Following the presentation of the competition design, the proposal underwent some adjustments to take planning requirements into account and was also reviewed extensively by the client and their representatives to ensure that the proposal was commercially viable and met institutional standards. Detailed elements of the design that were borne out in the development of the concept include rigorously detailed service cores expressed as separate elements attached to the ends of the office blocks, articulating the edges of the building as it tapers into the churchyard at one end and outwards towards the river at the other. These cores contain primary circulation (lifts and fire stairs) facing the churchyard, while secondary cores on the other side contain toilets, goods lifts and staircases, as well as the main service risers.
The cores, like the rest of the building, have clear glazing so that the movement of the lifts and the coming and going of people on the stairs animate the exterior of the building. The top of the building is elegantly terminated by an articulated roof line made up of the core towers capped by steel-clad banks of lift motor rooms; an elegant solution to a practical necessity. The listed 71 Fenchurch Street building was reorganised to contain a new 50 seat auditorium, formal rooms for conferences and entertaining, with more office space on the upper floors and a new service core attached to the rear.
Reduced energy consumption was one of the prime objectives of the project, and the building was designed to use 30 percent less energy than a conventional office building. Included among the energy-saving systems are external solar protection, reinforced concrete soffits, and a system of chilled beams. By reducing solar heat gain inside the building and using the thermal mass of reinforced concrete, it was possible to significantly reduce cooling needs. This allowed chilled beams to be used for cooling rather than a more conventional air conditioning system.
Highly transparent clear glazed atria, lifts and stairwells provide instant legibility, and allow views into and out of the building at all levels. Colour-coded steel work also acts as an orientating device that is legible both in the broader context of the city and from within the building.
The environmental strategy is based on utilising the thermal mass of the pre-cast concrete frame, the reduction of solar gain by high performance glazing, automatically controlled external louvers, and the use of an energy efficient chilled beam cooling system.
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