What happens if I have gaps in my insulation?

http://www.energy-imaging.com.au/ Heat like electricity tends to follow the path of least resistance.

From how insulation works:-

  1. The total power of heat through the insulation and the gaps in W is given by:
  1. The thermal resistance of the ceiling in K·m²/W is given by:
  1. Therefore the effective thermal resistance in K·m²/W is:
  1. Effective thermal resistance for R 2.5 with 1% gaps is:
  1. Effective thermal resistance for R 3.5 with 10% gaps is:

http://www.celltherm.com.au/ So R 2.5 insulation with 1 % gaps will only add R - Rg = 2.58 - 0.30 = 2.28 to the total R value. (This is a reduction of 8.8 %.)

So R 3.5 insulation with 10 % gaps will only add R - Rg = 1.75 - 0.30 = 1.45 to the total R value. (This is a reduction of 58 %.)

Cellulose fibre is a loose fill insulation which means it leaves NO GAPS.

This 'parallel paths method' is valid for heat flow through the ceiling. Other methods may be required for heat flow along a surface such as a concrete slab. For more information see James M. Fricker [2] and H. A. Trethowen [3].

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