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The energy performance of a window depends on how well it stops heat from passing through. Upgrading your windows by installing double- or triple-glazing is a cost effective retrofit measure which can dramatically reduce heat loss, as shown in the table to the bottom right.
In addition to improved comfort and reduced energy bills, glazing upgrades can have a number of benefits:
Quieter homes, as secondary glazing can reduce external noise levels by up to 80%.
Improved air tightness, reducing draughts.
Windows with trickle vents can improve ventilation in your home.
Illustrations of single, double and triple glazing
9.3.1
Planning permission is not normally required for glazing upgrades in houses, provided:
repairs, maintenance, and minor improvements, such as repainting window and door frames, are carried out.
windows and doors are of a similar appearance to those used in the existing house. Please note, a new bay window will be treated as an extension and may require planning permission.
new windows in an upper-floor side elevation are obscure-glazed, and either non-opening or at least 1.7m above floor level.
the proposal is for internal secondary glazing.
9.3.2
Where planning permission is required for window replacements, the following must be submitted:
1:50 existing and proposed elevations showing position of window(s) to be replaced.
1:20 elevations and cross sections of each window typology.
1:5 section showing the position of the window in relation to the masonry.
window product name, supplier and colours.
9.3.3
For replacement door proposals, the design and materials must be appropriate for the period of the building. Where planning permission is required the following must be submitted:
1:50 existing and proposed elevations showing position of door to be replaced.
1:20 existing and proposed cross sections of the door.
1:5 drawing of the panelling profile.
door product name, supplier and colours.
9.3.4
For homes within a Conservation Area there may be an Article 4 direction on the property, removing permitted development rights. Read more about this here.
9.3.5
Planning permission is always required for glazing upgrades in flats, proposals must adhere to building regulations, and a FENSA (Fenestration Self-Assessment) certificate will be required.
9.3.6
Application for planning permission will be required where works are proposed to stained glass windows.
9.3.7
For proposals involving installing secondary glazing in listed buildings, listed building consent may be required.
9.3.8
The replacement of non-original windows is usually acceptable where the replacement is like for like, closely matching the proportions and materials of the replaced window.
9.3.9
The replacement of original windows may be acceptable where the replacement is like for like, closely matching the same proportions and materials of the original window.
9.3.10
The opportunity to reuse and upgrade original windows should be explored in the first instance.
9.3.11
The building fabric around openings should always be properly sealed when windows or doors are replaced.
9.3.12
It is encouraged that new and upgraded windows include trickle vents to allow ventilation, and reduce overheating and condensation.
9.3.13
For guidance on upgrading glazing or replacing the windows of homes in conservation areas or historic buildings, residents should refer to these guides on Retrofitting Heritage Homes.
9.3.14
Consider choosing energy efficient low-e glass. This glass has a thin coating of metallic oxides or silver to reduce heat transfer, helping to keep buildings warm in winter and cool in summer. Low-e glass also helps to block harmful UV radiation.
9.3.15
Where possible, use of evacuated glass should be considered. This is vacuum-insulated glazing (VIG), which consists of two panes of glass with a vacuum in between, providing superior thermal insulation, even to triple glazing.
9.3.16
Solar shading devices can be integrated into openings to help reduce overheating during the summer months. This guide provides information on reinstating heritage solar shading devices such as awnings and external shutters.
Existing windows were upgraded at the same time as adding an extension to this home in Islington, by Neil Dusheiko Architects
Element
Heat loss reduction from baseline
Single glazing
0%
Modern double-glazing
91%
Slimline double-glazing
67%
Modern triple-glazing
88%
Modern vacuum-glazing
88%
This table shows the reduction in heat loss that can be achieved through different glazing options, indicating that the largest heat loss reduction can be achieved by upgrading single glazing to double-glazing
The energy performance of a window depends on how well it stops heat from passing through. Upgrading your windows by installing double- or triple-glazing is a cost effective retrofit measure which can dramatically reduce heat loss, as shown in the table to the bottom right.
In addition to improved comfort and reduced energy bills, glazing upgrades can have a number of benefits:
Quieter homes, as secondary glazing can reduce external noise levels by up to 80%.
Improved air tightness, reducing draughts.
Windows with trickle vents can improve ventilation in your home.
Illustrations of single, double and triple glazing
9.3.1
Planning permission is not normally required for glazing upgrades in houses, provided:
repairs, maintenance, and minor improvements, such as repainting window and door frames, are carried out.
windows and doors are of a similar appearance to those used in the existing house. Please note, a new bay window will be treated as an extension and may require planning permission.
new windows in an upper-floor side elevation are obscure-glazed, and either non-opening or at least 1.7m above floor level.
the proposal is for internal secondary glazing.
9.3.2
Where planning permission is required for window replacements, the following must be submitted:
1:50 existing and proposed elevations showing position of window(s) to be replaced.
1:20 elevations and cross sections of each window typology.
1:5 section showing the position of the window in relation to the masonry.
window product name, supplier and colours.
9.3.3
For replacement door proposals, the design and materials must be appropriate for the period of the building. Where planning permission is required the following must be submitted:
1:50 existing and proposed elevations showing position of door to be replaced.
1:20 existing and proposed cross sections of the door.
1:5 drawing of the panelling profile.
door product name, supplier and colours.
9.3.4
For homes within a Conservation Area there may be an Article 4 direction on the property, removing permitted development rights. Read more about this here.
9.3.5
Planning permission is always required for glazing upgrades in flats, proposals must adhere to building regulations, and a FENSA (Fenestration Self-Assessment) certificate will be required.
9.3.6
Application for planning permission will be required where works are proposed to stained glass windows.
9.3.7
For proposals involving installing secondary glazing in listed buildings, listed building consent may be required.
9.3.8
The replacement of non-original windows is usually acceptable where the replacement is like for like, closely matching the proportions and materials of the replaced window.
9.3.9
The replacement of original windows may be acceptable where the replacement is like for like, closely matching the same proportions and materials of the original window.
9.3.10
The opportunity to reuse and upgrade original windows should be explored in the first instance.
9.3.11
The building fabric around openings should always be properly sealed when windows or doors are replaced.
9.3.12
It is encouraged that new and upgraded windows include trickle vents to allow ventilation, and reduce overheating and condensation.
9.3.13
For guidance on upgrading glazing or replacing the windows of homes in conservation areas or historic buildings, residents should refer to these guides on Retrofitting Heritage Homes.
9.3.14
Consider choosing energy efficient low-e glass. This glass has a thin coating of metallic oxides or silver to reduce heat transfer, helping to keep buildings warm in winter and cool in summer. Low-e glass also helps to block harmful UV radiation.
9.3.15
Where possible, use of evacuated glass should be considered. This is vacuum-insulated glazing (VIG), which consists of two panes of glass with a vacuum in between, providing superior thermal insulation, even to triple glazing.
9.3.16
Solar shading devices can be integrated into openings to help reduce overheating during the summer months. This guide provides information on reinstating heritage solar shading devices such as awnings and external shutters.
Existing windows were upgraded at the same time as adding an extension to this home in Islington, by Neil Dusheiko Architects
Element
Heat loss reduction from baseline
Single glazing
0%
Modern double-glazing
91%
Slimline double-glazing
67%
Modern triple-glazing
88%
Modern vacuum-glazing
88%
This table shows the reduction in heat loss that can be achieved through different glazing options, indicating that the largest heat loss reduction can be achieved by upgrading single glazing to double-glazing
Illustrations of single, double and triple glazing
Existing windows were upgraded at the same time as adding an extension to this home in Islington, by Neil Dusheiko Architects