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Which window styles are the most energy-efficient?

Windows not only provide a balanced look to your house but are also essential to ensure energy efficiency. There are many designs and technologies used to make windows more energy-efficient. The aim is to improve a window’s aesthetics, durability and functionality. Before buying a window frame, you should definitely check its energy efficiency rating.

Heating and cooling a house consumes considerable energy, resulting in huge bills. If your home is not properly insulated and fitted with energy-efficient windows and doors, your house will lose the heat/cold quicker, leading to more air conditioners. This is when you face huge utility bills. 

So, before buying windows, you should consider a few things to ensure you are getting an energy-efficient window. You should check the window frame’s material, glazing, glass pane features, spacers and fillers, and the type of operation the window is used for. These factors are integral to buying the most energy-efficient window. 

Tips to Buy Energy Efficient Windows.

If you have ever asked yourself, “Which window style is the most energy-efficient?” then this article is for you.

Below, we have outlined the essential factors that combine to make an excellent energy-efficient window:

  1. Frame Material

Ensuring that you buy the right frame for a window is a huge factor in buying energy-efficient windows. Different types of frames offer varying advantages and disadvantages. However, fibreglass, timber, uPVC and composite material window frames provide maximum high temperature resistance as compared to metal window frames. 

1 – Metal window frames

Although metal window frames are considerably robust, lightweight and require almost no maintenance, they are good conductors of heat. Metal or aluminium window frames make for poor insulation material due to their tendency to absorb heat. 

To decrease heat flow, you can find metal window frames that should be fitted with an insulation process in which usually a strip of insulating plastic is fixed between the inside and outside of the window frame and sash. 

2 – Composite window frames

Composite window frames are made of composite timber products, such as laminated strand lumber, particle board or polymer-mixed plastic. 

Composite window frames are highly stable and offer flexibility with utmost strength. 

Composite windows are not only highly energy-efficient, but they also have better resistance to moisture and decay. 

3 – Fibreglass window frames

Fibreglass window frames are also extremely stable with air cavities. These cavities are filled with insulation. 

Fibreglass window frames have been known to perform on par with non-insulated uPVC and timber window frames. 

4 – uPVC window frames

uPVC window frames are made of PVC. It is integrated with UV (ultraviolet light) stabilisers which keep sunlight from damaging the material. uPVC window frames do not need to be painted and have naturally good moisture resistance. 

uPVC window frames are designed with hollow air cavities, which are usually filled with insulation to make the windows effectively energy efficient. 

5 – Timber window frames

Timber window frames are conventional and have been used for centuries. However, timber frames require constant maintenance. It is important to note that timber windows coated with uPVC or aluminium covers are significantly low maintenance.

   2. Glazing/Glass

The type of glazing used on the windowpane is another important factor that decides its energy efficiency. Interior experts recommend choosing the glazing according to the type of window and the room it serves. 

Single glazing window panes are conventional, while double and triple glazed windows are the norm today. These windows have different properties, depending on the type of glass, coating, gas and spacers used. 

Some of the most common coatings and glazing you can choose for energy-efficient windows include:

1 – Insulated 

Insulated window glazing involves using two or more panes of glass. The glass panes are fitted with a small gap in between and then hermetically sealed. This leaves an insulated air space between the outer and inner glass pane of insulated windows. 

2 – Low-emission coating

The low-emission coating on the glass is effective in controlling the heat transfer within the insulated glazing of the window frame. Such windows usually cost around 10 – 15% more than conventional windows. However, the higher price is justified by the ability of low-emission windows to reduce energy loss by as much as 30 – 50%. 

Low-emission coatings are extremely thin and practically invisible. These coatings usually consist of a metal or metallic oxide layer deposited on the surface of the glass pane. 

3 – Spectrally selective coating

Houses in hot climates can benefit from window glazing. These allow daylight to come in and a view of the outside but restrict the non-visible and harmful infrared radiation as much as possible. Advanced low-emission coatings are designed to be spectrally sensitive. This means that the coated windowpane can filter out 40–70% of the heat otherwise transmitted through insulated glass windows. At the same time, these window panes allow a clear view of the outside of your home too.

  3. Type of Window Operation

Last but not least, the operating type of the window will also determine the energy efficiency of the window. The type of function of the particular window will determine the extent of heat loss indoors. This has a direct effect on your home’s energy efficiency factor. Hence, the type of operation in a window can have an impact on energy usage. 

For instance, awnings, hopper and casement window operations have significantly lower air leakage as compared to fixed, single/double sliding and fixed types of windows. 


According to our research, awnings, hopper and casement window styles are the most energy-efficient. Choosing these window styles can help to add significantly to your home’s appearance. These window frames also help to lower your energy consumption and reduce your power bills every month. Keep the above-mentioned tips in mind to ensure that you always buy the most energy-efficient windows for your home or workplace.