Thermal Transmittance

Thermal Transmittance, the measure of how much heat will pass through one square metre of a structure when air temperatures on either side differ by one degree, is generally applied to doorsets. U-values are expressed in units of Watts per square meter per degree of temperature difference (W/m2K).

The thermal transmittance performance of a doorset will vary according to the particular doorset design therefore the following details need to be considered:

Doorset size and configuration

Frame component materials and dimensions

Operating gap dimensions

Type, size and position of seals

Door face material

Glass type and glazed area

 

BS EN 10077-2-2003 calculations have been determined for Forza 44mm and 54mm flush leaf based doorsets using the following criteria:

Door leaf dimension: 2040 x 926mm incorporating Forza standard hardwood lippings

Facing material: 0.5 veneer

Door frame: Forza type DFT104 2P

Door frame operating gaps: head/jamb & threshold 3mm

Acoustic and fire seals: product specific

 

BS EN 10077-2-2003 Calculated U-value

Forza 44mm leaf: configuration type SGS32AS 2.1W/m2K

Forza 54mm leaf: configuration type SGS34A60S 1.8W/m2K


The performance of glass within doorset vision panels and glazed screens will vary depending on the type and thickness of glass used. For guidance, typical (U-Value) performance for glazed elements are as follows:

Single Pane: 5.4W/m2K

Double Glazed: 2.6W/m2K