Multiservice Chilled Beam Case Study: Sovereign Building, Smales Farm, Takapuna

Following an in-depth assessment of options, ASB Property made the decision to use fully active multi service chilled beams (MSCB) to air-condition the open plan areas of the Sovereign Building at Smales Farm in Takapuna, Auckland.

Ravenscroft's Multiservice Chilled Beams (MSCB)

The MSCB system was selected as it was ideally suited to large open plan office areas with no ceilings and exposed structural mass. MSCB’s provided energy efficient air-conditioning and an integrated solution for reticulation of lighting and other services as well as reduced site coordination and construction time.

Halton was selected from a shortlist of three manufacturers following a visit to the UK and Finland by members of the project team to assess the chilled beams design and performance as well as related factors such as manufacturer’s quality control, R&D / testing capabilities, and technical support. The assessment included existing buildings, buildings recently commissioned and buildings under construction. A further important consideration was the extent of local representation and support in New Zealand and Halton had an established agency relationship with Ravenscroft’s.

From the buildings ASB viewed in the UK it became apparent that the extent of integration proposed for the Sovereign Building would be one of the first examples of MSCB’s to incorporate cooling, heating, lighting (including Lux control sensors), power, data, BMS controls, sprinklers and EWIS speakers. The majority of the examples viewed in the UK contained cooling, lighting, EWIS and PIR sensors. Heating was typically provided by perimeter radiators and power/data was run within a false floor.

The selected Halton CBH beam differed from others in respect to the path of the supply air. Primary fresh air is injected upwards to induce a secondary flow of room air through the coils and mixed air is delivered out the top of the beam, compared with most other beams where the supply air comes out the bottom. This was an advantage as the Project Architect was in favour of an industrial appearance without the typical chilled beam cosmetic shroud and this beam does not rely on a correctly formed encasement to ensure effective air circulation when active chilled beams are installed without a ceiling. It also required a lower primary air quantity which meant the air handling unit and duct sizes could be reduced, saving capital cost, energy and plant space.

Halton and Ravenscroft’s worked with the project team to design, build and test a unique custom solution for the Sovereign building which divided the two back to back chilled beam ‘engines’ and mounted them separately onto a support frame.

The central gap allowed a single row of lights to be placed centrally between the ‘engines’ and greater flexibility for location of sprinklers, lighting control sensors, EWIS speakers and umbilical droppers for reticulation of power and data to the workstations.

Another significant advantage of the selected CBH chilled beam is the ease of commissioning and the high degree of adjustability. Each beam has two slide plates that can be easily adjusted to vary the amount of room air induced and vary the supply air throw. This allowed the installation to be tuned to suit specific constraints such as structure that may impact on flow direction or to if necessary to improve the comfort perception of sensitive individuals by reducing air movement.

The beams were designed with chilled and heating water temperatures that facilitated free cooling of the beams direct from the cooling tower when ambient conditions suited and heating through heat recovery from the condenser water system.

From commissioning the Sovereign Building and through post occupancy tuning we have learnt that the active chilled beam is very resistant to condensation and have been able to increase the maximum moisture content set point above the values specified by the services design consultant and achieve energy savings through less dehumidification of outdoor air during summer.

Initiatives employed that improved energy efficiency further at times when full capacity is not required were using variable speed drives to reduce the primary air quantities and increasing the chilled water temperature supplied to the beams.

The Halton multi service chilled beams in the Sovereign Building have proven to be an energy efficient, reliable low maintenance method of air-conditioning large open plan spaces which delivers a high standard of environmental comfort.