One of the main aims of Claus’ work was to achieve airtightness at Hay Tor, which has been done by fitting an Intello membrane against the ceilings, taped to the walls and fitting tapes between the frames of the new windows, doors and reveals. Additionally any cables or pipes coming through the ceiling or walls are fitted with a special sealing grommet. Claus researched and fitted the membrane himself as part of the retrofit. Then a pressure test was conducted which gave a result of 2.05m3/(h.m3)@50Pa, considerably lower than the 5m3/(h.m2)@50Pa required by law for new dwellings or extensions.
An extremely efficient Viessmann system boiler with a weather compensation feed was fitted. This lets the boiler operate at lower temperatures, and a pressurised hot water tank linked to 4m2 solar panels fitted by Llani Solar with stainless steel pre-insulated flexible pipes were included in the retrofit. The house is ventilated permanently with fresh air by the Itho Eco4 – a mechanical ventilation and heat recovery unit (MVHR), which extracts 92% of the heat from the outgoing air and heats the fresh incoming air via an unconnected heat exchanger.
Even the bathroom has been overhauled and now includes a low flush toilet with a 2/4.5L dual flush. This compares very favourably with the 13.2 litres flush cistern as was the norm in the 1980s and beforehand or even modern models still using about 6 litres.An eco shower head was also fitted which uses around nine litres per minute – significant as showers are by far the biggest consumers of water in the home, using around a quarter of all the water.
Polyurethane roof insulation was sprayed between and below the rafters, achieving a u-value of 0.19W/m2K, while 100mm Kingspan boards were fixed to the external walls with a specific slim render product, producing a u-value of 0.21W/m2K. These were fitted by Claus himself and rendered by External Wall Solutions Ltd. As excavating the concrete floor wouldn’t have added greatly to the energy-saving result and would have proved costly, instead a layer of bamboo flooring, carpet or cork was added depending on the need in each room.In the living area there is a wood stove, energy-efficient LED light bulbs operate at 4 watt – the equivalent of 50 watt halogens – and there is enough storage outside for 1,400 litres of rainwater for garden use.