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One question that was nagging me after seeing Hong Kong’s “typical” tower typology was: what’s with the cruciform tower plan and all these notches and cutouts? Wouldn’t it be far more efficient to square off the floor plates? I figured that it had to be in response to building regulations. I was going to mention that in this post on the typical “8-units-per-floor” tower plan, but I wanted to first understand what was going on. Thankfully a reader of this blog who is from Hong Kong was kind enough to send me a wonderfully detailed email outlining some of Hong Kong’s building regulations and how they impact the design of tall buildings.
It turns out that there are requirements for both “natural lighting and ventilation” and for “external air.” All rooms for habitation, as well as offices, bathrooms, and kitchens, are subject to these requirements. There are prescribed window areas for the “glass areas” and for the “openable areas”, both of which are a function of the room size. The glass area must equal the room area divided by 10. And the openable area must equal the room area divided by 16. I presume that these are minimum sizes because they don’t feel all that big.
For the “external air requirement”, the room must face a street no less than 4.5m in width or it must face an unobstructed space as delineated by “rectangular horizontal planes” and by “inclined planes.” The incline planes are drawn in section from the sill of the window and the angle depends on the type of room. The rectangular horizontal planes are drawn in plan and have a minimum area of 21 square meters (or ~225 square feet). If you would like to deep dive into more of the technical details you can do that here. But suffice to say that it is these requirements which are driving all of the tower notches and cutouts.
The result is tower floor plates that can look something like this:
And if we zoom into a unit (this one being a 3 bedroom apartment), you can see that both bathrooms have a window, as does the kitchen. From what I saw, there appears to be less interest in open concept floor plans. You may also finding it interesting to note some of the room dimensions (in mm) and the A/C platform sitting outside of the master bedroom.
Finally, I should follow-up on my previous comment about tower separation distances and the ability for the above tower floor plates to be built directly adjacent to each other. Not surprisingly, this resulted in walls of towers being constructed. Ultimately this became known as the “wall effect.” So in 2011, the Sustainable Building Design (SBD) guidelines were put in place which stipulated that groups of buildings having a continuous facade length greater than 60m should comply with various separation and permeability guidelines.
So there you have it. Every market has its local nuances. The above post is a good example of that. I also love when this blog becomes a platform for two-way discussion. I learned something new today and hopefully you did too. Thank you Hiu Yeung for your emails and for providing me with all of this information.
Top image: Photo by me taken at Hong Kong’s Peak
This morning I took the mid-level escalators down to Hong Kong station so that I could catch the express train to the airport. At over 800m, it is supposedly the longest outdoor covered escalator system in the world.
If you’ve ever walked the streets of Hong Kong you’ll know that the ground plane can be inhospitable at times. There’s limited space, but no shortage of steep pitches. I can’t imagine having a physical disability and trying to navigate this city.
So this system must have been a real innovation when it was constructed in the early 90′s. In total it moves up and down about 135m in elevation. That’s about the equivalent of a 45 storey tower. And I got down from the mid-levels and was on a train to the airport within 15 minutes.
But because the streets here are so narrow it’s a unidirectional system with one line of escalators. They bring people down to the CBD during the morning rush, but then the direction flips and they bring people up the hill for the remainder of the day — until midnight I believe. Living near these escalators is considered a win.
Hong Kong Island surely isn’t the easiest of environments in which to build and operate one of the world’s most important global cities. There’s relatively little developable flatland. But they more than made it work by being creative and by building up. Hong Kong is not just a tall city, but a truly vertical city.
Too bad my efficient morning commute was followed by a cancelled United flight. Tomorrow is not going to be a fun day travel.
Take a look at this photo from Central in Hong Kong and note the MEP (mechanical, electrical, and plumbing) systems running up the cutout in the middle of the tower. Also note the bamboo scaffolding next door and the epic terrace on top of the ground floor bank. The building on the opposite side put parking on top of its podium.
One question that was nagging me after seeing Hong Kong’s “typical” tower typology was: what’s with the cruciform tower plan and all these notches and cutouts? Wouldn’t it be far more efficient to square off the floor plates? I figured that it had to be in response to building regulations. I was going to mention that in this post on the typical “8-units-per-floor” tower plan, but I wanted to first understand what was going on. Thankfully a reader of this blog who is from Hong Kong was kind enough to send me a wonderfully detailed email outlining some of Hong Kong’s building regulations and how they impact the design of tall buildings.
It turns out that there are requirements for both “natural lighting and ventilation” and for “external air.” All rooms for habitation, as well as offices, bathrooms, and kitchens, are subject to these requirements. There are prescribed window areas for the “glass areas” and for the “openable areas”, both of which are a function of the room size. The glass area must equal the room area divided by 10. And the openable area must equal the room area divided by 16. I presume that these are minimum sizes because they don’t feel all that big.
For the “external air requirement”, the room must face a street no less than 4.5m in width or it must face an unobstructed space as delineated by “rectangular horizontal planes” and by “inclined planes.” The incline planes are drawn in section from the sill of the window and the angle depends on the type of room. The rectangular horizontal planes are drawn in plan and have a minimum area of 21 square meters (or ~225 square feet). If you would like to deep dive into more of the technical details you can do that here. But suffice to say that it is these requirements which are driving all of the tower notches and cutouts.
The result is tower floor plates that can look something like this:
And if we zoom into a unit (this one being a 3 bedroom apartment), you can see that both bathrooms have a window, as does the kitchen. From what I saw, there appears to be less interest in open concept floor plans. You may also finding it interesting to note some of the room dimensions (in mm) and the A/C platform sitting outside of the master bedroom.
Finally, I should follow-up on my previous comment about tower separation distances and the ability for the above tower floor plates to be built directly adjacent to each other. Not surprisingly, this resulted in walls of towers being constructed. Ultimately this became known as the “wall effect.” So in 2011, the Sustainable Building Design (SBD) guidelines were put in place which stipulated that groups of buildings having a continuous facade length greater than 60m should comply with various separation and permeability guidelines.
So there you have it. Every market has its local nuances. The above post is a good example of that. I also love when this blog becomes a platform for two-way discussion. I learned something new today and hopefully you did too. Thank you Hiu Yeung for your emails and for providing me with all of this information.
Top image: Photo by me taken at Hong Kong’s Peak
This morning I took the mid-level escalators down to Hong Kong station so that I could catch the express train to the airport. At over 800m, it is supposedly the longest outdoor covered escalator system in the world.
If you’ve ever walked the streets of Hong Kong you’ll know that the ground plane can be inhospitable at times. There’s limited space, but no shortage of steep pitches. I can’t imagine having a physical disability and trying to navigate this city.
So this system must have been a real innovation when it was constructed in the early 90′s. In total it moves up and down about 135m in elevation. That’s about the equivalent of a 45 storey tower. And I got down from the mid-levels and was on a train to the airport within 15 minutes.
But because the streets here are so narrow it’s a unidirectional system with one line of escalators. They bring people down to the CBD during the morning rush, but then the direction flips and they bring people up the hill for the remainder of the day — until midnight I believe. Living near these escalators is considered a win.
Hong Kong Island surely isn’t the easiest of environments in which to build and operate one of the world’s most important global cities. There’s relatively little developable flatland. But they more than made it work by being creative and by building up. Hong Kong is not just a tall city, but a truly vertical city.
Too bad my efficient morning commute was followed by a cancelled United flight. Tomorrow is not going to be a fun day travel.
Take a look at this photo from Central in Hong Kong and note the MEP (mechanical, electrical, and plumbing) systems running up the cutout in the middle of the tower. Also note the bamboo scaffolding next door and the epic terrace on top of the ground floor bank. The building on the opposite side put parking on top of its podium.
I was told that systems are commonly run on the outside of buildings here to maximize interior square footage. Again, space is a precious commodity in this city. But it also speaks to not having to worry about freeze-thaw cycles. Winter in Hong Kong has so far equaled me walking around in a t-shirt.
These exposed systems look ugly as all hell, but I suppose they also mean not having to break open drywall when you have a problem.
I am fascinated by the relationship that buildings have between interior and exterior space. In cold cities like Toronto we are forced to hermetically seal off our buildings from the elements. We have to worry about thermal bridging and about heat tracing cold spots.
But in a city like Hong Kong I would imagine that the greater concern is stifling heat and humidity. All of this comes through in the built form.
I was told that systems are commonly run on the outside of buildings here to maximize interior square footage. Again, space is a precious commodity in this city. But it also speaks to not having to worry about freeze-thaw cycles. Winter in Hong Kong has so far equaled me walking around in a t-shirt.
These exposed systems look ugly as all hell, but I suppose they also mean not having to break open drywall when you have a problem.
I am fascinated by the relationship that buildings have between interior and exterior space. In cold cities like Toronto we are forced to hermetically seal off our buildings from the elements. We have to worry about thermal bridging and about heat tracing cold spots.
But in a city like Hong Kong I would imagine that the greater concern is stifling heat and humidity. All of this comes through in the built form.
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