PROJECT
T
hese days, it’s all eyes to the skies, and for good reason. The number of high-
• energy efficiency, operation cost, and maintenance cost
rise buildings has tripled since 2000 as
• alternative dispatching methods, such as con-
urbanization demands are driving the skyscrap-
ventional dispatching (estimated time of arriv-
er boom. While these massive structures and
al) or destination dispatching (estimated time
the technology supporting them are stealing
to destination).
all the headlines—you may have heard about a
Comparing estimated time of arrival (ETA)
sideways-moving elevator that was unveiled this
versus estimated time to destination (ETD),
year—mid-rise buildings remain equally vital in
with ETA, passengers have a shorter wait time
urban and rural environments.
but longer passenger ride time, while with ETD,
Designing for mid-rise buildings (7 to 20 sto-
there are longer wait times but shorter passenger
ries) presents challenges for architects and de-
ride times. In an ETA situation, the elevator has
signers, especially as it relates to the heart of the
one piece of information to analyze—the direc-
building, the elevator. Numerous elevator-
tion. Regardless of the number or demand of
related criteria must be considered in order to
people in the lobby or their destination, the ele-
maximize building-transportation efficiency,
vators work to bring one car down as quickly as
beginning with selecting the correct type of ele-
possible.
vator for a project.
elevators
These Factors Help Specify Elevators Several elevator options exist for mid-rise buildings. Jeff Walker, thyssenkrupp Elevator
The lone part of the ride that can be shortened is the ETA, but there are some things that
GAINING TRACTION
can’t be shortened or predicted, such as the un-
Traction elevators are most commonly used for
certainty surrounding how many people are
mid-rise applications as they travel much faster
boarding each elevator and where they want to
than hydraulic elevators and can travel to greater
go. This can result in all passengers crowding
heights than hydraulic elevators. Traction eleva-
into one elevator, and a number of multiple
tors use a hoisting system consisting of multiple
floors serviced on each run. Now imagine this
belts or steel cables connected between an ele-
happening throughout the entire building. This
vator car and a counterweight. The inclusion of
is common to all ETA systems; the only im-
multiple ropes increases suspension safety and
provements have been some logic enhance-
reliability. The ropes are wrapped over the ma-
ments, such as parking and zoning. But the only
chine drive sheave in grooves, where the friction
part of the ride that can be enhanced is the wait-
drives the hoisting ropes. Counterweights make
ing time until the elevator arrives.
elevators more efficient by offsetting the weight
Also, in large elevator banks, when a call is
of a car and its passengers, so the motor doesn’t
placed in the hall, only one car will arrive to
have to work as hard.
serve that request. The only way a second car
Gearless traction elevators, which have the drive sheave attached directly to the motor and
will come will be when the first car doors close and another call is registered.
can travel as far as 2,000 ft., are often more du-
Meanwhile, in an ETD situation, all passen-
rable than the building itself, use energy more
gers register their desired destination using a
efficiently, and can deliver energy back to the
touchscreen kiosk in each lobby, providing more
building.
information for the system to analyze. The en-
There are two types of traction elevators, ma-
tire ride of each passenger is known before the
chine room (MR) and machine room-less
elevator arrives, where a variety of things can
(MRL). Machine room includes larger mechani-
now occur. The elevator could bring multiple
cal components for higher duties, but requires
cars down at the same time if a high demand is
additional space for equipment outside the
recognized. Passengers can be grouped in to sim-
hoistway. Meanwhile, machine room-less has
ilar destinations, shortening the ride time. The
compact machines located in the hoistway but is
entire time to the destination can be made more
limited in duty, i.e. speed and capacity.
efficient. In some instances, a passenger may
Above. Traction elevators are the most commonly used for mid-rise applications as they travel much faster than hydraulic elevators and can travel to greater heights than hydraulic elevators. Below. All aspects of movement within a building need to be considered, factoring in lobby size, corridor size, the number of elevators needed, size of elevators needed, and stairways.
wait a little longer to get assigned their appropriKEY CONSIDERATIONS
ate elevator, but ultimately it will make fewer
When designing a mid-rise building, architects
stops enroute to their destination.
should consider the following:
• • • •
A traffic study should be performed when
population (number of occupants and visitors)
considering elevator options for mid-rise build-
distribution of people by floor
ings. A traffic study is vital to better assessing
typical times of arrival and departure
how many elevators and groups are needed, as
critical traffic periods
well as speed, capacity, elevator type (MR or commercialarchitecturemagazine.com
MAY 2018
COMMERCI A L A RCHI T EC T URE
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