Commercial Architecture May 2018 - 61

PROJECT

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

http://www.commercialarchitecturemagazine.com

Table of Contents for the Digital Edition of Commercial Architecture May 2018