Low Running Costs – This is achieved when Sunbloc Insulated concrete formwork is used to build the structure as they offer low ‘U’ Values from 0.20W/m2degk, down to 0.11W/m2degk (achieved with addition of insulation on either the inner or outer skin of the building), and they actually perform to their ‘theoretical calculated design performance’ unlike most materials where a lower U value simply means an improvement on previous.  Because dense concrete is the structural core and the layer of insulation is much thicker on the outer leaf (in the lowest U value requirements), “thermal mass” benefits are obtained which means that the building is warm inside when it is cold out-doors in winter and vice versa in summer.  This means that you can turn your heating on later in the year and switch it off earlier. Because there is better retention of heat within the building, you are able to use a small boiler than you would have to had the structure been built out of lightweight materials and in some cases – Passiv-Haus Design, a boiler will not be required at all. As summers in the UK get increasingly warm, air-conditioning will increase but thermal mass will minimise the need for air-conditioning offering further savings against lightweight framed structures