Load shifting is the strategy of moving HVAC energy consumption from peak-demand periods (typically 2-8 PM) to off-peak periods when electricity rates are lower and grid demand is reduced. This operational strategy reduces electricity bills by 10-25% without changing total energy consumption. Load shifting requires either thermal storage capacity or flexible equipment that can operate outside normal occupancy periods.
Implementation Strategies
Thermal storage systems (chilled water tanks or ice storage) cool to full capacity during off-peak hours (10 PM-7 AM) when rates are 50-75% lower, then discharge stored cooling during peak periods while chillers remain off. Pre-cooling buildings one to two hours before peak demand periods reduces cooling load by 20-40% during expensive rate periods. Heating systems can similarly preheat thermal mass in buildings during off-peak periods to reduce peak-period heating operation.
Equipment Requirements
Load shifting requires 4-8 hours of thermal storage capacity and building thermal mass sufficient to maintain comfort during peak periods without cooling operation. Control systems must predict occupancy patterns and weather conditions to optimize pre-cooling or pre-heating timing. Typical payback periods range from 5-8 years through electricity cost savings, with additional benefits from demand charge reductions of 10-30%.