Plug & Process Loads in Energy Modeling — and Why They Matter for NYC LL97

Ask most people what uses energy in a building and they will say heating, cooling and lighting. But a large and growing share comes from everything that simply plugs in — computers, monitors, servers, kitchen equipment, lab gear, elevators. In energy modeling these are called plug and process loads, and they are often underestimated. In New York City, where Local Law 97 caps a building's total carbon, getting them right is the difference between an accurate compliance projection and a costly surprise.

What counts as a plug or process load?

• Plug loads (receptacle loads) — anything plugged into an outlet: computers, monitors, printers, task lights, phone chargers, vending machines, TVs.
• Process loads — energy serving a specific building function: commercial kitchen equipment, data-centre and server loads, laboratory and medical equipment, refrigeration, elevators and conveying systems, industrial processes.

What unites them is that they serve the occupants' activities rather than the building's basic conditioning — which is also why energy codes have historically left them largely alone.

Why they're hard to model

Plug and process loads depend on how people actually use a space, so they resist tidy assumptions. Modelers typically estimate them with a power density (watts per square foot) plus an hourly usage schedule, drawn from standards such as ASHRAE 90.1 and 62.1, occupancy data or sub-metered measurements. Get the density or schedule wrong and the whole energy — and carbon — result shifts. In modern, efficient offices, plug loads can rival HVAC as the largest end use, so the assumption is anything but minor.

The compliance catch

Here is the part that trips owners up. In code-style compliance modeling (ASHRAE 90.1 Appendix G), plug and process loads are usually held identical in the baseline and proposed models, so they do not affect the percentage-savings result. That makes them feel irrelevant to compliance — but only for the percentage. For NYC Local Law 97, what matters is absolute emissions, and plug/process loads are part of the building's total energy. They count fully toward your carbon, even though the energy code never "regulated" them. This is the heart of the regulated vs unregulated loads distinction.

Reducing plug & process loads

Because they count toward LL97, they are worth managing: ENERGY STAR equipment, smart power strips and receptacle controls, server-room and data-centre efficiency, efficient commercial kitchen and lab equipment, and tenant engagement and sub-metering (which LL88 already pushes NYC buildings toward). None of these are glamorous, but together they can shave a meaningful slice off a building's emissions — sometimes the slice that brings it under the cap.

The takeaway

Plug and process loads are easy to wave away as "miscellaneous," but they are real energy, real carbon and, in NYC, real penalty risk. An energy model that treats them carefully — ideally informed by sub-metered data — gives a far more reliable picture of where a building stands against its Local Law 97 limit.

This article is general guidance and reflects information available at the time of writing. NYC requirements are set by the City of New York and may change — always confirm current rules with the NYC Department of Buildings for your specific building.