The company has refurbished two massive AHUs at 9 Appold Street, a unique business development between Liverpool Street station and Broadgate.

Both units - one providing a duty of 21 m³/s and the other 16 m³/s - are on the 10^th floor of the striking building, which offers fully fitted Grade A space providing outstanding office accommodation. The two AHUs provide tempered fresh air to the entire building.

The work done by ECEX operatives included fan upgrade, chilled water-cooling coil replacement, replacing the large fresh air inlet dampers and installing new ECEX air intake screens. The company also carried out general refurbishment comprising corrosion treatment, cleaning, painting, new latches and seals and new lighting circuits.

James Gafford, contract manager at ECEX, said: 'The main logistical challenge in this project was that the installation of these large units was in the top floor of a building accessed by a goods lift that was significantly smaller than the AHUs. This meant that we had to build the coils - which were around 3m wide and 2.5m tall - in kit form in situ because they were too large to fit into the lifts.'

ECEX replaced old, belt-driven centrifugal supply fans with a high-efficiency plug fan array which allowed it to increase the efficiency of the system while also allowing for an element of redundancy in case of future failure.

James explained: 'Rather than a single massive fan and motor which, if it failed, would involve considerable expense and disruption, we installed six high efficiency Nicotra RQM plug fans in each unit. In the event of a future motor failure, the remaining fans can ramp up to deliver the same capacity; the failed fan can then be replaced at a suitable time with minimal disruption or system down time.'

Nicotra Gebhardt RQM MultiEvo fans combine the compact design of plug fans with the benefits of traditional cased fans. In principle, they are direct driven centrifugal fans with spiral guide vanes. The unique design of the multiple discharge scroll far exceeds the efficiency levels of conventional EC plug fans.

The works completed by ECEX have effectively extended the working life expectancy of the air handling units and the new high efficiency fans have led to a significant reduction in energy usage which, through planned future BMS integration, can lead to close monitoring and management of energy usage.