Escaping the Density Anchor
I have spent a lot of time in the Durham Unified Development Ordinance (aka "the code"). I am familiar with the number of units per acre that different zones allow (don't quiz me, though)!
I realized recently that with so much focus on the Durham code, I have succumb to the classic cognitive bias of anchoring. Outside of the downtown "design" districts and a few spots where previously, light rail stops were planned, the highest density a project can achieve is 20 units per acre. The project has to be zoned RU-M and a development plan needs to be submitted and reviewed to achieve that level of density.
There are a few additional bonuses that you could use like the affordable density bonus (rarely, if ever used) and the major thoroughfare bonus, but for the most part 20 units per acre is the max. That 20 units per acre has been in my mind for a number of years now. Do I think certain situations call for more units per acre? Sure! But my mind dreams about 30 units or even 35 units per acre.
I have succumb to anchoring. The reference point of 20 units per acre has warped my sense of what the highest level of density in the urban tier should be.
What caused me to realize this? Erwin Apartments.
You may recognize this building. It's on N Buchanan Blvd, across from Duke's East Campus. I have passed by countless times and it has been striking, but I have never said to myself, "woah, that is WAY out of place". It was recently gutted and turned into condos, but beautiful facade remains.
I don't know how many condo units there are, but when it was an apartment building, it had 31 units. it sits on a 0.28 acre parcel. Quick math will tell you that is about 110 units per acre!
You may say, "yeah, but that was built in the 1930's. You need to have parking now". Good point, the parcel next to it serves as the parking lot. Still, both parcels combined are 0.5 acres. That is still 62 units per acre.
There are other ways to frame density as well. If we are talking about missing middle housing, 8 small cottages on a 0.25 acre lot (cottage court) would be 32 units / acre. I mentioned previously that I was recently walking around Burlington, VT. I happened to look up one property on their GIS. It was an old house that had been split into 6 units. The parcel was 0.16 acres. That's 37.5 units per acre! Take a look at this "crazy dense behemoth":
Here I am thinking that 20 units per acre is for large apartment complexes just outside of the downtown design district. In fact, 37.5 units per acre can be indistinguishable from the single family home right next to it.
Then, of course, European cities (areas without high-rises) can be in the 100s of units per acre range and still feel human-scale.
So now, I have shifted my thinking from a 20 unit per acre mindset to a mindset of "is that really the highest density we should be allowing outside of downtown?"
