I DID NOT UNDERSTAND ELEVATORS.
(read all the way to the bottom for the pub trivia answer)
The first time I took the PPD Exam, I had three questions regarding elevators, and I am certain I did not answer them correctly.
As a result, the ONLY SECTION in Mechanical and Electrical Equipment for Buildings I read was ELEVATORS because I DID NOT UNDERSTAND which one when, why, and how to power it. So let me help you with some things you need to know about elevators:
Elevators typically cost 5-10% of the overall construction budget.
When selecting elevators, consider 1. Desired wait time 2. Speed 3. Loading 4. Elevator cost and 5. Building Height and associated Space required
Hydraulic Elevators are basic (slow) piston-driven elevators for service and people up to max 6 floors (or 60 feet) depending on what reference you read.
Traction Elevators are lifted by ropes (or chains) attached to motors above. They are for mid to high-rise elevators, are counterweighted, and are considered high speed.
Geared Traction elevators are driven by gearboxes. They are not as fast as gearless, but they are faster than traction elevators.
Gearless Traction elevators are faster than geared and can be more efficient, quieter, and less maintenance with a longer lifespan.
Machine Room Less - are both geared and gearless traction options. They (MRL) are used often when the floor area is at a premium. The control room of an MRL Elevator is on the highest level of the building.
FYI - there is a type of elevator that I had never had any exposure to called a HOLELESS HYDRAULIC elevator. It is a low rise elevator for situations where the soil can not support an elevator shaft OR the building site has a high water table (so drilling a hydraulic hole would be dangerous to the environment)
BANKS OF ELEVATORS do not require as much power as a single elevator - i.e. there is a POWER REDUCTION FACTOR applied because NOT ALL ELEVATORS operate at once. This is explained really well in MEEB page 1500.
Elevator energy recovery can re-capture as much as 75% of the energy for the system.
Most commercial elevator doors are 3'-6" wide. There are single doors and 2-speed doors. A 2-speed door is a door with two halves that travel at different speeds to complete opening at the same time.
There are various control systems to elevator banks that I would rather YOU read about than try to explain myself.
FYI - Elevators are NOT a part of a building's Egress system.
During a Fire (when heat or smoke is detected) an elevator will:
* Open and pause at the next floor it reaches for passengers to exit
* Return to the designated emergency (recall) floor level (usually the ground floor unless otherwise programmed or that floor activated the fire alarm system)
* Once the elevator reaches its designated emergency level - the elevator will stop and doors will open for emergency personal - who will use the emergency override key to operate the elevator as needed.
* All call buttons will be deactivated / not responded to.
* The elevator will remain in its emergency position until after the fire system has been reset.
* It is never safe to use an elevator during a building fire, as the passageway is a vertical fire shaft.
(actual drawing in my sketchbook)
Fun story:
Philadelphia City Hall has an elevator up to the observatory tower, which is about 510 feet up under the William Penn statue. It is not the highest observatory in the city, but it is in the middle of the master plan on Broad and Market streets. When you go up to the observatory platform you can see for about 13 miles in each direction.
(TRIVIA: WILLIAM PENN in on top of Philadelphia City Hall).
It is an old elevator that bounces when it gets where it is going. I take every person who visits me and is not from Philadelphia up that elevator.
One day I asked the Elevator attendant how he liked his job.
His real-life answer that I am not making up was: