Thansk JSH.
A bit of history - the original Actis tests were done on 2 identical 'chalets', from memory in Limoges, France. This info may still be available on the internet somewhere. One chalet had 200mm mineral wool quilt in the roof the other Actis multi foil but not much other data on the construction. Actis measured 'heat loss' from the chalets and came to the conclusion that 200mm quilt = 30mm(?) Actis. There was never enough data to check if they were actually measuring heat loss through the roof alone or via a myriad other routes. Complaints to the ASA only resulted in a change of product name, Actis 8, 9, 10......It seems that only when BRE did their work, BR 443 was updated and other manufacturers of multi foil products gained certification using accepted test methods that Actis back tracked. They still use a mixture of in-situ and accpeted testing - not sure how they explain the huge discrepancy.
As you say - why trust them now! Hence my warning about thir claimed U-values!
