Is prefabrication just for the big boys? EMC looks at two initiatives that are making the benefits of off-site assembly available to more contractors

The building services sector is under incredible pressure to reduce costs and complete installations in ever shorter timescales. At the same time, skills shortages and punitive penalty clauses have become the norm. Against this backdrop, one firm has developed an innovative approach to the design, construction and installation of m&e plant rooms.

Constant Air Systems (CAS) has adopted a modular system that enables it to assemble and test the equipment before shipping the plant room to site. Once delivered, installations are completed by simple connections.

CAS’ construction method relies on suppliers that can match its tight schedules.

WF Electrical’s construction and installation team developed a partnering solution with Martin Wigginton, managing director of CAS, that sees WF providing not only a range of HVAC control gear, but also large 600 kW boilers, costing up to £7000 each, that form the heart of most of CAS’ heating systems.

Modules are prefabricated in CAS’ factory in High Wycombe, Buckinghamshire, to individual specifications, then transported to site and plugged into site services.

CAS applies careful attention to client requirements for off-site prefabrication of bespoke permanent or temporary plant rooms and skid-mounted arrangements. Prefabrication in a factory environment can not only improve installed quality but can reduce overall costs and programme time normally experienced by carrying out installations on site.

In the main, prefabricated units, which cost upwards of £100 000, are commissioned as part of a modernisation process where it would be far too costly in lost production time if an existing facility was demolished and a replacement installed.

What’s more, by building the plant rooms off site, the level of productivity can be 50% higher than for building conventionally on site. The element of control is greater and materials can be stored in a secure environment, ready for immediate use.

Although CAS has been undertaking this type of work since it was founded in the mid-1960s, as companies come under increasing cost and time pressures, this type of pre-assembled installation has increased in use. CAS’ client list includes public sector organisations such as hospitals, as well as a host of blue-chip companies such as Tesco, British Airways and Cable and Wireless.

The level of productivity can be 50% higher than for conventional building on site. The element of control is greater, and materials can be stored in a secure environment, ready for immediate use

Wigginton points out that some installations are far from standard, such as when CAS took responsibility for installing three units on the Forth road bridge to keep the humidity of the cables controlled.

The CAS approach to prefabrication and off-site construction provides many features and benefits. All plant rooms and skids can be individually designed to meet requirements. High engineering and quality standards are incorporated in packages.

On-site installation time is less – plant rooms can be operational within a short time of delivery. Best use is made of limited space, and detailed designs are prepared in advance using the latest CAD techniques.

Centralised control systems can be incorporated and services are pre-tested and certificated prior to delivery.

Factory inspection can be arranged for clients during the construction phases, and there is an unrestricted selection of equipment to choose from.

Typical prefabricated, packaged plant room applications include: boiler plant for heating systems; steam plant for heating or process systems; domestic hot and cold water plant; chilled water plant; air-handling plant; refrigeration and air-conditioning plant; and electrical switchgear modules.

Apart from building and installing pre-assembled plant rooms on request, CAS also offers turnkey solutions in carrying out site works associated with any prefabricated project, including builders’ work, mechanical and electrical services or craneage and positioning, as either a principal contractor or subcontractor.

WF Electrical was selected to partner CAS because of its exemplary service record, because it stocks equipment in a single national distribution centre and its strong relationships with manufacturers.

The fact that the company also stocks more than 20 000 electrical products, in addition to 1000 or so specific HVAC products, was a further factor in cementing the partnership.