The Demand Charge
Subject area

Peak Demand Management

Reducing a demand charge means changing the shape of a load curve, not its area. That is a different problem from energy efficiency, and it is often cheaper, because shifting a load costs less than eliminating it. This section covers the practical levers — sequencing and staggered startup, thermal storage, batteries, on-site generation, curtailment agreements, control settings and interval-data analysis — with the arithmetic for deciding which of them a site actually needs. It also covers the ones that fail: measures that cut kilowatt-hours while leaving the peak untouched, and control strategies that shave one meter while pushing the peak onto another. Every strategy here is judged against the same test, which is whether the next twelve bills fall.

Peak management

How to Reduce Peak Demand Charges

A ladder of measures from free to capital-intensive, with the diagnostic that tells you which rung your site is actually on and the arithmetic for deciding between them.

8 min read

Supporting analysis

Everything underneath the pillar, in this subject area.

Peak management

Demand Limiting Controls and How They Fail

A demand controller predicts the interval average and sheds load before the target is passed. The concept is sound; the implementations fail in a small number of predictable ways.

4 min read
Peak management

Load Shifting Is Not Energy Efficiency

Efficiency reduces the area under the load curve. Shifting changes its shape. They save money on different lines of the bill, and confusing them wrecks business cases.

4 min read
Peak management

Sizing a Battery for Peak Shaving

Power rating and energy capacity are two separate specifications. A battery correct on one and wrong on the other fails to shave the peak while costing the full price.

4 min read
Peak management

Thermal Energy Storage for Demand Reduction

Make cooling at night, use it during the peak. The cooling load is unchanged; the electrical load that produces it moves to hours where capacity is not being priced.

4 min read