CASE STUDY | 100 LIVERPOOL STREET that plant could be manoeuvred around the roof for removal, says Duncan-Bosu. The plants roof-top location enabled the plantrooms to be built off-site in modules and craned into position. Similarly, a separate pump room module was also built off-site and craned into position. The chilled water plant was not modularised. The roof houses six air-cooled chillers. To save energy, ChapmanBDSP has designed a heat reclaim loop to collect heat from the heat rejection side of the chillers which is then used to preheat the landlords domestic hot water feed in a dedicated pre-heat cylinder. From the roof, services drop down risers housed in the buildings three concrete cores. A common heating and chilled-water network serves all demises, including retail, offices and restaurants. Weve modularised both the heating and chilled-water systems so that at weekends, when the offices are closed, the retail outlets can still operate, says Duncan-Bosu. An advantage of ChapmanBDSPs top-down servicing approach was that ducts and pipes were smaller at the base of the building compared with roof level. This enabled the existing risers that pass through the Network Rail ground floor retail to be reused to service the retail at ground and lower ground. One of the benefits of this common approach to the provision of heating and cooling is that it will enable the scheme to be decarbonised more easily in the future. One of the things we looked at was the potential for connection to an energy network, explains Duncan-Bosu. Weve made provision to bring in external services and weve provided plant space for heat exchangers on both heating and cooling systems should a network become available, he adds. The building services for the office floors are designed on the basis that the building was to be let on a shell and core basis, with tenants undertaking their own fit-out. In discussion with British Land, ChapmanBDSP sized the central plant on the basis that most tenants will opt to use a fan coil system. The design assumes four-pipe units are located around the buildings perimeter, with two-pipe cooling only units serving the remainder of the floor plates. Weve influenced the tenants a little bit by guiding them on the energy rating of the fan coil units to ensure the building sits within certain parameters to achieve the overall EPC for the building, says Duncan-Bosu. Another area of discussion with British Land was on both air quality and quantity. ChapmanBDSP had monitored the site externally. The air quality was not great, so the client made the decision to install carbon filtration on all roof-top air handling units, which has helped improve air quality, Duncan-Bosu says. In terms of air quantity: the design was initially developed to comply with the British Council for Offices (BCO) requirement of 12Ls-1 per person. However, as the design progressed, the air supply rate was increased to 16Ls-1 per person to further enhance The ChapmanBDSP team tour 100 Liverpool Street 18 May 2022 www.cibsejournal.com CIBSE May 22 pp16-18, 20 100 Liverpool Street.indd 18 22/04/2022 15:11