UFH and heat loss calcs show insufficient heat

[Notch7]

The U value for solid brick walls is apparently 2.15 and upwards. Adding 50mm of insulating render on the internal face of the walls (we are not adding anything to the external) gives the walls a U value of 0.9

Could you not add 50mm of PIR insulation, then timber battens, then plasterboard.

50mm of PIR has a u value of about 0.45

 

[rangorgubbins]

That certainly would help. At the moment I'm trying to decide whats best between PIR plasterboard, or insulating render (http://bauwer.co.uk/). The render i like because it'll stabilise the old brickwork and is breathable, but the PIR boards have a slightly better insulating value.