Client:  Esure -  famous web-based insurance with sister company, Sheila’s Wheels.

Optima BES excels in commercial projects incorporating leading edge technologies.

Online businesses are 24/7 and Esure’s brief placed the greatest importance on a virtually fail-safe computer system where most of the essential hardware was contained within a principal communications room. Esure’s Head of Facilities was concerned about the reliability of existing upflow cooling units in this location at their Reigate office.

Optima BES’ was appointed to provide the solution to meet this challenge.  
•    The air handling unit was sited outside of the communications room within the office space ceiling void.

•    Ductwork was installed at high level within the communications room, to avoid removing the ceiling.

•    Fire dampers were linked into the Inergen fine suppression system to seal the space in case the Inergen system was activated on the 2nd stage fire alarm.

•    The control system was linked into the Building Trend System to include all four existing upflow cooling units, as well as the new supplementary cooling system.

•    The system had speed control so that when the cooling units were coping with demand, it would be running at low speed.

The project:

Air distribution was improved to reduce warm spots in circulation areas around the computers. The first limiting function was selecting a horizontal ceiling void closed controlled air handling unit that was sufficiently quiet above an office. We quickly recognised that an off-the-shelf product would not include humidity control and also fit in the ceiling void.

Optima BES sourced new products produced by leading commercial refrigerant cooling manufacturers, which enabled the connection of inverter-controlled refrigeration condensing units with propriety air handling units. This choice for the cooling function had the capability of receiving a 0-10V input from an outside control system.

Once the means to cool air for the communications room had been decided, the next challenge was to deliver heated air from the computer racks horizontally into the centre of the room.
 
Optima suggested discharging cooled air outside of the computer equipment, so it could be drawn through the cabinets. Optima explained that the heat in the centre aisle would rise to the ceiling and be extracted. This was the agreed strategy and to be on the safe side, spigots with drum diffusers were deployed facing into the centre aisle as well.

The height of the surface ductwork was limited by the available head height above the computer cabinets, so oval ductwork was chosen. As the images reveal this was devised to have a pleasing aesthetic quality.

The task:

  • The installation had to be carried out over a shutdown weekend with minimal computers running.
  • The pressure was on to work above the computers for 48 hours and be prepared for any eventuality.

When the system was commissioned at the end of the weekend, stability in cooling mode could not be maintained and performance was 30% of what was expected. The specification for the cooling coil supplied in the air handling unit did not meet Daikin’s criteria in one specific area despite being advised by Optima: the refrigerant volume of the cooling coil had to be within certain limits. When asked about this, the air handling unit manufacturer advised they could not provide such a coil after all.

Fortunately Beehive coils was able to provide a coil which met the refrigerant volume specification so critical to the requirements of Daikin.

With the coil volume requirement from Daikin met, the system immediately operated to the correct specification. It also controlled reliably through the range of volumes of the air handling units’ minimum to maximum fan speeds.

The benefits of locating the air handling outside the communal room soon became apparent as a water stain appeared on the ceiling. The air handling manufacturer attended the site and finally agreed to Optima’s suggestion to insulate between the bottom of the condense tray and the cover panel. Optima believed that cold was bridging from the condense tray through the inside panel of the insulated access door to the edge frame causing water to condense from the frame.  The insulation was applied and the condensation issue evaporated.

Whether the air handling unit manufacturer has taken up Optima’s suggestions to improve its product has yet to be seen!

Since the coil replacement and commissioning, the system has operated 24 hours a day since September 2007 with 100% uptime.