Elevator Energy Use: Hydraulic Elevators vs. Traction Elevators
Our friends at buildingwell.org were kind enough to share some of their extensive knowledge with us, so today we're hoping to provide you with some helpful information on elevator options.
Elevator choices can significantly influence a building’s energy use. The upfront costs of a traction elevator are higher than a hydraulic model, however, they are significantly more energy efficient.
According to an article written by Henry Gifford for Home Energy Magazine in their January/February 2010 issue, we learn that a hydraulic model uses 30 times more electricity than a traction elevator.
If your rehab will allow you to consider alternative elevator options, it is well worth considering a traction elevator if the budget permits.
If you are not doing an extensive rehab and are not able to switch from a hydraulic to a traction model, there are still things you can do to reduce energy use:
- Ask for equipment that does not need to be heated or cooled.
- Ask for LED lights in the buttons and cab.
- The elevator cab in traction elevators is lifted with cables, using weights to counterbalance the weight of the cab with the riders.
- It uses less energy than hydraulic elevators because the motor is only used to overcome friction - there is no lifting involved because of the counterweight system. The only time the motor is used in traction elevators to lift the cab is when the counterweight is not even with the cab weight.
- The most inefficient of these elevators are older models that use direct-current electricity - used because it is easy to control speed with DC current.
- Most of the energy used by these elevators happens when it is idle from the heating, cooling and lighting systems. Using LED lighting and timers for fans will help reduce the energy use.
- To put the energy use in relative terms, the energy used in light sensor stairways exceeds that of the energy used for a traction elevator ride.
- The elevators use a pump system to push a cylinder of fluid on a piston, lifting the cab.
- Energy used to lift the elevator does not get recovered on the trip going down, it is completely lost; this is because hydraulic elevators do not use a counterweight system.
- The fluid used in the pump system in modern elevators is oil versus the old systems that used water; this is because the elevators were experiencing rusting issues. The oil now causes major safety issues if there are any leaks in the system.
- One advantage is that hydraulic elevators allow for a simple building structure; the cylinder used to move the elevators up and down is supported by the soil beneath the building versus the building itself.
- Many of the major elevator manufacturers no longer offer hydraulic elevators.