Do conservatories conserve energy?
How does a conservatory affect your EPC?
While undoubtedly being great for providing additional light-filled living space, the question of whether conservatories are good for energy conservation is less straightforward. Just how much is your conservatory costing you and could it have a detrimental effect on your EPC?
A conservatory is a popular and relatively cheap way of extending a home. If it has a floor area of less than 30sqm, a door that thermally separates it from the house and it is not connected to the house heating system, a conservatory is also generally exempt from Building Regulations Part L controls, and possibly also planning permission, depending on its position and the history of extensions to the property.
However, all too often the conservatory becomes a very costly addition when on-going heating bills are considered. The cheapest, aluminium-framed conservatories of the 1970s and 1980s and those with polycarbonate rather than glass roof panels are particularly poor in terms of energy efficiency, and there is very little retrofitting that can be done to make significant improvements.
In the right place, conservatories are great for harvesting heat from the sun, but this can mean they become too hot in the summer while being very inefficient in the short and often cloudy days of winter. A south-east facing conservatory is generally considered best, as it will collect heat from the morning sun and be less prone to overheating during the warmest part of the day.
The positive side of the winter story is that a closed and unheated conservatory may provide a slight buffer to the rest of the house against cold weather, reducing the temperature difference between the main room and the outside by a few degrees. For this to be effective, the conservatory must be thermally separated from the main part of the house with solid, draught-proof doors, or glass doors with thick curtains. Thermal mass in the conservatory will store winter heat for longer, so exposed brick walls that catch the sun and a stone floor will absorb then slowly release the energy.
The downside is that many families need the conservatory as a living space year-round, and soon discover just how inefficient they are at conserving heat. It is simply not feasible to insulate such an extensively glazed space sufficiently, so the only energy and cost efficient way to run a conservatory is not to heat it.
While a conservatory can never be brought up to the thermal standard of even an un-insulated cavity walled room, for a family that has no option other then to use and heat the conservatory there are measures that can help a little. Modern double-glazing with ‘Four Seasons Glass’, blinds and shutters can all help to reduce the amount of wasted energy.
A more radical solution is to replace the glazed roof with solid, insulated panels. The situation in relation to planning permission and Building Regulations should be checked. Installers claim that modern panels can be up to eight times more efficient than a polycarbonate roof, and some fit ‘multifoil’ insulation which is very efficient at heat deflection in the summer while helping to protect against damp and condensation in the winter. This is said to reduce the hottest summer temperatures in the conservatory by 70% and make it 90% warmer in the winter. While such figures sound impressive, the conservatory will nevertheless still suffer a very significant loss of energy through the winter if heated.
Remember, conservatories that are not thermally separated can have a detrimental impact on your EPC score.