36 The Calls / Externalreference

Last week we featured the winning proposal for this competition in Leeds, UK, and now we feature the proposal by this young Spanish practice, Externalreference.

The competition site is located close to the main transport, cultural facilities and, at the same time, a five minute walk to the old industrial area. The location has good potential as a center for offices, business, conferences and leisure. Commercial and catering activities, which are intense in the city center, start to fade along the borders of the river. New commercial programs together with bars and restaurants will attract both the people who work on the opposite side of the river and those who live and work in the center. Before the Brewery wharf was built there were few conference venues close to the site. The introduction of new conference spaces will establish the area as an ideal place for business and meetings. There are few Spa centers in Leeds and new ones close to the site are reported to be lacking in service. Wellness activities integrate perfectly in business and city center environments.

Visual Landmark VS Periscope

Tall buildings, being visible from long distances, act as reference points but have no relation with the site context and with human scale. Landmarks do not interact with the city, they simply express their presence.

Our building functions as a periscope. Through the inclination of its glass facades the reflections of the city will be visible around the surrounding building area.

Basement: A ramp connected with The Calls allows access to the basement floor by car. The carpark has the capacity for 10 parking spaces that could be rented or sold to the tenants.

Ground floor: The building floats on the vertical cores leaving two open corridors on the sides allowing free access to the Calls Landing building and to the riverside terrace.

A transparent glass skin wraps the bar area providing for maximum natural light penetration and transparency. The street is visually connected to the river. The bar increases public use of ground floor and of the terrace.

First floor: The restaurant and lounge bar have direct views of the river and the city while the bookshop, on the road side, attracts the people walking along The Calls.

Second floor: A large open space facing the river could accomadate up to 200 people for conferences. The space could be divided in two smaller conference rooms with a sliding wall.

Third floor: The functions are divided in two halves. The gym is orientated toward the city center while the intimate space of the wellness area and the pool are situated on the opposite side.

Fourth floor: This is one of the most privileged floors of the building. A gym and a bar occupy half of the surface and the other half is an outdoor terrace and pool with incredible views of south Leeds and the river.

Typical office plan: From the fifth to the ninth level the floor area is designed for office use. The floor is free from any structural elements and could be arranged according to different distributions. Due to the block height there is a 360º view on all the city.

Orientation

The strategy of bioclimatic design is based on the excellent orientation of the main facades (north and south) of the building.

Thermal Insulation

On south and north facades a low-e glass and high thermal insulation provide for a high heat retention and also efficient use of natural light.

Solar Protection and Greenhouse Effect

A solar protection system on the south facade allows solar radiation in winter and intermediate seasons and protects them in the two months following the summer solstice. In this way the building has clear different behavioural patterns during the summer and winter time. The other building facades and the roof, are mosly opaque in order to reach a high level of thermal insulation and minimize energy consumption.

Cross Ventilation

The double block shape of the office block allows a good natural cross ventilation and reduces the energy required for cooling systems.

Water Gathering

The roof and tank storage of rainwater cover the needs of non-potable water (wc tank) of the building.

Energy Consumption

The construction process of the building will incorporate the largest number of components supplied by local dealers, recycled elements and lower lifecycle CO2 emissions products.

Structural Concept

The main aim of the stuctural design was to provide maximum flexibility of floor surface and avoid large structural elements. The main supporting system is a light structural skin called diagrid which wraps the built volume. The scale of the diagrid varies according to load distribution and building geometry and its density is calculated through a step by step process.

The floor slabs, the perimetral and transversal beams, the elevator/stair cores complete the structural system. The diagrid optimizes the use of metal elements through the concentration of matter in the most loaded zones and leaves large areas free of structural elements.

Tessellation and Optimization

The diamond tessellation of a diagrid base unit acts as a latticed load-bearing structure. Given a set of loads and an homogeneous frame, a structural software calculates the stress map. The less efficient elements (in grey) can be isolated and eliminated. With the new structure a new calculation is launched and a new configuration of inefficient elements appear. This step by step process transforms the original structure configuration into a more efficient gradation that is the result of the building geometry and program load distribution. The floor slabs are connected to the transversal beams which spreads the load into the diagrid intersection.