The systems were specified to provide cost-effective and reliable home heating and ventilation for the Great House Farm development in St Fagan’s on the outskirts of Cardiff. The new development’s one-, two- and three-bedroom properties boast some of the most advanced sustainability measures of any UK housing project.
As well as eight NIBE F470 EAHPs, the homes have been fitted with a wide range of other efficiency-enhancing features – many of them deliberately discreet to complement the traditional aesthetics of the Grade II-listed farm buildings.
Among these are rainwater harvesting systems, which collect and store rainwater for re-use on site (e.g. in gardens and bathrooms), low-energy, warm white LED lighting, smart meters (to help residents monitor their energy use), electric car charging points and Sedum Green ‘living roofs’. Unlike some green roofs, which require regular mowing at considerable heights – causing health and safety concerns – these are made up of a mixture of low-growing plants that require no cutting.
The properties also boast underfloor heating, extensive insulation and thermally treated windows throughout. As well as keeping the heat in, the toughened, double-glazed windows are said to be ‘burglar-proof’ and virtually unbreakable.
All of this means that when windows and doors are shut, the properties are completely airtight – achieving a Code for Sustainable Homes Level Four for building fabric alone. The homes’ sanitary systems are also highly efficient, using water from the rainwater harvesting tanks stored beneath the lawn – and there are even solar thermal and solar PV systems on site to help lower hot water and electricity costs further.
When embarking on the project, developer LivEco was tasked with ensuring any improvements to the listed farm buildings remained as sympathetic as possible to the original style – whilst also incorporating new features that would provide residents with optimum efficiency and comfort all year round. Having worked with NIBE products before, local architect Gillard Associates specified the F470 EAHPs to provide hot water and space heating, as well as an effective ventilation solution, given the development’s high levels of air tightness.
Daniel Ball, Director at LivEco, says: “Great House Farm was our first sustainable housebuilding project, and to establish ourselves as leaders in the field we knew we had to keep efficiency at the heart of every decision from the outset. We took a fabric-first approach to heat-loss protection, making sure there was absolutely no leakage through the walls, windows or roofs, with a warm building envelope throughout. This, matched with lower temperature underfloor heating downstairs and upstairs, means the homes have the ideal setup for the NIBE F470 EAHPs.
“The new units keep the homes well ventilated and at a warm, comfortable temperature – and have the added benefit of keeping bills down for residents. The all-in-one systems have intuitive touchscreen controls that are really easy to use, and an integrated hot water cylinder to take up minimal space. What’s more, with no outdoor units required, the EAHPs also meet the aesthetic constraints that come with developing around listed buildings.”
Now officially classified as a renewable technology, NIBE F470 EAHPs harness wasted heat from inside a property to efficiently meet its heating and hot water demands. The heat recovery and exchange process relies on a system of external vents, which allow fresh air from outside to enter the building and circulate throughout. This mechanical ventilation system forms an essential part of the technology – providing a comfortable, healthy living environment for residents, and helping protect against issues like damp and mould. Since EAHPs are designed for use in smaller, well-insulated properties, this circulating air is naturally warmed as it passes through each room. Internal air vents (positioned in the properties’ wet rooms, such as the kitchen and bathrooms) then draw this warmed air through a ducting system and back to the heat pump.
Inside the unit, the warm, stale air is passed through an evaporator, which extracts the energy present (an average of 20°C) and uses it to heat the refrigerant gas. This heated gas is then passed downwards through a condenser coil found in the unit’s built-in hot water cylinder. As a result, water stored inside is heated through the cylinder’s inner jacket, and can be utilised to provide space heating and hot water. The used cold air is then expelled outside using the external vents (which must be sited carefully as air leaving the system could be as cold as -10°C).
As well as making the most of energy present inside the buildings to meet the everyday heating and hot water needs of residents, the systems provide necessary ventilation without the need to open windows and waste heat – a must for well insulated buildings like Great House Farm.
Daniel Ball continues: “The benefits of more sustainable housebuilding – both for residents and for the wider local community – are undeniable, and at LivEco we feel passionately that it shouldn’t just be something that people see in big-budget projects or on Grand Designs. We want to see sustainable housing become the norm, and the only way to do this is to make it accessible for everyone. Great House Farm was built to provide lower impact living and reduced bills at an attractive price bracket, and the NIBE EAHPs are an important part of this.
“The feedback we’ve had from residents has been overwhelmingly positive, with everyone saying how warm their homes feel and how low their bills have stayed. All the residents have been given a full overview of how to set and operate their systems for best results, and will also benefit from annual service, maintenance and customer care support from Julian Jenkins at local NIBE VIP installer Celtic Energy. We will also be following on from this completed successful first phase with another 23 detached houses, which will be built to a similar standard later this year – and plan to use NIBE products again in this project as well.”
