Answers to the most frequently asked questions.
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Why do I have a haze appearance on my windows?

Haze can occur on most coated glass. However, the effect will be more noticeable on some types of coated glass than on others. Haze gives the appearance of a fine, uniform, layer of dust deposited on the surface of the glass. The effect is more noticeable when the glass is viewed at an angle or under strong light. In situations where the glass is in partial shadow, the shaded area will be free of the effect, giving a clean appearance in the shadow and a dusty appearance in the lit area. This contrast can be very noticeable. Hard coated low-E glass can manifest this effect.

Why do I need to use a low-E glass?

Government Building Regulations require us to save energy, to help protect the environment. Using low-E glass is the most efficient way of doing this with glazing. This also provides benefits to you as a property owner as money can be saved on heating bills as heat loss is reduced by a massive 75% compared to single glazing and at least 40% compared to traditional double glazing. Rooms are also more comfortable as cold spots near windows and drafts are reduced.

Will using a low-e glass cut down on my energy bills?

Low-E is designed to reflect heat back into a room, therforere reducing heat loss. By using a low-E glass in your windows your home will be better insulated, thus reducing your requirement for additonal heating.

Why have I got external condensation on my windows?

Due to the enhanced thermal properties of a double-glazed unit comprising a low-E glass, the outer pane of glass does not get warmed by heat escaping from inside the building through the glass. This results in the outer pane being kept cooler in comparison to a less thermally efficient insulating unit. Certain climatic conditions or high humidity levels, without rain can lead to the formation of condensation on the external surface of the outer pane. It is also possible that due to shelter from nearby trees or buildings, external condensation will appear on some windows but not others.

Where should the SGG PLANITHERM pane be positioned in my double glazing?

Ideally SGG PLANITHERM should always be positioned on face 3 of the double-glazed unit. However, if necessary it can be positioned on face 2 as long as it is facing the cavity and thus protected from the external atmosphere.

I have been told that I need to use a 'low-E' glass in my home, what does this mean and is it far more expensive?

A low-E glass is a glass with a special coating designed to reflect heat back into the room, thus reducing heat loss. The extent to which low-E glass reduces heat loss is measured by the U-value, the lower the U-value the better the thermal insulation. You are required to have a low-E glass in your windows to comply with the latest Building Regulations.

What is a U-value?

The U-value of a window is a measurement of the rate of heat loss indicating how well your windows are keeping valuable heat in. It is expressed as Watts per square metre Kelvin W/m2 K. The lower the U-value the better the thermal performance of the glass. So called 'Low-emissivity' or 'Low E' glass offers improved thermal insulation denoted by very low U-values.