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Drive Savings with Elevator Efficiency Upgrades
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of elevator energy efficiency updates as being more costly than the service contract required to implement them is outdated.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.PageBreak
Barriers to Adoption
In addition to elevators’ small share of annual energy use, several obstacles interfere with greater adoption of efficiency technology.
1) Sticker shock. “Although architects and owners care about the elevator experience as an extension of the building’s presentation, incremental costs are a barrier regardless of payback or return on investment,” the study authors write. “The challenge is to help customers understand that lifecycle costs matter much more than first costs.” Unfortunately, elevator replacement payback periods can be long – especially in low-rise buildings where trips are shorter and fewer than those in taller buildings – which can dissuade potential investors.
2) Tenant-landlord bundles. Elevators are generally considered as common space in buildings with multiple tenants, so the associated energy consumption is usually bundled with the energy use and upkeep of other common areas and billed to tenants as a general O&M charge. “The overall reduction in costs per tenant is usually not significant enough to motivate an upgrade,” ACEEE says.
3) Difficulty in quantifying soft benefits. Some upgrades, particularly advanced software packages, offer shorter wait times, higher reliability, and rides that are smoother and faster in addition to lower energy consumption. However, it’s difficult to assign a dollar value to an improved experience, so these benefits are underrated.
4) The lack of an established performance metric. ASHRAE is currently attempting to develop credible minimum efficiency levels for elevators, including a usage-based elevator classification and maximum standby and travel energy. Including elevators in ASHRAE 90.1 would go a long way to establishing much-needed performance requirements, ACEEE believes: “This would conform to long-standing incentives practice for HVAC equipment, for which the baseline has been the relevant legal federal minimum energy standard.”
The study also calls for an industry program to identify the top performers in elevator efficiency, but notes that ENERGY STAR inclusion may not be appropriate. “For mass-produced products in the ENERGY STAR program, 20-25% of the models offered would meet the proposed criterion … [However,] elevators are typically built to order, not mass-produced, so the concept of ‘model’ is quite different.”
Instead, a performance-based elevator efficiency recognition should be based on the NEMA Premium motor specification and the Consortium for Energy Efficiency’s public awareness program Motor Decisions Matter, ACEEE argues.
To learn more about your upgrade options and what’s ahead for elevator technology, read Advancing Elevator Energy Efficiency at aceee.org.