THE GHOST OF THE MACHINE
Saying Good-Bye to Elevator Machine Rooms
It is hard to determine, without considerable research, who first conjured the idea of the machine-room-less elevator. It could have been an architect looking for design freedom, developers urging suppliers to reduce construction costs, or building owners trying to maximize rentable space. Anyway you look at it, the result is the same – elevators without machine rooms are now, if only on a limited scale, available to the market and are worthwhile considering for new construction and retrofits.
Some of the systems referred to here are not yet available in Canada, because the revolution in and enthusiasm for this technology first took hold in Europe and Asia. It is only now attracting significant attention in this part of the world.
The selling points for the technology are that it reduces construction costs, is very energy efficient, and is environmentally friendly. The only down side is that it has limited applications right now due to speed and height restrictions.
Changes were heralded in the elevator industry when noisy generators that often caused leveling problems and emitted carbon dust were eliminated. They were replaced by variable voltage, variable frequency (VVVF) drives. The complete drive system includes the main motor, the power supply to it, the monitor and control of speed (acceleration and deceleration) as well as the position of the elevator in the hoistway.
When the VVVF drive is used in concert with a gearless hoist machine, the result is an alternating current (AC) gearless system, the basic elements of an elevator without a machine room.
Reduced Construction Costs
Such an elevator reduces building construction costs by requiring less material and less space. For example, the Fujitec Eceed elevator uses a slightly different format. It is designed with the hoist machine in the hoistway pit and the control system adjacent to the elevator entrance on the second landing. According to the company’s marketing material, which focuses on installations in Japan, this configuration reduces elevator installation space by about 36 per cent of a conventional roped elevator, and about 31 per cent of a hydraulic elevator.
The cost benefit also extends to the construction of the elevator. Without machine rooms, cranes for hoisting heavy machinery to build those rooms are unnecessary.
Greater Energy Efficiency
Building owners should enjoy long-term savings with these installations,
because they are more energy efficient. Kone Inc., the leader in the
race to market the technology (with approximately 23,000 units installed
worldwide) claims that its MonoSpace system, using the EcoDisc AC
Gearless machine, provides “up to 60 per cent reduction in energy
consumption compared to traditional traction and hydraulic elevators.”
There is always a risk that the hydraulic elevator cylinder of a
standard elevator, buried in the ground, will develop a leak and thus
contaminate the soil. This has become less of a concern with the protection
of polyvinyl chloride (PVC) cylinder encapsulation, or holeless installations.
However, the threat still exists. With a machine-room-less elevator,
this concern is eradicated.
The gearless machinery that powers this innovation has become known
throughout the industry for its exceptional performance. Unfortunately,
the gearless machines used in typical elevator installations are very
expensive, hence are most often only used in tall commercial building
applications that require high-speed elevators.
Hoisting the Load
Otis Elevator has incorporated another new technology with their
Gen2 system. For this model, Otis uses polyurethane-coated steel belts
rather than traditional steel hoist ropes to support the load of the
elevator cab and counterweight. Otis must be credited for their efforts
to take the design of these elevators one step further. One advantage
of the coated steel belts is their tremendous flexibility and enhanced
traction control, which allow for a more efficient power transfer,
further reducing the size of the machine required to operate the elevator.
Speed and Height Restrictions
The down side to machine-room-less elevators, as mentioned before,
is that they are still limited in their application due to height
and speed restrictions. KONE Inc. is currently installing models in
Canada with rises of up to 90 feet and speeds of 200 feet per minute.
Also, because they are new they have yet to prove their longevity.
Michael Morgenstern is a partner at National Elevator Consulting, based in Toronto, Ontario.