How Tall Are Boston's Buildings and Should They Be Taller?

Arlington

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I'm unlocking this thread. Let's start by not re-hashing arguments, but by posting useful links.

In the XMBLY thread, we touched on height (and probably fanned the flames), so I'm re-opening this thread, in the hopes that we can constructively engage. (If we can't, mods will lock it again).

In the XMBLY thread, I introduced, without evidence, the reasons why Somerville might want to only allow 250' worth of building in a space where the FAA would permit 500. Here I'm going to stack them up and give them links.

Here are some natural "step function" points:
- 260' = 25 stories a [construction-cost] break-point reported by Glaeser in NYC
- 208' = (20 stories) the height at which energy use per square foot is fully double that of buildings of 5 stories or shorter.
- 158' = (15 Stories) a [construction-cost] break point reported by Glaeser in NYC
- 137' = The height of north america's tallest Aerial Ladder Firetruck. In Somerville, where the first floors are 18' and uppers are at least 10', an 13-storey building would be 128' tall.
- 108' = (10 stories) the height above which a service elevator is recommended
- 70' = The height at which a building is considered "high rise" in Mass (many safety costs start here)
- 75' = of elevator travel requires elevator lobbies or smoke doors or elevator pressurization
- 70' = Six Story mid rise a break-point in price reported by Glaeser
- 40' = The most energy-efficient height for a building (minimizes energy in lifting, minimizes surface area to building volume heat gain/loss)
- 40' = (4 stories) the height at which "gurney sized" elevators are needed (so firefighters can carry a sick person down)


Other Breakpoints I'd like to better understand
- Typical "Second Bank of Elevators" height. Breaking elevators into 1-12 and 14-22 etc. happens at different points, but there is going to be some point at which the "high people" demand it.
- Typical "Fourth Elevator" Height. Seems determined by a mix of "how many units are served by this bank of elevators" (some say 1 elevator per 90 units). At some point you've maxed your 3 elevators and adding one more floor's worth of units triggers the need for a 4th elevator
- Typical "Third Elevator" Height. Seems determined by a mix of "how many units are served by this bank of elevators" (some say 1 elevator per 90 units). At some point you've maxed your 2 elevators and adding one more floor's worth of units triggers the need for a 3rdelevator
- 200 unit price break point (while costs per unit are fairly constant between 20 and 200 units, there's a step at 200. I suspect this is where the "3rd elevator" break is. (see Table 1)
- Utility line losses (if there's a central source of steam or chilling, at what point do the efficiencies of scale get lost to the inefficiency of pipes
- Utility piping cost, space wasted on vertical shafts and lifting water. Every new set of units added to the top of a building increases the diameter / cross section of the pipes needed to raise the gas or water (or take the sewer)
- Streetwall: you can activate more street with more-but-shorter buildings (ask Paris)
- Tenant preference: Nobody likes long elevator waits nor long elevator rides.


Bibliography:
 
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Arlington

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I am also going to posit that there’s another cost or functional breakpoint at around the 44th floor since that’s about where the sky lobbies are in tall buildings as diverse as Chicago’s Hancock and Burj Khalifa. I posit that any economic builder on a normal CBD parcel would design to either stay below 44 or jump to 88 floors
 

Arlington

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I think we are going to find that there enough ergonomic, economic, ecologic, and safety factors that for more a combination of reasons, buildings come in logical steps, for about the same reasons that cubes and spheres end up being optimal and that skinny shapes are sub-optimal.

Let me try this:
68' The 5+1. Avoids "high rise" regulations, can have 180 units and two elevators, uses wood construction, 36 units per floor, moderately long walk to the elevator

130' Still 180 units, but now 18 per each of 11 floors (and still only 2 elevators

250’ four elevators 18 units per floor for 20 floors, 360 units
 

chrisbrat

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can't fault your logic and reason, but for many -- particularly on aB -- the passion for taller buildings in boston is just that: passion. and something so driven by emotion will never concede to rational thought.
 

Arlington

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can't fault your logic and reason, but for many -- particularly on aB -- the passion for taller buildings in boston is just that: passion. and something so driven by emotion will never concede to rational thought.
True, buy allow me to try to direct that passion to parcels for which tall makes sense. And I get that it is really hard to "see" the logarithmic decay between the very best sites in the world, and sites that are just enough "off center" that they drop several orders of magnitude in what you can build. And then several orders of magnitude later, you're at XMBLY.

It is a lot like hosting the Olympics, really. It is hard to see the huge swing that happens as you move from LA/NYC/London/Paris to Atlanta/Athens/Boston but a lot deteriorates very quickly as you move away from the truly exceptional to the merely great.

A wild swag at how "the dropoff" happens as you move away from being "The Site"* to "any old site"
20 sites globally will get 120 stories or more
100 sites globally will get 100 stories or more (currently there are 21, with 16 under construction but about 40 cancelled)
200 sites globally will get 80 stories or more
2000 sites globally will get 60 stories or more
20000 sites globally will get 50 stories or more
200000 sites globally will get 40 stories or more
millions of sites will get 25 stories
hundreds of millions of sites will get 12 stories.

And this will happen less because of zoning and planning or the FAA, and more because of things like surface area to volume ratios, the length of a human on a gurney, the height of the tallest fire engine, the tolerance of people waiting for elevators, the tolerance for schlepping to an elevator, the incompressibility of water, the weight of food and waste, the duration of construction loans from ground breaking to full occupancy, etc. etc.

* We do get what it means to be "atop PATH on Wall Street " or "a Chicago Loop site closest to the Metra" or "atop both Red & Commuter" or "atop both Pike and OL" but what I hope we will come to see is how as you move each block away the economics drops by 20 to 40 stories per block. And that at most sites around boston, while a great place, turns out, economically, to be where if it made sense to collect X number of 500' buildings, it probably makes better sense to collect 3X of 200' buildings (Seaport, Assembly, MIT, Longwood...)
 

fattony

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True, buy allow me to try to direct that passion to parcels for which tall makes sense. And I get that it is really hard to "see" the logarithmic decay between the very best sites in the world, and sites that are just enough "off center" that they drop several orders of magnitude in what you can build. And then several orders of magnitude later, you're at XMBLY.

It is a lot like hosting the Olympics, really. It is hard to see the huge swing that happens as you move from LA/NYC/London/Paris to Atlanta/Athens/Boston but a lot deteriorates very quickly as you move away from the truly exceptional to the merely great.

A wild swag at how "the dropoff" happens as you move away from being "The Site"* to "any old site"
20 sites globally will get 120 stories or more
100 sites globally will get 100 stories or more (currently there are 21, with 16 under construction but about 40 cancelled)
200 sites globally will get 80 stories or more
2000 sites globally will get 60 stories or more
20000 sites globally will get 50 stories or more
200000 sites globally will get 40 stories or more
millions of sites will get 25 stories
hundreds of millions of sites will get 12 stories.

And this will happen less because of zoning and planning or the FAA, and more because of things like surface area to volume ratios, the length of a human on a gurney, the height of the tallest fire engine, the tolerance of people waiting for elevators, the tolerance for schlepping to an elevator, the incompressibility of water, the weight of food and waste, the duration of construction loans from ground breaking to full occupancy, etc. etc.

* We do get what it means to be "atop PATH on Wall Street " or "a Chicago Loop site closest to the Metra" or "atop both Red & Commuter" or "atop both Pike and OL" but what I hope we will come to see is how as you move each block away the economics drops by 20 to 40 stories per block. And that at most sites around boston, while a great place, turns out, economically, to be where if it made sense to collect X number of 500' buildings, it probably makes better sense to collect 3X of 200' buildings (Seaport, Assembly, MIT, Longwood...)
Bravo. This 👆 is a very good post.

Obviously there are real numbers to crunch for any specific project on a specific site, but the principles you outline are an excellent guideline and should give everyone interested in height and density something to contemplate.
 

chrisbrat

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True, buy allow me to try to direct that passion to parcels for which tall makes sense. And I get that it is really hard to "see" the logarithmic decay between the very best sites in the world, and sites that are just enough "off center" that they drop several orders of magnitude in what you can build. And then several orders of magnitude later, you're at XMBLY.

It is a lot like hosting the Olympics, really. It is hard to see the huge swing that happens as you move from LA/NYC/London/Paris to Atlanta/Athens/Boston but a lot deteriorates very quickly as you move away from the truly exceptional to the merely great.

A wild swag at how "the dropoff" happens as you move away from being "The Site"* to "any old site"
20 sites globally will get 120 stories or more
100 sites globally will get 100 stories or more (currently there are 21, with 16 under construction but about 40 cancelled)
200 sites globally will get 80 stories or more
2000 sites globally will get 60 stories or more
20000 sites globally will get 50 stories or more
200000 sites globally will get 40 stories or more
millions of sites will get 25 stories
hundreds of millions of sites will get 12 stories.

And this will happen less because of zoning and planning or the FAA, and more because of things like surface area to volume ratios, the length of a human on a gurney, the height of the tallest fire engine, the tolerance of people waiting for elevators, the tolerance for schlepping to an elevator, the incompressibility of water, the weight of food and waste, the duration of construction loans from ground breaking to full occupancy, etc. etc.

* We do get what it means to be "atop PATH on Wall Street " or "a Chicago Loop site closest to the Metra" or "atop both Red & Commuter" or "atop both Pike and OL" but what I hope we will come to see is how as you move each block away the economics drops by 20 to 40 stories per block. And that at most sites around boston, while a great place, turns out, economically, to be where if it made sense to collect X number of 500' buildings, it probably makes better sense to collect 3X of 200' buildings (Seaport, Assembly, MIT, Longwood...)
That was a stunningly well presented and informative reply. Much appreciated.
 

Arlington

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My personal feed is filled with stories of NYC and Miami supertall residentials. I think it is easy to think "we're not that different from NYC, why isn't Boston getting supertall (or even 40+ story) residential?" I think NYC and Miami have two things no other American city (and few global ones) have:

1) Global buyers parking millions, never intending to live in the place
2) Non-residents who don't care how long they wait for too-few elevators, nor how fast the ride is to their too-high floor.

My impression is that only Austin TX is currently building tall residential buildings that people actually intend to regularly reside in
 

DZH22

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My impression is that only Austin TX is currently building tall residential buildings that people actually intend to regularly reside in
Nashville and Philadelphia are a couple of others. Nashville is building at Austin levels, except will ultimately be capped at 750' (yes there's a tower this high in the works) while for Austin the sky is the limit.
 

Arlington

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I think it notable that neither Tennessee (Nashville) nor Texas (Austin) have an income tax, making them
1) good places to park $$$ in real estate if it also gains you residency
2) generally faster-growing metros (Austin is #1 fastest (2016–2021): +14.1% , Nashville is #5 (2016–2021): +9.3% )

What's up with Philly? Leveraging the "Acela to NY or DC?" or late getting its own "30 Dalton"
 
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DZH22

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What's up with Philly? Leveraging the "Acela to NY or DC?" or late getting its own "30 Dalton"
Not as much as I thought but it's throwing up a bit these last few years. The Laurel and Arthaus are both just finishing up. Philadelphia has big plans but, like Boston, those are often glacial while the sub 300' construction marches on unabated.
1673581115899.png
 

DZH22

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One city that isn't often discussed is Montreal, which is essentially a peer city of Boston's across the border. They have a strict height limit due to Mount Royal, but are building right up to it. This diagram is only since 2020!!!

1673581376992.png
 

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