Seattle-ite Patrick McGrath asked the following question in a comment to the “Density Game” below:
Are high rises the best way to move people into the urban core? How do they compare to 3-5 story apartment blocks in terms of their affordability and population density?
Well, Patrick … it depends.
As the post notes, the density for highrise and lowrise can be exactly the same. In fact, the highrise could be less dense – assuming we’re comparing floor area, not population. For instance, a 20-storey building with floorplates that are 5,000 square feet in area on a lot that is 25,000 square feet has (I simplify) a Floor Space Ratio (FSR) of 4. A five-storey building that almost covers the site would likely have an FSR of around 4.5. The lower building would be denser.
But what you probably want to know is how many people could be accommodated – and that depends on the number of units, and the number of people in each unit. Let’s say you have a luxury highrise with one suite per floor and two people per unit. The highrise in the above example accommodates only 40 people. But the lowrise, if converted, for example, to SRO (single room occupancy) with suites of 300 square feet (even if floorspace is lost in the conversion), could still house over 200 people.
On the other hand, take a look again at St. James Town. The highrises are accommodating large families in a few rooms, and would be significantly more crowded than ‘luxury’ lowrises. (Though the term ‘luxury’ is nearly useless as a qualifier since it’s applied to suites of such varying size and quality, let’s assume it means less people in larger suites.) Here’s the point:the heights of these buildings don’t necessarily tell you which is denser, which is more crowded, or even which is more affordable.
But, as my post suggests, people bring preconceived ideas about the virtues of height and density to the discussion. Many people assume higher buildings are more alienating – which may be true, for them. Others appreciate both the privacy and views that highrises allow. (My experience in Paris in a classic medium-rise courtyard apartment building revealed that noise and lack of privacy are significant negatives, and the views are non-existent.)
Both lowrise and highrise buildings have their places. In fact, a mix is preferable. Above all, whether low or high, the building needs to relate well to the street and to what designers call the public realm. If done well in the first three storeys, then the height of the tower is largely irrelevant. That’s why the so-called Vancouver Style encourages the use of podiums and townhouses. You can pile up the density while still maintaining a lot of open space between the windows of adjacent towers – a minimum of 80 feet in Vancouver.
Nonetheless, in the newly developed Triangle West neighbourhood, I think there are too many towers of the same height, proportions and colours, even if widely separated.
Diversity, it seems, is desirable in both the built and natural environments.
Gentlemen – if one is talking about residential development, it is very difficult to achieve more than, say, 3 FSR in a lowrise configuration – 4 storeys here in Canada, since building depth is limited by light and air requirements. (I’d like to know what FSRs are achievable in the 6 storey format typical in the Seattle area, if anyone knows.)
With “tower in the park” concepts, like Vancouver’s West End, where pencil towers are situated in the middle of landscaped yards and with underground parking, the density maximum is typically 2.6FSR, but can be higher with bonuses, and were, before the West End was down-zoned in the early 1970’s.
On the other hand, in Vancouver’s Downtown South neighbourhood, where the typical density is 5 FSR and heights are 300 ft., and the required form includes a 2-3 storey streetwall “podium” or base (i.e., no “park”), there is clearly more floor space available than in a highrise format than lowrise one, on a similarly-sized urban parcel. With density bonuses for amenities, heritage protection and the like, the effective density (FSR)can be substantially higher still.