Fitting more housing into the city

Seattle is suffering from a deep housing affordability crisis, with more and more people being priced out of living there. At the same time, it’s been deeply resistant to changes in zoning that would allow enough new housing to be built. One of the examples of this is that it has a program called “Encouraging Backyard Cottages”, and has gone through at least two rounds of legal reforms to support that, but figuring out whether one can be built on any given lot still involves going through a long checklist about the exact dimensions of the site and intricacies of zoning.

In theory, DADUs (Detached Accessory Dwelling Units, the much less appealing legal term for “backyard cottages”) allow a lot of small, affordable housing to be added to single-family zoned neighbourhoods and spread out enough to not feel like a radical change in the streetscape. In practice, the complicatedness of the process adds enough of a barrier that relatively few have been built so far. Hatchback Cottages has a plan to solve this with a set of ready-to-build designs and a package of support to help people through the process.

Even with their expertise, assessing a site under the arcane rules is a time consuming process. But computers are good at applying lots of rules and calculating all the measurements, so Hatchback contracted me to run a GIS analysis assessing every residential lot in Seattle for suitability.

A map of one city block with individual lots shaded green if they could have a DADU and red if they couldn't.  Existing building outlines and the area in which a DADU might fit are also shown.

Fortunately for us, Seattle and King County publish very comprehensive and regularly updated open data about zoning and development, so I had a lot to work with. The analysis takes into account existing building footprints, lot characteristics and potential complicating factors like steep slopes and landslide hazard areas. It will never be a complete replacement for a knowledgeable human looking at the site, but by ruling out all the sites that definitely won’t work it saves my client a lot of time. Now the experts can solely focus on sites that have a relatively good chance of working out.

Pacific Northwest climate trends

The University of Washington Climate Impacts Group has built a new visualization tool for the state climatologist, which makes it easier than before to explore the whole climate record for Washington and some data for neighboring US states. The data itself is nothing new,  but being able to explore it can help to get a handle on what’s going on.  I rather arbitrarily picked my life to date as the range to compare, and got the sobering result that every single monitoring station has registered an increase in temperature since I was born; most statistically significant.

A map of Washington, Oregon, Idaho and western Montana, showing temperature increases at every station, and line charts for each state showing the overall trend

Of course, there’s no scientific basis for picking that particular range, but I wasn’t cherry-picking either (I’d have picked 1985-2015 if that were my goal). I just wanted dates that felt personally meaningful, and even as someone who considers myself relatively well-informed about climate change the sheer scale of the trend was breathtaking.

Housing: short vs long views

If you know contemporary Seattle, you probably know that we have a housing crisis. If you know me at all, you’ve probably heard about how I grew up in London and most of my school friends can’t afford to live anywhere in London, which terrifies me about Seattle’s future. So it should be no surprise that housing affordability is a huge issue in local politics, and one that I pay a lot of attention to. Equally unsurprising: even among people who agree that we have a problem and it’s important, there’s wide disagreement about what to do, and these disagreements often get very bitter.

Against that background it was a relief this evening when a panel discussion about the housing crisis managed not to bring out any of that vitriol, and stayed a respectful, interesting airing of differing views. At the risk of caricaturing the panelists’ views a little, I would summarise them as:

  • Hodan Hassan of Got Green, making a strong and convincing moral case against displacement and for paying particular attention to the displacement of minorities, and opposing market solutions because capitalism and land ownership are themselves the problem.
  • Zach Lubarsky of Seattle Tech 4 Housing [full disclosure: I’ve done a tiny bit of volunteer work for this org], arguing that the market has to be used in solving this problem, and the reason it hasn’t worked so far is restrictive zoning getting in the way.
  • Laura Loe, who did an outstanding job of threading the needle between these two positions, which is what I really want to talk about.

Continue reading “Housing: short vs long views”

What would it take to predict climate change inundation well?

Last week I ranted about a poorly executed report claiming to show which properties around the US are at risk of climate change driven flooding. Peter Abrahamsen responded with:

Also, mean sea level, however it’s measured, doesn’t tell you who’s at risk of flooding.

and then pointed me at a couple of much better examples, most notably the Victoria, BC Capital Regional District’s climate change modeling project. I think it’s worth looking at all the other questions that would have to be answered to really get this right. Before diving in, I want to make clear that I’m not piling on Zillow any more: last week’s post was about flaws they should have figured out as a real estate data company, while most of what’s below will be details that they never claimed expertise in or took a position on. Continue reading “What would it take to predict climate change inundation well?”

Blindly trusting data will leave you all at sea

Zillow recently published a report on how many houses are at risk from sea level rise around the US. It’s a good idea, but looking closely at where I live reveals some… issues in their analysis. Here’s a screenshot from the Seattle Times’ article with the local angle on the report:

Homes that Zillow thinks are at risk of flooding from sea level rise in Seattle

If you know Seattle, you can probably spot the first problem. For those who don’t: the Eastern shore, and the cluster N of the word “Seattle” on that map are all lakefronts, separated from the sea by the rather large Ballard Locks. The local article’s been updated to mention that, but Zillow’s downloadable data hasn’t. And even the local article misses a detail: if sea levels were to rise by a foot more than the analysis assumed, the highest tides would still only be 4¾ inches over the lock gates—a problem for some houses for sure, but nothing like the 7 feet of flooding we’d have on our sea side, and much less than the amount the lake is already allowed to rise and fall by.

But there’s another problem, unrelated to quirks of Seattle’s Herculean engineering, and much more worrying for the reliability of this analysis. Continue reading “Blindly trusting data will leave you all at sea”