I'm about to remove an external wall which is constructed of studded plasterboard interior wall which is clad in what I can only describe as Cedarwood planking to the external. As you can imagine it's not very energy efficient in terms of heat loss and so the intention is to replace with a wall constructed of breeze block and then rendered. It is only a small area, approx 4 metres width by 1.5 metres height (to the exsiting window). I'm looking for any suggestions in terms of preferred thermal blocks for this type of project, internal and external finishing i.e plaster and render, and whether there is a calculation or on-line calculator that will give me an idea of the number of block required.