Phantom loads are equipment that draws power 24/7 even when the building is unoccupied or the device is nominally off.
Common phantom loads in commercial buildings
Equipment Standby Power Qty Total
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Computers (sleep mode) 3–10 W each 200 600–2,000 W
Monitors (standby) 1–5 W each 200 200–1,000 W
Vending machines 300–700 W each 5 1,500–3,500 W
Copiers (ready mode) 20–100 W each 10 200–1,000 W
Network switches/APs 10–50 W each 30 300–1,500 W
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Typical office total 3–9 kW continuous
Why phantom loads are expensive
The energy formula:
kWh = kW × hours
A 5 kW phantom load running every hour of the year:
5 kW × 8,760 hrs = 43,800 kWh
43,800 × $0.15 = $6,570/year
The 66% problem
Hours in a year: 8,760
Typical occupied hours: 3,000 (50 hrs/wk × 50 wks + overtime)
Unoccupied hours: 5,760 (66% of the year)
Operating loads run during 3,000 hours. Phantom loads run during all 8,760. That means phantom loads accumulate 2.9× more hours than occupied-only equipment.
The night audit
Walk the building at 10pm on a weeknight when it should be empty:
1. Note every screen that glows
2. Note every light that is on
3. Note every device that hums
4. Note every indicator LED
Each one is drawing power that nobody budgeted for.
The meter check
Compare overnight base load to daytime peak:
Overnight / Peak = base load ratio
< 25%: excellent phantom load control
25–35%: typical, acceptable
35–50%: high, investigate
> 50%: excessive, immediate action needed
Cost per device category
Device Watts Hours/yr kWh/yr Cost/yr
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1 computer (sleep) 8 W 5,760 46 $6.91
200 computers 1,600 W 5,760 9,216 $1,382
1 vending machine 500 W 8,760 4,380 $657
5 vending machines 2,500 W 8,760 21,900 $3,285
10 copiers (ready) 500 W 5,760 2,880 $432
Note: computers and copiers use unoccupied hours (5,760). Vending machines run all 8,760.
The fix
Most phantom loads are eliminated through operations, not capital:
Fix Savings estimate
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Computer auto-shutdown policy $1,000–$2,000/yr (200 PCs)
Scheduled outlet strips $500–$1,500/yr
Vending machine occupancy ctrl $2,000–$3,000/yr (5 units)
After-hours lighting sweeps $1,000–$3,000/yr
Network equipment scheduling $500–$1,000/yr
Total potential: $5,000–$10,000/yr for a mid-size office building. Implementation cost: near zero for policy changes, $500–$2,000 for smart strips and timers.
