How to choose the right window frame

Window frames are an important component of every window and can greatly affect their energy efficiency.

In addition to its strength, a window frame works with the glazing component to affect the efficiency of the whole window. The most energy efficient window frames are made from materials that won’t transfer heat and cold, such as timber, uPVC or combination frames.

Timber frames

Timber window frames are highly energy efficient as they do not conduct heat. They perform extremely well when combined with double glazing, but do require more maintenance than either aluminium or uPVC frames.

uPVC window frames

Another efficient frame type used with double glazed windows is uPVC, or un-plasticised Polyvinyl Chloride. uPVC frames have been used in Europe and the United States for many years, as they perform in a similar manner to timber frames but are more durable and require little maintenance.

Combination frames

Alternatively, aluminium window frames that combine aluminium and timber are more efficient than thermally broken aluminium frames. These frames usually combine low maintenance aluminium as the external component and timber, which acts as an insulator, as the internal component of the frame.

Aluminium frames

Aluminium is a popular choice for window frames because it’s light, strong and requires little maintenance. Unfortunately, it’s not the most energy efficient choice. Because aluminium is a good conductor, you can lose a great deal of heat through the frames in winter and gain unwanted heat in the same way during summer. This could impact the comfort of your home and undermine the overall performance of double glazed windows.

To reduce heat loss and heat gain through aluminium window frames, be sure to install a thermal break. A thermal break is an insulating material placed between the interior and the exterior elements of the window frame, which will minimise the transfer of heat and cold through the frame.

Questions to ask your window supplier

When selecting window frames, it's important to ask your window supplier the right questions.

What is the material of the window frame?

Your supplier should ensure that the window frame meets your specifications. If aluminium is selected, check that the window has a thermally broken aluminium frame.

What is the frame-to-glass ratio of the windows?

The frame-to-glass ratio of a window will affect its energy efficiency. Choose a thin aluminium or metal frame, and thicker timber or uPVC frames.

More information

The Window Energy Rating Scheme (WERS) rates a window’s glazing and frame energy performance in the form of stars. This will help you to compare the relative energy performance of different windows and decide which type is best for your needs. Find out more by using the Window Energy Rating Scheme.