leed & process loads

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Cramer Silkworth's picture
Joined: 2011-09-30
Reputation: 0

Dear Cramer,

A recent LEED Silver project used this explanation:

"Process load is comprised of receptacles and elevators only, and accounts
for slightly less than 17% of the total energy cost. The receptacle load is
assumed to be 0.75 W/sf throughout, which is consistent with ASHRAE 90.1 and
reflects the tenants' concern for efficient office equipment. The receptacle
loads also use diversity factors that roughly parallel occupancy. The
elevator energy is derived using actual KW and a diversity schedule that
reflects normal usage patterns.
The Diversity schedules are shown on the accompanying updated "HVAC Data
Summary". These values are based on actual, designed peak energy use and
appropriate diversity. Therefore, even though somewhat lower than 25% of
the total energy cost, we are confident that they reflect the actual
situation adequately and should be considered acceptable."

James V. Dirkes II, P.E., LEED AP

James V. Dirkes II  P.E.'s picture
Joined: 2011-10-02
Reputation: 0

You are fortunate that the explanation worked. I used a very
similarly worded explanation for a project I submitted and the
reviewer didn't go for it. "Inconsistency" seems to be the keyword
for the review process.

Chris Jones

Chris Jones2's picture
Joined: 2011-10-01
Reputation: 0

My engineering sensibilities say, "If the facts bear out a lower-than-25% situation, then that's what should be accepted." I'd be interested to hear what objections have been raised by reviewers who disputed your explanation......

James V. Dirkes II, P.E., LEED AP

James V. Dirkes II  P.E.'s picture
Joined: 2011-10-02
Reputation: 0

FYI? We have actual detailed measured data from two recent projects. By measuring fans, pumps, fan powered VAV boxes, electric heat on VAV boxes, chillers, lighting, etc. and then subtracting all of that off the total building electricity ?. we found that for one of the buildings the misc equip was 10% and the other was closer to 25%. The misc equipment did include elevators but we didn?t break out elevators separately. The building with 10% misc equipment loads was a higher education type building with a mix of classrooms and offices. The building with 25% misc equipment was a 8-5 M-F state office building. I was kind of surprised that the misc equipment was as high as it was for the office building. I didn?t think it would get that high? but it was. Maybe something for the building to work on with their energy management program (i.e. space heaters ???). It would be nice if we had better or more benchmark data for misc equipment to compare to. Something for our industry to work on. If everybody who is doing detailed M&V out there could report the results to a common entity for data sharing, that would be a good idea. That could give people a range of real numbers to compare to.


James A. Hess, PE, CEM

James Hess's picture
Joined: 2011-09-30
Reputation: 601