22 Park Crescent

Retrofitted and upgraded residential blocks

Two existing buildings with 92 apartments have been retrofitted and upgraded, while the residents remained in occupation. Designed and built in the 1960s, they form part of the new Regent’s Crescent development which reinstates residential use to the Grade I listed crescent.

Client: CIT
Location: London
Size: 92 retrofit apartments
Cost (overall development): £180m
Status: Complete

Located at the rear, these buildings were part of a facsimile rebuild following bomb damage in WW2, when the crescent was developed as a series of offices. The recent decision to take down the ‘60s office development and rebuild did not include these two blocks, instead, a strategy was formed to save and upgrade them using a fabric first approach.

The transformation of these two buildings is truly remarkable, demonstrating how a failing building can be saved and given a new lease of life for many decades to come. A key challenge for this site was how to assimilate the new envelope with its 1960s proportions and levels to connect aesthetically with the new rear façade of the heritage building, with its Regency proportions and levels.

Of typical design and construction of the time, the two poor quality, concrete and masonry buildings were fitted with single glazed Crittall windows; apartments were cold in the winter and tended to overheat during the summer months. In addition, the masonry was spalling, to the point where it was cracking and falling off the building.

A total retrofit overclad solution was conceived with a thermal upgrade to the envelope comprising the roof, windows and walls. An external fabric first approach was needed so the residents could remain in occupation. The warm jacket consists of a mineral wool, rendered wall insulation, with aluminum faced timber windows to provide acoustic attenuation. In terms of ratio from an existing masonry wall, a 100mm overclad insulation is a major improvement. The thermal mass of the existing walls assists with reducing the diurnal temperature changes and release of energy into and out of the building. Thermal bridging was checked at all key floor and window junctions, and fire and cavity barriers installed.

The improvements have almost halved the space heating demand in each unit (there were no works to the internal heating infrastructure). More importantly is perhaps the significant improvement to comfort levels with overheating considerably reduced and acoustics improved