I deduce from that comment that the new EPC is still based on the assumption that houses are heated at full blast for a few hours twice a day. Low temperature heating, of the type you get from condensing boilers actually set to condense or from heat pumps, operate over more hours to output the same amount of heat. In that case response time is not relevant.
1 Like
Hey welcome! You should look for a builder who specializes in retrofitting or eco-friendly construction. They should know about underfloor insulation and air tightness. Maybe try local green building groups or ask around for recommendations.