The first UK commission for world-renowned American architect Richard Meier has been completed using a wealth of renewable heating technology.
A 1930’s villa in Oxfordshire, the winner of a Royal Institute of British Architects (RIBA) award, has been completely renovated into a spacious, modern home with an integrated energy solution consisting of heat pumps, solar PV, solar thermal and a heat recovery system. The property is set in the Oxfordshire countryside and features a swimming pool, tennis court, guest house, three bedrooms and a further 10 rooms.
Richard Meier took the view that passive design principles should first be used to ensure the fabric of the building reduced energy demand. Potential overheating from the widespread use of natural light would be minimised by the building’s high thermal mass and passive cooling techniques. The homeowner’s interest in cutting-edge technology, and the lack of a gas supply, lead to the inclusion of a renewable heating system using multiple energy sources.
Three renewable technologies working together
A challenge of such a system would normally be getting the different heating products to work together to meet energy demands in the most efficient way, without distracting from the aesthetics. However, Viessmann recommended an integrated Viessmann package of ground source heat pump, solar thermal and solar PV panels, managed by one control system that was capable of supplying the most efficient energy at any time.
The house is heated throughout by underfloor heating powered by a Viessmann Vitocal 300-G 42kW ground source heat pump, which is the lead heat source. The energy for the heat pump is collected from 3,200 m of pipework buried in trenches in the field in front of the house.
In addition to the ground source heat pump, 20 kW of Viessmann evacuated tube solar thermal collectors sit on the house’s flat roof. The energy from this solar thermal system supplements the demand from the heat pump to supply heat to the pool, hot water and heating systems. Intelligent controls allow the solar thermal system to take the lead when the sun is shining and supply energy where required.
Only when the solar thermal cannot support the load is the heat pump activated. Having multiple sources of heat demand, with a low temperature swimming pool in the mix, is an advantage in this set-up: it allows the lower temperature output solar thermal system to continue to contribute as much energy as it can to heat the hot water, prior to the heat pump taking over. This means the system runs more efficiently.
Hot water is stored in a two-stage tank system consisting of a pre-heat tank and a main potable water storage tank. This provides ample hot water to the house at all times. To keep the heat pump running at the highest level, an LPG boiler was installed for back-up purposes to raise the hot water to the final required temperature.
Results
It is estimated that the heat pump alone will have reduced the site’s potential carbon footprint between 40 and 50 % compared to oil or LPG and reduced its potential running costs by 50 % at today’s prices. With the solar thermal contribution and solar PV electrical generation factored in, the savings are substantially higher.