Had a brutal one this month folks. Manufacturing client in Wichita on Westar's Schedule LGS got hit with a 47 kW demand spike during morning HVAC startup. Their normal peak is around 85 kW but this pushed them to 132 kW for billing purposes. That's an extra $2,400 on their July bill at $51/kW. The kicker? Their old energy management system failed and all six rooftop units started simultaneously at 7:18 AM instead of the normal 15-minute staging. Anyone else seeing these kinds of startup disasters?
Westar HVAC startup just cost my client $2,400 in demand charges
Ouch Bonnie, that hurts. Duke Energy here in Charlotte uses 15-minute intervals too and I've seen similar carnage. Had a client last year where a lightning strike reset their building automation system and every piece of equipment came online at once. 78 kW spike became their billing demand for the entire year under Duke's Schedule LGS. We ended up installing soft-start kits on their biggest units and saved them about $18K annually. The payback was under eight months.
PSE&G up here in Seattle area has been cracking down hard on demand charges lately. Their Schedule 31 industrial rate went from $8.50/kW to $12.75/kW last year. I'm telling all my clients to invest in proper HVAC sequencing controls because one bad startup can cost thousands. The worst part is most facility managers don't even know it happened until they get the bill.
TVA territory here in Knoxville and we see this constantly. Most commercial buildings have zero staging on their HVAC startup sequence. I always recommend time-delay relays at minimum - costs maybe $200 per unit versus thousands in demand penalties. Derek's right about the soft-start kits too, especially on older equipment. The inrush current on a 10-ton unit without soft-start can be 6-8 times the running amperage.
Terry good point on the time delays. This client actually had them installed but they were set for only 30 seconds between stages. Apparently that wasn't enough when all six units were trying to start after being off all weekend. I'm pushing them toward a proper energy management system with 2-3 minute delays minimum. Westar's demand charge is brutal enough without giving them free money.
MLGW here in Memphis and I've got a warehouse client that learned this lesson the hard way. Their Schedule D rate has demand charges at $19.50/kW and they got nailed for 34 kW over normal when their old pneumatic controls failed. All four package units started simultaneously on a 95-degree day in August. The compressor inrush alone was devastating. We retrofitted them with a simple sequencer and demand limiting controller for under $3,000. Saved them $8,000 the first year.
APS here in Phoenix and summer HVAC startup is absolutely critical. We hit 118°F last week and I watched a client's demand spike to 240 kW when their BAS crashed and everything came online at once. Their normal peak is maybe 180 kW. That's an extra $1,800 on Schedule E-32 just from one morning. The facility manager was literally sweating more than the building trying to explain it to corporate.
Entergy Louisiana and these demand spikes are killing my industrial clients. Had one last month where a power outage reset their controls and six 25-ton units all restarted when power came back. 89 kW demand spike on Schedule LGS at $15.20/kW. That's $1,353 extra per month for the next 12 months since Entergy uses ratchet billing. Simple staging controls would have prevented the whole mess but nobody wants to spend money until they get burned.
Georgia Power Schedule PL-1 and I see this every summer. The key is education - most facility managers think demand charges are just about total consumption. They don't realize that 15-minute peak can cost them all year. I always show them their interval data from the meter and point out exactly when the spike happened. Once they see that 7:15 AM startup costing them $5K annually, they usually find budget for proper controls pretty quick.