All-electric, plus-energy Passive House Plus home with absolutely zero energy costs. One of the most advanced houses in the UK, perhaps only bettered by Brambles.
This north-facing, all-electric, Passive House Plus home is one of the most advanced, high-performance houses in the UK. The occupants have no energy costs. The owner earns several hundred pounds a year selling energy to the grid from solar panels on the roof via a feed-in tariff.
The house is a certified Passive House Plus and additionally incorporates a well-matched battery for greater utilisation of on-site renewable energy and to provide resilience in the event of power outages.
The ground floor was cut into the hill to meet the planning requirements of building a new house in a designated Area of Outstanding Natural Beauty. Reinforced concrete retaining walls were used to hold back the ground, and they rise to the first floor in the form of eight columns to provide stability to the timber walls and to the roof of the open-plan space.
High thermal mass, combined with superb insulation and super-clear energy-absorbing glass, create incredibly stable indoor temperatures. Due to its glazed wall facing NNW, it does not need external shading to keep cool in the summer. This house proves the veracity of the Passive House energy calculations, even for a north-facing house.
Between April 2019 and May 2020, energy usage was monitored at 5-minute intervals, along with another house of ours; Brambles (see link below). The full report will be published early 2022. This will show that Lark Rise generated 38kWh/m2/yr, which is significantly less than Brambles, because the power distribution network operator (DNO) has enforced a consumer export limit from the property. So, for much of the summer, the power generation system at Lark Rise partially shuts down to avoid exceeding permitted export limits.
Despite export limits, because of its extraordinary energy-efficiency, Lark Rise generates ~1.5x more energy than it imports from the grid each year (26kWh/m2/yr) and earns money from the exports. It imports ~88% less than an ordinary house, despite its north-facing aspect.
This all-electric house is comfortable, healthy, secure and resilient. The extremely low energy demand is largely met by its own rooftop solar panels. A home battery stores energy for when direct renewable energy is not available. Not only does Lark Rise have an extremely low peak energy demand, but its demand-shifting capability enables it to avoid drawing energy when most other users need it, thereby helping to stabilise the grid.
In concert with other similar buildings, Lark Rise reduces the need for national infrastructure expenditure on power-generating devices. This fact is all the more significant over time in terms of financial and embodied energy investment, because Lark Rise is likely to outlast at least four generations of national power-generating infrastructure devices.
An electric heat pump is used mainly to heat water for bathing and kitchen use. The 100% fresh air ventilation system is fitted with pollen filters and also constantly cleanses viruses and other indoor contaminants from the house. The house treats effluent ecologically, returning it to the land locally (where it arguably belongs).
This house demonstrates how we can build today to support the needs of generations of future occupants, protected from any energy costs despite rising prices, and meet the ecological imperatives of our time. It will protect against a changing climate and will last several times longer than a power station. As such it will be a gift to future generations, not a liability.
CIBSE Awards 2019, Project of the Year (Residential); RIBA Regional Award 2019; Constructing Excellence Award 2019, highly commended for Sustainability; shortlisted for 'House of the Year 2019' by the Royal Institute of British Architects (RIBA).
Photography: Tim Crocker & Peter Cook