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DFP CASE STUDY | 1 BROADGATE LEADING THE CLIMB Engineer Hilson Moran explains why accurate modelling is key to achieving peak performance at 1 Broadgate, a pioneering project on the Design for Performance initiative. Andy Pearson reports B ritish Lands 1 Broadgate development in the City of London is one of 13 schemes that is trialling the Better Building Partnerships Design for Performance initiative. The mixed-use 13-storey scheme, which incorporates 14,000m2 of retail and 37,000m2 of office space, is currently at RIBA Stage 4, with a planned completion date of 2024. It has an estimated target base building energy rating of 4.5 to 5.0 stars. The schemes design was under way when the BBPs Design for Performance (DfP) initiative was formally set up. British Lands sustainability brief for the project initially targeted the buildings energy performance at the design stage using a simulation following CIBSEs TM54: Evaluating Operational Energy Performance of Buildings at the Design Stage. As the DfP initiative has gathered momentum, the projects MEP engineer, Hilson Moran, evolved this model to include the buildings HVAC systems in operation. Design for Performance looks at systems in much more detail than TM54 to see how they perform under various conditions and control strategies, says Hugh Gordon, Hilson Morans modelling specialist. Matthew Webster, head of sustainable and smart buildings at British Land, agrees with Gordon: I would say DfP is an evolution of TM54; DfP provides the rigour and a process for dynamically modelling likely operational performance, he says. In the early stages of the HVAC design, Hilson Morans ambition was to go beyond developing a design for Part L compliance alone rather than for energy performance in use. The engineers have opted for a mixed-mode solution for the building, along with demand control, all monitored via a smart system. We knew which system would give us the best Part L result and now were taking that system and fine-tuning it to optimise its operational energy usage, says Duncan Woods, project director at Hilson Moran. If we can take full advantage of mixed mode that will have huge benefits on operational energy. Early engagement with client FMs is essential and Hilson Moran was fortunate in that it was able to work with British Lands FM team early in the design development. This team will be responsible for the buildings operation when it is occupied; it reported that many of the other buildings for which it was responsible were not running at the full capacity set out in the design brief. 52 November 2020 www.cibsejournal.com CIBSE Nov 2020 pp52-54 DFP Case study.indd 52 23/10/2020 16:38