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Architectural Doors & Windows Ltd
9 South Wardpark Place
Wardpark South
Glasgow G67 3HX

Tel: +44 (0)1236 780022
Fax: +44 (0)1236 780021


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Architectural Doors & Windows Ltd
Kirkwood Business Park
AB51 7LE

Tel: +44 (0)1330 830115
Fax: +44 (0)1330 830065


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Rationel energy terms Scotland Edinburgh Aberdeen Inverness

energy terms


Window placement and configuration has noticeable influence on both heating demand and electricity consumption. When building low-energy buildings, the thermal performance of the windows has even greater significance and can be important for reaching the desired energy goal.

But how do you ensure that you have chosen the most energy-efficient windows?

There is no clear answer to that question, since it requires a weighting of different values in relation to the specific context in which they are placed.

Our experience is that the energy balance approach is the best guiding principle on south-facing windows, whereas windows facing north should be optimized toward the lowest U-value.


Uw Whole unit U-value, expressing the amount of heat loss through the unit and measured in Watt/m2K.
Ff Percentage of glass. The visible glass compared to the size of the element.
Gg An expression of total solar energy that passes through the glass and into the building.
Ug The U-value of the glass.
LTg An expression of light transmission. The percentage of light passing through the glass.
WER Window Energy Rating takes in both solar gain, heat loss, and heat lost through air infiltration into account and is calculated in kWh/m2/year.


Rationel energy terms Scotland Edinburgh Aberdeen Inverness

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