The system in Test 4 is similar to the combination in place on 4 buildings owned by the City and County of Swansea, samples of which had previously been tested by the BRE.
Mae’r profion hyn yn cynnwys samplau preswylwyr o Gymru sydd wedi’u cymryd mewn canolfannau profi yn Lloegr a phecynnau profi gartref.