NABERS UK | DYNAMIC MODELLING In a Part L or TM54 model, you have an estimation. With Nabers you have a huge amount of data, and its granularity means you have more information to evaluate scenario modelling to stress test and refine the design. The sophistication of the software meant that Hoare Lea could model a large number of variables such as ventilation airflow rates and supply temperatures, fan and pump efficiency curves, ductwork heat losses and gains, demand control ventilation, FCU operation (variable temperature and flow), air source heat pump (ASHP) temperature and load dependant performance, plant sequencing and heat recovery to align with the engineering design. The richness of the data enabled a level of outcome-focused decision making that would not have been possible otherwise. For example, the HVAC analysis informed the decision to have three heat pumps per building rather than two. Having two would have led to one of the heat pumps running for longer periods at low loads, which would have affected plant efficiency and energy consumption. Two on-floor climate control options fan coil units (FCUs) and active chilled beams were also modelled, says Henry Burrows, lead mechanical engineer for the project. As the active chilled beams rely on central ventilation to meet the Nabers UK DfP design process RIBA Stage 2 Concept design RIBA Stage 3 Developed design RIBA Stage 4 Technical design Developer to sign DfP agreement Early Stage 2: faade Client to produce rating- Address IDR comments Outcomes of IDR used to inform optimisation for solar and daylight control Late Stage 2 once frozen GAs are available: Initial HVAC modelling in line with Nabers UK requirements (include review of faade/ servicing options for impact on operational energy) achievement plan Progress detailed HVAC modelling Scenario modelling to stresstest the design Develop metering strategy End of Stage 3: independent design review (IDR). Significant input/documentation required from the design team design improvements within Stage 4 design Submit final Nabers UK DfP report to the BRE Full licence to promote target rating Table 1: What is expected at each of the RIBA design stages when following the DfP design process ThermShield EIS classified fire dampers Fail-safe close For maintaining compartmentation Up to EI 120 (ve ho i <-> o) S classification, see the DoP for specific details ThermShields EIS classification plays a crucial part in fire compartmentation. Swegon offer the widest choice of dampers and damper controls to meet the envolving needs in the UK market. Visit swegon.com/uk to find out more 22 August 2022 www.cibsejournal.com cooling load, we couldnt utilise the full benefit of demand control ventilation with this solution, which is a key benefit in a post-Covid environment. The FCUs would not conflict with the demand control ventilation, so they were the preferred option, he says. Modelling influenced the DHW strategy for the office WCs, leading to the selection of electric point-of-use water heaters after they were compared to a central hot water system connected to the ASHPs. While incredibly powerful, the modelling required is complex. With Nabers quality advanced simulation you have information on every level, and every change affects everything. says Owen Boswell, Nabers UK assessor and simulation lead for the project. In a Part L or TM54 model, you have an estimation. Nabers is now the gold standard. You have a huge amount of data, and its granularity means you have so much more information to evaluate. However, Boswell says there is an acute skills shortage in this level of modelling in the UK, which Hoare Lea has been tackling through training and global knowledge sharing, as part of its net zero strategy. A firm-wide working group made up of representative of all disciplines ensures that lessons learned across Nabers projects are translated to every project in the firm through guidance and specification updates. There havent been the industry drivers to implement this level of modelling at scale in the UK over the last decade. Nabers UK and the drive towards net zero is the prompt to upskill. The talent and enthusiasm is there, but its a steep learning curve initially, says Boswell. CIBSE provides training courses on Advanced Simulation Modelling for Design for Performance. For more details visit bit.ly/ CJAug22Nab1 EIS classification for integrity, low smoke leakage and insulation in demanding projects.