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What energy efficiency questions should I ask before signing up for a new conservatory?

Posted by Helena Ripley on 28 October 2015 at 10:15 am

Conservatories give you extra living space which is filled with natural light, but so often they are too hot in the summer and too cold in the winter. So what do you need to know about the energy efficiency of a conservatory before you sign up for it?

How energy efficient are the windows? Is the glass double glazed? Or triple glazed? Triple glazed conservatories are available but, unless you want to be super energy efficient, double glazed with an inert gas and a low-e coating should be enough. The inert gas between the panes helps prevent heat from escaping, and the low emissivity coating keeps harmful ultra violet radiation out and infra-red radiation (heat) in. Although triple glazing is more efficient, that may just end up causing overheating problems in the summer, unless the conservatory is extremely well ventilated.

What is the frame made from? Most conservatories have uPVC frames. This is a good material for insulation, and the cheapest of the three we look at here. Timber frames are pricier and don’t provide such good insulation, but they may fit better with the style of your design. Aluminium frames are an option but will increase thermal bridging and heat loss. To know how much heat will escape overall you have to consider the U-value of the frame and glass together: the lower the U-value, the more heat will stay inside.

What other materials are used? How much of the conservatory is glass? What will the roof be made from? Tiled roofs are more acceptable in conservation zones, which may help if you are struggling with planning permission. Glass and tiles both provide better insulation than polycarbonate, as well as being quieter when it rains. Also, polycarbonate causes condensation on the inside of the conservatory, so unless you are on a tight budget go for a glass or tiled roof. Will there be any brick sections? These can be insulated – look for cavity wall insulation or internal wall insulation. There’s no point getting super insulated glass if all the heat can get out through the bricks.

How well ventilated is it? It’s important to allow fresh air through the conservatory, particularly in the summer when overheating could be an issue. The air which is warmed in the conservatory will travel through your house, which is a great benefit in the winter but potentially problematic in summer. Orientation is a big factor here. A conservatory on the south side of the house will trap more heat than one looking north, so ask yourself: which way will it face? If south facing you’ll need it to be well ventilated in the summer to avoid overheating; if north facing then keeping the heat in during winter will be a priority. 

Can blinds be installed in the roof and sides? This will help keep the conservatory cool and pleasant in the summer by blocking out sunlight and reducing glare. On top of that blinds work as extra insulation in the winter, though you’d only want to close them when you’re not getting any direct sunlight. And of course, they also give you more privacy.


Photo credit: SuperHomes

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3 comments - read them below or add one

Malcolm M

Malcolm MComment left on: 2 November 2015 at 9:44 pm


Your supplier/installer is correct

Consevertories are mostly too hot in the summer, when you do not require additional heating within the house, (open the house-to-conservatory door if you do need top-up heating) and are too cold in winter to successfully use as a source of heat for Mechanical Ventilation with Heat Recovery MVHR. Also the MVHR is used to introduce fresh air into the house and expell stale air, whereas the conservatory would soon be filled with stale air expelled from the house.

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robcartwrightComment left on: 1 November 2015 at 8:50 pm

And that was by manufacturers trying to sell us a system.

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robcartwrightComment left on: 1 November 2015 at 8:49 pm

We were told we couldn't take input from the conservatory via an MVHR system as you can't import from within the house, it has to be from outside.

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