IES-VE User Forum

I'm trying to understand auxiliary energy.

I've setup a single room building in this case a classroom heated by underfloor heating and a local MVHR unit providing ventilation.

Therefore the Auxilary energy is the sum of the pump power density and the fan power density multiplied by any PFC/metering correction factors applicable. I am fine with this and I can replicate the calculation arriving at the same result as IES. What I can't understand is why the auxiliary energy seems to start 2 hours before the ventilation kicks in? Any ideas? (see graph below)

Thanks to Phil at IES support the answer is:

Auxiliary energy follows the plant profile which ramps up 2 hrs earlier. Whilst the ventilation follows the ventilation profile. Doesn't seem quite logical that there is a variation between the two, but that's the way it works. It is the same for the notional building.