A plasterboard sheet being lifted into place in the mezzanine bedroom by Laurent Maziere and Benoit, his young assistant. Note the shiny multi-refelctive insulation just behind the plasterboard. The decision to use this was difficult because it is not favoured by ecological building theorists. But I thought about it very carefully and calculated that the extra insulation value and energy saved outweighed the objections to it - it is made of aluminium and thin reflective plastic and is not recylable. Another objection is that it prevents the roof from "breathing", but the glue in plasterboard makes it an impermeable vapour barrier anyway. Another objection is that there is sometimes a risk of condensation, but by putting it under the hemp insulation means that its temperature will be above the dew point and there is no risk.