T101 Thermal performance
Window energy rating
T101-2006
Energy rating schemes
NFRC
National Fenestration Rating Scheme, USA
BFRC
British Fenestration Rating Scheme
EWERS
European Window Energy Rating Scheme
T101-2006
FENSA
FENestration Self Assessment
Approved by ODPM as complying with Part L1
Self certification by dealer/installer
Administered by the GGF
T101-2006
FENSA
Self certification
Frame type
Thermal break
Low e-coatings
Gas filling
Part L1 U-values
T101-2006
Part L2 2002
T101-2006
Part L2 2002
T101-2006
Part L2 2002
T101-2006
NFRC
Operating for 15 years in the USA
Rating scheme showing;
U-value
Solar Heat Gain Coefficient
Air leakage
Factors combined differently for different climates
T101-2006
NFRC
6 climatic regions cover USA
Heating climates
Cooling climates
Sunny climates
T101-2006
NFRC
U-valueSHGC Light
transmittance
Airleakage
T101-2006
BFRC
Independent UK body
Spun out of UK Government funded research
Partners were Trade Associations, Laboratories, Analysts and Universities
Establishing links in Europe
May feature in the next version of the Building Regulations
T101-2006
BFRC rating
Takes account of;
U-value
Conduction, convection, radiation
SHGC
Solar Heat Gain Coefficient
Air leakage
Air leakage at 50Pa, L50
T101-2006
Original BFRC label
T101-2006
BFRC rating
DWERS
Domestic Window Energy Rating Scheme
Ratings in the range G - A
A is most energy efficient, DWER > 0
Today’s good windows normally fall in band C, -20 < DWER < -10
T101-2006
DWER
DWER = 218.6 x Window Solar factor – - 68.5 x (Window U-value + Air infiltration factor)
Factors of 218.6 and 68.5 recognise the influence of Window Solar factor, U-value, and air leakage in the UK
Windows will perform differently in different UK climates but will always be ranked consistently
T101-2006
BFRC rating
Separate values given for:
Window U-value, Uw
Window solar factor, gwindow
Window air infiltration factor, 0.0165L50
To allow for fuller consideration
T101-2006
Light transmittance
A good DWER can be achieved by selecting right SHGC
This can be achieved by using a tinted glass
Heavily tinted glass will affect light levels in a building and may lead to an increased energy use for artificial lighting
The light transmittance value is given to allow specifiers to avoid this problem
T101-2006
EWERS
European Window Energy Rating Scheme
Adopted in Denmark
Uses scale of A,B,C,D,E
Similar to rating schemes for domestic appliances
May be taken up in UK with BFRC as the operating agent
Will use a common label but each state will set its own classification on the basis of climate and window styles!
T101-2006
EWERS labelling
T101-2006
Linking rating to regions
T101-2006
BFRC rating label