#ThatsRosedene #RosedeneWindows

We supply double and triple glazing to ‘A’ and ‘A+’ specifications and install to our exacting standards. Our window frames come in a variety of styles and colours and come as standard with a 10 year guarantee on the frame, covering against discolouration, 5 years guarantee on the glass and a 12 month guarantee on all moving parts. We have a wide selection of opaque and frosted glass and we are fully insured, we offer an insurance backed guarantee and fully registered with FENSA.

Window Energy Ratings provide the annual energy balance for a window and are calculated by taking the annual heat loss through a standardised window and offsetting it by the annual solar gain through the window (kWh/m²Year).

You must first calculate the overall U value of a window (at an industry standard size). To do this you need to calculate the sum of the area weighted heat loss though the window frame, glass and glass edge or spacer bar. The Air leakage and solar gain must then be calculated.

Where AL (or air leakage) though the window in m³/h.m² at 50Pa pressure difference. The solar gain of the window is then calculated from the g value of the glass multiplied by the visible area of glazing (or glass minus the window frame).

From the U value and air leakage you can work out the amount of heat that is lost through the window per year, this figure is then take away heat gained through solar gain. If the result is 0 or positive your window is ‘A’ rated. If the result is between 0 and -10 then the window is ‘B’ rated. If the result is between -10 and -20 then your window is ‘C’ rated.

We can also supply and install hardwood windows.

Guarantee (windows)
Frame discolouration
10 years
5 years
All moving parts
12 months


What you need to know about double glazing