IES-VE User Forum

Hi,

Has anyone else experienced the BRUKL document not matching the U values and lighting systems inserted within a IES 2013 SBEM model.

We did have this issue approx. 12 months ago with the floor U value and was informed by IES that it was a bug in the software, not ideal when issuing to building control

just working on the latest release experiencing it again but now with the floor, roof and doors. In addition the lighting design in the model is not the same as shown on the BRUKL.

Selected is 'Lighting Chosen But Not Calculated' with figures for lumens / circuit watt and LOR and the Brukl indicates luminaire lumens per watt. i haven’t told the software the luminaire type.

All lumens per watt are above 65 and LOR or 0.76.

any comments appreciated

thanks james

U-values

Check the model has been set up as per the guidance for modelling conditioned and indirectly conditioned spaces from the iSBEM User guide.

Lighting on BRUKL

If the space is an office, storage or industrial area then the Luminaire luminous efficacy is checked on BRUKL.

If any other activity type is selected then it is the Lamp luminous efficacy that is checked.

The relationship between these three parameters is
L = Llamp ro

Where
L = Luminaire Efficacy (lm/W)
Llamp = Lamp Efficacy (lm/W)
ro = Light Output Ratio

Terence

On the issue of how the lighting results are reported.

The problem I have at the moment is that when a particular lighting scheme is input as a 'full design' using the design W/m2 and maintained lux, the published results, as expressed as luminous efficacy, on the BRUKL are far lower than they should be, indeed some, but not all, are highlighted in red as being below 65 lm/W (Welsh Regs). And this is causing questions to be asked, (even though the lighting as a whole easily beats the notional building's, and the actual luminous efficacies are nowhere near 60 lm/W [all lamps LED]).

For example a particular office, when input as 6.43 W/m2 and 365 lx, is reported as 57 lm/W and 139 W on the BRUKL (the actual luminous efficacy is 100 lm/W and the circuit wattage is 126.5 W).

But when the same room is input via the (less favourable) inference method as 100 lm/W LOR = 1 then the BRUKL reports this room correctly as 100 lm/W and 146 W (the higher circuit watts would be expected when using and inferred design).

How can this be?

Why in the first place does the BRUKL incorrectly infer a luminous efficacy of 57 lm/W from a full design, and then secondly gives the correct luminous efficacy from an inferred design?

Wasted

When you enter the inference value, you are directly entering the value reported on the BRUKL (assuming a Light Output Ratio of 1).

When you enter the full design values I think SBEM Calculates it as: Luminaire Efficacy, L = Design illuminance (lux) / Wattage (W/m2)

Note that it is SBEM/BRUKL that performs this calculation, not the VE.

Terence

I thought you might say something like that.

I've posted a query via the NCM website, but I doubt I'll get a response.

Thanks anyway.

Wasted