nav arrownav arrow
Energy Efficiency
Related image

Energy Ratings vs U-values

Whether it is new-build or replacement windows, it is likely you will have heard about energy ratings and U-values at some point.

You may know that these are important, but you might not know exactly what a U-value is, what is included in an energy rating, or how to choose your doors and windows wisely, based on the ratings you need to achieve.


Related image

What is a U-value?

A "U-value" is the measurement of heat transferred from one side of a window (or door) to the other. 

You can also call it "thermal transmittance".

The lower the U-value, the less heat that would be lost through the door or window.

A U-value is used to determine the energy efficiency of windows, doors and other building products.

Putting it technically, it is the rate of transfer of heat through a structure, divided by the difference in temperature across that structure (W/m²K).


Related image

What is an Energy Rating?

Energy Ratings provide an overall rating of how energy efficient a window or door is, taking into account several different factors including the U-value, air flow, etc.

Window manufacturers can show the energy efficiency of their products using an energy-rating scale from A++ to E. The entire window (the frame and the glass) is assessed to allow for heat loss, draughts and solar gain, giving a rating that indicates the overall impact of fitting that window in your home.

Single, double or triple glazing - the differences

Minimal insulation with the least heat retention and greatest cold transmission.
The optimum balance in terms of insulation, solar control and weight.
The best performing glass unit construction
Related image

Single glazing allows much of the cold from outside to transmit into the house rapidly reducing the room temperature and necessitating the use of more heating. With a -5 degree outdoor temperature, the inner pane of the glass is only +2 degrees.

Pre-2000 double glazing without Low-E glass makes a significant improvement with inner panes now reaching +10 degrees, helping the room stay warmer.

Modern double glazing using Low-E glass makes an even greater improvement with inner pane temperature now up to +18 degrees. The Low-E coating reflects heat back into the room whilst reducing UV rays.

Triple glazing using Low-E glass means an inner pane temperature close to the ambient room temperature for maximum warmth and minimal heat loss.

close button
There are no tracking or monitoring cookies on this website.