Drive Savings with Elevator Efficiency Upgrades

04/01/2015 |

Evaluate current offerings and understand major hurdles

Elevator shaft

Elevator energy efficiency is within reach for many owners, but is often overlooked because elevators only use 2-5% of whole-building energy.

Energy savings of 40% or more may be possible for your elevator – and in many cases, the improvements needed are cost-effective, according to a new study.

The American Council for an Energy-Efficient Economy (ACEEE) estimates that about 900,000 elevators are currently in operation in the U.S., with upgrades of cabs, controls, safety features, and hoist mechanisms occurring every 20-25 years. However, because elevator energy usage generally accounts for only 2-5% of whole-building energy consumption, efficiency technology targeting this area is often unfairly ignored. The organization advocates a shorter upgrade cycle, arguing that the perception of elevator energy efficiency updates as being more costly than the service contract required to implement them is outdated.

Understand Upgrade Options
For hydraulic elevators serving low-rise applications, ACEEE notes that regeneration (in which the motor also acts as a generator feeding power back to the grid) is generally cost-prohibitive given hydraulic elevators’ nearly universal low-duty cycle. The biggest energy savings for hydraulics, therefore, lie in proper valve adjustment, sequential standby modes, and cab improvements such as lighting, ventilation, and door-operating motors. These modest changes offer roughly 50% savings on energy use in these models, the study authors write.

Traction elevators, which can serve anywhere from five to more than 20 floors, enjoy a much wider spectrum of upgrade choices. New approaches such as permanent magnet motors and advanced belts and lift ropes no longer require penthouses and extra HVAC technology, the authors note. Instead, machine room-less (MRL) technology allows compact drive equipment to be installed directly into the hoistway, cutting down on space requirements.

Advanced software packages also benefit traction elevators by allowing energy-efficient approaches like destination dispatch, real-time wait-duration control, standby, and grid response.

However, standards tend to focus almost exclusively on individual elevators rather than banks of multiple elevators serving the same floors, an area where market innovation has outpaced standards, the study continues. Smart strategies for grouped elevators include configuring dispatch controls based on the maximum likely wait for service, meaning the number of elevators required for a specified service level are dispatched at any one time. For example, in an office building, usage tends to be heaviest at the beginning and end of the day and over the lunch hour, so fewer elevators are needed during late morning and early afternoon.

Destination dispatch also helps drive savings in banked elevators by allowing users to select their destination floor in the lobby and share rides with people heading to the same or neighboring floors.

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