The existing equipment onsite was almost 20 years old and comprised of 134 internal AC units connected to 6 external Mitsubishi Electric Heat Recovery VRF systems. The systems had historical faults which had left only 40% in operation at the time of survey, resulting in the rest of the building experiencing extreme temperatures in the summer months and cold temperatures in the winter.
The fresh air to the building was supplied by a large plantroom AHU fixed to solid state ductworks and 4-way ceiling mounted diffusers. Due to occupancy level increases since the AHU was originally designed, the required amount of fresh air to meet building regulations was no longer possible and modifications would be required.
Design Principle
Setpoint22 were awarded the order to remove all of the existing equipment and replace with new Heat Recovery energy efficient VRF systems linked back to 3 AE200E touchscreen central controllers to ensure the systems set points and schedules were set for optimum energy efficiency.
The design comprised of 6 Mitsubishi Electric Outdoor Heat Recovery VRF systems ranging from 25HP-35HP connected to 134 indoor 4 way blow internal cassette units and wall mounted units where ceiling void space was restricted.
The fresh Air system was modified by stripping back and capping off sections of ductwork on the second floor to allow more fresh air on the lower floors. The Fresh Air Requirements on the 2nd Floors were achieved by the installation of 5 HRV Systems supplied by Mitsubishi Electric c/w new solid-state ductworks and grilles.
Following electrical load test by our regular team of Setpoint22 approved & vetted sub-contracted electrical engineers, the electrical supplies to the building were found to be very close to capacity and the mains incoming fuses were upgraded to suit the new design.
Each outdoor unit had new 3 phase power supplies fed from a new distribution board and the indoor units benefited from new internal ring mains throughout all carried out by qualified electricians.
Site Restrictions
The site was a fully occupied office environment made up of three floors separated into wings i.e. Ground Floor Wing A, Ground Floor Wing B etc, and the logistics of installing new Air Conditioning and associated services above desks was problematic. Some ground floor areas were occupied 24 hours a day where interview rooms were in constant use, the outdoor units were in a bespoke compound where the only access to crane lift the external systems in and out of the compound was through a third party property and car park.
It was not feasible to decommission all air conditioning systems and leave the site with no heating or cooling. There was also not enough power available to provide enough temporary heating systems.
Solution
In order to provide as much heating and cooling as possible to the office areas whilst works took place Setpoint22 engineers carried out in-depth checks on the old existing systems and were able to use parts of systems that were deemed beyond repair and fit these onto other faulty systems to allow for a temporary solution. In all around 70% of the systems were back in operation meaning temperature discomfort for all staff was kept to a minimum.
Between ourselves, our client and the end user, we planned to carry out the external unit replacements. These works all took place over the course of a weekend to ensure minimal disruption the occupant company operations and car park.
A strategically planned a programme of works of devised which incorporated vacating staff from 1 Office Wing and closing the floor to allow works to proceed. The programme was tight and it was essential each area was completed with the new system installed and commissioned on time to allow staff to move back into that area, whilst vacating another area to allow further works. This continued throughout the building finishing on the ground floor areas where a mixture of day and night shifts were carried out to minimise disruption to the staff and business operations.
The project was delivered on time and on budget leaving the client very happy with the overall experience of Setpoint22 Ltd.