Building height and density are not one and the same. You can have tall buildings configured in a low-density way (think post-war towers in the park). And you can have low/mid-rise buildings configured in a high-density way (think Paris and Barcelona). This is one of the reasons why it is important to decouple density and tallness when thinking about our cities.

This line of thinking is the approach that a recent study took when trying to determine the optimal built form for minimizing climate impact. In the study they define four building typologies: 1) high density, high-rise, 2) low density, high-rise, 3) high density, low-rise, and 4) low density, low-rise.

What they found was that taller environments tend to have higher life cycle GHG emissions, but that lower-density environments are (obviously) far more land consumptive. To determine life cycle GHG emissions they looked at both embodied and operating emissions, which is why the taller stuff didn't score as well under their methodology. There's typically a lot of concrete and steel in tall buildings.

This lead the team to conclude that if you want to optimize around climate impact, you should probably aim for that perfect middle ground: dense, but not super tall.

But as Joe Cortright (City Observatory) rightly pointed out in his email newsletter, one of the big limitations of this analysis is that it does not consider transportation-related impacts. And since we know that transportation is one of if not the largest source of GHG emissions and that how we get around is heavily dependent on land use patterns, it is probably an important piece to consider.

Photo by Alfons Taekema on Unsplash

In the world of development, there is something known as a floor space index (FSI). Some places call it a floor area ratio (FAR), but they mean the same thing. It is one measure of density. To calculate it, you simply divide the total building area by the site area. For example, if you had a 25,000 square foot piece of land and you were to build a single storey building that occupied every bit of the site (also 25,000 sf), you would have an FSI or FAR of 1.0. If you built a two storey building on only half of the site, you would similarly have an FSI or FAR of 1.0. The area didn't change, you just moved things around. That's how FSI's work.

A ratio like this tells you how intensely you may be using a piece of land, but it doesn't tell you everything or necessarily give you the full picture. Which is why I find it silly when too much emphasis is placed on this singular number. I don't think anyone in the history of the world has ever traveled to a city -- let's take Paris -- and remarked how beautiful it is because of its floor space indices. Nobody thinks like this. It's way too esoteric. What guides our experiences is built form, the ground plane, relationships to streets, materiality, light, context, and many other important things.

To give a specific example, let's take One Delisle. This project was in effect approved twice. After it was approved by City Council in July 2020 an adjacent land parcel was acquired. It wasn't absolutely necessary to do this, but we felt it made for better city building and so we did it. (We wanted to look back knowing we did the right thing.) That meant that we needed to go back to Council to revise our approvals, which ended up happening at the beginning of this year (public staff report, here). There was no change to the tower and and no change to any of the key setbacks or stepbacks. But the overall FSI did go down!

Will anyone notice or care about this lower ratio? I doubt it. Which is why I think it's silly to try and plan our cities around them. It feels like design by spreadsheet. Thankfully, I think many people recognize this.

Photo by Thibault Penin on Unsplash

The web in its current state is like a city without public spaces. People can only interact in places owned by someone else, and a small group of landlords captures an oversized share of all economic activity. - Dror Poleg

I would encourage you all to read Dror Poleg's recent article called, "The Token Society: Cryptocurrencies will change the way we work, live, and love." It's an interesting read, particularly for us urbanists. Poleg starts with urban history. He first talks about how the emergence of industrial cities allowed for new divisions of labor. The example he gives is that of the quatorzième, which is a job that emerged in Parisian society sometime in the late 19th century. The job of a quatorzième was literally to be the 14th person at dinners and functions. Since a headcount of 13 was thought to be bad luck, it was important to be able to call on someone at a moment's notice to fill this critically important role. While this probably seems silly in today's context -- I mean, who goes out anymore? -- it was a real thing and it was a thing that the modern city was suddenly able to provide. Poleg goes on to thread this idea all the way through to today. Web 2.0 enabled a new sharing economy and much larger digital communities (though note the quote at the top of this post). However, we're nowhere near done yet. Web 3.0 is going to, in his words, enable "the finalization [or tokenization] of all human activity." Welcome to the new token society.

P.S. I'm by no means an expert on cryptocurrencies. I have just been watching from afar for the past several years. But over the last few months, it has been hard not to pay attention to what is happening with NFTs and the Ethereum network. And I'm not just talking about the price of ETH (which is up ~56% over the last month alone). I am now of the opinion that we are seeing one of the first mainstream use cases emerge on top of a blockchain network. And yes, I believe it will also change our cities.