Heat-loss estimator
How fast a home loses heat, and a season of fuel. Learn the ideas behind it in Lesson 30: How heat moves.
Planning tool
Estimate how fast a small home loses heat, and what a heating season costs in fuel. Change insulation and air tightness to see which matters most.
Not sure? See Lesson 3. Data is a teaching approximation for one city per zone.
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A planning estimate, not a design. Take it to a qualified professional before you buy or build.