IES-VE User Forum

Hi All,

Just wondering what people are using for VRF efficiencies these days for Part L compliance?

I've been seeing some rather high figures quoted and am a bit nervous about using them (4.24 cooling 3.82 heating) What do you think is a reasonable figure with todays current technology?

Cheers,

C

For heating I tend to get suspicious if it's higher than 3 for an annual efficiency in most UK locations. It's an area of the regulations which needs tightening up IMHO since the actual efficiency is going to be very bespoke in each case and so quoting some figure from a manufacturers spec sheet feels wrong.

Daikin have made strides in dealing with this using their plug-in for IES which bespokely calculates the annual efficiencies. It's free but it only works with Daikin products at the monent.

Thanks for that response.

I've heard some dubious figures being quoted and i'm just not confident in using them. sure it makes for great results in compliance but are they realistic, I'm not sure.

I've had a look at the Daikin plug-in, pretty useful if you're definitely using Daikin units!

I use 3 to 3.5. From experience i note that this is reasonable to assume. However as a previous poster stated 3 is a good start. If its okay at 3 then i leave it. I only use 3.5 when i need to tweak. I would advise against going above this unless detailed design has been carried out and you know the actual figure.