A year on from COP26 and during World Green Building Week it feels timely to look at retrofit in more detail.

The basic idea of retrofit is to improve the efficiency of existing buildings whilst assuring their continued sustainable use by replacing certain elements with new materials and technologies. The general driver, amongst others, is to make a positive contribution to addressing the climate emergency whilst meeting 21st Century needs and expectations of buildings.

Of course, it goes without saying, that from an embodied carbon perspective the continued use of historic structures is a green no-brainer. But whilst Historic Environment Scotland’s (HES) publication on retrofit for COP26 focusses, rightly so, on energy efficiency – improving insulation, windows, etc., in practice, retrofit means much more than just this.

To upgrade our old buildings, we first need to identify what can be improved and what is no longer fit for purpose, assess these assets, and determine how they can be improved. Interestingly, this also leads to the conclusion that by using heritage-friendly, modern materials, an extension can be considered a retrofit project, something we are seeing getting more widespread acceptance.

When we attended the SPAB/ HES retrofit tour of Glasgow, 90% of the buildings on the tour were façade retention projects – essentially coring out an old building, completely modernising the interior and retaining the historic shell. This means the scope of retrofit is massive if the assessment and justification is correct.

This method of retrofit has allowed us to move more confidently into demolition of listed buildings and demolition in conservation areas. Sacrilege I hear you cry! But in Scotland it has become a more accepted practice.

HES has a whole series of guidance notes entitled Managing Change in the Historic Environment., including sections on Demolition, Demolition of Listed Buildings, Extensions and Micro-renewables.

As a testament to the forward thinking of the public sector in Scotland, these guidance notes are regularly being used to inform developments that enhance listed buildings and conservation areas by replacing the underused with good, future-proof designs as well as providing sensitive treatment of the historic elements that are retained.

So this week for WGBW we can consider how our outlook on retrofit has developed since COP26 from a method of upgrading existing buildings to a wider philosophy of enhancement through sensitive demolition and smart replacement.