If you find yourself standing in a salesroom looking at different types of uPVC windows, without a clue as to which one you should select for your home, then this article should be able to help you. We will look at some of the factors that effect a window’s performance and show you that not all of these types of windows are the same. Quite simply, some of them are better performers than others with regard to energy efficiency, and you need to know why. This 4 step guide should explain this “why?”.
Window units for sale should be displayed with a label on them displaying information. It is compulsorily for the manufacturer to display some of the information pertaining to the window, while other ratings are optional as yet. However if you ask for this information to be provided, it should be.
1. Consider the U-factor of the window. This is a measurement of the ability of the window to transfer heat. Its better known cousin, the R-value is a measurement of the resistance to heat loss. Therefore you want a window unit with a low U-factor, or a high R-factor.
2. Study the Solar Heat Gain Coefficient. The SHGC measures the ability of the window unit to block heat from the sun. This is a very important attribute for a window to have during the hot months of the summer. The lower the SHGC the more capable the product at carrying out this task.
3. Look at the ‘air leakage’ measurement of the window. This measures the amount of air that can come through the window from the outside. If the window has a low AL this is good. A window unit is made up of various seals, frame and glazing and having a window that does not leak air into the living environment is important.
4. Look at the ‘visible transmittance’ ability of the window. Having a window that blocks the heat from entering a room, but that also blocks light is not so good. Visible transmittance measure the ability of the uPVC window, or any window, to allow light into the room.