Windows 99

You may not have heard of US software mogul Charles Wang. But if you fly in to Heathrow, you will not be able to miss the new European headquarters of his company, Computer Associates. The refreshingly idiosyncratic building in nearby Ditton Park is shaped like a letter W, in honour of the firm's founder, chairman and chief executive.

Its distinctive shape has been achieved at a cost. Two corners of the 23 000 m² office are so sharp they cannot be occupied, a luxury that usually would be out of the question in a corporate headquarters.

One of these corners is even cut off from the rest of the building. It forms a curtain-walled prism rising three storeys and has no apparent use. This is perfectly set off by a giant, 3 m wide concrete cupola in the roof between the prism and the main building.

The cupola is "just a feature", says Computer Associates project manager Roger Glew.

Although Computer Associates has stumped up for these architectural eccentricities, it has taken a more cautious approach to other areas of spending. For example, the company has a novel way of checking that it is getting value for money from subcontractors.

Glew explains that, in the USA, where Computer Associates is building a 75 000 m² world headquarters, the company favours construction management as it allows it to keep close control of the project. In the UK, though, the company does not have enough expertise to go down the CM route. So, Computer Associates let a £22.6m lump-sum contract for the shell and core with main contractor Mowlem in January 1998, but insisted on setting budgets and target cost savings for each subcontract package. This meant that each package was value-engineered to try to meet the target savings.

Even though the client has questioned each package let by the main contractor and has maintained a constant presence on site, Mowlem project director Colin Eastman has not found the contract onerous. This is less of a surprise when you consider that Eastman's last job was the construction of the Ministry of Defence's defence procurement headquarters at Abbeywood, near Bristol, which led to massive public rows and numerous financial claims. Compared with Abbeywood, Computer Associates' headquarters is an uncomplicated project that is likely to hit handover dates in August and September.

Once finished, the building form will be roughly two triangles joined together. The bases of these triangles are linked by a single-glazed, three-storey elevation that is 250 m long. Each triangle has a central triangular atrium: one is open to the elements, providing a recreation area; the other has a fully glazed roof and houses a restaurant. Amenities for the 1000 staff also include a fitness centre with separate aerobics room and a crèche for 75 children.

Built on an insitu concrete frame, the headquarters is shrouded in green-tinted glazing. Dutch-based curtain-walling specialist Witte is completing the £4.5m cladding contract. It was taken on in January 1998 when Mowlem began working up the extensive curtain-walling contract.

To minimise costs, Witte bought the glass from Pilkington in Germany and shipped it over to Cork in Ireland where it was built up into double-glazed units. These units were then shipped to The Netherlands, where Witte installed them into frames before shipping the curtain walling into Britain.

The extensive glazing allows a lot of natural light in, and its tinted form reduces solar gain. Further heat control is provided by temperature-controlled internal roller blinds. To maximise the amount of natural light entering the building, US concept architect Spectre Group and UK executive architect Blair Associates developed a 10 m wide moat around the building's southern perimeter. This is intended to reflect low-angle winter sun rays into the building.

However, services in the building do not reflect this low-energy lighting philosophy – it is being fitted with a full air-conditioning system. Glew explains that the fast-moving nature of the software business makes it difficult to predict what heat loadings might be next month, yet alone next year. In this situation, air-conditioning is the lowest-risk option.

Computer Associates does intend to minimise the amount of energy it expends in heating and cooling, though. It has developed a software package, The Next Step, that allows the building-management system to be monitored and changed in real-time from the USA. This enables US facilities managers to benchmark the Ditton Park headquarters against other offices around the world.