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Conservatory Glass

One of the main benefits of a conservatory, and one of the more common reasons for building one, is the opportunity to enjoy more of the sun; despite the unpredictability of the British weather. The type of glazing used for the conservatory can have a big impact on the amount of heat and light, which is allowed into the room as well as the aesthetics, the insulation and the energy efficiency of the conservatory.

The choice of glass or polycarbonate for your conservatory may depend on the eventual use of the conservatory; if it is to be used throughout the year and heated during the winter months, glass may be the best option for both windows and roof. If the conservatory is being built purely to house plants, polycarbonate would usually suffice.

Heat and light coming into a conservatory is affected by the type of glass in the windows.

Glass used in a conservatory affects the amount of heat and light admitted.


It is possible to buy many different types of glass, and some glazing units are produced specifically for conservatories to counter the glare of the sun.

Self-cleaning glass can be particularly useful for conservatory roofs, reducing the amount of maintenance required; while glazing units can be bought with different coatings pre-applied to the outside surface which reflect the heat and light from the sun and help to keep the conservatory cool.

Reducing the amount of direct sunlight which enters the conservatory will also help to protect your furniture from fading due to exposure to light. If style is at the forefront of your conservatory design, you can also buy tinted glazing to give the exterior a unique look.

Some modern glass, such as Pilkington K-Glass, has a coating applied which also helps to insulate the conservatory by reducing heat loss. The coating reflects the heat of the sun from outside to prevent the conservatory becoming too hot during summer, but also reflects heat back into the room during colder spells, helping to lower heating costs.

In general, the glass you use for a conservatory should be double glazed, and should be supplied by a FENSA registered glazing or conservatory company. If the conservatory is just for plants, you could consider


single glazing; but if it is for your own use, double glazing is essential due to its better insulating and soundproofing qualities.

Special highly soundproofed glass is also available specifically for conservatories if reducing outside noise is particularly important to you.



Polycarbonate is a feasible alternative to glass, and is most commonly used for conservatory roofs. It has the advantage of being lightweight and easy to handle, and in most cases will be cheaper than glazing. The material distorts the light and does not have anything like the clarity of glass, which is why it is less often used for windows. It is less energy efficient than glass and also requires more maintenance.

A polycarbonate roof is likely to need cleaning twice a year and they tend to suffer from a build up of dirt and grime between panels. Polycarbonate also has the disadvantage of being much less soundproof than glass, a heavy downpour of rain for example, can sound unbearably loud on a polycarbonate roof.


Energy efficient glazing is necessary for conservatory comfort.

Energy efficient glazing is necessary for conservatory comfort.

Energy efficiency

The energy efficiency of conservatory glass is measured in the same way as double glazing and insulating products; by its U value. This is a value given to the glass based on how much heat is lost per square metre. The lower the U value, the better the glass is at insulating the conservatory and retaining the heat within it.

As a general guide the U values of some different types of glass are listed below:
· Standard single glazing can have a U vale as high as 5.
· Double glazed units filled with air could have a U value of around 2.7.
· Pilkington Activ Suncool glass, which is double glazed, self-cleaning, and has a solar control coating, can have a U value as low as 1.1 when filled with Argon gas.
· In comparison, Polycarbonate of a 16mm thickness has a U value of 2.6.
· 25mm thick Polycarbonate has a U value of 1.6.
· 32mm thick Polycarbonate has a U value of 1.5.


Although the initial cost of the glazing for your conservatory windows and roof can be expensive, it will prove to be a worthwhile investment in the long run. Much of the double glazing on the market today is filled with Argon or other gases rather than air, as they have better insulating properties; it is often worth the extra cost.

The more efficient the glass is at reducing heat loss, the less the conservatory will cost to heat; and this will save you money on energy bills in the long term.


Choosing the glass for your conservatory can be a daunting task, as there are a variety of factors to consider. If you are planning a conservatory, now is a good time to speak to some conservatory companies and look at some brochures to see what types of glass they are offering. This will give you an idea of the options available, their specification, and most importantly, their costs.

The design and the style of your conservatory may lend itself to a particular type of glazing or roof, and you should also think about the final use of the conservatory and how the glazing might affect the comfort factor of the room.

If you are planning to use it as an extra room for the home and intend to keep it fully heated all year round, you should consider double glazing for both roof and windows. If the conservatory is simply a nursery for plants, a polycarbonate roof might be the cheaper option.

Glazing for conservatories has developed over time, it is now possible to buy glass with a number of different coatings, designed to reduce the glare and the heat of the sun. The most efficient types of glass will also reflect heat back into the room and act as insulation during the winter.

If you are in the process of designing your conservatory, take the time to think about the type of glazing you want to use and how it will impact on the room once completed.

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