Low Emissivity Glass

Guidance Notes

In the event that you purchase your replacement windows from Tayside Windows you will benefit from our Low-E glass specification fitted as standard to our product range. The guidance notes that follow are intended to explain the reasons for fitting this enhanced glass specification to your windows and should be carefully studied.

New Thermal Insulation Regulations

The Building (Scotland) act 1959 Technical Standard Part J was amended on 4 March 2002. Part J introduced new thermal standards for windows, doors and rooflights for dwellings in Scotland.

It is your responsibility as the householder (building owner) to ensure that any replacement window work carried out at your premises meets the new Building Standards.

Low emissivity (Low-E) glass must now be fitted in your windows, or you have little prospect of meeting the new requirements. Failure to comply with these regulations may cause problems with selling your house,

What is low emissivity (Low-E) glass?

Low-E glass is a vital component of energy efficient windows. It has a surface coating that operates as follows:

1. It allows short wavelength heat from the winter sun to enter your home through glazing.
2. This solar energy works with your domestic heating system to warm up your room, which then gives off long wavelength heat radiation.
3. A large portion of that long wave heat would vanish back out through windows fitted with ordinary glass. However, the Low-E coating reflects that heat back into your room, i.e the coating traps heat in your home.

As a consequence, you will feel much warmer during winter, and you will benefit from reduced heating costs and further reduce any possibility of internal condensation.

Will Low-E glass meet the Building Standards?

Better than merely meeting the Regulations, Low-E glass is virtually essential to enable you to achieve the new targets, for windows.

Are there any disadvantages?

We have discussed the significant advantages to your pocket and comfort above. Given the substantial benefits of Low-E any disadvantages are insignificant. You are now having to use a coated glass and this means you can see evidence of the coating in some or all of the following ways:

As a tint, making some materials appear differently when viewed directly through the glass

As a “haze“, when viewing the glass at some angles and in some lighting conditions.

By the appearance of condensation on the outside surface of the glass under certain weather conditions. This being positive proof that the glass is preventing heat loss from your house, as the glass is becoming cooler than normal and allowing dew to form.

It may also be possible that Low-E glass may exhibit minor blemishes and the tint may also change if windows are made at different times or from different batches of glass. These are not detrimental to the functioning of the unit and are deemed not to be a defect.

How is the visual quality assessed?

The visual quality of a window is assessed by looking through it from the room side, at right angles to the glass, standing at a distance of not less than 3 metres from the glass, under natural daylight and not direct sunlight, with no visible moisture on the surfaces of the glass. Provided your vision through the glass is not impeded under these conditions, for example, by scratches, bubbles, or distortion of external objects, your windows are of good visual quality,

Feel warmer during the winter and reduce your heating costs, contact Tayside Windows on Tel: 01382 772855.