Building Construction Handbook, Eighth Edition

* Tables and charts † Insulation manufacturers' design guides

and technical papers (walls, roofs and ground floors).

* Calculation using the Proportional Area Method (walls and roofs).

* Calculation using the Combined Method † BS EN ISO 6946

(walls and roofs).

* Calculation using BS EN ISO 13370 (ground floors and basements).

Tables and charts † these apply where specific U-values are

required and standard forms of construction are adopted. The

values contain appropriate allowances for variable heat transfer

due to different components in the construction, e.g. twisted

pattern wall-ties and non-uniformity of insulation with the

interruption by ceiling joists. The example below shows the

tabulated data for a solid ground floor with embedded insulation

of= 0.03 W/mK

Typical table for floor insulation:

90 mm of insulation required.

Refs. BS EN ISO 6946: Building components and building elements.

Thermal resistance and thermal transmittance. Calculation

method.

BS EN ISO 13370: Thermal performance of buildings. Heat

transfer via the ground. Calculation methods.

P/A 0„020 0„025 0„030* 0„035 0„040 0„045 W/mK

1 „0 6 1 76 9 1 1 07 1 22 1 37 mm ins.

0„9* 60 75 90 1 05 1 20 1 35 .. ..

0„8 58 73 88 1 02 1 1 7 1 32 .. ..

0„7 57 7 1 85 99 1 1 3 1 28 .. ..

0„6 54 68 82 95 1 09 1 22 .. ..

0„5 5 1 64 77 90 1 03 1 1 5 .. ..

Thermal Insulation, Methods for Determining U-Values