The UK-based company AET Flexible Space has created an Underfloor Air Conditioning (UfAC) System that utilizes the few inches of space beneath a raised access floor for the distribution of air, eliminating most ducting and pipework.

By moving air conditioning underground, the company says owners can reduce construction material costs, installation costs, fit out and reconfiguration costs and, in new build construction, can free up additional lettable space or reduce overall building height. As for how much comfort can an underground, ductless HVAC system really offer occupants of a commercial space, a recent project at the One Benjamin building in Central London sheds some important insights on what could be the future of heating and cooling. 

One Benjamin building in Central London

One Benjamin is a new mixed-use address in Farringdon, Central London. Designed by world-renowned architects Alford Hall Monaghan Morris, the building provides 43,562 square ft of office, retail, and residential space.

The original air conditioning design specified four downflow units per floor: two supplying the rear zone of the building and two for the front zone. Each zone was split into two further zones; one supplying cool air towards the perimeter of the building (where it is needed more to combat solar gain), and the other providing warmer air to the central areas of the office space where there is less heat generated by the sun.

Knight Hardwood, the building's main contractor, saw the opportunity to redesign the building's original Stage 3 hot/cold aisle design and implement AET’s underfloor air conditioning solution for the three floors of office space. Considering the variations in temperature across the building caused by increased/decreased sunlight, Hardwood felt AET underfloor air conditioning system could follow the temperature changes in the space. 

AET’s underfloor air conditioning systems make use of the space beneath a raised access floor to create the air ventilation path, eliminating the need for ceiling-based services and associated duct and pipework. At One Benjamin, each of the three floors was divided into zones of up to 300m2 depending on the potential use and occupancy density of the area. Each zone is then supplied with chilled or warmed air by a zonal air handling unit or CAM (Conditioned Air Module) and the conditioned air is then delivered into the space using a number of recessed fan terminals (Fantile).

One Benjamin selected AET’s "most flexible system," the CAM-V, which makes use of the raised floor void as a plenum for the distribution of supply air, whilst receiving return air back to the CAM unit at ceiling or high level. With a CAM-V system there is a considerable amount of flexibility in where the fantiles can be placed, allowing for easy reconfiguration depending on the particular needs or layout of an office. For maximum flexibility each fantile is supplied with onboard Fanspeed and Set Point adjustment, but in meeting rooms and cellular space AET offers Flextouch wall-mounted controllers which allow users not only to adjust the fan speed and temperature, but also CO2 and humidity monitoring and control.

Headroom Height was a key consideration during the design and build of One Benjamin, and by using the AET underfloor air conditioning system the contractors were able to eliminate much of the ceiling-based services and ductwork. The offices were developed to provide a sustainable workplace, and have been awarded a BREEAM ‘Excellent’ rating. The reduced amount of building materials needed for an AET underfloor system, as well as its long-term flexibility, make it an excellent choice for sustainable building projects.

Overall, AET was able to provide One Benjamin with a high-performing and flexible air conditioning system which was more suited to its needs than the originally proposed downflow system. The building was completed in July 2019 for the Girdlers Worshipful Company and is now beginning to rent its office space and residential units.