The glass in your windows absorbs heat then radiates it again on the colder, outside, surface.

Guardian offers a new improved ClimaGuard® A+, a thermal insulating glass meeting the highest performance and quality standards that is designed to exceed your expectations on transparency and solar heat gain. The new and improved Low E glass maintains the same thermal performance with an increased level of solar heat gain. Using ClimaGuard A+ should not only have a positive effect on your heating costs, it may also help improve levels of comfort in your home. ClimaGuard® A+ is specifically designed to satisfy all national and local building regulations through out the UK and Ireland, achieving the highest window energy rating performance and U value compliance.

The low emissivity coating is a poor radiator of heat. So the heat absorbed by the coated glass does not travel across the air gap to the outer pane and the cold outside world. Instead the coating reflects the heat back into the room.

Windows incorporating Climaguard A+ allow heat from the sun through and keep heat inside, making it easier and more cost effective to keep buildings warm.