A typical house loses 20% of its heat through the windows
. This means that you are also losing 20% of the money you pay on your heating through your windows. Many window companies class their windows on a scale known as the Energy Index. This index rates products on a scale of A to E where A is the most efficient and E is the least.
The Energy Index shows how much energy the window will save or lose once it has been installed. Of course this valuable also has variants and it will depend on the building, local climate and indoor temperature of the place where the window is installed.
A positive value means the window will enable more energy [free heat] to pass through the glass and into the room than is going to be lost through the window, therefore the window is a 'free energy' supplier.
Double glazed windows cost different amounts according to many different variables of the window i.e. it could be a different size use safety glass or having a special design. The cost of a window is dependent on how special it is. This cost also varies between the various ratings [A to E] As a guide it can be said that A rated windows will cost more than B, C, D and E rated windows, however this cost can be negated as it should be set against the energy savings you will make as you go up the ratings scale. You should also take into account the face that Energy Efficient Windows cost less than the heat you will be losing from a less energy efficient alternative over a period of time.
So in fact the best plan is to buy the highest rated window that you can afford as it will mean that your heating bills will be lower in the long run.
In addition to the Energy Index rating there are also new components that have been developed to insulate the glass. These can create an even more energy efficient glass.
Energy efficient windows make sense, they conserve energy and will save you money in the long run.