CASE STUDY | LARK RISE The extremely low energy demand, PV and battery almost eliminates the winter energy gap in renewable energy supply relative to demand continuously, providing ventilation that can be temporarily boosted if desired. For most of the year, however, the occupiers adjust the ventilation by simply opening windows. Thewindows have a secure, inwardopening, tilt-and-turn feature to help the occupants feel safe when windows are providing enhanced summer ventilation. A final airtightness test and MEP system commissioning visit from an independent services engineer not the design team services engineer ensured the building was handed over to the client operating asdesigned. Heating, hot water, lighting, sockets, cooking, ventilation, PV production, and Grid energy import and export are all metered. Real-time and recorded data can be accessed 24/7 from a mobile phone, along with graphs of total energy consumption, production, battery storage and Grid energy export and self-consumption energy levels, plus data on the state of battery charge. Monitoring data has been used in postoccupancy evaluation discussions with the building occupants and to give them building-operation advice. The occupants have been interested in, and are happy to contribute to, our research, says Bere. A performance-monitoring report is available from bere:architects website at www.bere.co.uk/research/lark-risemonitoring-report If the rollout of this concept is scaled up, money spent on new and retrofit buildings such as this will significantly reduce national peak energy demand, says Bere. If we can reduce peak energy demand, then we can reduce the need for new power stations. Instead, the many billions of pounds saved on building, operating, fuelling and, eventually, decommissioning each power station can go into creating and converting more buildings like this, thereby producing more savings in power station expenditure and more low carbon jobs a really healthy feedback loop. Lark Rise firmly establishes the building as a power station concept and demonstrates the viability of a future electrical Grid powered by renewable energy, says Bere. It shows how the Smart Energy Revolution has the potential to enable the UK to be fuelled entirely by renewable energy. CJ ENERGY DATA The annual energy demand of Lark Rise is negative because it produces far more energy than it consumes each year: Breakdown of energy balance: Gross demand: 32.23kWh.m-2 per year (5,640kWh per year) (monitored) (all electric, for all uses including heating) Gross generation: 10,978 kWh per year of renewable electricity (modelled) Grid export (after self-consumption): 5,338kWh per year (modelled, with monitoring ongoing since battery installation) Grid import (to cover small winter gap): 592kWh per year (modelled, with monitoring ongoing since battery installation) Breakdown of energy consumption: Heating: 22% 7.11 kWh.m-2 per year DHW: 10% 3.38 kWh.m-2 per year MVHR: 9% 2.89 kWh.m-2 per year Power sockets: 25% 8.05 kWh.m-2 per year Cooking: 5% 1.61 kWh.m-2 per year Miscellaneous: 9% 2.89 kWh.m-2 per year Lighting: 19% 6.11 kWh.m-2 per year For space-heating consumption, we can benchmark Lark Rises 7.1kWh.m-2 per year (monitored) (renewable electricity) against: Standard UK home (DECC 2017 ECUK Overall and Domestic Data Tables) (85m2): 124kWh.m-2 per year AECB Silver domestic heating requirement: <40kWh.m-2 per year Passivhaus requirement: <15kWh.m-2 per year Bere Architects Camden Passivhaus: 12.9kWh.m-2 per year (gas) For annual net energy requirements (consumed v generated), we can benchmark Lark Rises negative demand of -35kWh.m-2 per year against a typical 85m2 UK home (+213.67kWh.m-2 per year) and against other eco homes such as the Bedzed development (+90kWh.m-2 per year), the Long House(+80kWh.m-2 per year), the Bioregional One Brighton apartments (+72 kWh.m-2 per year), and the Princedale Road Enerphit retrofit (+62.5 kWh.m-2 per year). 26 May 2019 www.cibsejournal.com CIBSE May19 pp24-28 Lark Rise.indd 26 26/04/2019 17:05