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Conservatory Insulation

When conservatories were first built it was thought that they may save householders money. The idea was that heat energy gained from the sun would be collected in the conservatory and distributed into the house, reducing the amount of heating required.

Unfortunately this concept was based on a conservatory only being used during the hot summer months. In reality, people use their conservatories all year round and heat the room throughout winter. Conservatories can suffer from heat loss at up to ten times the rate of a well insulated room within the house and could be a drain on your heating bill if not insulated correctly.

Conservatory roof and windows need insulating to prevent heat loss.

Window with double pane to prevent heat loss.

As you would expect, most of the heat lost from a conservatory is through the roof and windows. If you want to build an energy efficient conservatory, these are the main areas to concentrate on. There are a variety of different products available which offer low U values and low heat loss.

A conservatory can also lose heat through the floor and the walls – hence the importance of using good quality insulation materials that reduce heat loss and improve the energy efficiency and the comfort factor of your conservatory.


Conservatory Roof Insulation

The majority of conservatory roofs are made of glass or polycarbonate, which we will look at later. Glass roofs on the market today are double glazed, the very best come with extra energy saving features.

Glazing designed specifically for conservatories can have an external coating applied to reduce the glare of the sun; while some glazing also has an internal coating which will reflect heat back into the room when the outside temperature is colder.

Another practical way of adding conservatory roof insulation is to install roof blinds. They can be fitted either internally or externally, although they do little to protect against heat from the sun coming in, they are very effective at preventing heat escaping through the roof.

Some conservatories use polycarbonate roofs and the material is available in varying thickness from 10mm to 35mm. The thicker the polycarbonate, the better it is at insulating a conservatory. 10mm polycarbonate has a U value of around 3.2, while thicker material at 32mm has a U value of 1.5.If you go for a polycarbonate roof, or you are replacing an existing roof, make sure you select the thickest material.


Conservatory Floor Insulation

Insulating a conservatory is a difficult task as every surface is susceptible to heat loss. The floor is another area which will require attention, particularly if you are installing underfloor heating. Heat can be lost to the ground through the floor, when a conservatory is built a layer of insulation can be laid in the base to prevent this.

The insulating layer is usually at least 100mm and it is advisable to make sure it is installed during the build and that the best products are used. If you are installing underfloor heating, it should be noted that insulation is a requirement under building regulations.


Prevent heat loss in conservatory by having cavity walls.

Cavity walls in buildings prevent heat loss.


If a dwarf wall forms part of your conservatory design, it should be a cavity wall, pre-filled with insulation. A cavity wall consists of an inner and an outer leaf, the gap between the two walls is referred to as the cavity.

This gap can be filled with a variety of different insulating materials to reduce heat loss through the walls.

The insulation can be retrofitted to a wall by drilling holes and injecting the material, so if you have an existing building without insulation, it is strongly recommended.

If you are still in the process of planning a new conservatory, make sure that any walls are fully insulated cavity walls.



After the roof, windows are the biggest cause of conservatory heat loss and double glazing is essential. Single glazing has a U value of around 5, making it very inefficient. Almost all conservatories constructed today include double glazing and many are now filled with argon or other gases due to their high insulating properties.

Much like glazed roofs, windows have been designed specifically for use in conservatories with insulation in mind. Windows can be coated on the outside to reduce heat and light from the sun in the hot summer months and can also have a coating on the inside, which will reflect heat back into the room during colder spells.

Window blinds are also a good option to help improve insulation. Most people now install blinds in their conservatories, as they add to the look and style of the room, as well as providing privacy when it is dark outside. Blinds act in the same way as curtains by preventing the heat escaping and can add extra insulation to the windows.

The most highly efficient glazing units can have a U value of 1.1 or lower. If you intend to use your conservatory all year round, then you can expect to heat it for several months during the winter. It may be worth the extra expense of efficient glazing, as it will save you money on heating bills in the long run.



Conservatory insulation has become much more an integral part of the overall design. In general people are using their conservatories more as extra living space than as garden rooms and this means people are heating their conservatories in the same way they would heat a room in the house.

By their nature, conservatories tend to be mainly constructed of glass and can lose heat much quicker than the rest of your property. If you intend to use your conservatory throughout the year it is important to insulate it properly to reduce heat loss.

The floor should be insulated when the conservatory is built, as should any cavity walls, but the roof and the windows are the main culprits for heat loss, it is worth investing in double glazed units for both. If your budget can stretch far enough, argon filled glazing will be more energy efficient than air filled double glazing; while specialist conservatory glass with reflective coatings will further reduce heat loss.

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