paddle

Looking to extend my 1930's semi (corner plot) to the side and incorporating a loft extension. it currently has a ground floor rear kitchen extension done to building regs at the time but I have noticed that the property isn't at all efficient to run and so am looking at making it as efficient as possible. The plan is to make it a 5-6 bedroom all ensuite with walk-in wardrobes so going forward it has good appeal to renters as it has great local amenities. I am looking at ewi for the old front and rear walls and hoping to insulate the old floors somehow and then run an ashp and have as much solar on the roof as possible and also battery storage. ideally I want it to be a bill free house going forward. also draughtproofing the house so it can be as efficient as possible and having some form of heat recovery system for replenishment of air. I am having some difficulty getting my head round how you can avoid thermal bridges on a retro fit. any tips on reading, videos I could use to help my understanding and/or any good builders who have experience in deep retrofit in and around the Birmingham area would be most appreciated. kind regards paddie pd - sorry if this is in the wrong part of the forum please move to wherever is most appropriate