EPC Rating Not Right?

bobster2

Bilivino said:

From further research I've learned there are three datebands regarding the assumption of insulation in 'As Built' cavity walls:

Prior to 1976 - assumption for 'As Built' is no insulation

1976-1982 - assumption for 'As Built' is partial insulation

1938 onwards - assumptin for 'As Built' is insulated

You mean 1983 not 1938 for the 3rd category!

Those might be the standard assumptions. But they are not applied consistently.

E.g. on an estate I've looked at - houses all built in the early 1970s - I've seen a mixture of assumed "no insulation" and assumed "partial insulation" for houses built at the same time.

(And if you look behind the cladding they do have insulation! But that's a different matter).

stuart45

FreeBear said:

Bilivino said:

From further research I've learned there are three datebands regarding the assumption of insulation in 'As Built' cavity walls:

Prior to 1976 - assumption for 'As Built' is no insulation

1976-1982 - assumption for 'As Built' is partial insulation

1938 onards - assumptin for 'As Built' is insulated

1938 cavity walls will most certainly NOT have any insulation as built.

1976-1982 might have insulation, but it is not guaranteed - My 1976 extension didn't have anything in the cavity, nor in the flat roof.

I built a house in the late 80's with no insulation in the cavity, only thicker Thermalite blocks. Partial insulation is a bit confusing, as a partially filled cavity with insulation boards could have the same U value as a full fill cavity with batts. The year of build will give the RDSAP the assumed U values of the walls, although if the plans were passed a few years before the build started, the old values would be used on a later build date. 
It's all theoretical anyway, because a badly built cavity wall could have a much higher U value in practice than a well built one with exactly the same design. 
Also in practice it's been found that some 9 inch solid walls have a much lower U value than the 2.1 assumed, and some of the older cavity walls have a much higher one than the 1.7 quoted.