## Tall buildings provide space for living and working. Elevators enable people to use this space. Consequently, building and elevator planning should complement each other. Layered Zoning of buildings and multi-deck elevators enable efficient buildings and optimal elevator performance.

# Introduction 2021

**During the 1960’s Mr. L. W. Port invented destination group controls by moving the floor buttons in the cars to the call panels in the lobbies.** His concept is brilliant because it enables control of car operations by assigning passengers to specific cars. For the story of the first group with a destination control, refer to chapter 4: Group “brain power”.

Until the re-introduction of destination controls by Schindler, traditional groups, with up /down call buttons in lobbies and floor buttons in cars made efficient car operations impossible, because the random destinations of passengers controlled numbers of car stops. For traditional groups, *large cars were essential to satisfy heavy traffic.*

**Assignment of passengers to specific cars enable "intelligent" groups to control numbers of permitted stops, i.e. to control round trip times of cars, relative to traffic densities.** This ability is very important for single-deck groups because they serve many destinations. For multi-deck groups it is less important because Layered Zoning facilitates low numbers of destinations. For example, one group of triple-deck cars can simultaneously serve six sub-zones of A, B and C floors in a building zone of 18 floors. The number of destinations served by this group is six. Layered Zoning and multi-deck cars reduce numbers of destinations. This is the basis of the superior efficiency of groups with multi-deck cars.

**Numbers of permitted stops, i.e. the dimension time, controls the efficiency of groups. **Each permitted stop of a car implies considerable time “costs” for deceleration, re-acceleration, door opening, door closing and dwell time for passengers going out and/or coming in. Consequently, control of permitted numbers of stops is the basis of efficient group controls. Contract loads and contract speeds are also relevant for the performance of groups; however, these are set values for each group.

**For multi-deck groups, low numbers of destinations imply low numbers of stops, i.e. high transport capacities and best possible time-dependent service qualities.** For *low traffic densities*, their time-dependent service qualities are slightly worse in comparison with single-deck groups, because multi-deck cars may make an extra stop(s) to serve a passenger(s) on another deck(s). S*tress tests* reveal the typical performance- and time-dependent data of multi-deck groups for all traffic densities.

**To appreciate the inherent relativity of group characteristics imagine a building served by one large car.** If we replace this car by two cars, their contract loads can be much less, i.e. much less than 50 % of the large car, *because during the same traffic conditions two cars make less stops, *i.e. have shorter round trip times and higher transport capacities. *This implies each increase of the number of cars of a group facilitates a reduction of its contract load*, moreover time-dependent service qualities improve. The “standardization” of 1600 KG as contract loads for groups in tall buildings, without consideration of the number of cars of a specific group, is absurd.

**The mathematical formula for the number of probable stops affects all performance evaluations.** For example, a car with 10 passengers, to 12 possible destinations, has 7.18 probable stops. For more info, refer to Chapter 13: “Transparent performance calculations”.

For multi-deck groups the *total of passengers on all decks* define the number of probable stops.

**The author claims**** the planning and performance of groups of elevators is an exact mathematical problem that is resolved by the logic of the mathematical models.**The mathematical models make simple calculations based on

*exact data*to assess group performance data. The recorded data of installed groups will confirm the calculated data.

**The author will greatly appreciate independent verification of this thesis by other parties.** The author will report relevant comments or corrections on this website.