The Energy Impact of Elevators

The Ups and Downs of Elevator Usage

In 2020, a million U.S. elevators made 20.6 billion passenger trips totaling over 2.8 billion miles. Those numbers are impressive, but they're still just the raw totals. Like every building's operational systems, each elevator is a unique set of components designed to deliver according to individual criteria.

Also like buildings, the energy consumption of elevators is affected by many factors, including the type of elevator drive (hydraulic or traction, geared or gearless), the occupant levels, the cabin equipment, the height of the building, the efficiency of the control system, and the braking technology.

Despite all these variables, data is available for benchmarking average elevator electrical demand. The American Council for an Energy-Efficient Economy estimates typical consumption for a lightly loaded low-rise elevator at 1,900 kWh/yr and 15,000 kWh/yr for a heavily used elevator in a high-rise. A single elevator in a 30-story high-rise might use ~35,000 kWh per year, or about as much electricity as the average Midwestern home uses in 9 months.

These estimates hold up with our real-world experience. For example, demand for elevators in one mid-rise mixed-use building we monitor ranged between ~7200 kWh and ~28,000 kWh last year.

In addition to direct loads, elevators also have indirect energy costs that should be considered in a broader review of building efficiency. Most elevator braking systems dissipate energy as heat, which can add up to 30% to a building’s total cooling load.

Ways to Reduce Elevator Electric Load

Because elevators are not mass-produced widgets but custom-engineered systems, it's difficult to make general statements or recommendations for a specific building. But there are best practices that can kickstart the elevator efficiency journey.

Of course, machine efficiency and performance is often about maintenance. Elevators must be inspected and serviced regularly to maintain federal compliance. In addition, cities and states often have their own rules that impact this schedule, so check your local standards and codes to determine your specific requirements.

When it comes to the main components of an elevator, the car itself and the hoistways, these can last the life of the building. But given that each elevator carries an average of 20,000 people a year, some pieces of the system are naturally going to wear out with use, and others will be superceded by more efficient versions over time. The ACEEE recommends a renovation cycle of 20–30 years as a balance between capital investment and efficiency of operation. Depending on their vintage, upgrading your components can improve your elevator's efficiency by as much as 40%.

For example, switching to a regenerative braking system packs a double efficiency punch because it lowers both the overall electricity demand of the elevator and the total cooling demand by producing much less heat. In simulations of commercial mid-rise and residential high-rise buildings, regenerative brakes reduced elevator electricity use by 30% compared with standard geared traction systems.

But not all meaningful efficiencies require lots of capital. One of the most consequential ways that buildings can lower demand immediately is to evaluate their elevators' standby loads. Too many elevators stay on all day, even when no one is using them. The average standby power rating for an elevator is between 0.8 and 2 kilowatts, which can really add up for an elevator that’s “on” but not in use for 5,000 of the 8,760 hours in a year.