CASE STUDY | AGAR GROVE that enables the flats to enjoy high levels of natural light while avoiding overheating. Phase 1A was completed in April 2018. To help residents adapt to their new low-energy homes, the contractor, council and their design teams created guides to explain how their Passivhaus home operated, including guidance on the use of ventilation three-speed control. As part of Camdens ongoing support to residents, occupant feedback enabled Camden Council to identify how residents could make their homes more comfortable (see panel, Occupant feedback). Agar Grove is one of the few Passivhaus schemes to use a communal MVHR system Distribution heat losses The total amount of heat going into the system (primary) was compared with the sum of the amount of heat going into each HIU. This was done at four moments in time, which were then averaged to obtain one figure. Time 13:15 13:30 13:45 14:00 Primary HIUs 1.54kW 4.47kW 2.21kW 5.24kW Primary HIUs average 3.37kW The average of 3.37kW was compared to the total distribution heat losses in the PHPP, which according to Warm were 4.23kW (sum of the instantaneous heat losses through each piece of circulation pipe). So, the measured figure showed better results than the modelled figures. the blocks are not always orientated in the optimum direction for solar control. Fortunately, Phase 1A was orientated north-south, which helped the designers manage solar gains in the most economical manner. At the time Phase 1A was being designed, there was no specific methodology on how to analyse overheating in housing, so Max Fordham created a strategy to appraise the risk and ensure the design could adapt. Modelling was carried out using the Islington 2030 DSY from the Prometheus probabilistic weather data website. The results were compared against CIBSE TM52s adaptive overheating criteria. The modelling determined that living rooms would not overheat providing the windows could be opened during occupied hours. On noisier faades, large openings flush heat from the spaces quickly, preventing the need for windows to remain open for long. Control of overheating was also helped by the majority of apartments being dual aspect, allowing the cross-flow of air. In addition, external balconies have been integrated into the design to help control solar gain. In midsummer, the balconies block out the high sun, but heat from lower-angle sunlight can enter the dwellings in winter, says Clemence. It is a solution Future phases The CIBSE Award was for Phase 1A, and the design team adopted a similar approach to ensure Passivhaus compliance for Phase 1B. Detailed design of Phase 1C is about to start; its design has evolved significantly in response to changes to the carbon factors for gas and grid electricity. The carbon factors have changed, so the energy strategy of having communal boilers in the blocks will shift to one based on a heat pump solution, says Scott Crease, senior partner at Max Fordham. The design team is looking at an installation based on an ambient loop system, such as Dimplexs Zeroth or Daikins Altherma Geo3. The ambient loop will have a flow temperature of about 25C. A water source heat pump in each apartment will draw heat from the ambient loop for space heating and domestic hot water. Its a more expensive solution, but in carbon and energy terms it is completely the right solution, says Crease. Phase 1A of Agar Grove proved that Passivhaus principles can be applied successfully to large-scale residential developments. Phase 1C is set to take largescale low energy housing to a new level. CJ The CIBSE Building Performance Awards 2021 are now open for entries. Visit cibse.org/bpa Command smoke and save lives Actionair SmokeCommand CE marked smoke control dampers tested to EN 1366-10 and EN1366-2 fulfilling the requirements of EN 12101-8 swegon.com/smokecommand SmokeCommand Ad quarter page.indd 1 24 September 2020 www.cibsejournal.com CIBSE September 2020 p20-24 Agar Grove.indd 24 14/01/2020 14:26:39 21/08/2020 14:54