U Values For Doors And Windows

For most energy efficient windows the whole window u factor is higher than the center of glass u factor.

U values for doors and windows.

Typical u values on windows and window energy ratings are similar to the familiar energy labels you see on home appliances rated from a the lowest up to g the highest or worst performing. Improved education and awareness of the cost of heating and cooling that escapes from poorly insulated components and glass panes have led to window and door manufacturers developing energy efficient windows and doors typically labeled r5 u 2 meaning the glass is the most energy efficient possible at a 5 rating and the window or door with all of it s built out components are a 2 which is almost as low as any rating can go remember a 5 is the highest energy rating for r value which is. Thus a single paned window with a basic aluminum frame has a u value above 1 usually around 1 25 while triple pane windows may have u values around 25 or lower. This calculated value conforms with bs en iso 10077 part 1.

Window energy ratings provide a simplified method of understanding the energy saving properties of a window. High performance double pane windows can have u factors of 0 30 or lower while some triple pane windows can achieve u factors as low as 0 15. This is desirable in very hot and sunny locations to avoid the greenhouse effect inside a home. According to part l1a of current building regulations a domestic window installation should achieve a u value no higher than 1 4 w m k.

Double glazed windows filled with argon are typically 1 4 w m2k while thicker triple glazed windows can go as low as 0 7 w m2k. In the case of a window it s 1 6 w m2k. The lower the u factor the better the window is at keeping heat inside this is desirable in colder climates like the northeast. Some window performance figures are expressed with a u value and others with a window energy rating although the latter has been adopted as the more commonly used.

We can advise on how you might achieve the required standard. The lower the u factor the better insulated the window. A higher u factor allows heat to escape. To comply with building regulations windows like every other element of your property must meet a certain minimum u value.

How is u value determined. Typically double glazed windows record a u value of between 1 2 w m k and 3 7 w m k while triple glazed windows are usually rated below 1 w m k. A u value calculated by us should be sufficient to satisfy the requirements of building regulations.