Sir John Egan’s ‘Rethinking Construction’ report was commissioned to look at better ways of building and it summarises the requirements of many developers, building owners and occupiers who call for major improvements:
- faster design and construction, without compromising choice and quality;
- reduced cost, to be achieved through efficient design and procurement not reduced specifications;
- cost and time certainty at the earliest possible stage and therefore reduced risk for business cases;
- maximised development value.
The principal aim is to offer design choices, with swift delivery at competitive pricing. Choices in:
- building layout and number of storeys;
- configuration of reception and atrium spaces;
- external building envelope options including glazed, metal or stone curtain walling, tiled rain-screen or brick cladding;
- solar control glass, external sun shading or combinations of the two;
- internal finishes to the client’s particular preference.
The structural approach combines flexibility with efficiency. It comprises a number of pre-designed building elements which can be used to build up a building layout in a infinite variety of forms. The customised building is based on a 9m by 9m column grid.
Suspended floors are constructed either from a 250mm post-tensioned concrete slab or a 300mm reinforced slab to give span/depth ratios which minimise building weight and overall height.
The standard column components are pre-cast off site using high strength concrete. This means smaller diameters which maximises internal floor space. Pre-casting in factory conditions also brings the highest quality so enabling untreated exposed finishes. A braced steel core incorporating service riser, staircase and lifts provides structural stability.
Reid Architecture’s most significant design idea at the start of this process was to provide a range of different ventilation solutions within a standard storey height. This allows columns, stairs, core walls and cladding components to be standardised and lead-in times reduced.
The services design provides for four alternative HVAC options:
- fan coil air conditioning
- under floor air conditioning
- high capacity displacement comfort cooling
- natural ventilation
The façade design has been closely developed in conjunction with the services. Typically, each HVAC will work with either solar control glass, shading or a combination of both. In each case, the aim is to optimise the proportion of glazing to maximise daylight penetration without exceeding the capacity of the chosen system.
The first two ‘Customised Office Solution’ projects have been progressing at Crossways Business Park near Dartford, a primary location in Kent close to the proposed new Eurostar Terminal.
The first building has just completed and is tailored for occupation as headquarters accommodation. The 7,274 sq m development, built over 4 storeys, uses a fully unitised curtain wall system and is prefabricated in modules off-site.