The best way to create an energy-efficient home that has running costs as low as its carbon emissions is to build ‘green’ technologies into the earliest design stages of a new build – as was showcased in a recent MGA project in the Lune Valley where the client was keen to prioritise energy-saving measures.
It’s important to consider the natural hierarchy of factors that contribute to energy performance:
Using less energy
Supplying energy more efficiently
Using renewable technologies
In this case, by specifying the mechanical and electrical services required to deliver against the energy brief at the outset, we were able to integrate a carefully considered suite of renewable technologies in a way that was sympathetic to the building and its surroundings.
To address our primary consideration – that of using less energy – the house was insulated to circa 40 percent higher than that required by current Building Regulation standards. This not only helped lower the level of heating required but also reduced the size, output and capital cost of equipment that needed to be installed. We reviewed a variety of renewable technologies and took into account practicality, carbon emissions, capital costs and payback periods.
The location of the new build meant that mains gas wasn’t an option. After careful consideration of alternative systems, we agreed that a ground source heat pump would provide the most appropriate renewable technology. The 18kW ground source heat pump uses ‘free’ heat from underground pipes in the garden and transfers it into the house to run 100 percent of the underfloor heating and hot water. The system is 400 percent efficient, which means it produces 4kW of heat for just 1kW of electricity. The pump is about the size of a washing machine and sits neatly in the garage with no need for a flue. We carefully designed the system to ensure a back-up conventionally fuelled boiler was not required.
To support the electricity requirements needed to run the heat pump, a 9kWp Solar Photovoltaic (PV) system – in a design sympathetic to the roof and its surroundings – was installed to the main roof of the house and also on the adjacent carport. The system provides free electricity to run the heat pump and reduces reliance on electricity from the national grid. Electricity from the PV panels also feed a battery storage system which intelligently stores excess electricity through the day and delivers it into the house during the evening. This type of system is really at the cutting edge of technology and we are proud to have incorporated it successfully into the home.
Mechanical ventilation can often get overlooked, although the days when simple extractor fans were installed into a bathroom are long gone. Having considered the options and cost, a whole house heat recovery ventilation system was sympathetically installed throughout the home. This system extracts stale damp air from kitchen, bathroom and utility areas, transferring its heat into fresh incoming air, which is then directed back into living areas to give the house a fresh, well-ventilated feel. In summertime a constant controllable flow of fresh air can also be drawn in to keep the house feeling cooler and less stuffy. The unit sits comfortably inside the garage, so there are no noisy fans running in the ensuite – often a bugbear during the night!
A plan coming together
Other systems included solar-controlled glazing, intelligent heating controls, electric-car-charging points and low-energy LED internal and external lighting. Along with the low carbon advantages, the Ground Source Heat pump and solar panels are also eligible for the Governments Renewable Heat Incentive (RHI) and Feed-in-Tariff (FiT) Schemes, both provide an attractive annual income for the client.
This was an exciting project to be involved with. By beginning with a well-insulated and airtight design before incorporating carefully selected renewable technologies, we were able to deliver an ‘A' Rated new build home, which our clients will enjoy for many years to come.