OTTV FOR NON ENGINEERS. OTTV OVERALL THERMAL TRANSFER VALUE.

OTTVFOR

NON ENGINEERS

OTTVOVERALL THERMALTRANSFER VALUE

architect

OTTVWATTS PER M2

OTTV x skin area

HEAT W / m2 =

architect

externalenvironment

Qgcglass

conduction

Qwcwall

conduction

Qgsglasssolar

OTTV x (1-WWR) x Uw + x WWR x Uf + x x WWR x

CFTdeq SCSFDT

DIFFERENTIAL TEMPERATURE EQUIVALENTTEMPERATURE DIFFERENCESOLAR FACTORSOLAR CORRECTION FACTORSHADING COEFFICIENT

15 (1 −WWR) + 6(WWR) + (194 x x WWR x )

OTTVα Uw Uf SCCF

BLACK 0.9 – 1.0

WHITE 0.15 – 0.3

SILVER / ALUMINIUM 0.1

SOLAR ABSORPTION FACTORU VALUESOLAR CORRECTION FACTORSHADING COEFFICIENT

α (1 −WWR)Uw + (WWR)Uf + ( x CF x WWR x SC)15 6 194

WALL HEATWINDOW HEATSOLAR THROUGH GLASS

OTTV

Qgcglass

conduction

Qwcwall

conduction

Qgsglasssolar

5%

10% - 20%80%

SHADINGCOEFFICIENTSC

SC = SC1 x SC2

USC

α

OTTVISFOR

NON ENGINEERS

THANK YOU