Cities on the rise, picture by Ruslan Bardash, taken from unsplash.com
Skyscrapers (worm’s eye view), picture by Scott Webb, taken from unsplash.com
Making the match: finding the perfect elevators for every building
How do architects and builders find the “perfect” elevator solution for a mid-rise office building vs. a supertall, mixed-use skyscraper? They get help from experts who know the options. Two specialists from TK Elevator, Andreas Schmidt and Sushanthan Somasundaram, offer their insight.
Bigger cities mean taller buildings and more elevator options
With the population growth of urban centers skyrocketing, the transportation solutions within buildings are an essential component of the overall public transport structure of cities. According to Sushanthan Somasundaram: “As cities are booming and urban space is limited, there is only one direction in which cities can grow – and that is up. This development will require building and mobility solutions that are more flexible, versatile, and modular. Elevator technologies must continue to evolve to meet the demands of high-density urban living.”
Andreas Schmidt adds: “It was the invention of the elevator that made skyscrapers possible, but over the years elevators did not keep pace with the innovative ideas of architects. Only recently have elevators come of age. Today, elevators can travel in any direction, reach limitless heights, and finally navigate even the most creative building geometries.”
If anything is possible when it comes to elevators – and choices abound – how does one pick the right elevator or elevators for a building?
A look at building types and how they affect elevator selection
To put it simply, there are different types of elevators for different types of buildings – but it’s not quite that simple. When selecting the elevators, the first step towards a holistic overview is to look at the size and shape of a building, how it will be used, and how many people will use it. This makes it possible to calculate the anticipated circulation. For more complex buildings, getting the right fit also involves sophisticated programs that simulate the predicted travel behavior (i.e. circulation) of people within the building for an overall view that compares and contrasts the costs vs. benefits of different elevator types.
Low-rise buildings are defined by elevator speeds of up to 1.75 m/s. Many are mixed-used buildings: residential, office space, and retail. With only a small number of users, smaller low-rise buildings can meet their people-moving needs with one single-cabin elevator. For large low-rise buildings, like department stores and malls, a mix of multiple single-cabin elevators, freight elevators, and eye-catching escalators is normally the best choice.
Mid-rise buildings are defined by elevator speeds of up to 3 m/s. Buildings of this size are most commonly commercial buildings. When a building of this size has two distinct user groups (e.g. office & hotel), it might have two completely separate lobbies and elevator systems. This type of building often uses several single-cabin elevators, but occasionally double deck or more versatile TWIN elevators can be used as well. A TWIN elevator has two independent cabins in a single shaft, which doubles the person-moving capacity of that single shaft.
All of these elevators, however, must operate in harmony with one another. That’s why new systems normally employ a so-called destination dispatch system, such as AGILE, to ensure that users are grouped and assigned to elevators in the most efficient way possible. Older buildings can also be modernized with AGILE.
High-rise buildings or skyscrapers (40+ stories and 150+ meters) can be further divided into 3 categories: tall buildings (150-299 meters), supertall buildings (300-599 meters), and megatall buildings (600+ meters).
In the past, as buildings became higher, they needed more and more elevator shafts. This is because traditional elevators always involved one elevator cabin in one shaft. The taller you went, the more shafts you would need to keep people moving. Those shafts, however, occupy a lot of valuable space.
Nowadays, however, it is possible to move even more people while utilizing fewer shafts, regardless of building height. This is thanks to destination dispatch systems and predictive maintenance, along with innovative new elevators such as high-speed lifts, double-deckers, the TWIN (two independent cabins in one shaft), and the MULTI (multiple mag-lev powered cabins that can circulate through multiple shafts horizontally and vertically).
When experts in the elevator industry talk about circulation, movement, or people flow, they mean the desire to ensure the constant, uninterrupted movement of people. Waiting times at elevators are the biggest hurdle to the efficient flow of people. High-speed elevators are often important, but the most efficient way to move a large number of people in buildings is to find the best mix of elevators for each building to reduce waiting times.
Andreas Schmidt, Head of Consulting & Pricing for MULTI at TK Elevator, explains how it’s done: “We have a sophisticated and comprehensive calculation model that helps us design the best elevator configuration for a building. To arrive at the ideal mix and the best solution for our customers, we have to precisely evaluate the stops, special hotspots in the building (restaurants, observation decks, etc.), the number of elevator cabins and shafts, and peak and off-peak times (think: rush hour). The ultimate goal is to ensure that end-users can move throughout a building efficiently and easily. Ideally, there would be a constant flow of people and no waiting times at all. The multiple cabin system of MULTI is currently the most efficient method of keeping waiting and traveling times as short as possible.”
Effects of building taller on elevator design
Sushanthan Somasundaram, Head of New Installation at TK Elevator, explains the effect of building tall: “As buildings become taller and more complex, the elevator industry has to adapt. There are several aspects and interdependencies we have to consider. When thinking about it, should we use ropes or is it more effective to use a magnetic system and get rid of limitations in height and direction?”
“The increasing size of a building is often accompanied by a mixed-use of different floors. We increasingly see mixed-use buildings that include a hotel, residential space, offices, retail at the bottom, and a restaurant at the top. That makes it more complicated to ensure efficient transportation for all users in the building while keeping safety and security in mind – not everyone is always allowed to access all the floors, but quick emergency evacuation should still be ensured. At the same time, quality of life and work/life balance must also be included in the planning of a complex tall building.”
“On a technical level, making buildings higher increases natural effects, such as wind or earthquakes, on the building structure, and these factors also impact the elevator solutions inside the building. When planning for elevators, we have to take building sway and stack effects into account, as they have direct repercussions on the potential sway of elevator ropes. Differences in air pressure can also affect the elevator doors.”
Choosing the right elevator mix for skyscrapers
For mixed-use buildings, the interaction and cooperation of different elevator types are very important. Below, Somasundaram explains how that choice becomes particularly critical for supertall buildings.
Choosing the right elevator solutions for a building
Somasundaram: “Our local teams work very closely with almost everyone involved in the planning and development of a new building, but especially with architects, investors, and lift consultants in order to define the optimum vertical transportation concept for a given building while keeping the size of the building core as small as possible.”
“For this, the first and foremost task is to understand the correct demands and future proposed usage of the building: how are the different sections of the building to be used and what are the specific demands of those areas concerning the elevator system, building access, and security. We have to ask many questions: Where will people access the building and how many people will arrive within a given amount of time? When are the different populations of the building (office workers, residents, restaurant or club guests, etc.) present inside the building, when do they typically move around in the building, and can the different populations be mixed within the elevator cabins or do they need to remain separate?”
“At the same time, we also need to consider the movement of freight within the building, especially if we have residential, hotel, or restaurant levels. Finally, the local regulations concerning firefighting and evacuation procedures also need to be taken into account when planning a building.”
“Once the usage and flow are understood, our local teams can start planning the different elevator groups and compare possible solutions using a traffic analysis software, which can simulate the different ways in which the circulation of people changes depending on the elevator systems or their technical specifications.”
Building transportation at TK Elevator
Somasundaram: “TK Elevator is the only elevator manufacturer that can supply the complete scope of elevators currently available for taller buildings, ranging from traditional elevators (with one cabin, one machine and one counterweight per shaft), double-decker elevators (two cabins fixed one on top of the other with one machine and one counterweight per shaft), all the way to the TWIN elevator (two independent cabins, each with their own machine and counterweight inside the same shaft), and the MULTI® elevator (many cabins inside the same shaft, working without ropes but with a linear motor system allowing for horizontal as well as vertical movement).”
“TWIN requires fewer shafts to move the same amount of people as traditional elevators, and it increases the flexibility of the building. Unlike a double-decker, for example, the floors don’t always have to be the same distance from one another, and the two cabins can be used to adapt to changes in building populations. Another key advantage of the TWIN system is efficiency: during low demand, we can put the unneeded cabin in a temporary parking position.”
The rise of mixed-use buildings
According to Schmidt: “Mixed-use buildings are the key for efficient cities of the future.” He believes that “pure” residential and office buildings will become less common: “Buildings keep getting bigger. The number of buildings over 200 meters in height has tripled since the year 2000. These gigantic skyscrapers are becoming small cities of their own with work, residential, and leisure areas. Elevators must move users between these zones, taking the shortest possible paths.”
Schmidt goes on to explain that when it comes to mixed-use buildings, certain user behaviors become less important, while others become more so: “In a typical office building, we have to consider three rush-hour phases: morning, lunch, and evening. These rush hours become less pronounced in a mixed-use building as the building experiences a near-constant flow of people. On the other hand, individual stops might become more important. Apart from the ground level, floors with retail might be especially busy, and all these factors must be taken into account.”
When elevators add value
Yet another point to consider is whether you want more out of an elevator than only mobility. Can an elevator make a building more attractive, allow for new designs, and create more rentable space? Schmidt discusses how the MULTI elevator can do all that and teases two upcoming projects involving the MULTI.
How elevators can add value to a building
Schmidt: “MULTI not only offers spectacular features like linear propulsion, horizontal movement, and multiple cabins in one shaft, it also provides tangible benefits to architects and building owners: the multi-cabin system reduces the footprint of the elevator system by up to 50 percent. That means more space to rent or sell.”
“Its ability to move horizontally makes new connections possible. Connections at height, so-called skybridges, are much more attractive if elevators can travel across them. Linear propulsion makes ropes unnecessary and makes the height limits of traditional systems (approx. 500 meters) a thing of the past. New building shapes and record heights can be achieved with MULTI without interruption or any additional elevator banks. It also eliminates the need for a mechanical room above the shaft, so MULTI can even serve the very top floor of a building. Altogether, this means that we will be seeing some interesting and unique buildings, some of which are already being designed today.
MULTI projects in Germany
Schmidt: “We are currently working on two concepts for large buildings in Germany, one of them will be a new construction, the other one involves a building that will be renovated and adapted for new uses. MULTI will be the main element of transportation, but not just because it will offer several horizontal paths within the building. It will also offer transportation between the building interior and local metro stations. The entire concepts are brought to life with MULTI. We are confident that both projects will be completed within a few years.”
Our urban future goes further with elevators
As cities grow and buildings become taller, we need elevator solutions that ensure that people can move smoothly from place to place with as little interruption as possible. But to maximize convenience in cities, we also need to start thinking more about connections between buildings, and how elevators like MULTI can make those connections possible both underground or via skybridges. With creative ideas like the Hanging City concept, it seems clear that the sky truly is the limit.