Technical Information

What is the U value

U value is a method of comparing the heat lost through various parts of a building. For example: a part of a building with a U value of 4.0 W/m2K will lose twice as much heat as one with a U value of 2.0 W/m2K.

The lower the U value the less heat you lose

A single glazed window has a U value of 5.6, with secondary glazing this can be reduced to 1.8 – 1.9. Low E glass in secondary glazing reflects most of the heat back into the room.

How does sound travel

Sound travels through the air like ripple on a pond surface. The sound radiates outwards in all directions from the source, gradually reducing the intensity or until an object stops the progress.

Sound (dB Decibels)

Sound is described in different ways but primarily in terms of intensity and frequency. The sound intensity is described in dB. A low dB indicates a soft sound; a high dB value indicates a loud sound. Frequency describes how high or low pitched the sound is(Hz).

Sound Reduction

A sound’s volume at 60dB decreased by:

3dB is just perceptible

5dB clearly noticeable

10dB half the original volume

Recommended indoor ambient noise levels in dwellings:

Bedrooms 30-35 dB

Living Rooms 30-40 dB

Test Results carried out at BRE

At the buildings Research Establishment in Watford, a primary window with 4mm glass was tested with our secondary glazing installed behind and achieved the following results.

The Existing Window Achieved a Reduction of 26 dB

With secondary glazing installed with a 100mm air gap between the gap, the following results were achieved

4mm Glass 39 dB estimated 65%

6mm Glass 39 dB estimated 65%

Laminated 40 dB estimated 70%

Acoustic Glass 45 dB estimated 75%