I recently read an article by Architect Lyz Dunn for AIA Seattle where she makes a great case for preserving old buildings during the densitification process. The paper is very good and I recommend everyone read it. In this post (with extensive footnotes!), I’d like to expound on a certain part of her argument, and explain why, at least in Seattle, there’s nearly no well-reasoned pro-urbanist argument for tearing down a single moderately dense old building, especially those of the pre-automobile sort (roughly anything Depression era or earlier, though I include any moderately-dense oldish building without parking).
I see three reasons you (or anyone) might want to replace old buildings with newer ones. First, you may not like old buildings, or you may prefer the look of new buildings. These are aesthetic arguments we can dismiss out of hand; everyone’s tastes differ. Second, you may have support for a sense of property rights that entitle people to tear down old buildings they own if they want to. This is a philosophical argument that is outside the scope of this post, but as I have said before, I am wary of the actual intentions of most people who make these arguments. Finally, you may like to tear down old buildings and replace them with something more “dense” for standard urbanists reasons: walkability, sustainability, transit-use and economics. This is the argument I will address today.
As for sustainability, as Liz Dunn points out, the vast majority of the savings in green house gas emissions (nearly 96%), difference in vehicle-miles-travelled, and choice for alternate transportation are achieved by getting from standard single family home density to 50 units an acre. In fact, the VMT and driving reductions from going from 9 units an acre (typical 5,000 square-foot-lots) to 50 units an acre are 15 times the difference between 50 units an acre and 200 units an acre. Put another way, 94% on the VMT and transit benefits to extreme density are accomplished by getting to 50 units an acre. I’d further like to add that building a new building isn’t free environmentally, but leaving an existing building more or less is.
Moreover, urban form is as important to these same sustainable goals as is density. This comparison of density and travel distances in the US and the UK showed that land-use patterns had as much an impact on trip length and mode choice as density did. Old neighborhood forms with ten small shops per block are much better for walkability – and thus better for reducing car trips – than are monolithic buildings with just a few shops in them. Furthermore, no single factor has a larger impact on whether or not someone will choose to drive for his or her trip than the existence of a parking spot on either end. Most of our heritage buildings – both commercial and residental – have very little or no parking. In this regard, they truly don’t make them like the used to.
Another factor most people overlook is the massive increase in housing unit size over the second half of the last century and the first decades of this one. As Matthew Yglesias pointed out in The Rent is Too Damn High, the average house in the US has more than doubled in size the last 60 years, and this census data shows the average apartment size has more than doubled in just the last forty years. For most heritage buildings, even replacing them with a building twice as large wouldn’t result in an increase in net density. The new buildings would have to be even larger still to get an increase in units when parking is considered. And that’s what density is right? Units and people? It’s certainly not height, it’s also not square feet, and it sure as hell isn’t parking.
I believe the Seattle urbanist’s instinct to support destroying already moderately dense buildings in order to allow for new construction stems from a lazy borrowing of the arguments against over-used landmarking in places like San Francisco and New York. In those places, it really is the case that the only way to get new housing and commercial space is to remove already-present, moderately-dense buildings. However, this is clearly not the case in Seattle. The vast majority of housing in our region – including nearly half of the housing just in the city limits – is contained in very low-density construction and is completely unremarkable from both an aesthetic and a historical standpoint. The same is true for commercial space; again the vast majority of retail space – even in the city limits – is contained in strip malls, big box retail stores and other auto-oriented, pedestrian-and-transit-unfriendly places.
We seem to have a problem of not providing enough incentives to create infill development that doesn’t destroy our heritage buildings. But our problem isn’t that we’re overprotective of our small stock of heritage buildings; it’s that we are overprotective of the millions of unremarkable houses, strip malls and big-box retailers in our area. The problem isn’t that our heritage buildings aren’t dense or green enough – in fact they are probably much more dense and much more green than most realize – it’s that we have so few places we can build densely. Even in the places we can build densely the incentives aren’t large enough to make the new development happen fast enough. Our current system would have us canabalize the very best examples of walkability and urban form we have to get just a few more units. This is completely unacceptable and we shouldn’t support this. We certainly shouldn’t fight for it. Where we should be spending our energy is toward expanding where we can build densely and toward making it easier to do so where we already can. We can do this and still leave the old buildings alone, leaving future generations to make the choice for which walkable neighborhoods to canabalize, as they are forced to in New York and San Francisco.
 In fact, since we cannot build new old buildings, but there are lots of places we could put new new buildings, this argument has little merit.
 There’s more on that here, if you don’t have the book.
 This is usually how heritage buildings play into affordability. The apartments are usually smaller and lack parking, making them significantly less expensive than the larger, parking-provided apartments that replace them. A similar argument goes for heritage storefronts and office space.
 The number approaches 100% in most places outside of Seattle and Tacoma, and in most of these places there is virtually no up-zone movement.
 The Dunn piece in the first link gives many very easily accomplished ideas on how to encourage this.
 Thanks to Adam for linking me to this article. Yes, this endnote is not linked to anywhere in the text.