Optimised cooling system brought major savings

Navy Dockyard in Devonport, England

The Royal Navy Dockyard in Devonport, near Plymouth in the south of England, is the oldest and largest naval base in Europe. The dockyard at the base has now been fitted with a new waste-fuelled power station for the generation of electricity and steam. Local waste is incinerated at the station to produce 800,000 tonnes of steam at 420°C and 190,000 MWh.

Limited space called for unique solutions

In order to provide electronic and computer equipment rooms with adequate cooling, it was necessary to convert the old system to meet the project requirements. The CHP plant was forced to comply with stringent energy-efficiency standards. Free cooling and direct expansion (DX) cooling were the most efficient options, but since space in the plant was limited and noise restrictions were very strict, it was essential to come up with some unique solutions.

Swegon’s ventilation products complemented the cooling systems from BlueBox

The previous design was based on free cooling with Uniflair cooling units and computer room air conditioning (CRAC) units. The contractor, including consultants, contacted the specialists at the Swegon company BlueBox to find a solution that would improve the design and performance of the system. Since the buildings at the CHP plant also housed a number of offices, it was highly advantageous to have access to Swegon’s complete range of ventilation products.

DX cooling is as good as free cooling

An energy efficiency report was produced, based on local weather data. The report showed that DX cooling was as important as free cooling for the energy efficiency of the facility.

Excellent results at the naval base

The upgrade at Davenport was successful and the energy consumption in particular was drastically reduced. It was possible to extend the period of free cooling – TFT 8.5°C – and achieve considerable energy savings. Each year, the FC and DX operating modes saved 48,000 kWh +
24,000 kWh, and the CRAC units’ EC fans 78,600 kWh, amounting to energy savings of no less than 150,600 kWh.

Substantial efficiencies

Two Tetris/FC/Basic/LNST1PS-27.4 chillers were installed. These compact, free-cooling chillers saved a lot of space at the site and, with four compressor chillers, could guarantee reliable capacity control in low load conditions. The BOSS/Runner2 sequence controller optimised the free cooling control and the EC fans were installed in the CRAC units. The lifespan of EC fans (Electronic Commutation) is far longer than traditional AC fans and they are more energy-saving and quieter too. EC fans were therefore an obvious choice for this type of installation.

The air distribution through the Data and Electrical rooms was also redesigned to ensure optimal operation. In addition, 18 Datatech units, 8 Swegon GOLD AHUs and a Celest DK/RF heat pump were installed.