Webinar

[00:00:00] Sara Korolevich: Good morning, everybody—and good afternoon to some of you. Welcome, and thank you for joining our webinar, “Elevator Design for Tall Buildings.” My name is Sara Korolevich, and I lead content and campaigns at VDA. I'm based in Phoenix. Please say hello in the chat and let us know where you're joining us from.

Many of you are clients of VDA, D2E, or GUNN—welcome. For those who may not be familiar with VDA, we are a vertical transportation consulting firm serving clients across the U.S., Canada, and the U.K. VDA provides elevator consulting services across the life cycle of your buildings, helping you make decisions with the full picture in mind, whether that involves elevator and escalator design for new construction or modernization planning for existing installations.

Programs like this webinar are intended to help building owners, developers, and architects better understand vertical transportation design challenges and solutions.

Just a few housekeeping notes. You can use the Zoom chat for comments, and we'll be sharing some links. Please use the Q&A box at the bottom of your screen for any questions, and we will get to those at the end when we have our live Q&A session. If you need a live transcript, you can click the CC button.

Just a reminder: the recording and slides will be shared after the webinar. If you're joining us for continuing education credits through the AIA in the U.S., Canada, or the U.K., we'll explain how to receive those credits at the end of the presentation. All right, one quick disclaimer: the information provided during this webinar is for general educational and informational purposes only.

It does not constitute professional or legal advice. Attendees are encouraged to consult a qualified professional about their specific situation before taking any action based on the presentation. Now, let's get to the good stuff: our presenters. This is a unique opportunity to hear from three vertical transportation experts within the VDA family, representing three of our global offices.

Michael Muñoz is VDA's senior vice president of design services and brings 20 years of experience leading the planning, design, and coordination of elevator and escalator systems for projects worldwide. Eric Peterson is president and CEO of GUNN. He is a professional engineer and qualified elevator inspector with nearly 30 years of experience in elevator system design, engineering, inspections, and construction oversight.

Paul Burns, based in London, is the [00:03:00] design director at D2E and brings more than 20 years of experience developing vertical transportation strategies for complex projects in the U.K. and globally.

Here's our agenda for today. We'll discuss tall-building code requirements, elevator strategies, design issues for tall buildings, and international perspectives. Then, of course, we'll move into a live Q&A session. I'll also share information about continuing education credits and how to contact our presenters or VDA generally. With that, I'll hand it over to Michael Muñoz.

Michael's going to speak a little bit about tall buildings generally around the world what that looks like. Michael, I'll hand it over to you.

[00:03:50] Michael Muñoz : Great. Thanks, Sara. Appreciate the introduction. So obviously we're talking about tall buildings here, and the word tall is maybe subjective, and so we want to make sure everyone's using the same definition or vernacular.

These are some statistics showing where tall and supertall buildings are located around the world. The information comes from our friends at the CTBUH, the Council on Tall Buildings and Urban Habitat. We define a tall building here as one measuring at least 200 meters, or 650 feet, and a supertall building as one measuring at least 300 meters, or 984 feet. One quick point of clarification: the supertall buildings listed in the table on the right are also included in the table on the left because they exceed 200 meters.

And so what we can see is that for both tall and super tall buildings, the majority, overwhelming percentage are in Asia, right? There's a good amount in the Middle East, followed by North America, then Europe, Africa and lastly, South America. What's really interesting here, though, is that the spread doesn't change too much from tall to super tall.

A little less than 10% of tall buildings qualify as supertall: 256 out of 2,580. This helps frame the types of buildings we're discussing and provides a sense of how many currently exist worldwide. We can go to the next slide.

And we'll just point out a few projects that the VDA family of companies has consulted on that fall into the super tall. These are all, 1,000 feet or better. Strong presence of projects in New York City, but also we've got some from we've got a project from Egypt, the Iconic Tower, and we've got the Al Hamra Tower in Kuwait.

Many more buildings qualify as tall by exceeding 200 meters, but we wanted to provide a small sample of projects this group has [00:06:00] worked on in the past. From here, we'll begin discussing codes, and I'll turn it over to Paul Burns.

[00:06:12] Paul Burns: Thank you, Michael. Thank you very much, and Sara, thank you for the introduction. So I'm Paul Burns. I'm with D2E based here in London in the U. K.. And for the next few minutes I'll be exploring some of the challenges associated with compliance and safety around vertical transportation in tall buildings.

Next slide, please. Codes, standards, regulations, guidance, legislation, bills, and acts are all terms that describe the national and international rules we collectively agree to follow. They range from full legal requirements to general best practices. Although their primary purpose is to protect passengers and those who work on or around elevators, some also address how elevators should behave in an emergency, equal access for people with mobility impairments, continuity of elevator operations in certain geographic regions such as seismic zones, and compatibility between lifts or elevators and other electromechanical systems in the building.

Next slide, please

And in addition to these national and international rules, developers and operators of particular types of buildings often have their own requirements that have evolved over years of experience, particular customer feedback, and so on. And whilst these requirements aren't enforced by approving authorities, knowledge of what they are and compliance with them is no less important to the projects we work on and we support.

Next slide, please.

Most regions of the world—and most individual countries—have a national body responsible for certification, inspection, and standardization related to construction in the built environment within that jurisdiction. The VDA Group of companies is uniquely positioned to support international projects, with offices not only across the United States and Canada, but also in the United Kingdom, Mumbai, Jordan, and, most recently, Dubai. This allows us to draw on international knowledge and firsthand local experience.

A large number, if not most, of these national regulatory bodies tend to leverage the North American ASME/CSA harmonized code or the European harmonized EN 81 code series when setting their own requirements for vertical transportation. Next slide, [00:09:00] please. And in addition to those particular codes and standards, there are other frequently used international standards, which include the ISO 8100 series, of which ISO 8100-1 for passenger and goods passenger lifts was recently published in Europe.

The National Fire Protection Association, NFPA 70, also known as the NEC or National Electrical Code, which focuses primarily on a building's electrical requirements and protection in fire. And the International Code Council's International Building Code, IBC, which began its life in North America, but is increasingly being seen and adopted around the world.

Its North American origins mean it tends to reference ASME and CSA rather than EN 81. And chapter 30 is of particular relevance for elevators and conveying systems. Next slide, please

So fire and life safety codes tend to be a particular and an obvious focus for elevators and buildings in general. So I'm going to spend the next few minutes reviewing fire and life safety requirements of the ASME/CSA codes, code and the EN 81 series. The elevator codes themselves have very little to say about how many firefighters’ lifts a building needs, or in- or indeed where they need to be located in the building.

ASME/CSA requires at least at least one firefighters’ lift in a building. And EN 81-72, which is the firefighters code in the European harmonized codes, really has very little to say about that subject at all. This information should come from the fire strategy, and that is produced and the domain of the fire consultant.

So that collaboration and coordination is important. There are other documents available which have relevant information. For example, in the U. K., we have the U. K. Building Regulations Part B British Standard BS 9999 for buildings that are not dwellings, or BS 9991 for dwellings, that provide particular guidance on the number and location of, and when a firefighters’ lift is needed.

So specifically buildings that have an occupied level greater than 18 meters above the fire service access level or 10 meters below that level require a firefighters’ lift. For floor areas greater than 900 square meters, a second firefighter shaft is required. The firefighters’ lift has to serve every floor in the building except the top floor, if that is a plant floor.

And there are particular requirements in terms of how many shafts there should be and to what distance they should be, which is governed by the maximum hose distances, which themselves are governed [00:12:00] by or contingent upon whether the building includes sprinklers or not. So next slide, please.

The fire and life safety codes do, however, provide good guidance on how firefighters’ elevators and lifts are required to be configured. And whilst the themes, the general principles are similar, there are specific differences. For example, the ASME/CSA code has a minimum capacity requirement of 900 kg or about 2,000 pounds.

All levels need to be served. It limits a changeover to just one to reach the top of the building, an elevator change to reach the top of the building of just one. Standby power is a requirement. There must be communications between a fire command center or central alarm control facility and the elevator itself.

The command or control center requires a secondary elevator recall switch or function, and initiating the firefighters' emergency operation function triggers pit drains and sumps in all elevators. Next slide, please. Compared to EN 81-72, the minimum capacity requirement in EN 81-72 is 630 kg or about 1,390 pounds.

And EN 81-72 gives minimum requirements for the car footprint, the area of the car, and entrance dimensions. This code requires that the firefighters' lifts reach the top of the building in 60 seconds or less for buildings up to 200 meters, so tall buildings. And thereafter, there are concessions of an additional second for every three meters in height for the lift to reach the top of the building.

Again, standby power or standby power is a requirement. There must be means to control water, so that is, as a preference, prevent water getting into the shaft in the first place. Again, communications between the car, the lift control points, the machine room or the machine-room-less control panel, and a command center are required.

And also electrical components in the shaft and in the car need to be protected from water. Next slide, please.

So when it comes to fires in buildings, it's pretty much universally accepted that you don't use the lifts. However, lifts can improve upon the speed and efficiency of that process of how buildings are evacuated. So strategies have been evolving and have evolved. In North America, an occupant evacuation operation, or OEO, was developed following the 9/11 attacks in New York.

And in Europe, the EN 81-76 code specifically developed for evacuation lifts was published just last summer. [00:15:00] Next slide, please.

So OEO is not mandatory under code, and it's the local authority that approves the protocol. Also, OEO is intended as a support to normal evacuation by stairs. Next slide

In terms of evacuation elevator operations, once initiated, OEO monitors the presence of smoke at the lobbies it serves and will prevent an elevator stopping at an affected lobby to avoid putting passengers at risk. Floors where fire is detected, as well as typically the floors above and below, or a number of floors above and below that level, the phase one recall zones, will not be served by an activated OEO elevator, again, to protect passengers.

OEO is an automated system adjusted by inputs from the fire alarm system and monitored from the central alarm control facility or the fire command center.

[00:16:00] Eric Peterson: Next slide.

[00:16:01] Paul Burns: EN 81-76 by comparison, or on the other hand, is intended for the safe evacuation of people with mobility impairments who can't use the stairs, and it's increasingly becoming mandatory where the fire strategy requires evacuation lifts. Although there are alternative strategies, which again emphasizes the importance of coordination with the fire consultant.

Under EN 81-76, there are different considerations for smaller low-rise buildings identified as Class A, compared to larger higher-rise, more complex buildings identified as Class B. EN 81-76 limits the vertical distance between landings or between lobbies to 7 meters. And uniquely EN 81-76 describes three operating modes for evacuation lifts.

So with the illustrations on the screen now, starting on the right-hand side, we have driver-assisted operation, where an assistant is inside the lift car and drives the lift to evacuate people from occupied refuges. In the middle, we have remote-assisted operation, under which the assistant is remote from the lift, not in the lift, but in the same building, and directs the evacuation from there.

And finally, on the left-hand side, we have automatic evacuation operation, under which the lift follows a predefined protocol to automatically carry out the evacuation without an assistant, similar to the protocol for the OEO. So that concludes our overview of codes and standards. Clearly, there's a lot more detail behind each of these, which we're happy to explore and to discuss with you if you have questions and need support.

In the meantime, I hope this has given you some insight into the subject, and now I'll hand over to Eric Peterson

[00:17:58] Eric Peterson: Good day, [00:18:00] everybody. I'm Eric Peterson. I manage the operations in Canada for GUNN Consultants, as Sara said. I'm going to talk to you today about some elevator strategies, some techniques that can be used in tall or supertall buildings. Next slide, please. So first, many of you may be familiar with this technology.

Destination dispatching is what it's called. It started as a technology used in class A office buildings. It's now starting to move into residential towers. Basically, what it entails is the buttons that are typically in the elevator cab, right? You push your up/down hall button, an elevator arrives.

You go in the elevator cab, push your button, telling the system what floor you want to go to. Those buttons are not in the elevator cab, but instead they're in the hall, right? And it's not a button panel, but rather a kiosk, typically at least a touchscreen kiosk, right? So you enter your destination floor.

So what that means is when you arrive in the elevator cab, you can see in the top left photo there are no car buttons. Some of you may see some buttons there. Those are buttons for door-close, door-open alarm button, etc., but no floor call buttons, right? And it assigns people to a specific elevator, whether elevator A, B, C, D, etc., based on their destination floor, where they're going to, right? And as I alluded to a moment ago, the elevators are designated alphanumerically they wouldn't be called elevator one, two, three, etc., which is what we're typically used to. They would be called elevator A, B, C, D, etc., right? So that's so we don't create conflict between the elevator designation and the floor designation, 'cause the floor designations obviously are numbered.

Next slide. So how does this technology work?

So in a conventional dispatching system, and this is when I say conventional, I mean what people are used to seeing, where you walk up to the elevator and there's an up/down hall button in the hall, and an elevator arrives, and there are call buttons inside the elevator cab. So with that type of system there isn't intelligence in terms of what elevator people are assigned to, right?

They simply go to the first elevator that arrives. And the color coding that you see on here is to denote the destination floors people are going to, right? So you can see different colors arriving at the same elevator. So what does that mean? It means you get that, what we call a milk run scenario, right?

You get an elevator that is making a lot of stops, right? 'Cause it has to stop for every destination floor. So what does destination dispatching do? I'll explain that on the next slide. So instead, what it does is it aligns people with an elevator designation that corresponds to their destination floor.

So for example the green, the people designated as green, they might be going to floor ten, say, or maybe even [00:21:00] floors nine and ten, close to one another. But in any case, what it's done is effectively reduced the number of elevator stops that any elevator is going to make on a cycle through the building, 'cause that's basically what your elevator is doing on a given trip.

It's going up into the building sending the people to their floors, reversing direction, and coming down to the main lobby, right? So it's a more intelligent system. This kind of system emphasizes the time to destination rather than the wait time, right? Wait time is something that we're all used to as a measure of the quality of elevator service.

How quickly does my elevator get there? But in fact, what we're really concerned with is time to destination. So that's the wait time plus the transit time in the elevator. You add those two figures together, you get your time to destination. So there would be cases, potentially, with destination dispatching, where you might actually wait longer, slightly longer for an elevator to arrive, but the idea is that it gets you to your floor quicker.

So it's kind of like taking the, I don't know, the subway as opposed to a bus, right, which is making more stops. It's going to make less stops, so it's going to get there quicker. Next slide, please So why would we use destination dispatching? Now What I've been describing in the previous two slides is more akin to scenario three that you're seeing on the slide here.

This is, okay, I've got a large building, I've got many elevators, and I need to organize my passengers better, right? So I have my elevators making less stops. So that is definitely a scenario where you would use it. High traffic, high number of floors. How do I organize my people better? But there are actually two other scenarios where you might not guess that you would use it, right?

So scenario one, multiple user groups. So what I mean by that is, let's say, for example that on the far left, I've got this scenario one tower, and in the brown or the peach section of the buildings, let's say, for example, that's a hotel, and above it in blue is residential. Now, traditionally what we would do is we would have a dedicated group to serve the hotel, say a three-car group, for example, and maybe a three or four-car group to serve the high-rise residential.

And by doing so, I separate my user groups, right? I don't have my hotel passengers or my residential passengers in the same elevator, which is what I want, right? But what if, instead of having two separate groups of elevators, we used one group of elevators serving all floors, and we used the dispatching of the elevators to separate our traffic?

You can do that with destination dispatching. You can have it knows basic—for example, like who is in the elevator cab. If there's a residential passenger in an elevator cab, it could be programmed so that it would not respond to a call from a hotel passenger, and vice versa, right? So we use the logic of the elevators to separate our traffic.

And the benefit of that is, perhaps that scenario I just described to have a three-car low-rise and a four-car high-rise, that's seven elevators. [00:24:00] What if I could serve this entire building with, say, five or six elevators? I'm reducing my elevator count overall and achieving the same end goal, right?

When else might you use it? Scenario two: different floors served. So what we're representing there in that green tower is this is a five-car elevator group, right? And on the left, cars one, two, and three have a gap where they don't serve, and elevators four and five near the top of the building, they don't serve there.

So if you are at the main lobby, say, for example, and you need to call the elevator to, say, the top floor of the building, right? You need elevators A, B, or C, one of the first three elevators. You cannot be dispatched to elevator D or E, right? Because it doesn't serve that level. So the destination dispatch, it can handle that.

So if you have any kind of building where not all the elevators are not serving the same levels, we see this often in office buildings with overhead restrictions where you might have an elevator group that serves nearly to the top of the building, but then, say, only a portion of the elevators serve the last few floors, right?

Because of the overhead restrictions. So in that kind of scenario, you would want to use destination dispatching so that you can be intelligent. Otherwise, you're just taking a chance that you'll get the right elevator. Next slide

Another technology that can be used, stacked cabs. We don't see this very often, but stacked cabs is basically one cab coupled to the other, directly coupled. Okay? They are independent of one another independent physically speaking, but they are interconnected. They do not operate independently of one another.

But what you require for this technology at the bottom floor is you require two access floors, right? You require the bottom-most entry floor and then the floor above that to get into the upper cab, right? It does increase the overall capacity that you can move through the elevator system. You can see this example in Montreal where this was used, eight low-rise elevators, eight high-rise elevators, all operating at twelve hundred feet per minute.

And yeah, they were all stacked cabs. So this was basically a strategy to increase the handling capacity of the elevator system. Now, there are some inefficiencies built into this. You can imagine that, for example, if you're in the upper portion of the elevator cab and the lower portion has to stop to answer, the elevator has to stop to answer their call their doors are going to open, yours are not.

So you're sitting around waiting while that call is answered. So that introduces some inefficiency, but it does overall increase the handling capacity of the system. Next slide. Twin, TKE twin, which is kind of one step ahead of what I just talked about with stacked cab. So this is also two elevators in the same hoistway, but now they're independent, believe it or not.

They operate off two entirely separate drive machines, and they can move entirely separate from one another. So the upper elevator cab can move and the elevator—the lower elevator cab can be stationary. Now, the lower elevator [00:27:00] cab can't bypass the upper elevator cab. It has to always be below the upper cab, but it does increase the efficiency.

These installations exist in Europe, the U.S., and Asia. There are none in Canada yet, but eventually I'm sure there will be a project where this technology is used. Next slide. This graphic illustrates how the system works. On the left is a conventional arrangement with five independent elevator hoistways, requiring the footprint of five hoistways.

On the right, shown in orange, is a twin configuration. This is only an example, but it provides five elevator cabs within three hoistways, reducing the footprint from five hoistways to three. That is the primary benefit of the twin system. However, it comes at a significant cost premium.

This technology is not inexpensive; it will cost more than installing five independent elevators. However, given the value of leasable floor space, the investment may be worthwhile. Elevator hoistways consume valuable floor area and can significantly affect project economics.

Next slide.

Now let's move on to technologies used in tall and supertall buildings. A sky lobby is one strategy used from time to time. The diagram here shows a conventional building, with the blue, green, and pink sections representing the low-, mid-, and high-rise elevator banks.

The example shows a five-car low-rise bank, a five-car mid-rise bank, and a five-car high-rise bank. The lower portion of the building is not served by the mid-rise elevators, while roughly the bottom two-thirds is not served by the high-rise elevators. Those elevators bypass those floors in what is effectively an express zone.

That is the traditional configuration. We modeled a sample scenario to demonstrate the time to destination for a passenger traveling to a floor in the high-rise portion of the building. Using our assumptions, the estimated time to destination was 100 seconds, which is generally considered acceptable.

Next slide. What if we use a sky lobby? What does that mean? This represents a similar building, except that now our high-rise elevators—the same five-car high-rise bank—are stacked on top of the mid-rise bank. But when you do that, of course, you cannot bring the high-rise elevators down to the main lobby.

So how do you get to that sky lobby above the mid-rise bank? You use shuttle elevators. We can use fewer shuttle elevators in this scenario because they effectively have only two stops. [00:30:00] That makes the system very efficient, so you don't need as many elevators.

We can reduce that five-car bank—this is just an example—down to two cars. All of a sudden, our footprint is no longer fifteen hoistways; it is twelve hoistways. It does have a minor impact on time to destination. What we modeled here was a high-rise passenger starting at the main lobby.

I push the button for the shuttle and wait for it. It arrives, and I travel up to the sky lobby. I walk over to the high-rise bank, push the button, repeat the same process, and then arrive at my floor. What does that mean? Yes, there was a minor impact, but it was not significant. It is still in the same order of magnitude.

In this case, we came up with 105 seconds. If it is designed correctly, you can get elevator service that is very comparable to conventional dispatching while reducing the number of elevator hoistways. Moving on to the next slide: jump elevators.

I don't know how many of you are familiar with what we call jump elevators. This is a construction technology, not a technology used in the finished building. Everyone is familiar with construction hoists that run on the outside of a building. They are typically very slow—say, 100 to 125 feet per minute—rack-and-pinion, noisy, and disruptive to work on the building's exterior.

Impacts your ability to finish the outside of the building. But what if you could use the elevator hoistways? Everybody's familiar, I'm sure, if they've done a construction project. Eventually, the elevators in the interior of the building are going to be finished at some point during construction.

But typically, you have to wait quite a while for those elevators to be used for construction use. With a jump elevator, we can do that from day one effectively, right? So we install what we call a jump elevator within the elevator hoistway. We can, in some cases, avoid the construction hoist on the outside of the building entirely.

These elevators are much faster—700 or 800 feet per minute, for example. You're protected from the elements, and you can move construction workers up and down through the building much more quickly. Where does the name jump elevator come from? We call them that because we jump them up. Let's say, for example, your building will reach level forty, construction is currently at level ten, and the elevators serve through level nine. You wait until construction reaches, say, level fifteen, and then hoist the elevator up to the next position.

You might move it up to level fourteen. It is recertified, and then you use the elevator to travel to that new level. You can work with two jump elevators, for example, and move them in tandem. You do not have to jump both at the same time.

So that's a technology that we've seen used, we've used on some of our projects, and [00:33:00] it can be an effective way to increase your efficiency on construction. Again, with all these things, it comes at a cost premium, right? It doesn't come cheap. But it increases your efficiency and can ultimately save you money in many cases.

Next slide. And with that, I'll turn it over to Mr. Michael Muñoz to talk to you about some design issues that we see come up in new construction.

[00:33:25] Michael Muñoz: Sure. Thank you, Eric. So we're here today talking specifically about tall and supertall buildings, and as buildings grow in height, there are some design considerations that on shorter buildings you wouldn't have to think about.

We want to give everyone a general overview of some of the phenomena and concerns that come with taller buildings. Next slide, please.

Inherently, the first one that comes to mind is that there's an effective travel limitation on a conventional elevator system, right? As a building gets taller, if you want the same elevator to serve from the ground to the top floor, there are steel ropes that are connecting the cab and the counterweight, and as the building gets taller, those steel ropes get longer, and all of that converts to the total weight of the ropes.

And all of those ropes hang from a machine that's all the way at the top of the elevator shaft, right? And so you can imagine that an elevator machine that's actually moving the car up and down, there's going to be a physical limitation on how big that machine is, the largest available machine commercially available, and then also there's going to be a maximum load that given machine can handle.

The current industry standard uses steel ropes for elevator suspension. Roughly 1,600 feet is where that technology reaches its limit, although it varies. A bigger, heavier cab may have a shorter maximum rise than a smaller, lighter cab because it is all about the system's total mass.

When you think about some buildings that are taller than 1,600 feet and may have an observation deck at the top, what do we do? With conventional steel ropes, you need to create a transfer: run the first 1,600 feet up, have passengers exit the elevator, cross what is effectively a sky lobby comparable to what Eric just described, and transfer to another elevator for the remaining part of the building.

What do we do about that? It depends. Next slide, please. One technology, developed by the OEM KONE, is called UltraRope. They said, "Instead of using steel ropes, with the weight concern we just discussed, let's use an [00:36:00] alternative material: carbon fiber coated in a proprietary polymer."

The ropes are effectively carbon fiber and significantly lighter than steel. That weight reduction allows a much longer rope before reaching the maximum capability of a machine. What does that do? It allows travel distances of nearly 1,000 meters, or 3,300 feet—almost double those of a conventional steel rope.

I bring this up because, again, there are perhaps 256 buildings currently classified as supertall. It is worth noting that this technology may also make sense for shorter buildings from an energy-efficiency standpoint.

If you're looking to make a very green building, the reduced mass, total mass of the system that you're moving results in a lower power consumption. So while this was designed for these one-off supertall buildings, there are additional applications where it could make sense. Again, as with all new technology, it does come at a premium.

But for every project, there may be a cost analysis to see where this does or doesn't make sense. But here, we just want you to be aware that the technology is out there. Next.

Sway mitigation. As a building gets taller, it tends to do a lot more of this, right? The wind blows, the building sways. And remembering that the elevator shafts go vertically through the building, that means effectively the elevator shafts are also moving. And then you remember that we effectively have a weight hanging from a steel cable, right?

What happens when the building is swaying and there is an elevator in it? The ropes will also tend to sway, and this can become a major concern if the natural frequency of the elevator system aligns with the natural frequency of the building's movement. When that happens, the amplitude of the elevator components' movement continues to grow until the ropes may make contact with other elevator components or even the hoistway walls. The design team—particularly the structural engineer—needs to be aware of this when designing a tall building.

There are other concerns besides elevators, but on a project of this nature, you want to insist that a wind-tunnel study be performed early in concept design. Models of the proposed concepts are produced and tested in a wind tunnel with very high-resolution cameras. The footage can be slowed down to model the building movement that will occur in the real world once it is built.

All those movements can be recorded and studied in detail to understand how they will affect the elevator system. Next, please. All the OEMs [00:39:00] provide similar engineering. This is just a sample from a project Otis worked on.

But what you're seeing here on the right side is a diagram that represents every floor of the building, with colors showing where the building's movement impacts the elevator system and creates enough movement that the elevator system would be compromised in operation. And so at the bottom of the slide, what you're seeing is an elevator diagram.

The blue circle represents movement that's safe, right? The ropes and other components. The ropes can move in and out of this circle without causing any operational concerns. The yellow circle represents the first obstruction point, right? So just enough movement that the elevator ropes can make contact with something other than air.

In this diagram, that obstruction would be the landing door. The red circle represents thirty-three percent more movement than the initial-contact movement. In that extreme scenario, the car ropes could contact the counterweight behind the elevator, possibly snag on the rails, and strike the side and rear walls of the hoistway. All this is to say that this level of analysis is required to understand how the proposed elevator system will respond to windy-day conditions.

And then with that, once the worst-case scenario is understood, mitigation techniques can be put in place, such as parking the elevators at floors or setting a maximum parking time at floors that would align with the building's natural frequency, right? So maybe during a storm, an elevator can only park at certain floors for no more than fifteen seconds before needing to move.

It could be reducing the speed of the elevators so that as the ropes are swaying, they're moving at a slower speed. You can think of that as like a bandsaw, right? The quicker it's moving and making contact, the more damage it will do. And so if you can slow down the operation, and understand that the ropes are still going to move, but at a slower speed, if they make slight contact, less damage will occur to the elevator system.

Or in severe cases, there may be just such an extreme wind condition that the programming parameters are set to recognize there is no safe operation during this period. The elevators will go somewhere safe, park to make sure no passengers are in there while this is happening, and then wait until wind-monitoring devices report to the elevator control system that the sway has been reduced and the elevators are again safe to operate, right?

This is something to be aware of in tall buildings, and, as I said, the wind-tunnel study is a very important first step. Next, please. The piston effect is aptly named. You can think of an elevator as a piston inside the cylinder of a car engine. As it moves up and down, it compresses the volume of air above or below it, depending on the direction of travel. [00:42:00]

As that happens, that higher pressure air is pushed through doors as it passes landings. This can often result in audible whistling and door panels popping in and out. And this, of course, becomes more pronounced as the elevators move at a higher speed, which of course higher speeds come with taller buildings, right?

The biggest issue here is when you have a single elevator in a hoistway without elevators to the left or right in a common shaft, because that gives very little pathway for air to be dispersed as an elevator moves and that exacerbates this piston effect. Next, please. So what we want to do is try to avoid single car hoistways wherever possible.

You could reduce the pressure that's created by reducing the speed of the elevator. But from a performance standpoint, people do have an expectation of total time to destination and average waiting time. Reducing the speed may not be viable in a class A commercial office building if it means that elevator performance no longer meets current market expectations for leasing.

You can increase the size of hoistways to allow for more free space for the air to flow as the elevator moves. But as Eric alluded to, many projects, or all projects, area is king. It translates directly to the leasable area. The more space the elevators take, the less rentable or sellable space, right?

And so that's usually a hard negotiation to make. And then the last resort would be if you have no other avenue and you have a single-shaft elevator, you have to start looking at alternate ways to relieve that air pressure. And on the next slide we'll look at a couple of diagrams that demonstrate how you might achieve that.

These are both projects in Canada. On the left side, you can see that we have a single elevator on the same side of the core as a staircase and opposite another single elevator. And both of those in their own right would have piston effect concerns. What we're doing here is connecting the two opposite elevator shafts with a horizontal duct.

What that does is allow air to cross between the hoistways. Let's say the elevator on the left is moving up. As it pushes air above it, the air can cross into the free space of the hoistway across the hallway, mitigating the piston effect. Is this something you want to establish as the basis of design without first discussing alternative core arrangements?

Absolutely not. This does require a significant amount of coordination with your MEP and HVAC. Each and every one of these horizontal connections, remembering that the elevators opposite each other are [00:45:00] separate rated, fire-rated hoistways. These horizontal connections would still need a fire damper so that in the event of a smoke condition, each elevator hoistway remains independent and does not allow for the spread of fire or smoke from one to the other, right?

Similar condition on the right side, but instead of going across a hallway, two elevators back to back, you create an opening in the shear wall between the two to allow air to pass. But again, this would also require a fused damper to separate the shafts in smoke conditions. Next, please. And lastly today, we'll talk about the stack effect.

As buildings get taller and when you deal with variation of temperature inside the building and outside the building, you create a condition where the building and namely the elevator shafts or the vertical connection through the building begin to act as a chimney or a smokestack, hence the name stack effect.

We have diagrams kind of showing a winter and a summer condition here, right? I will say that we'll focus on the winter condition because it tends to be the more pronounced impact on buildings. If you think of somewhere that has the winter season and inside of the building they've got heating to keep everyone comfortable, you've essentially created a huge temperature variation between the outdoors and the indoors.

The hot air is rising, similar to the concept everyone knows, a hot air balloon. That hot air that's being warmed by HVAC is getting pushed up the elevator shafts, and that's creating a draw. And when you do that the negative pressure that's created behind that, and when you open the doors to let people in the main lobby of the building, the air wants to rush in to fill that vacuum, and it just continues to feed the cycle of air moving up the elevator hoistways.

This is also a huge problem with loading docks 'cause they're typically unconditioned space. And so you've got a massive volume where trucks are able to pull in and park unconditioned. And if that space is not effectively separated from creating an air pathway to the elevator shafts, it will feed the stack effect constantly, right?

What do we notice throughout the building when there is a stack-effect issue? You will hear air whistling as it moves up the hoistway. In extreme cases, the pressure differential may be so great that when the elevator doors open and then try to close, they cannot complete the final half-inch or quarter-inch of travel because the air is moving at such high velocity.

And so it can become an issue where the elevators effectively will shut down, right? So now you've impacted the users of the building significantly here. Next slide, please. Mitigation is not purely an elevator issue, it's a design issue for the entire building. You can compartmentalize the building and interrupt the vertical pathways by [00:48:00] having an elevator that doesn't run the entire height of the building, but maybe operationally that doesn't make sense.

You can try to use only revolving doors at the front of the building, rather than swing doors that may remain open and allow more air to rush in and travel up the elevator shaft. The point is that the real way to mitigate this is not through the elevator system; it is through the overall building design.

And that's why we want to bring it to your attention that it's something to focus on early on in a project to ensure that there are not issues at the end. And if you do end up with a condition on the elevator side, what can we do? We can install high-horsepower door operators. We can install high torque door closers at every landing to ensure that final bit of door close occurs, but that's a repeated cost at every landing of the building, and it adds up, right?

That is a summary of some of the issues that come with tall buildings. The takeaway is that you need to think about all of them very early in the design process. Next.

That brings us to the end of the presentation. This is the contact information for continuing education credits in the U. S. and Canada. We know that all of you have different continuing education bodies, but the relevant information is here. Sara, where does that take us next?

[00:49:29] Sara Korolevich: Thank you very much, Michael. Yeah, exactly. Continuing education. We are going to share these slides in your emails and the recording, so you'll have this information. And we're also going to put it in the chat, so if you want to just click on the link through the chat, that works too. For our design services, just want to remind everyone, we are available for consultation.

You can contact one of our experts, our teams around the world. These are the types of design services that we provide through VDA, Gunn, and D2E, and our global teams. We do have a quick poll. If you want us to reach out to you just to make it easy, we can certainly email you if we can get that poll launched.

Do you want VDA to reach out to you? Please just click yes here. And we'll definitely do that, and in one second, I'm going to share the information. Actually, I can click over. There you go. If you'd like to reach out to any one of our experts, you can go to that webpage, our family of brands, all the different offices that we have.

Contact information for Michael, Eric, and Paul as well, and we're excited to get to the live Q&A. I do see some questions if I can just remind our speakers to probably remain unmuted; that will be easiest. [00:51:00] That way you can jump in and respond to some of these questions. So let's get going. Okay, we have one question regarding jump elevators.

What are the cost benefits for this application when comparing the use of the outside hoist option? Are the OEMs the only companies that offer this technology? Is the jump system self-climbing when the core or building structure moves ahead?

[00:51:30] Eric Peterson: I can take that one. Eric here.

There are a few questions embedded in there. How does it create efficiency compared with the alternative? Jump elevators are significantly faster, and you can have more lifts than you would on the outside of the building. Basically, they move workers through the building more quickly and at a higher rate.

That is how they create efficiency and save money. Let's pick a number: it might cost a million dollars per elevator to install this kind of technology. It does not come cheap, but it benefits you by moving people more quickly and shortening the construction schedule.

That is the idea: shortening your construction schedule. Can it self-climb? Yes, depending on the technology. Otis, for example, has technology that essentially climbs by itself. There is some intervention from mechanics; it cannot do everything on its own.

Okay. They do have that technology. And can you remind me, Sara, was there something else?

[00:52:32] Sara Korolevich: No, I think you caught them all.

[00:52:34] Eric Peterson: Okay, good.

[00:52:35] Sara Korolevich: Thank you. I'd—

[00:52:36] Paul Burns: I would just add—

[00:52:36] Eric Peterson: I don't know whether you want to add to that.

[00:52:38] Paul Burns: Yes, Eric. I was just going to say that I completely agree with everything you've said.

One other significant advantage, particularly in the far Northern or Southern Hemisphere where weather is an issue, is that having jump elevators inside the building, rather than hoists and mast climbers on the exterior, means fewer days lost to weather because everything happens inside the building and is protected.

The scheduling advantage is that you do not lose those days to inclement weather.

[00:53:12] Eric Peterson: You'd think being from Canada, I would've highlighted that first, right? But I didn't. Yeah, no, good point. Excellent point.

[00:53:16] Paul Burns: The other thing to add is your point about climbing. Again, I completely agree. It means there must be coordination among the elevator supplier, the subcontractor, and those responsible for the construction and design of the hoistways, because the hoistways need recesses for the steel beams used by the elevator system as it climbs.

You cannot decide that you want jump elevators late in the process, once hoistway construction has started. They require that level of coordination.

[00:53:48] Eric Peterson: Absolutely. Yeah.

[00:53:51] Sara Korolevich: Thank you. All right. Next question. This one has a lot of acronyms. The [00:54:00] AWT for sky lobby elevators. AWT is generally defined by CIBSE requirements.

[00:54:09] Sara Korolevich: Here, shuttle AWT plus main lift AWT will be higher than the AWT described by CIBSE Guide D. So how do we define that the strategy is good and not going to be higher AWT or queue for passengers in the lobby, particularly during start of office or lunchtime?

[00:54:33] Eric Peterson: So we don't put people to sleep, AWT means average wait time, and the CIBSE Guide D defines what is considered an acceptable wait time.

CIBSE is what the question refers to. Every case is unique. I offered an example for demonstration purposes, but every situation is affected by how many floors you serve, how many people occupy those floors, and when peak traffic occurs.

These are all things that you would want to assess. And look, with any of these analyses, like it could be that, for example, it, there's a small penalty to be paid by a certain portion of the people in the building. But, when we're assessing elevator systems, we want to look... Yes, we don't want any one group to be unnecessarily penalized, but you are looking at a global view of this, looking at the entire building, and how do we make the entire building function better, right?

[00:55:40] Michael Muñoz: I would add to that, Eric, that the way we've seen this approached is this, right? Who is ultimately going to take space in the building? And is this transfer experience something that would be palatable or acceptable?

[00:55:54] Eric Peterson: Good point.

[00:55:55] Michael Muñoz: And if the answer is yes, what we've seen design teams do is to make the transfer a pleasant experience.

So you tell the high-rise tenant that you're going to have your own lobby at the top of the building, and when you get out of these shuttle elevators, it's going to have all these great amenities. It's going to have coffee, it's going to have food, and it's going to be beautifully finished. And all of your employees are going to be happy to get up on a shuttle elevator, get out, congregate in the morning, and then move over to their local elevators, right?

You almost create a building within a building. Rather than looking at it as pure arithmetic—in Eric's example, it went from 100 seconds to 105 seconds—design teams try to present it as a pleasant experience and therefore less of a concern. We understand the concern about meeting CIBSE guidance. If someone peer-reviews a building design that uses a sky lobby, it becomes a little grayer, but it is about the end-user experience and whether the developer can market that experience.

[00:57:00] Paul Burns: Yeah, I think that's a really good point, and it's about how you sell it to the occupants and how you sell it to the tenants.

So in very tall buildings that are zoned, so we have these kind of low-rise, high-rise elements in the elevators, or we have a sky lobby as described, as the questioner described. Effectively, you're putting one building directly on top of another in order to save core space and make the building viable.

So if you're doing that, then it's a question of talking to the developer and the tenants, the occupants, and say, "Okay, your building is up here. You start at level 50," or whatever it happens to be. Your journey to your building includes that shuttle lift or that sky lobby element. And then, as Michael very eloquently put it, sell the fact that we've got this incredible lobby and that's where your average waiting time starts from.

Although the questioner was talking about average waiting time, what we are trying to minimize is the average time to destination, or total journey time. We want to start measuring it from their specific lobby in that building-on-top-of-a-building concept. But it requires a conversation with the developer and tenant to determine what is important to them.

[00:58:07] Sara Korolevich: Okay, thank you. We are over time, but I do have a couple more questions in here if people want to continue hanging out and listening. We have a question, it's a follow-up question. What elevator speeds are typically available in the market for high-speed elevators?

[00:58:24] Michael Muñoz: I can take the first stab at that one.

As far as a maximum, they can go very high. Shanghai Tower's observation deck is 18 meters per second or 3,600 feet per minute, if I'm not mistaken. Very high speed. With that comes specialization of cabin pressurization. It actually travels slower in the down direction to be sensitive to people's ears and popping of ears because of change in pressure.

What's more typical is you would cap a speed around 10 meters per second or 2,000 feet per minute. Those are more commercially available speeds from OEM standard product offering. Those super high speeds are all custom-engineered solutions. I hope that answers the question.

[00:59:09] Sara Korolevich: Another question: How often are you seeing occupant evacuation operation used? Is it gaining traction? What are the primary use cases, pros, and cons?

[00:59:24] Michael Muñoz: Yes. The major benefit is that the IBC allows a reduction in the number of egress staircases in buildings over 420 feet tall if you provide enough evacuation elevators to equal the capacity of that third egress stairway.

So there is a huge motivation from developers to recapture that area because it's typically at the top of the building, right? And the third stair is all the way up, and [01:00:00] that's more leasable area. So there's a huge financial incentive to make it work. What I will say is I've seen many schemes where it's looked at, and then you get into the local acceptance.

And I don't mean by the authority having jurisdiction. If it's in the code, they'll accept it. What I mean is the end users and the acceptance of not having that additional staircase. So for example, OEO as noted, was created after the 9/11 attacks, and in a market like New York City, it's a really hard sell to convince people that we're going to get by with less egress stairways, regardless of the elevators, right?

And so I have many projects in New York where we've gone through what it would mean and how much savings it would be and how much square footage that generates to sell. But at the end of the day, I have seen very few projects, for example, in New York, that have decided to go that route. A few projects on the West Coast, San Francisco have used this that I'm aware of.

Again, the real incentive begins at 420 feet in height, which already narrows the number of buildings that benefit. From there, it is a conversation. So, after that long-winded answer, I would say I see it implemented in only a very small percentage of projects.

[01:01:18] Paul Burns: To give the European perspective—sorry, Eric, were you going to say something?

[01:01:22] Eric Peterson: No, I was going to ask—

[01:01:22] Paul Burns: You were going to ask for my perspective.

[01:01:24] Eric Peterson: Yeah.

[01:01:24] Paul Burns: To give the European perspective, in the U. K. we had a real tragedy called the Grenfell Tower fire some years ago, and that changed everything.

It was a game changer for building codes and regulations in the U. K. and London, and it drove a root-and-branch review of building construction, stair cores, firefighters' lift cores, escape stair cores, and so on. In parallel was the development of EN 81-76, which I referenced in the code section. It is a code specifically for evacuation elevators, or evacuation lifts.

As I said in the presentation, that is specifically for people with mobility impairments who cannot use stairs, rather than for everybody. I think occupant evacuation operation is leading the world in innovation by suggesting that elevators can be used in an emergency to evacuate everybody.

We have one building in London, 22 Bishopsgate, that has an occupant evacuation operation-style evacuation system using lifts because it is a very tall building. In general, EN 81-76 is now in place in Europe, so we have an evacuation elevator code. In the U. K., we require a secondary escape stair in most buildings, and a secondary firefighters' lift core includes a stair, a lift, and protected lobbies.

The industry is moving in that direction. But, as I said, it is for people who cannot use stairs, whereas occupant evacuation operation is [01:03:00] intended more broadly for everybody.

[01:03:01] Sara Korolevich: Okay. Thank you. One last question and then we'll wrap up. What acceleration and jerk values are normally used or considered for high-speed elevators?

[01:03:12] Michael Muñoz: Yes, so that comes down to human factors, right? There's only so much acceleration that the human body's going to be comfortable taking.

Typically, you would see acceleration around 2 meters per second squared. In very specialized applications, it may be pushed to 2.5 meters per second squared. Jerk is even more perceptible than acceleration, so you typically would not see it exceed 3.0 meters per second cubed.

[01:03:45] Paul Burns: Yes, I agree, and I think there are regional variations as well. In Europe, we tend to think we need a gentler ride. We tend to think North Americans like a fairly aggressive ride and focus on getting to the destination.

We would typically use values slightly lower than what you described, Michael. There are regional requirements, and it comes down to what is acceptable in the area where you happen to be.

[01:04:17] Sara Korolevich: And with that, I want to thank everyone for joining us today. Thank you to our presenters for this information. And again, we'll send out the recording and the slides, so you'll have those in your inbox. Thank you, everyone.

[01:04:34] Eric Peterson: Thank you.

[01:04:35] Paul Burns: Thank you.

[01:04:35] Eric Peterson: Good day, everybody.