Thermal Performance

Ranking the thermal performance of your new home addition

More and more people today are concerned about their energy bills - that’s why we’ve tried to come up with a simple ranking for each design of conservatory, orangery or extension.


These rankings are based on the thermal performance (heat loss or sometimes called ‘U’ value, the lower the figure the more thermally efficient) of the various elements that are used in the construction of the home addition – items such as the base/foundations and the amount of insulation used, the specification of the walls, windows and doors and of course the roof itself, be it glass or solid.


Take a look at our rating scale alongside to give you an indication of where an older conservatory fits on the scale (in fact not even on the scale!!) versus a new standard conservatory (C rated) and then right at the top of the scale is the Building Regulation Compliant Extension Collection Plus (three specifications) rated as A++


Check out the list of all the building types that make up the Conservatory, Orangery and Extension range - review their individual ratings and see where they fit on the rating scale.

Depending on the function you will be using your new room for, in what seasons of the year and for how long each day will help you determine which is the optimum specification for you. 



Each category is ranked by its thermal performance based upon the complete conservatory U-value with windows and doors remaining constant throughout at 1.6 W/m2K. Typically a 10yr old conservatory would have a U-value of 2.14 W/m2K

Thermal Performance Indicators