Studio Libeskind has a recently completed project in Brooklyn that looks like it was designed by Studio Libeskind. It has angled facades and, judging by the comments on Dezeen, its design is polarizing. But it is an affordable housing project for seniors, and it does have a large atrium in the middle of it.

Atria are a bit of a unique feature in multi-family housing (at least in this part of the world). For better or for worse, the gold standard has become the double-loaded corridor. And that's because it's "efficient." It helps you maximize the amount of rentable or saleable area to gross construction area.

Here in Toronto, a typical efficiency -- calculated as the net saleable/rentable area divided by the gross construction area -- would be somewhere between 75-80%. Though many factors can affect this percentage, such as the amount of amenity space in the building.

There is certainly the option of just building a less efficient building, but then it means you'll likely need to increase the price of the homes to compensate for this loss in efficiency.

This is the trade-off that is often made with smaller suites. More and smaller suites usually translate into more corridor space (i.e. a lower overall efficiency). But it may make sense to do this if you think your smaller suites will generate more revenue on a per square foot basis.

Off the top of my head, I can only think of two residential building in Toronto with an atrium. And that's 71 Front Street East in the St. Lawrence and "The Atrium" at 650 Queens Quay West. The latter is pretty neat inside. The last time I checked, it even had fake palms.

In the case of both The Atrium and Libeskind's Brooklyn project, the atria result in single-loaded corridors. (I'm not sure how 71 Front was designed.) Here's what Libeskind's project looks like:

The obvious advantage of this condition is that you get natural light into the corridors, whereas with a typical double-loaded corridor you don't. But again, the disadvantage of this design is that you only have apartments on one side, instead of both sides.

In this case, the thermal envelope of the building is the outside face of each corridor (atrium side). This means the corridors are interior or conditioned spaces.

Another option would be to create open-air corridors, like in this example from Montreal. This creates corridors exposed to the elements, but now you've reduced your overall energy consumption (less space to heat/cool) and you've created the possibility of double-aspect units.

Personally, I'm a fan of atria and courtyards in residential buildings. But for the reasons we just talked about, they're not that common. My sense is that they're far more common in commercial buildings. John Portman, for instance, made a name for himself designing and developing hotels around them.

What are your thoughts, though? Would you pay a premium to live in a residential building with a nice atrium? I bet some of you would if it meant an improved suite design, such as more windows and more natural light.

Photos: Hufton + Crow

Understanding building areas is a fundamental component of real estate and development. But it can actually get surprisingly complicated. Definitions, naming conventions, and measurement techniques vary greatly around the world. 

To some, “GLA” means gross leasable area. But to others, it means gross livable area. So it’s important to understand what exactly is being measured when someone tells you that that a building is X number of square feet. Are we talking gross building area, gross floor area, or rentable area? Does that number include the below-grade areas or just what is above-grade? To make matters even more complicated, there are nuances to consider depending on whether it’s a residential or commercial building. 

By now, I am sure you’re starting to see how complicated something as seemingly simple as building areas can get. So let’s talk about some of the basics today. Again, definitions might vary depending on where in the world you area. They might even vary based on conventions you’ve adopted within your particular firm.

Gross Building Area: Also referred to as Gross Construction Area by some, this is the total area of the building, measured to the outside walls without any deductions. As you’ll see later, some area definitions allow for certain deductions. Gross Building Area is important because it’s a big driver of your costs – specifically construction costs. This is how much building you’re building. But, and this is important, it does not drive your revenue. That comes later.

Gross Floor Area: This is usually a specific locally-defined measurement convention. It often allows you to deduct certain areas from your gross building area, such as “major vertical penetrations” and below grade parking areas. This number doesn’t directly drive construction costs or revenue (saleable/rentable area), but it’s important because it’s what the city will use to determine important planning numbers such as the building’s density/floor space index and to calculate any applicable levies. It’s also a fairly public number and might be what the brokers are using to calculate, as one example, what certain land sold for on a per buildable square foot basis.

Net Saleable/Rentable Area: This is a hugely important number because it directly drives revenue. It’s your top line. It’s the amount of space you can collect rent on or the amount of space that you can sell. And unless your revenue exceeds your costs (which you’ve calculated using the numbers above), you’re not going to be able to build. 

Note: Commercial spaces (at least in this part of the world) often work a bit differently in that there is what is known as a gross-up factor. What that means is that tenants pay rent on portions of the common areas (such as corridors) that fall outside of what is known as their “usable area.” In this scenario, the rentable to usable area ratio (R/U) becomes important. Naturally tenants don’t like paying for a lot of space beyond their usable area.

This is just a brief overview of building areas. A good architect will make sure that your building area calculations are meeting all local rules and conventions. But as a developer it’s important to know and understand what exactly is being measured and what the “loss factor” of your building is. In other words, how much space is being lost to areas that cannot be sold or rented? Typically, you want to minimize lost space, unless maybe you’re pushing some new concept.

Anything to add to this building area summary? Do you use different terminology or conventions in your part of the world? Let us know in the comment section below. That would make for a fascinating discussion.