How much does a 100 W office PC cost to run? Fleet energy calculation

How this is calculated

A "100 W" office PC is the PSU rating, actual desktop draw for light office work is typically 25-45 W with occasional bursts to 70 W during compiles or video calls. The 60% utilisation figure here is calibrated to capture that mix across an 8-hour day, including lunch and meetings where the machine is mostly idle. Aggressive sleep policies can reduce this further, though in a business context the trade-off with user productivity typically keeps machines awake.

Verdict

The arithmetic: 100 W at 60% utilization for 8 hours daily at $0.18/kWh consumes 175 kWh annually and costs $31.54 ($2.63 monthly). The 100 W figure is the PSU rating - actual desktop draw for light office work is typically 25-45 W with occasional bursts to 70 W during compiles or video calls, and the 60% utilization assumption is calibrated to that mix across an 8-hour day including lunch and meetings. At 500 seats the fleet consumes 87,600 kWh and costs $15,770 a year, which is when enterprise IT starts specifying Mini PCs or thin clients over full towers. A 45 W thin-client swap cuts that fleet bill by roughly half, about $17k a year at the 1000-seat scale. Aggressive sleep policies (a 15-minute idle timeout dropping draw under 2 W) cut further but trade against user productivity in a business context.