Frequently Asked Questions

This new regulation in particular affects the minimum levels of insulation that replacement windows must have when fitted in your home. Levels of insulation are measured as U values. The lower the U value, the better the insulation level. To get the required level of insulation it is a requirement that LOW E glass will have to be used. It may also be necessary for the sealed double glazed units to be Gas Filled (Usually Argon).
The U-value measures the rate at which heat is lost through a material. The lower the U-value, the lower the amount of heat lost and the lower the amount of energy wasted. U-values are measured in Watts per square metre per degree of temperature difference (abbreviated as W/m²k).
It is worth noting that currently document L applies to replacement windows only and does not apply to conservatories

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