Heritage Retrofit

44 BCD SPECIAL REPORT ON HERITAGE RETROFIT FIRST ANNUAL EDITION conservation dividend. As well as the mansion becoming self-sufficient in heat, the new woodland being planted to secure future fuel helped reinstate lost design features from the Grade II listed park and gardens. The more actively managed woodlands are also helping to create larger, better habitats and improve nature conservation. Following the success of these schemes and the experience gained, the ten-year REI programme was launched with the expectation that it would enable the trust save up to £4 million on its energy costs each year. Electricity generated from some of the projects will be sold to the grid providing a new source of income. The trust is investing in more than 40 further projects which include: • a 200kW lake source heating project on the Blickling Estate in Norfolk, which will remove two oil tanks and 25,572 litres a year of oil consumption with an estimated saving of 68 tonnes of CO₂ per year • two biomass boilers at Upton House in Warwickshire to heat the mansion and other areas, saving an estimated 55 tonnes of CO₂ per year • a 250kW hydro scheme at Hayeswater in Cumbria where there is a legacy of hydropower from historic corn mills and water wheels – this project will provide an income stream to support conservation work on land the trust cares for. As well as generating and using renewable energy, the trust has set about implementing high energy efficiency standards in all buildings and operations. This is being achieved by increasing standards of insulation and draught proofing, using water-saving devices and smart meters, fitting double or secondary glazing, using thermostatic heating controls, and installing energy-efficient equipment and lighting. Many of the properties in the trust’s care are energy intensive and in remote areas without access to mains gas. So far, the trust has fitted over 60 of its properties with renewable heating systems tailored to the needs of each property. Ultimately, the overriding goal is to switch to sustainable forms of energy to reduce reliance on fossil fuels. HEAT PUMPS The REI Programme has achieved results by fitting both biomass appliances and heat pumps, depending on which technology suits the individual site. At Plas Newydd, on the Menai Strait in North Wales, a 300kW marine source heat pump fitted the conservation heating needs of the property. And at Blickling Hall in Norfolk, the trust has nearly finished installing a 200kW lake source heat pump to heat the main hall. At more isolated, rural properties such as Blickling, getting the right electrical load on site can prove challenging. Prior to installation of the heat pump, the system was already operating at the capacity of its electrical load so a system upgrade was required. This can be challenging, particularly if the electricity distribution network operator (DNO) needs to upgrade the invertors, cabling and/or transformers required to power the heat pump. The DNO often has its own operational constraints and challenges. It is also expensive because the technology and materials are complex and use a significant amount of copper, and the costs incurred by the DNO must be met by the developer. When considering whether a lake is suitable for a water source heat pump, distance from the property is important both in terms of cost for civil engineering and pipework, and for heat losses in pumping a longer distance. The relative elevation of the property and the water will be relevant too because more energy is required to pump uphill. The volume of water in the lake, its depth and the flow rate of water refreshing it impact on how much heat can be generated without significantly altering the overall temperature. How much energy the heat pump needs to take out will depend on the size and heating requirements of the building it is being used to heat. Crucially, the sensitivity of the ecology in the lake or river to temperature change and to disturbance caused by the installation of collectors has to be taken into consideration. The trust has to select lake sites for extracting heat carefully to ensure that the area, depth and flow rate can be maintained over the course of the year. Many trust lakes are spring-fed, ensuring that the ‘fuel source’ is replenished constantly. Independent studies by SEACAMS, a marine science research scheme, have shown that disruption to biodiversity can also occur during construction. Mitigation measures need to be carefully considered and incorporated in a method statement agreed with the Environment Agency and other statutory bodies as necessary (such as planning and heritage authorities where archaeological sites are involved). It is important to keep these bodies fully engaged during the design stage of the project. Sometimes the trust also faces challenges around the sensitive archaeological nature of its sites. It is Used to heat the property and for cooking, the wood pellet range cooker trialled at Hafod y Llan in Snowdonia reduced fuel costs considerably and demonstrated that wood pellet ranges are a viable alternative to the oil‑fired models used in many similar properties.