SECONDARY GLAZING

Description
Supplementary glazing attached to window frame on the inside of single glazed windows.

Unit cost of installation
�1200 - 2000.

Bulk cost of installation
Data not available.

Indicative cost and carbon saving

�/yr saving		kgC/yr saving
from	to	from	to
20	70	85	195

Maintenance
None normally required.

Technical suitability
Need to consider ventilation issues when installing secondary glazing. Secondary glazing should be draught stripped, but the original frame should not (to prevent condensation between the two). Other issues raised under draught stripping are relevant here. Secondary glazing can restrict safe egress through a window in an emergency, so consideration should be given to the choice of an appropriate system or possibly leaving one window untreated. Need to ensure that rapid ventilation can still be achieved (i.e. that the SG does not prevent easy opening of windows).

Non-technical constraints
Secondary glazing may not be wanted in summer particularly if it restricts the opening of windows, so occupants may try and take it down. This can lead to a storage problem, and potential danger of breaking the panes leading to personal injury.

Potential concerns with fuel poor
No specific issues.

Ancillary benefits
SG can improve sound insulation if air gap between SG and original window is 150mm or more. Condensation on windows can be reduced.

Trigger points for work
Small refurbishment works and decoration.

Technical Guidance Available
» GPG 295 'Refurbishment site guidance for solid-walled houses - windows and doors'