Energy Efficient Escalators
Escalators: Variable Speed or Stop Mode vs. Continuous Operation
Sensors that begin escalator operation when occupancy is detected and operates for a preset time after the occupant reaches their destination.
Item ID: 546
Transportation--Elevators & Escalators
Technical Advisory Group: 2014 Commercial Building TAG (#9)
Average TAG Rating: 2.59 out of 5
TAG Ranking Date: 03/17/2014
TAG Rating Commentary:
- Widely used in Europe; what are we waiting for.
- Not very applicable to smaller commercial buildings, difficult to quantify baseline and savings
- This is such an easy efficiency gain with a very quick payback.
Escalators are the most efficient way to move large groups of people. They are widely used in airports, bus and train stations, commercial and office buildings, shopping malls, hotels, hospitals, universities, and government buildings. Energy use of an escalator is dependent upon its step width (proportional to peak load carrying capacity), traffic patterns, control type, annual operating hours, and vertical rise. A shopping mall escalator with a 15-foot rise that operates for 14 hours per day/6 days per week might use between 4,000 to 10,000 kWh/year (Carlos Patrao, "Elevators and Escalators Energy Performance Analysis", 2010 ACEEE Summer Study). A bigger escalator with a 20-foot lift that operates continuously in a hotel or convention center might consume 31,000 kWh annually. An escalator at an airport with a 35-foot lift might use about 60,000 kWh annually.
Several energy savings approaches are available. With low traffic or long periods of no traffic, stop-and-go operation is a possibility. The elevator stops running when not in use and re-starts when the passenger is detected by pressure mats, photocells or infra-red beams. Soft-start capability is required so the elevator can gently accelerate to full-operating speed. This method of operation may be precluded by building codes is often not recommended as it involves liability issues. People who see a stopped escalator also tend to assume it is broken.
An option that is popular in Europe and Asia is to slow the elevator down when no passengers are present. Installing variable speed drives or use of variable voltage motor controllers can result in energy savings of 15% to 40%. This alternative is useful with medium traffic. Regenerative braking can be employed on heavily used down escalators and finally, LED light sources can be installed for skirt guard, comb, and rail lighting. Lighting improvements alone can result in 1,600 to 2,000 kWh/year of energy savings.
Baseline Description: A Conventional 15-foot Lift Escalator in a Shopping Mall
Baseline Energy Use: 7500 kWh per year per Escalator
Manufacturer's Energy Savings Claims:
"Typical" Savings: 40%
Savings Range: From 10% to 73%
Best Estimate of Energy Savings:
"Typical" Savings: 35%
Low and High Energy Savings: 10% to 50%
Energy Savings Reliability: 4 - Extensive Assessment
Kone reports energy savings of up to 40% when inverter control is available and reverts to a "stand-by" speed. Patrao and deAlmedia report that power in a "reduced speed" mode is less than half of the requirement in full-operating mode. Savings of up to 50% are achievable with "stop-and-go" operation (From Kone "Eco-efficient Solutions"). The Hitachi VX Series escalators offer an automatic turn-off option that turns off handrail and skirt guard lighting when no passengers are present.
Energy Use of Emerging Technology:
4,875 kWh per Escalator per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Potential number of units replaced by this technology:
In their "Elevator and Escalator Fun Facts", the National Elevator Industry Inc indicates that there are 35,000 units in the United States. Assuming that 4% of these units are in the Northwest (i.e. that escalators are proportional to population), an escalator population of 1,400 units is estimated.
Regional Technical Potential:
0.00 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Installed first cost per: Escalator
Gutting an old escalator down to its truss frame and installing a modernized unit with controls can cost from $200,000 to $500,000. Another option is control system modernization, which involves installation of variable frequency drives and control panels.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
Reference and Citations: