The challenge
London Borough of Camden has committed to net zero carbon emissions by 2030, having already achieved a 61% reduction against its 2009/10 baseline. Swiss Cottage Library was identified as one of its most energy-inefficient assets, and became the focus of a £2.8m refurbishment, part-funded through the Public Sector Decarbonisation Scheme.
The Grade II listing brought a hard constraint: principal contractor Ergo Group could not alter the existing façade, including the low parapet wall running around the roof. That ruled out any build-up thick enough to compromise sightlines or upstand heights, while the roof still had to reach a demanding U-value of 0.18 W/m²K. The refurbishment also had to proceed with the library open and operating throughout.
The solution
Working alongside Langley, the design retained the existing waterproofing as a base rather than stripping it back, overlaying it with Langley's TA Flat Roofing System of layered mineral felt. This approach kept embodied carbon locked into the existing roof structure and reduced material sent to landfill.
The clearance constraints set by the parapet meant conventional insulation thicknesses weren't an option. Recticel specified 60mm of Deck-VQ vacuum insulation panels - delivering the thermal performance of a significantly thicker PIR board in a fraction of the depth, and allowing the 0.18 W/m²K target to be met without touching the protected upstand heights.
Project outcome
The refurbishment more than doubled the building's targeted carbon reduction, delivering 138 tCO2e in annual savings against an original target of 55 tCO2e. Our vacuum insulation solution (Deck-VQ) allowed the existing roof buildup to be overlaid rather than stripped out, embodied carbon was retained and waste to landfill along with the transport emissions associated with it was minimised.
Why Deck VQ?
On a Grade II listed building, the roof build-up had to work around the existing fabric, not the other way round. The protected parapet wall set a hard ceiling on upstand height, which meant the usual route to a 0.18 W/m²K U-value - simply adding more PIR wasn't available. Achieving that figure conventionally would have needed a board thickness that pushed the waterproofing above the parapet line, putting the listing at risk.
Deck-VQ's vacuum insulation panel construction gave the design team a way round that trade-off. The thin profile also meant the insulation could sit directly on top of the retained waterproofing as an overlay, rather than requiring a full strip-out to accommodate a deeper build-up. That kept the specification aligned with the wider approach of preserving embodied carbon in the existing roof and minimising material to landfill - Deck-VQ solved the clearance problem without working against the project's carbon reduction goals.
