Windows and Doors’ Energy Efficiency: A Helpful Guide

Energy Efficiency is an important factor to consider when having new windows and doors installed. If you want to save on energy costs your window should have low heat conductivity. However, a balance needs to be struck between energy savings and cost, which is why timber windows, which have the lowest heat conductivity of any windows but the highest cost in terms of purchase and maintenance, are not your best option if you want to save money.

Typically, there are three options as far as window materials go: PVC, aluminium and wood.

PVC is generally considered to be the ideal material if you want to save money, due to its low thermal conductivity and low cost. Aluminium has a very high thermal conductivity which makes it a less attractive option in terms of energy efficiency. However, modern aluminium windows are far more thermally efficient than the older ones as they include thermal breaks and multiple chambers to lower the material’s inherent conductivity. As mentioned above, timber windows have the lowest thermal conductivity but the highest cost both initially and in the long term as they are prone to rot and warp which increases maintenance cost and reduces lifespan.

Increasingly, residential windows contain Argon gas. This substance has high energy saving and sound proofing properties and is relatively inexpensive as well as being non-toxic, which makes it a better option than having air between the panes. Low E coating is also becoming more common. This thin, transparent coating is applied to glass to make it keep warmth in during the winter months and reflect warm air out during the summer.

Opting for a double or triple glazed window will also make a big difference to heat efficiency. The extra panes of glass provide higher levels of insulation. The benefits of Argon gas and low E coating can be maximised with triple glazed windows.

Another thing to consider is your window’s spacing bar. This is the hollow frame that separates the two panes of glass in a double-glazed window. In the past, they were made of aluminium which is a poor insulator. These days they are made of PVC and are part of what is termed ‘warm edge technology’.

Finally, you must take into consideration the thickness of the window. Thicker window units have a higher thermal efficiency, which is why modern window systems allow for thicker windows.