Building Population
Estimate a building's population, Pop = (area per floor × number of floors) ÷ density, from the usable area per floor (m²), the number of floors and the occupancy density (m² per person). The result, in people, is the total population to be served by the vertical transport — the starting point of elevator traffic analysis. Occupancy density varies with use: ~10 m²/person in dense offices, ~15-20 m²/person in standard offices, with specific values for hotels and residences. Compared with the elevators' handling capacity, it tells whether the system is adequate. Enter the area per floor, the number of floors and the density.
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Building population
Every vertical transportation analysis starts with one question: how many people must the elevator system serve? The building population estimates exactly that: Pop = (floor area × number of floors) ÷ occupancy density, dividing the total usable area (area per floor × number of floors) by the occupancy density (how many square metres, on average, per person). The density varies with the building use: dense offices (call centres, open-plan spaces) reach ~8-10 m²/person; standard offices, ~12-15 m²/person; premium offices (individual rooms), ~18-25 m²/person; hotels and residential buildings apply criteria of their own (people per room or apartment). The result is the total population to be served. From it comes the peak demand for transportation: the share of the population that must be moved during the five most critical minutes (12-15% for offices at the morning up-peak, less in other uses). That peak demand, compared with the handling capacity of the elevators, tells whether the system is adequate or whether elevators are missing (or in excess). The population also drives the sizing of stairs, emergency exits, restrooms and parking — it is a fundamental parameter in the design of any building. Enter the floor area, the number of floors and the occupancy density.
Related Tools
Number of Elevators Required
Calculate the number of elevators required, N = peak demand ÷ capacity per elevator, dividing the peak transport demand (people in 5 min) by the handling capacity of a single elevator (people in 5 min). The result is the minimum number of elevators in the group to meet peak demand. In practice, round up and also check the resulting traffic interval (waiting quality). Peak demand comes from the building population times the peak percentage (12-15% in offices). Undersizing causes queues and long waits. Enter the peak demand and the capacity per elevator.
Probable Stops
Calculate the probable number of stops of an elevator, S = N × (1 − (1 − 1/N)^P), from the number of served floors N and the number of passengers P in the car. The result is how many floors, on average, the elevator actually stops at during a trip (probabilistically, two passengers may go to the same floor). It is an essential parameter of the round trip time calculation: more stops raise the RTT. The formula assumes passengers choose destination floors randomly and uniformly. With a full car, S approaches N (stops at almost all). Enter the number of floors and passengers.
Elevator Traffic Interval
Calculate the traffic interval (average waiting time) of an elevator group, INT = RTT ÷ N, dividing the round trip time RTT (s) by the number of elevators N in the group. The result, in seconds, is the average time between elevator arrivals at the main floor — the main service-quality indicator perceived by users (waiting time). Intervals up to 30 s are excellent; above 50-60 s, poor. More elevators in the group reduce the interval. It is the key criterion in sizing the number of elevators. Enter the RTT and the number of elevators.
Round Trip Time (RTT)
Estimate an elevator's round trip time (RTT), RTT = 2·(H ÷ v) + stops × t_stop, from the travel height H (m), the speed v (m/s), the number of probable stops and the average time per stop (s, including deceleration, door opening/closing and boarding). The result, in seconds, is the time of a complete up-and-down cycle with stops — a central parameter of vertical traffic analysis. The higher the RTT, the lower the handling capacity and the longer the interval between cars. Enter the height, the speed, the number of stops and the time per stop.
Handling Capacity (5 min)
Calculate an elevator's handling capacity over 5 minutes, HC = (300 × Q) ÷ RTT, from the car capacity Q (people) and the round trip time RTT (s). The result, in people carried per 5 minutes, is the standard vertical-traffic performance metric (building peak demand is usually measured over 5 min). The factor 300 is the seconds in 5 minutes. Multiplied by the number of elevators and compared with the building population, it tells whether the system meets demand (typically 12-15% of the population in 5 min in offices). Enter the car capacity and the RTT.
Hoist Rope Tension
Calculate the resultant force in an elevator's hoist rope, F = (Q + M_car − M_counterweight)·g, from the payload Q, the car mass and the counterweight mass (kg). The result, in newtons, is the unbalanced effort the steel ropes must transmit, already net of the counterweight's balancing effect. It is the basis for sizing the ropes (number, diameter and safety factor, typically ≥ 12 in elevator codes) and the traction sheave. When the load is such that car + load ≈ counterweight, the force tends to zero (balanced system). Enter the load, the car mass and the counterweight mass.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.