Your fridge has one, your dishwasher has one, and later this year, your new window might well have one, too. The European energy label, which rates the efficiency of white goods, is about to hit fenestration. And although the European Window Energy Rating System will start life innocuously enough - as an optional sticker for those manufacturers who want to use it - the system it represents is likely to become rapidly more influential. The British Fenestration Rating Council wants it to become an alternative method of demonstrating windows' compliance with Building Regulations, and is quietly confident that it will eventually replace the U-value for this purpose. The EWERS began life in 1997 as the brainchild of university academics who were dissatisfied with the U-value as a guide to a window's insulating properties. Kevin Cubbage, chairman of the BFRC, says: "U-values measure only the thermal conductivity of window materials." In other words, they only measure the heat lost through a window and do not take into account the heat gain through it when the sun shines. The BFRC was formed in 1998 to develop a window-specific rating system in conjunction with the industry. The problem is that although it is fairly straightforward to rate a fridge on the power it consumes; windows are trickier prospects.
展开▼
