Actionair
Aeropac Airside Fan Coil units are helping to provide air-conditioned
comfort for BSkyB's new Network Building in West London. The television
company has a complete campus of buildings on a site at Isleworth
in Middlesex. At the heart of the complex is the new 60,000ft2
Network Building which houses two large studios and a wide range
of production and post production facilities including a large
graphics department and extensive office facilities.
The extensive arrays
of powerful lighting coupled with the high heat gains from the
electronic equipment used at every stage of programme production,
mean that BSkyB's network building has a higher than usual cooling
load at around 1.5 MW (1.0 MW heating). Because of the high load
on the building services system and the stringent acoustic requirements,
chillers, boilers and other primary plant are housed in a separate
two storey energy centre adjacent to the main building. Dedicated
air handling plant is located in a number of plant rooms throughout
the main building.
Cundall Johnston and
Partners mechanical and electrical consultants for the project,
opted for a ducted air system to serve the main studios and a combined
fresh air/fan coil system to serve the rest of the building.
An airside fan coil design was preferred by reason of its more simple installation
and long term reliability. Noise was also a crucial factor affecting the eventual
specification of Actionair Aeropac units. Some areas within the BSkyB Building,
such as the production suite, were required to achieve noise levels as low
as NR15, although these areas are densely packed with electronic equipment
resulting in a high heat gain. The Actionair Aeropac design is able to provide
output up to 6.7kW cooling with all the low noise advantages of air flow thanks
to the incorporation of a unique diverter mechanism.
The cornerstone of the
Aeropac concept is a unique trilateral aerofoil zone regulator
designed and developed by the company's in-house technical team.
Use of this diverter mechanism eliminates the problems of noise
and air leakage which are often associated with airside control
units. Balanced airflow is achieved in all modes with a continuous
airflow being diverted through the appropriate zone or zones. Modulation
of output is achieved by blending throughput of heating or cooling
with a variable proportion of bypass. Water flow through heating
and cooling coils is constant with no need for expensive multiport
valves.
Direction of the air
is achieved by means of the aerofoil, which operates in response
to a single modulating, or positional actuator attached directly
to an extended shaft. The system ensures a continuous airflow at
the required temperature with no noise rush.
A number of Actionair
Aeropac Fan Coils have been installed at the BSkyB Network Building.
Located in the ceiling voids, they supply conditioned air via swirl
diffusers in those areas with high heat gains and a combination
of swirl and linear diffusers in other areas.
The location of the
BSkyB Network Building - it lies under the Heathrow flight path
- required careful acoustic consideration for the upper storey.
Working in conjunction with Architects, Ware MacGregor Partnership,
Cundall Johnston developed a double void technique for this part
of the building. The Actionair fan coils are located in the upper
void beneath the roof and separated from the lower void by a barrier
of rigid acoustic insulation. Ductwork runs from the Actionair
units through both voids delivering conditioned air into the room
space via diffusers integrated into the acoustic ceiling. This
design greatly limits noise penetration into the building by creating
a substantial air gap and providing sufficient duct length for
the inclusion of attenuators. Control of the building services
system at the BSkyB Network Building is by means of a Trend BMS.
Terminal units were supplied f.o.c to Actionair for incorporation
into the Aeropac Units at works.
Actionair Aeropac fan
coils feature a nine step transformer with pure sine wave fine
adjustment for accurate on-site Commissioning. Use of the transformer
permits a choice of nine outputs for each of the three fan speeds
giving a total of up to 27 different settings and making it possible
to match precise system requirements with optimum energy saving.
