExpert review: pendingSources checked 29 October 2026

Quick card · Shelter that heats itselfSources checked 29 Oct 2026

Before

  • Find your DOE climate zone (1 to 8). It sets how much insulation and which windows you need. 1
  • Face main windows within 30° of true south, unshaded from 9 a.m. to 3 p.m. in winter. 2

During

  • Store the sun's heat in thermal mass: concrete, stone, brick or tile floors and walls. 2
  • Shade south windows in summer with roof overhangs or trees. 2
  • Cold climates: cut window area on north, east and west walls. Warm climates: use north windows and well-shaded south windows. 2

After

  • Ask your local building department which energy code applies before you build. 3

What to have

  • Compass, or a phone app that shows true south 2

Why passive solar

The cheapest heat comes through a window. A passive solar house is laid out so the winter sun heats it and summer sun is kept out, with no panels, pumps or fuel. DOE says the approach works in every climate zone. 2

Know your climate zone

DOE climate zones run from 1 (hot) to 8 (subarctic), with moist, dry and marine types. 1 Your zone decides the balance between catching heat and shedding it. DOE’s Building America program publishes construction guidance for each climate. 4

The five elements

DOE describes five parts that work together: 2

  1. Aperture: windows facing within 30° of true south, unshaded from 9 a.m. to 3 p.m. in winter.
  2. Absorber: the hard, dark surface of the storage element that takes in sunlight as heat.
  3. Thermal mass: materials that store that heat, such as concrete, stone, brick and tile. Floors and walls that absorb heat help most in cold climates.
  4. Distribution: how heat moves from where it’s collected to the rest of the house. Some homes add fans or ducts.
  5. Control: roof overhangs, trees, awnings or blinds that shade the windows in summer.

By climate

  • Cold and snowy (zones 5 to 8): cut window area on the north, east and west walls, and put mass where the winter sun lands. 2
  • Hot and dry or hot and humid (zones 1 to 3): use north-facing windows and generously shaded south-facing windows. 2

Building it yourself

Building codes vary by state and county, and some apply to owner-built homes. In Pennsylvania, for example, structural lumber generally needs a grade stamp, with exceptions for agricultural buildings and recreational cabins. 3 Talk to your building department before you design, and see our portable sawmill guide if you plan to cut your own lumber.

Sources

  1. PNNL for U.S. DOE, Guide to Determining Climate Zone by County (PNNL-33270)
  2. U.S. DOE Energy Saver, Passive Solar Home Design
  3. Penn State Extension, Using Your Own Lumber for Building Projects
  4. U.S. DOE, Building America Climate-Specific Guidance