Architects, Change Of Use in Listed Buildings

The challenge for Architects when renovating historic buildings

Designing a new build house to give acceptable heat insulation when presented with a blank canvas is quite straight forward and informed by current building regulations.

However, we are increasingly presented with, and encouraged to use, brown field sites when developing housing. This could be anything from a disused hospital, school, factory or office block that may lie within a conservation area or itself may be listed. Changing their usage to domestic housing and upgrading such properties can provide a challenge in meeting building regulations.

The likelihood is that the existing building will have single glazing in the windows which may have a U value of 5.7 W/m2K. which is totally unacceptable by today’s standards. So perhaps after the windows are repaired they will be fitted with a form of secondary glazing to boost heat retention.

Whilst the end result will be effective in meeting building regulations the total cost for the dual works (repairs with draught proofing and secondary glazing) will be high and the eventual homeowner will be faced with both the primary and the secondary ‘windows’ to operate and clean. Also, period features such as decorative architraving, shutters etc. may be lost or hidden.

So a more practicable solution could be to retain and retro-glaze the existing window (subject to Conservation and Planning Officer approval), using the increasing range of Ultra-Slim Vacuum Glazing products.

With heat insulation U values ranging from 1.1 down to as low as 0.48 W/m2K in a unit ranging from 6.5mm to 8.3mm thick the acceptable insulation value can be achieved and make a positive contribution to the overall building thermal performance.

Warranties of between 10 and 15 years with life expectancy of 25 years provide peace of mind for the homeowner in the long term, see: