Design and architecture trends can lead to a number of challenges for consulting engineers specifying heating, ventilation and air conditioning. Traditional ceiling based systems are usually fixed and inflexible due to associated duct and pipework. Making use of the plenum beneath a raised access floor as the ventilation zone for air conditioning can overcome a number of these challenges and by adopting an air conditioning system which can both supply and return air via the floor plenum, architects are free to make use of ceiling space and features in a very different way, as well as attracting significant height savings.
The trendy feature of exposing ceilings in commercial offices lends to spacious, open interior space. Structures and beams become interior features and are often left unfinished. Current new build designs incorporate large floor plates, high ceilings and windows to maximise available light and enhance natural ventilation. In refurbishments, space and access is often restricted, however there could be scope to add a further floor with dormer windows; often referred to in the industry as a dormer floor.
AET Flexible Space has worked with architects to help achieve their design goals. Jersey Energy undertook a complete refurbishment of the 10,000 sq. m Powerhouse building in the early 2000’s; the ceiling is a lattice of riveted steel ribs and Architects Manser Associates have achieved pleasing results with up lighting and underfloor air conditioning and at The Weighbridge Building in Marlow, designers were able to retain the existing beams by adopting underfloor air conditioning as part of a full refurbishment.
As well as increasing floor to ceiling height, plenum based air conditioning also allows the architects to retain structural features. Many older buildings have beautiful ceilings, some of which have listed classification and must be preserved. Modern buildings may have a lightweight structure in the form of a building envelope, such as the Arup designed Parkview Green building in Beijing. New and older buildings may have an atrium incorporated into the design, and again, underfloor air conditioning systems can satisfy cooling and heating requirements within these open areas.
The options for providing comfortable heating and cooling in these modern spaces can be limiting and create a number of airflow challenges. Yes, you can install traditional ceiling based air conditioning systems; exposing the ductwork can be considered artistic in an industrial way and some will look more aesthetically pleasing than others; but adopting an underfloor system allows architects to eliminate pipe and ductwork and experience total design freedom with regards to ceiling and other features. This option is particularly suitable for historical and listed buildings where it simply may not be possible to introduce ceiling based systems such as chilled beams, VAV systems and fan coils as they virtually eliminate the possibility of retaining the architectural detail.
Other benefits of Under Floor Air Conditioning include excellent indoor air quality and the ability to introduce fresh air into a building without experiencing loss of some of the fresh air before it is adequately mixed into the space. This loss of fresh air directly affects the ability of the selected system to dilute pollutants and minimise cross contamination; whereas underfloor supply systems introduce 100% of the fresh air without loss; creating high quality indoor environments.
Combined with the above is the enhanced user control of such systems. Ceiling based systems are typically static with fixed centralised control. Users are unlikely to be able to adjust temperature and fan speed or airflow to suit their optimum conditions. This individual personal control of simple settings can enhance user comfort and satisfaction of the individual’s working environment, and the flexibility of modular systems means that fan terminals can easily be relocated to adapt to changing use of environment.
With the above in mind; is using a traditional ceiling based HVAC system as part of an exposed design the best option for providing comfort cooling to the occupants of the space? Underfloor systems can offer the best of both, and it can be easily adapted and reconfigured for future changes in the use of space and occupant density. AET Flexible Space are specialists in underfloor air conditioning technology and have worked with designers for over twenty years to overcome structural and height restrictions; as well as design challenges associated with new build and refurbishment casestudies alike.