This is a fascinating little experiment:

From Oct. 12, 2020 to Jan. 3, 2021, Redfin ran an experiment on 17.5 million of its users across the US. As prospective homebuyers entered the site, Redfin assigned them randomly to either a group that was shown flood-risk information on each property or a group that was not.

The flood-risk scores came from First Street Foundation, a climate and technology nonprofit that works to make climate hazards more transparent to the public. In June 2020, First Street published the first public maps that revealed flood risk for every home and property in the contiguous US. 

First Street scores properties on a scale of 1 to 10 based on the likelihood that they will flood in the next 30 years (which is assumed to be a typical mortgage term). A score of 1 means the property has "minimal" risk and a score between 9-10 is considered "extreme" risk.

So what happens once you start showing people flood-risk information? They, not surprisingly, start systematically looking for safer properties. After one week of users being exposed to this new information, prospective buyers who were previously looking at "extreme" homes started looking at homes that were about 7% safer.

After 9 weeks, these same "extreme" home buyers were looking at properties that were about 25% less risky. And for some buyers, in particular those working with a Redfin agent or partner, their flood-risk tolerance dropped by over 50%. (Embedded in this data might be a sales pitch for working with a knowledgeable Redfin agent or partner).

Also interesting is the fact that below "severe" flood risk (a score between 7-8), there was very little change in behavior. "Major" flood risk, it would seem, isn't all that concerning to most buyers. It needs to be "severe". Nevertheless, it is noteworthy that people will in fact make behavioral changes when presented with clear climate-risk data.

I spent a good chunk of this morning talking and thinking about underground building details that most people (unless you're in the industry) would never think to consider. This is not a criticism on most people. I mean, I don't know how iPhones are made. I just use and enjoy them. But when it comes to buildings, I'm paid to ask questions and understand how things work.

There's a lot of risk in the ground.

You have to think about things like bearing capacity, environmental contamination (usually), hydrostatic pressure and, generally, how you're going to manage water, particularly if you have a high groundwater table. Usually this last one is about making sure you're keeping the water out. A pretty important detail both below and above grade.

So when I came home tonight and saw the below tweet, I felt obligated to write about it.

If you read the reply from NYC's Metropolitan Transportation Authority, you'll see that this is them testing something they call a "flex gate." It is a flood barrier that allows them to seal off subway entrances in the case of a storm surge and they run these tests (shown above) for 4 hours at a time to make sure they're installed property. This one was.

Managing water is a big part of city building. New York City, Miami, Venice, and countless others know this all too well right now.

This is a fascinating little experiment:

From Oct. 12, 2020 to Jan. 3, 2021, Redfin ran an experiment on 17.5 million of its users across the US. As prospective homebuyers entered the site, Redfin assigned them randomly to either a group that was shown flood-risk information on each property or a group that was not.

The flood-risk scores came from First Street Foundation, a climate and technology nonprofit that works to make climate hazards more transparent to the public. In June 2020, First Street published the first public maps that revealed flood risk for every home and property in the contiguous US. 

First Street scores properties on a scale of 1 to 10 based on the likelihood that they will flood in the next 30 years (which is assumed to be a typical mortgage term). A score of 1 means the property has "minimal" risk and a score between 9-10 is considered "extreme" risk.

So what happens once you start showing people flood-risk information? They, not surprisingly, start systematically looking for safer properties. After one week of users being exposed to this new information, prospective buyers who were previously looking at "extreme" homes started looking at homes that were about 7% safer.

After 9 weeks, these same "extreme" home buyers were looking at properties that were about 25% less risky. And for some buyers, in particular those working with a Redfin agent or partner, their flood-risk tolerance dropped by over 50%. (Embedded in this data might be a sales pitch for working with a knowledgeable Redfin agent or partner).

Also interesting is the fact that below "severe" flood risk (a score between 7-8), there was very little change in behavior. "Major" flood risk, it would seem, isn't all that concerning to most buyers. It needs to be "severe". Nevertheless, it is noteworthy that people will in fact make behavioral changes when presented with clear climate-risk data.

I spent a good chunk of this morning talking and thinking about underground building details that most people (unless you're in the industry) would never think to consider. This is not a criticism on most people. I mean, I don't know how iPhones are made. I just use and enjoy them. But when it comes to buildings, I'm paid to ask questions and understand how things work.

There's a lot of risk in the ground.

You have to think about things like bearing capacity, environmental contamination (usually), hydrostatic pressure and, generally, how you're going to manage water, particularly if you have a high groundwater table. Usually this last one is about making sure you're keeping the water out. A pretty important detail both below and above grade.

So when I came home tonight and saw the below tweet, I felt obligated to write about it.

If you read the reply from NYC's Metropolitan Transportation Authority, you'll see that this is them testing something they call a "flex gate." It is a flood barrier that allows them to seal off subway entrances in the case of a storm surge and they run these tests (shown above) for 4 hours at a time to make sure they're installed property. This one was.

Managing water is a big part of city building. New York City, Miami, Venice, and countless others know this all too well right now.