Demand Limiting is an HVAC control strategy that automatically reduces or cycles equipment operation to prevent peak electrical demand from exceeding a predetermined threshold. This technique protects facilities from costly demand charges by ensuring power consumption stays within contracted limits. Demand limiting systems monitor real-time electrical usage and make automatic adjustments to major loads.
Technical Details
Demand limiting controllers track cumulative kilowatt consumption over 15-minute intervals, which determine utility demand charges. When usage approaches the facility’s demand limit (often specified in the service agreement), the system automatically reduces HVAC operation by increasing setpoints, cycling compressors, or deferring non-essential loads. Modern demand limiters integrate with building automation systems and can prioritize critical loads. Typical demand limits for commercial facilities range from 200 kW to 5 MW depending on facility size and contract terms.
Applications and Benefits
Demand limiting is standard in commercial buildings, hospitals, manufacturing plants, and data centers. The strategy typically reduces demand charges by 10-30% without compromising occupant comfort when properly configured. It requires coordination with HVAC scheduling and load management protocols.