Elevators are bandwidth.
Who This Matters To (And Why)
Critical: Architect,Developer,GC. These parties make or lose money directly based on this thesis.
Important: Engineer,Banker,Investor. These parties execute decisions shaped by this thesis.
Context: City,Inspector,Interior Design. These parties need to understand it to avoid friction.
Highest typology impact: Office,Multifamily,Hotel,Mixed Use. Lower impact: Retail,Industrial.
Elevators are bandwidth. Core count is the network capacity of the building.
How It Shapes Development
Elevators are bandwidth because they are the vertical channel capacity of the building's circulation network. Each elevator car has a rated capacity and a round-trip time. Multiply cars by capacity by trips-per-hour and you get the building's total vertical throughput in persons-per-hour. If that throughput is less than the peak demand generated by the building's occupancy, the elevator system is undersized and occupants wait. The elevator count is a capacity planning problem, not a design preference.
High-rise office buildings size elevator banks for an 11–13% handling capacity: the system must be able to move 11–13% of total building population in a 5-minute peak period. A 300,000 SF office building at 200 SF per person has 1,500 occupants. 13% handling capacity requires moving 195 people in 5 minutes. With a 3,500 lb capacity car (about 21 persons), a 40-second floor-to-floor travel time, and typical loading/unloading times, each car delivers roughly 10–12 persons per 5-minute interval to upper floors. Hitting 195 persons requires 16–20 cars. Undersizing to 12 cars saves capital cost but creates 8-minute average wait times at morning peak, which tenants will report to brokers and competitors will use in their marketing.
Destination dispatch systems are a bandwidth optimization. Traditional elevators assign cars to calls inefficiently — multiple cars answer the same floor call. Destination dispatch groups passengers going to the same floor into the same car, increasing car utilization and reducing average wait time. The same handling capacity can be achieved with fewer cars, or the same number of cars can serve a taller building. Destination dispatch is a software upgrade that expands bandwidth without adding hardware. It is common in high-rise buildings where elevator core size is a premium cost.
Residential elevator sizing follows simpler rules but the bandwidth logic is identical. A mid-rise multifamily building of 150 units typically requires 2–3 elevators. Peak demand occurs at move-in/move-out periods and weekend mornings. A single elevator serving 150 units creates unacceptable wait times during peak periods and is a single point of failure during maintenance. Two elevators provide redundancy and adequate throughput. The third elevator is often justified by the building height — above 12–15 stories, round-trip time increases enough that two cars can no longer maintain adequate handling capacity without a third lane of bandwidth.