Peak loads - model vs design calculation comparison

asked 2022-01-18 05:59:31 -0600

Jim Dirkes's avatar

Have any of you been involved in a thoughtful discussion of "real" peak loads vs those typically calculated by the design form?

Our experience is that a typical (designer) load calculation includes exaggerated lighting and plug loads, does not account for non-coincident load schedules AND adds safety factors - sometimes in multiple levels. We think the actual load may be 30% lower, affecting fan sizes, coil selections, duct and piping, control valves, chillers, boilers.

We'd like to initiate a discussion with the design firm(s) and want to be confident we consider all of the key factors, since there is some risk if we undersize....

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In my experience when doing equipment sizing there are too many safety factors that at the end gives you an oversize cooling equipment. However, as a designer over sizing the system could be useful for future increase of loads. If you donĀ“t take enough safety factors you could risk under sizing the system and then you are in big troubles. I think lighting and computer loads are getting smaller with more efficient technology but designer always try to avoid taking to many risks and it is understandable for me.

obuchely's avatar obuchely  ( 2022-01-20 07:11:46 -0600 )edit

Exactly! Regarding future loads, it seems that lighting and plug power are only becoming lower as technology improves, as you say. The biggest issue, it seems is the conservative, risk-averse nature of design engineers.

My question is directed to those who may have attempted to show the COST of oversized systems and also attempted to make sure that all of the risks are included in their evaluation.

Jim Dirkes's avatar Jim Dirkes  ( 2022-01-20 08:38:29 -0600 )edit