Until recently, all clear glass was the primary building material used in windows. Although glass is durable and allows a high percentage of sunlight to enter buildings, it has very little resistance to heat flow. Choosing energy efficient windows is one of the simplest and most cost effective measures you can take to ensure a comfortable home all year round.

It has long been recognised that conventional single glazed windows are the weakest thermal link within a home. Even though windows generally account for a small area of the building envelope, they are the area of greatest heat loss in winter and heat gain in summer.

One of the most important characteristics of a good window is thermal efficiency. A window must not only admit maximum light, it must be energy efficient. It must function to maintain internal room temperature with a minimum use of energy. A window does not consume energy by itself, however it can have a significant impact on the amount of energy consumed by the building as a whole.


On a cold day, a single glazed window will lose up to ten times the amount of heat than an insulated wall of the same size will. A window with poor energy characteristics will also cause discomfort. Energy efficient window insulation can be achieved without losing your views, simply by double glazing. There are many glass and glazing combinations to choose from when double glazing your windows. Your Rylock representative can advise you on the most suitable combinations for your home and lifestyle.

Energy Efficient Windows - pdf

Link to 5 Star House website