What is thermal heat loss in relation to windows and doors?

Your home needs to be as energy efficient as possible in order to save money heating and cooling it, make it more comfortable to live in and to reduce carbon emissions.

Single-glazed windows with gaps around the frame and badly fitting external doors with letter boxes that flap in the wind provide an easy route for heat to escape your home, making them inefficient at conserving energy.

New dwellings have to meet rigorous standards, and existing homes also need to be upgraded when you renovate more than 25% of a thermal element like a roof, floor or wall and sometimes this can be achieved by replacing those windows and doors with more energy efficient units (alongside other insulation upgrades).