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Problem

Cold at the floor, warm under the roof

The heating runs, yet people are cold while the air under the roof is warm. Why it happens, what it costs and what helps.

When a hall feels cold at the floor and the thermometer under the roof shows several degrees more, the heat is in the wrong place. Start with why warm air collects under the roof, then see how much of it leaves through the envelope.

Suggested order. Jump to whatever is most useful.

  1. Warm air under the roofWarm air rises and collects under the roof, where it costs the most. See how much of the heat bill stratification accounts for, and what mixing the air saves.
  2. U-values and heat lossHow much heat leaves a hall through its roof, walls, windows and floor over a heating season, and why the roof usually loses the most.