Demand limiting / peak-shaving

1 post / 0 new

Has anyone successfully implemented demand limiting? The project I'm
working on has a pretty extreme demand ratchet, and there appears to be
significant cost savings to be had if I can reduce my peaks.

It looks like the load management feature will have a "peak shaving"
option in a future version, although I'm not entirely sure it's what I'm
looking for either. I'm hoping to modify temperature settings at the
zone level and have the reduced load "trickle down" to my AHU's and
plant. I'd like to avoid resetting my plant, only to have my fans speed
up to compensate.

This is essentially the idea:

Each zone will have 3 temperature setpoints: Normal,
first stage demand limit, second stage demand limit. Each zone can be
programmed individually, so critical zones will have all three setpoints
at the normal level. As the building demand approaches a setpoint, the
first stage limiting setpoints will override the normal setpoints
(approximately 2F warmer). If the demand continues to rise towards the
setpoint, all zones will be adjusted upwards again to their second stage
limiting setpoint (approximately 4F warmer than normal setpoint).

Ultimately, I think I'm going to need to build a schedule that has user
expressions for my summer daytime hours. Unfortunately, I really don't
know what I'm doing with user expressions...

I've set 5 global parameters for easy modification:


And then I'm going to insert the following into my temperature schedules
(#VALUE is the variable I'm looking for)

{if (#VALUE<#PA("kWlimit1"))
then #PA("RegTemp")
else if (#VALUE<#PA("kWlimit2"))
then #PA("DemTemp1")
else #PA("DemTemp2")

What can I replace #VALUE with that's going to call up this hour's (or
last hours) demand? Will this work?



Eric O&amp;#039;Neill's picture
Joined: 2011-09-30
Reputation: 0