Kram

Hello all I am currently planning a refurbishment of my 1960's Bungalow in North Wales, and this forum seems to have a wealth of useful information, and very knowledgeable people on board ?My aim is to undertake as much of the design, planning and actual work as possible, out of personal interest in the technology available, and to reduce costs. I have a construction management background and have reasonable ability in the DIY department. Currently researching options for improving heating & insulation, so i'm hoping someone, or the man himself, could let me have a copy of Jeremy Harris' heat loss calculator spreadsheet? As it stands, the loft has been insulated, and we have cavity wall insulation installed, heating is provided by an old Johnson & Starley ducted warm air heating system. Many thanks in advance.