Some 90.1 schedules start HVAC equipment after receptacle / lighting loads?

asked 2019-03-19 10:34:20 -0500

dhollman's avatar

updated 2019-03-21 07:12:36 -0500

The ASHRAE Std. 90.1-2013 User's Manual contains schedules for various building types & functions. I noticed that a few of them follow a pattern where the lighting & receptacle loads ramp up an hour prior to the HVAC system operation. This seems a little bit odd because that would mean in some cases that space temperatures could start rising before the A/C is capable of controlling them.

Here's an example, for the Office building schedule:

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Are these schedules meant to represent actual typical building operation? Or were they constructed this way for some other reason?

Furthermore, in the original Std. 90.1-1989 (the last year these schedules were included in 90.1 itself) the Office schedule was actually a little different and had the plug loads & HVAC schedules come on at the same time. This seems to further muddy the waters - why was a revision to this schedule made (at some point in time)?

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