The trend for green living has never been so strong. Consumers are striving to make as little impact as possible on their environment. They are choosing locally sourced products, and reusing, reducing and recycling more than ever before. Soon they will be able to extend these sentiments to the home that they live in.
A development in Scotland is aiming to embody the ideals of green living. Kincluny village, just south of Drumoak, will be the country’s first sustainable housing development. Developer CHAP Homes is planning to build 1,500 houses on the brownfield site of a soon-to-be-disused quarry that lies roughly 12km from Aberdeen city centre. The development will be powered and heated using natural and renewable resources available locally. Even the water supply will come from boreholes drilled on the site and recycled rainwater run-off.
The developer has set itself the ambitious target of making the village carbon neutral. Renewable sources of energy and heat such as wind turbines, solar panels and ground-source heat will help keep the carbon footprint of the village low. But even Bill Burr, managing director of CHAP Homes, admits that this target may be difficult to achieve.
Burr is working with Dr Alan Owen, a sustainability expert from Robert Gordon University in Aberdeen. Owen explains that the fact that the development is located on the site of a quarry gives carbon savings. Owen says: “It is fairly dug over and the gravel and sand has been extracted.” This means that infrastructure for the development can be put in place without digging over a fresh greenfield site. “The CO2 output of stripping turf off a site is quite considerable,” he says.
The embodied energy of the project will be measured during the construction of the village. “My expectation is that if we can make the development carbon negative then over a period it may actually absorb the CO2 output from building.” Building could begin by the end of next year if the local council grants planning permission.
In line with the sustainability aim, the village will keep utility inputs and outputs to a minimum. As well as providing its own heat, electricity and water supply, the village will also have an on-site sewage treatment plant.
Homes will be partly heated by a large-scale ground-source heat pump that will feed into a district heating system. A branch of the system will be connected to every house to heat the floors or walls. The heat must be passed through walls and floors as they provide the large surface areas needed to dissipate ground-source heat, which is typically lower in temperature than that used in conventional radiator systems. The developer claims that the district heating system will make heating the house as cheap as running a stereo or a washing machine.
Hot water will also come from renewable sources in the form of solar panels. An electrical system will top-up the water temperature when the sun is not strong enough. Owen says: “Even in Scotland on a frosty but sunny day solar thermal panels on a roof will generate 45°C.”
Potable water will come from 20-30m boreholes. If necessary, a treatment plant will be built on site that will use ultraviolet light or other methods to treat the water to get it up to the standards required by regulators. Non-potable water for the garden, flushing the toilet and washing the car will come from a rainwater collection and storage system. Water will be harvested from roofs, gutters and roads. Houses will be grouped into clusters so that run-off can feed into underground drains and storage tanks.
Owen says: “We are looking at needing 1m3 of storage for every 5-10m2 of hard surface.” Inside homes, the potable and non-potable water supply will be clearly marked and have separate taps.
With hot water and heating requiring little electrical input, each house will use just 10-12kWh of electricity a day, down from the 15-20kWh used in a conventional house, according to Owen’s calculations. Electricity will be generated from roof-top solar panels and wind turbines. The turbines are likely to be located off-site where conditions are more favourable.
A proportion of the electrical energy will come from a more unconventional source – the sewage processing plant. Owen explains: “Human waste is a phenomenally useful source of energy. A typical human being produces about 0.5kWh per day.” Sewers from homes will be directed to a biogas fermentation plant where methane will be extracted. The methane will be burnt-off in a combined-heat-and-power plant. One plant, measuring 12m by 6m, will be needed for every 1,000 people living in the village. Each plant will be partially or completely buried to improve the look of the surroundings.
The entire utility system has been designed with substantial redundancy in mind so that residents are not left in the dark and cold if a problem occurs. Owen explains: “We haven’t just got one combined-heat-and-power plant. We’ll probably have three smaller plants so that if one does fail or needs to be taken out of service for repairs then the other two can continue.” Homes will also have a hook-up to the national grid and water services in case there are any major problems.
Owen says the technology used in the village is tried and tested. “We have deliberately chosen technologies that have a known track record. The last thing we want is householders getting fed-up with being experimented on with novel technologies,” he adds.
These technologies do not come cheap. The project is only affordable because CHAP owns the quarry on which the development will be built. Not having to pay out for the land gives the developer cash to invest in the project as, despite the sustainable credentials, homes in the village are unlikely to be sold for a premium.
The choice of site brings other advantages too. CHAP Homes’ Burr explains: “A brownfield site gives you a blank canvas, you’ve got more design opportunities to think about things.” The site design considers the direction of the sun and the wind. The team will model the master-plan layout using computational fluid dynamics to minimise wind flow over the buildings to prevent high-speed wind tunnels developing between houses. This level of detail will also mean the layout is planned to reduce heat losses from the buildings.
Maintaining and updating the infrastructure has also been thought out, with the responsibility and cost falling to a social enterprise trust set up by the developer. The trust, which will count all homeowners as members, will own and manage the technology and make its money by selling energy to homeowners.
Burr explains that energy will be priced slightly below the market value but it should bring in enough money to maintain the infrastructure and provide funds for the future.
For the time being Burr, Owen and their colleagues are fleshing-out the plans for the £400 million development.