How many floors can one set of elevators service?

kenratboy · #1 Posted **Mar 31, 2007, 4:15 AM**

For example, lets say you had a very tall residential skyscraper with only a few units per floor - how many floors can one elevator car/shaft service (as opposed to having one set for the bottom half and one set for the top half)?

Do you think 50 floors could be done?

Also, are there any rules of thumb for a residential tower as to how many elevators are needed to service a given number of units (for example, a 20 story building with 30 units per floor, how many elevators would be needed if all of them went to all floors)?

Thanks!

Kelvin · #2 Posted **Mar 31, 2007, 4:41 AM**

The old rule of thumb for proportioning elevators was 1 standard cab per 45,000 sq.ft gross floor area. However, today elevators can be a little faster and more programmable, so some additional efficiency is likely achieved. That is for commercial space.

I can only assume that there is less demand in a residential application.

mthd · #3 Posted **Mar 31, 2007, 8:54 AM**

Quote:

Originally Posted by Kelvin

The old rule of thumb for proportioning elevators was 1 standard cab per 45,000 sq.ft gross floor area. However, today elevators can be a little faster and more programmable, so some additional efficiency is likely achieved. That is for commercial space.

I can only assume that there is less demand in a residential application.

beyond the old 1:50 or 1:40 rule, the number of stops will come into play on an office building with smaller floor plates. more than 15 floors tends to be pushing it, so a bank of 4 elevators serving a boutique office tower with 10,000 square foot floors may end up serving even less than 40k per cab. at the opposite end, banks of more than 8 become problematic because the lobbies are too large and people standing in the wrong spot don't have time to make it to the cab, among other things. at 1:50 that means one bank won't usually go past 400,000 square feet, or 15 26,650sf floors. many very large office buildings have bigger footprints than that, so you may not even get 15 floors. this is why really big office buildings have sky lobby floors - so you can stack the shafts for the banks on top of each other, e.g. 6 banks serving 10 floors each can be stacked so that they only take the space of 3 banks plus one bank for the shuttles.

in residential the number of units per floor and the number of stops is all you care about, and the number of stops tends to be a bigger factor except in very low end buildings. the minimum is 2 and you can serve up to about 65 stories in a single bank of 4-6 elevators.

destination elevatoring might save you a cab or two per bank.

kenratboy · #4 Posted **Mar 31, 2007, 6:21 PM**

OK, so about 60 floors is the max (like some of these ultra-small Hong Kong towers with only 2-3 units per floor)?

Any idea on the ratios for a residential building?

mthd · #5 Posted **Mar 31, 2007, 8:59 PM**

in residential it ends up having more to do with the number of stops than the number of units. i suppose by taking typical footprints and unit sizes you could say around 100 units per cab. i don't think it's a very meaningful way to analyze residential elevatoring.

on a typical office floor, lets say 20,000sf, you could have 100 to 150 employees. a 10,000sf residential floor might have 8 units, a mix of one and two bedroom, giving you something like 20 people. per square foot, that's well under half the number of people, so the elevatoring usually is determined by the number of stops - not the size of the floor. the service interval has more to do with travel time than wait time...

kenratboy · #6 Posted **Mar 31, 2007, 11:38 PM**

How about this, just as a good guess. For a non-premium building (a little wait is not going to be a big deal), each floor has 8, 1 bedroom and 6, 2 bedroom units (max of 34 people per floor), using a 4-elevator bank, how many floors would it be able to service (again, this would be for a lower-end building)?

Oh, and LOL at the Google ads, three are for 'home' elevators, one is for...and one for an elevator expert witness (there is such a thing!?)

Thanks!

Just playing around with some designs and I have never had a good idea how to get a rough idea of ho much capacity would be needed for elevators.

mthd · #7 Posted **Apr 1, 2007, 5:32 PM**

i would guess 50 or so.

kenratboy · #8 Posted **Apr 9, 2007, 5:35 AM**

Thanks for the info!!!

rich1077 · #9 Posted **Apr 21, 2007, 1:49 PM**

I work in the mori tower in Tokyo and we have double stacked cabs, 8 elevator shafts each has 2 cabs so 16 total cabs and they only service 8 floors.
It seems like a cool idea, has anyone seen this before? The one thing I’ve noticed is they seem to be very slow, sometimes we have to wait while the other cab loads-unloads so a trip to the upper floors can take awhile.

SapphireBlueEyes · #10 Posted **Apr 21, 2007, 3:55 PM**

We have three residential elevators that service floors 44-91. They are express elevators, and some of the fastest in North America [I think the Sears Tower has the fastest in North America].

-SapphireBlueEyes-

MolsonExport · #11 Posted **Apr 23, 2007, 4:21 PM**

Remember the dreaded elevators of Simtower?

MayorOfChicago · #12 Posted **Apr 23, 2007, 11:33 PM**

^ GOD I hated those.

My friend lives on Diversey and the lake here in Chicago and has I think 4 elevators serving 50 floors. I was kinda weirded out cause all 4 of them served ALL 50 floors. That was a lot of buttons!

I'm use to office buidings where I'm always looking for the right bank of elevators to take.

JAM · #13 Posted **Apr 26, 2007, 4:40 AM**

Interesting topic. So I presume the Hancock and Sears are the fastest in the NA for a reason, given as old of buildings as they are. There must be some max tolerance an average human can take before the acceleration make them sick. That would also have to be factored into your design.