For most people and most properties, it's basically highlighting what is a no-brainer; improving poor insulation will provide huge returns on investment. My only caveat is for properties old enough not to have been designed with cavity walls. In those cases simply reducing the heat-losing airflow is highly likely to introduce humidity problems so the process of insulating an old property needs to be tackled with the involvement of an expert. I certainly wouldn't suggest it can't be done but it needs to be done using advice from someone who understands the technicalities of retaining heat whilst still allowing the building to breathe.

Fortunately there are a number of good firms out there to consult with on this and some fantastic "heritage" insulation products available. Still a very worthwhile step to take.

https://www.youtube.com/watch?v=DGlLGA2e5MY