36 The Calls Leeds - Competition Submission, 2009

Introduction

The design competition for 36 The Calls, Leeds asked for an innovative design solution for this small but challenging site on the Leeds Waterfront. The brief called for a Landmark building that had excellent green credentials whilst maximising the development potential of the site.

Approach

Our approach was to develop a scheme that took advantage of its unique position on the elbow of both the River Aire and The Calls; maximising the achievable footprint whilst respecting the adjoining properties and retaining and improving the pedestrian connection to the River frontage. Fundamental to the scheme was the integration of Sustainable design at the very start of the process.

Passive Design Approach

The building form developed to both enhance the environmental aspects of the proposal whilst maximising potential floor plate size on the site. The buildings form pushes out into both the River Aire and The Calls at the upper levels creating a dramatic form which optimises north light whilst providing natural shading to the South facing elevation. This reduces solar gain whilst maintaining the magnificent views of the river.

The important connection to the riverside is maintained with the new build element set away from the face of the adjoining property, maintaining natural daylight to the West facing elevation of Calls Landing. A series of slender bridges connect the two buildings together providing further flexibility whilst resolving existing core/access issues with the Calls Landing building.

The Ground floor which was proposed for public usage benefits from a riverside terrace area together with a proposed Floating Garden, which would also act as a mooring point for a Waterbus/Taxi.

Utilising the developed form of the building the proposals sought to maximise both natural ventilation and natural daylight to the office floor plates. The exposed soffit of the flat floor slab providing both passive cooling and a relatively high floor to ceiling zone which maximises airflow across the floor plate. Suspended raft lighting optimises the artificial lighting and wellbeing solution.

Structure

Working with Ramboll a triangulated 'bird-cage' structure was designed that permitted the cantilever form of the proposals to be developed without the need for internal columns. The plan form incorporates two cores to the centre of the site which provide the necessary anchorage and stiffness required. Floors were proposed as post stressed concrete with a connecting steel bird-cage structure providing lateral stiffness and support.

Envelope

A lightweight built up system was proposed for the external envelope with a timber frame sheathed in external grade plywood to achieve the form required whilst incorporating a high level of insulation. A waterproof membrane from recycled material would then cover the whole with a final protective and visible layer of patinated perforated copper panels, ensuring longevity of appearance whilst complimenting the red brick of the architectural vernacular.