We’re renovating our 1950s house with a view to adding a major extension in the future. We want to reduce energy bills as far as possible and are struggling to find information on how to do this with a renovation/extension of a comparatively modern building, rather than a new build or rebuild.

For instance, airtightness! Is it possible to make a 1950s building airtight? Is it possible to retrofit an MVHR system? We don’t want to finish the renovation, add the extension and find that energy efficiency measures in the extension are pointless because of the original house, or that we could have put things in place during the renovation to avoid that. Any help or suggestions of where to get advice on this would be greatly appreciated.