# The Science Behind The Elevator Algorithm

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You press a button and wait. For anyone who has partaken in the delicate dance of pushing ‘up’ or ‘down’ and letting fate decide when that carriage door opens, you’ll understand the mystery of the elevator algorithm. It might seem like elevators have a mind of their own — and well, in many ways, they do.

Elevators are part of a complex yet greatly intelligent computing system. A lot happens when someone pushes that lift door. From an outside view, someone traveling from the lobby to the top floor will just see a metal box with doors.

Behind those metal walls, however, is some unique hardware and software working together under a sophisticated and energy-efficient elevator algorithm.

## How do elevators work?

Commercial elevators typically fall into two types — traction or hydraulic. With traction elevators, the carriage is hoisted up and down using a system of cables, pulleys, and counterweights.

Traction elevators are considered to be more energy-efficient than hydraulic elevators as they rely on the counterweight to share some of the load. A hydraulic elevator, however, uses an electronic pump to power up pistons that causes the elevator to rise. These types of elevators are more commonly used in buildings 5 stories or less.

Whether traction or hydraulic, all elevators have a special “elevator algorithm” that is fed into the lift’s computer software. This computerized blueprint is what dictates which floor the lift will stop at and which sequence it will take when multiple buttons are pressed.

## How are modern elevators energy-efficient?

The elevator algorithm consists of two rules:

• Keep heading in the same direction if all passengers are requesting to go in that same direction;
• If there are no further requests to head in the same direction, stop and become idle or change direction if there’s a request for the opposite direction.

This computerized system is extremely energy-efficient, as it gets all passengers on the lift in one round-trip. Each lift in each building will have its own unique dispatch direction.

This is because the elevator algorithm used in such software is entirely based on past usage patterns — called traffic studies. Therefore, modern elevators operate in the most optimal, efficient way for their building.

### Regenerative power

Elevators have always relied on energy. In order to get from the ground to the top floor, modern traction lifts use what’s known as a regenerative drive which captures the downward energy of the carriage and converts it to power.

This electrical power is then pumped back into the building’s energy grid. The use of regenerative systems can offer energy savings of over 1,000 kWh per year as opposed to non-regenerative drives.

### Efficient hardware

Energy-efficient elevators use AC (Alternating Current) driven electric motors, producing energy savings of up to 50% compared to DC (Direct Current) hoists.

They also come equipped with energy-efficient lighting such as low-heat LED lights and door drive motors that can go into standby mode when not in use — saving energy and reducing operating costs.

### Efficient software

There are many different dispatch controls in an elevator’s computer algorithm. One strategy that is among the most popular is called ‘estimated time of arrival control.’

This is where the computer considers all carriages moving toward a call and assigns the carriage that will get there in the fastest time possible. Modern elevator algorithms, therefore, minimize passenger waiting and journey times while using the least amount of energy.

## Summing up

With all these options, engineers can deliver energy-efficient elevators that not only save on power but provide passengers with the most time-saving and comfortable ride. For building owners, changing to modern hardware and software systems will improve the efficiency of their lifts and make them cost-effective to run.

While elevators may remain a mystery to most, smarter technology and improved science allow for continued optimal operation and an environmentally friendly way of transporting passengers within a high-rise structure.

The most efficient of elevators combine a range of hardware and software systems that reduce energy consumption and have the ability to make smart choices to decrease any wasted energy output.

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