Flexible friend

Flexibility is now a vital factor of office servicing. Current economic conditions mean firms must constantly adapt to survive, changing the size and format of their workforce and the technology that they use to do business. Although for some these changes may mean moves to new premises, for the majority it means rearranging the existing office layout. And with such moves becoming commonplace, demands on office servicing are increasing.

Traditional offices have virtually immovable sources of power and hvac services. When changes to use are made in the space this can create two main problems: lack of power where it is needed and poor control of environmental comfort conditions.

Speculative open plan offices with ceiling-mounted fan coil units and evenly spaced exhaust and fresh air ducts may work when staff can be accommodated in a single room without division, but what happens when meeting rooms are added or certain groups have to be separated by more than a low partition?

By changing the layout of a building the balance of the air conditioning will be affected. Draughts and pockets of heat may be created, and the need for power in new areas poses the problem of changing cable routes and extending systems. Reconfiguring the existing services can be expensive and time-consuming – both are unacceptable in modern business. But a solution exists.

Air conditioning manufacturers and designers are turning to flexible, underfloor systems that allow office reorganisation with minimal disruption and cost. The aim is to make a space adaptable to any use, while meeting the energy efficiency requirements of the Climate Change Levy and tackling the problems associated with Sick Building Syndrome, such as airborne contaminants and unhealthy humidity levels.

The systems focus on using raised modular floors to create a void for distribution of services. Easily removable units that are interchangeable with standard floor tiles hold dedicated tracking for power and data cabling, and can be moved and rearranged quickly.

Air conditioning in such systems is distributed underfloor also, with the floor void acting as a supply plenum for the conditioned air.

With such systems occupants can design and use their internal office space as needed without having to add equipment that may use valuable floor space. With services below floor level this also removes the need to design layouts around pipework, etc and there are no high level wet installations. The systems are also a cost-effective solution for refurbishment projects, where the floor-to-ceiling height may not be large enough to accommodate standard air conditioning systems in ceiling voids, or where special consideration must be made for architectural features or preservation orders.

The market choice
Several systems are now on the market as manufacturers aim to satisfy the increasing demand. York and Kingspan Access Floors, Denco and AET all offer solutions for office flexibility.

A recent entrant to the UK market is the Building Technology Platform, which has been developed through a collaboration between York International and Kingspan Access Floors. This system combines York's FlexSys vav air conditioning technology with a Kingspan raised access plenum floor.

The FlexSys system uses Plug-n-Play power and control wiring systems. Operation is simple: an air handling unit (ahu) pressurises the floor void with conditioned air, which is supplied to the space via removable Modular Integrated Terminals installed in the raised floor. A perimeter seal on the floor panel modules tackles air leakage.

The firms claim that installed costs for the system is up to £50/m2 less than traditional fan coil systems and running costs are around 44% lower.

The system is already established in the USA, with five million square feet installed to date. It has been adapted to meet European standards.

Air conditioning manufacturer Denco's offering was launched in late January 2002. The Flexible Office again makes use of proven technologies and products.

The system is based around Denco's Toscana intelligent air conditioning technology. The main components are an air handling, or zone, unit; a local environment control unit (lecu); and the raised floor plenum. Three sizes of zone unit are available – 10, 20 and 30 kW – each one incorporating cooling and heating coils, electrically commutated fans, control valves, filtration, humidification and a control system. These can be upgraded to suit higher cooling loads. The lecu is a standalone fan air terminal that includes a modulating damper, controller and two air grilles. Controls closely match output to demand to minimise energy use, The access floor is a variable height steel substructure. Individual 600 x 600 mm fan tile units are independently controlled and can be moved to suit the required load by replugging into a 240 V power supply.

As Flexible Office uses Denco's close control technology, temperature can be controlled to within 51°C and humidity to within 10% of the target 50% relative humidity, meeting the requirements of the Health and Safety at Work Regulations.

The zone air handling units provide conditioned air to the floor void and constantly monitor and control temperature and humidity while providing high-grade filtration. The underfloor air terminals draw air from the plenum for distribution via recessed floor grilles with onboard temperature sensors that control automatic dampers during cooling/heating or recycle modes. Air returns via the zone units.

Several options are offered for cooling, including chilled water, variable refrigerant flow and heat pump, with Ambicool 'free cooling' also possible. Several installations of Flexible Office are now underway.

The Flexible Space System from Advanced Ergonomic Technologies (AET) is long-established. It incorporates Hiross underfloor air conditioning and is claimed to generate significant savings compared to standard vav or fan-coil air conditioning systems. It has been proven to reduce overall construction costs by up to 7%, while cutting on site installation time for contractors by as much as 25%.

The system works on a zonal basis. Each zone is supplied by a conditioned air module (cam), while the underfloor void is divided into supply and return air channels using relocatable, airtight baffles. Supply air is drawn into the occupied space by recessed fan assisted terminal units that plug into an underfloor power source. These have individual controls to provide variable speed and temperature. They are not restricted by duct or pipe connections, so are easily interchangeable with floor panels. All other services and cable management can be integrated within the floor plenum, making initial installation and any maintenance straightforward.

All units are data linked to a central cam to ensure intelligent and flexible unit control, and can also be easily interfaced with any major brand of bms.

Over 1·5 million m2 of commercial building space has been fitted with the system to date. Analysis of these installations has shown that as the need for a ceiling void is effectively removed, the overall building height can be reduced by up to 10-15%. This can generate cost savings in associated materials and labour costs of between 5-7%.

On a recent project for BAA Lynton developments at Gatwick and Stansted Airports, the use of the Flexible Space System gave a programme reduction time of 25% (30 weeks instead of 40 weeks) and capital cost savings of £200 000.

With office churn increasing, the demand for such systems is likely to increase. If you haven't installed one yet, you can be sure that you won't have to wait long.