Working detail: Ropemaker Place
[WORKING DETAIL 12.08.10] Ropemaker Place- facade detailing
The facade design integrates architectural treatment with performance and is a key part of the environmental strategy. A bespoke system of unitised 1.5m-wide cladding modules, designed as storey-height insulated cassettes with projecting and tilting vision panels where required, reduces the average annual energy consumption for cooling by up to 27 per cent compared to a flat facade.
The option of a twin wall was rejected because budgets were limited, and because it would have significantly reduced the net area. Natural ventilation was ruled out on grounds of noise, which would have been reflected by the nearby CityPoint Tower.
The windows to the east and west project from the flat facade and, on their vertical axes, tilt away from the sun towards the north to reduce incident solar radiation, lowering peak cooling loads and annual energy consumption. South-facing windows rotate about a horizontal axis, leaning forward to provide self-shading.
These projecting windows form serrated compositional blocks that, together with the large areas of optical spandrel glass, create additional surface animation and modelling. The design minimises space heating demands and infiltration by achieving high insulation and airtightness levels. The double-pressure gasket line reduces air leakage to 5m3/hour/m2 of facade at a pressure of 50Pa, an improvement on Part L of the Building Regulations, which requires 10m3.
Internal sill heights of the projecting windows are 500mm, increasing the area of insulated spandrel. Glass units are frameless and bonded to carrier frames by structural silicone. Mick Brundle, director, Arup Associates