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The city may need to build fewer housing units than many have been thinking.
On paper, anyway, Cambridge needs to put up between 3,100ย and 6,200 more units of housingย during the years that started in 2010 andย end inย 2030, according to Holly St. Clair, director of data services for the Metropolitan Area Planning Council.
The figure was produced Wednesday in a blog post by city councillor Dennis Carlone, who said he saw that โmany residents are asking the question: How much housing does Cambridge need by the year 2030?โ
In explaining the figures he was passing on, Carlone continued:
While the MAPC analysis calls for up to 6,200 new units in Cambridge by 2030, it’s also worth pointing out that in just the past year, some 2,450 units of new housing were either completed or in construction across the city, according to the Community Development Department’s 2014 Year In Review. Taken together, theseย numbers indicate that Cambridge is making real progress toward MAPC’s 2030 goal.
A Better Cambridge figures
In late February, the โsmart growthโ group A Better Cambridge said projections by the council showed a need for 400,000-plus more housing units to meet demand for housing in Greater Boston, with Cambridgeโs contribution being 8,500 units.
The figure drew immediate questioning from growth skeptics who wanted to know its source. โABC provides no link, either here or on their websiteโs version of this letter, to the MAPC report with those Cambridge numbers it refers to. Several people have looked for it with no success,โ resident Mark Jaquith wrote in reply.
After Carloneโs post, the Cambridge groupโs Jesse Kanson-Benanav sent a correction acknowledging the lower figures as accurate and explaining that โour number was derived by subtracting the existing number of occupied units in Cambridge according to the 2012 American Community Survey from MAPCโs projection for the number of units Cambridge needs under a โstrong region.โโ
Still room for debate

Under that scenario, the council has sketched out goals that โwill not only help ensure that every household in the region can afford a home, but will also help the region maintain a robust and growing workforce that forms the backbone of a competitive economy. โ
There is still room for debate as the city heads into creating a master plan that could reshape Cambridge for decades, with a key issue being how the city can guarantee affordable rents and sales that stop squeezing out middle-class earners and families.
After a Planning Board and City Council housing roundtable asked in December how many more units would accomplish that, Northeastern economics professor and Cambridge resident Barry Bluestone said it could take as few as 600 vacant rental units โ although substantially more would have be builtย to get to the point where at any given time the city had 600 vacant units. Bluestone generally targets a rental vacancy rate of about 5 percent โto keep rents from rising faster than inflation,โ and said Cambridgeโs rate, according to the U.S. Census Bureau, is about 3 percent (or a five-year estimate of 2.2 percent for 2008-12). Bluestone said that below 3 percent vacancy, rents rise very rapidly.
โRelatively inelasticโ
In 2012, Stuart Dash, director of community planning with the cityโs Community Development Department, acknowledged the city had already been in a growth spurt, without seeing much effect.
โRecently itโs been relatively inelastic in term of the economics,โ Dash said. โUsually the elasticity of supply and demand is that if supply goes up, then price comes down. In recent years itโs not seemed to be that way. It doesnโt mean it will stay that way forever or that increasing supply at a certain point wonโt push down prices. If you look at it over a long number of years youโll see dips and ups and downs based on supply and demand.โ
Saul Tannenbaum, a Cambridgeport resident and CCTV blogger who is on A Better Cambridgeโs leadership committee, felt Bluestone would have more-informed insights. In 2013, Bluestone was asked to weigh in on Dashโs analysis.
A good test
Bluestone was asked at what point supply started affecting demand and stabilizing or even lowering prices, and how much housing stock must be added in Cambridge to achieve better, practical results for less-rich renters and buyers. A concern expressed to Bluestone was that with only a little more than six square miles in which to build, Cambridge might be altered so dramatically by denser, towering housing that what residents loved about the city would be lost.
Bluestone replied in August 2013:
I think we are going to have a good test of rental prices in Cambridge in the next year or two. Finally, there has been an substantial increase in housing permits and we will see if new construction begins to moderate rents relative to past years and possibly relative to other communities. The problem is that the demand for Cambridge housing keeps rising because of Harvard and MIT and the explosion in the bioscience firms. What I hope we will see is that younger folks move into some of this new housing and vacate some of the older stock in the city.ย If that happens, landlords will have less leeway to raise rents. I do not expect rents to fall, but I would hope to see rent increases moderate.
The test period identified informally by Bluestone ends in August.
John Hawkinson contributed to this report.


I was among those who questioned ABC’s original number. I would not describe myself as a “growth skeptic.” Rather, I would prefer “planning advocate” — growth is needed, especially in the affordable segment, but let’s not plan it piecemeal through developer-initiated rezoning petitions like we are seeing at Mass + Main.
Also, based on Fred Salvucci’s piece in the latest MIT Faculty Newsletter, I would assert that MIT should do far more to house its affiliates, so that all of the housing growth didn’t have to come from private developers, where 80% of what’s built is market rate “luxury” units.
http://web.mit.edu/fnl/volume/273/salvucci.html
Jan Devereux
Questioning is one thing rubbing it in is another. There are several reasons to create housing none of which have a thing to do with whether sky is falling and we need housing by Saturday or the sky is falling and we need to stop everything lest we descend into a dystopian hellscape. If you cannot see the opportunity inherent in finding a reasonable solution within the Normandy project, C2, or anything else in the pipe then how can you guide Cambridge into the future? ABC, CRA, FPRA, people’s popular front of judea…you’re all the same. You espouse your opinion, rarely based of facts, and tout it like it twere gospel and even more infrequently do you listen to those who are experts in their fields. Jan, you’re a good egg but please don’t let yourself fall victim to the religious argument that is taking place.
There are lots of good reasons to build housing in Cambridge. Keeping Our Fair City fair means careful planning is necessary. Balancing commercial growth with housing and ancillary service and retail businesses is a part. Balancing the mix of market rate, moderate income, and lower income targeted housing is a part. Balancing the needs and desires of residents who have lived here for years and shaped the city they love with those of recent arrivals is also a part. Managing the effect of students and tech workers on the local housing market while encouraging all benefits of having two of the planet’s top universities and an amazing concentration of innovative industry. Good urban planning means considering all this and more.
A physicist, a philosopher, and a truck driver walk into a bar. You’re in Cambridge.