New windows can raise the value of the house itself.Ĭommon mistakes made in answering exam questions.New windows can be more secrure - include window locks and help prevent house break-ins.Double glazed units can have low maintenance frames (no painting needed).Double glazing reduces sound transmissionĪnd can help reduce (not stop!) unwanted noise.Payback time on installing double glazing tends to be long - therefore double glazing installation is usually done in response to a range of other benefits - not just the savings from reduction of heating costs. But overall heat transfer by radiation is hardly changed by double glazing a window - it is conduction and convection that change the most! Heat radiates through air and glass - as it does so some of it is reflected (but this is virtually the same as for single glazing) and some of it is absorbed (mainly by the glass itself) this percentage increases as there is more glass. The room in the house therefore stays warmer for longer reducing heating costs. The trapped air reduces the rate of heat loss through the window by conduction and convection. This therefore reduces the rate of heat transfer by convection. The air gap is too narrow to allow the air to circulate easily. The trapped air in the gap is an insulator - it does not stop heat being conducted from the inner pane to the outer pane - but it does slow heat transfer by conduction down a lot! In secondary glazing an inner frame is added to the existing window and the extra pane is often made to open out - some condensation will occur within such units. In 'sealed units' this is sealed at low pressure (it is NOT a vacuum!) and the air is dried to prevent the misting up of the unit. This can be either installing a sealed glass unit or adding an extra pane that has not been sealed in a factory (secondary glazing). A Level and AS level - UK KS 5 (Age 16 - 18)ĭouble glazing involves putting an extra layer of glass in front of a window pane.
GCSE and 'O' Level - UK KS4 (Age 14 - 16).
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