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Conservatory Glass U-Values


Glass U–Values are a measure of the rate of heat loss through different types of glass. You should choose the lowest U–Value as possible as this will allow less heat will escape from your conservatory, reducing your heating bills and making you energy efficient.


U–Values are calculated as a measurement of the amount of heat lost in KiloWatts, through one square metre of glass per hour.


These are the typical U–values for different types of glass:


   Single–glazing 5.0

   Double–glazing 3.0

   Triple–glazing 2.2

   Double–glazing with low–e hard coating 1.6 to 1.7

   Double–glazing with low–e hard coating and Argon filled 1.2 to 1.3

   Double–glazing with low–e soft coating and Argon filled 1.1 to 1.2

   Triple–glazing with multiple low–e coatings and Argon filled 0.8

   Triple–glazing with multiple low–e coatings and Xenon filled 0.4

   Double Glazed Tinted Solar Control with low-e coating and Argon filled

   1.0 to 1.2

   Celcius Clear Solar Control Glass with low-e coating and Argon filled 1.0

   Celcius Elite Blue Tint Solar Control Glass with multiple low-e coating

   and Argon filled 0.9


There will be a point at which the investment in better rated glass may not be cost-effective, this will depend on the total area of glass, your current and predicted energy costs, as well as how much time you plan to spend in your conservatory when the weather is colder.


If you are planning a north-facing conservatory that receives less direct sunlight than conservatories positioned elsewhere, selecting the best U-value glass will be very important. A glazing or conservatory consultant should be able to help you with these calculations.