The five-bedroom construction sprawls across 360m² of Great Glen, Leicestershire, and incorporates technology that allows the offset of 100% of its energy requirements using on-site generation. Electricity will still need to be bought to run the heat pump when there is no light for the panels to generate electricity, but this will be offset by the energy sold back to the National Grid. This means running the house should be cost neutral — in fact, with the relevant subsidies in place, the lucky owner should be in a cash positive position.
Newform Energy sees the technology used as a viable alternative to heating and powering homes through traditional fossil-based energy sources. Data from the building is being gathered and analysed independently by De Montfort University, and the evaluation is crucial to the credibility of both the project and the science behind it.
The Solar House cost about £550,000 to build, and the additional cost of the technology — over and above what would be used in a conventional house – is around £45,000. ‘This makes it around 5% more expensive than the average selling price for a similar-sized property in the area,’ says Newform Energy, ‘which isn’t far off stamp duty.’
‘Stealing energy from precious resources with little regard for the consequences is a short-sighted and risky approach. We have an abundance of sustainable energy; learning how to tap into it and developing a unique approach could revolutionise our ability to deliver zero carbon buildings.’
Anthony Morgan, CEO and founder of Newform Energy
The brainchild of Michael Goddard of Caplin Homes, the Solar House was intended to demonstrate a repeatable methodology for zero carbon buildings. For Newform Energy it was the final piece in the jigsaw puzzle: inter-seasonal energy storage in a cost-effective package, that could be deployed across the mix of high- and low-density development schemes. The symbiotic relationship between the different technologies means that the sum of the parts is greater than the individual components. Here’s how it was done.
The windows are triple glazed with a generous south-facing area. Newform Energy is also evaluating passive solar walls, which pre-heat the incoming MVHR (mechanical ventilation heat recovery) air and help with the overall energy equation.
Water-to-water heat pump
A water-to-water heat pump is a device that transfers low grade thermal energy from a source, such as the ground, to a higher temperature destination, such as a DHW cylinder.
The device uses a compressor to take the low grade heat, then applies mechanical work to raise the temperature so it can be used within a building. It’s similar to a fridge working in reverse: the cold part is the part in the ground and the hot element, like the one found at the back of your fridge, is used to heat the building.
The conventional timber frame has low embodied carbon, as well as being a much better insulator than mineral-based alternatives. The base level of insulation (100mm) sits within the studs of the frame, which keeps wall thickness down.
In order to attain the required u-values (the measure of heat loss for a particular part of a building — a lower value means a more efficient transfer of the building’s heat), multi-foil cladding (as opposed to more foam insulation) is used between the studwork and the service void.
This means that, with its larch cladding, the walls of the Solar House are only 250mm thick, yet have a u-value of 0.14. Current building standards (Part L) place the maximum u-values for walls at 0.3.
The smart controller calculates energy flow, working in a slightly different way from either a more conventional differential controller (such as a solar controller) or a BMS (Building Management System). In essence, it calculates the amount of energy required to hit a target within a given time frame.
It then works out, from the resources available, the most efficient place from which to draw energy — always prioritising free power.