Calculating the lighting load for a area in a schedule in Revit MEP

[Enlightened]

I'm currently using Revit MEP 2010 and will be installing 2011, in the next few days.

I'm currently trying to do a schedule to calculate watts per square metre (lighting load) for lighting to get the actual and the specified for an area (space).

Also to get the schedule to highlight spaces that are over the specified watts/m².

I'm using a 'space schedule' with an embedded 'lighting fixture' schedule, as the 'lighting schedule' does not have a parameter for area for a space only volume.

I can get everything to work except the actual load for the space, which is giving me about 5% less then what the total should be. The load parameter that is in the lights is right and when I turn on the 'calculate' for the load parameter column, it is giving the right amount. I can't find any setting in the light/space families that might be causing this error, or in the electrical settings.

Has anyone had excess with doing this, or know what could be causing this error.

[tys90]

This is kind of a guess, but it might have something to do with the way Revit handles rounding. Can you give an example?

[kalimazoop]

For the lights being less than the wattage specified, it sounds like you might have a power factor set in the electrical settings of the fixture family. That would be the first thing I would check regarding that.

For the schedule, we have accomplished what you are trying to do. The space schedule can do what you ask without embedding the lighting schedule. The embedded light schedule just shows you what lights are mounted in a particular space, although this is a good way to spot check that your space is seeing all the fixtures mounted in it.

In the space schedule, are you using the Calculated power density value, or the Actual value? Using the Actual value reads the load values from the lighting fixture connector into the space.

If you can provide a screen shot of the schedule and the settings that may help.

[james.klatt]

I agree with kalimazoop check your power factor under the connector properties in the family. That drove me crazy for a while not understanding how revit calculated the load from watts.