There seems to be a lot of existing IEV fans being left in homes where fabric measures
are being lodged with Trustmark as PAS2035 compliant, anecdotally without any
air pressure test being completed to ascertain whether the air permeability of the
building envelope is above or below 5 m3/m2h at 50 Pa after the installation. My
understanding is that if the air permeability is not known, you must replace IEV
with an alternative such as continuous MEV or PIV, as IEV “shall be assessed as
inadequate” (C.2.4). This is also explicitly stated in C3.3 and C3.5. Please confirm
if my understanding is correct? If so, what will Trustmark look to do with all of the previous non compliant measures? As a follow up to this, if an air pressure test is completed post installation
and it can be evidence that the air permeability is above this threshold, does PAS2035 require all
IEV fans to be tested using a calibrated anemometer and if so, does the tester need to hold a
suitable qualification (NICEIC etc) to ensure that the extract rates meet those required in Approved
Document F? Or is it acceptable to just assume that the fan is designed to extract at the required
rate for the wet room it is in and that the in-situ extract performance is actually still delivering this
minimum required rate? Presumably where an air pressure test has been completed, if brand new
IEV fans are fitted with known extract rates that meet ADF, the RC can assume compliance without
the need for any testing of the fans? (Assuming it is needed)