Let’s assume Somerville’s accessory dwelling unit proposal is meant to increase Somerville’s stock of affordable housing, giving the city another tool along with Affordable Homes Act and the current zoning ordinance. In fact, the Planning Department ADU proposal undermines this goal.

Instead of increasing the number of affordable dwelling units, the proposed Planning Department ADU proposal creates an incentive for developers to buy up lots in lower income neighborhoods that are able to accommodate a Backyard Cottage, split them into separate lots, and build a larger number of condominium dwelling units than permitted on the pre-existing single lot – and sell them at the high-priced end of the market. That is happening in Cambridge with a backlash from the unintended consequences of its loosened zoning restrictions and few affordable units. 

In particular, the ill-conceived ADU proposal

  • allows lot area available for affordable ADUs to be split and used for expensive, unaffordable large units,
  • does not require a percentage of the new Accessory Dwelling Units to be affordable,
  • is in violation of the state’s Affordable Homes Act.

Some speculate that just increasing low-rise housing stock will improve affordability through market forces of supply and demand. That is not how it works in an already exceptionally dense city,  as our Senator Pat Jehlen has pointed out. And Somerville does not have the luxury of testing out that theory, given the telling example that Cambridge is now reconsidering. Of course, high prices do lead to more tax revenue, but solving Somerville’s short-term financial issues should not be the goal of promoting ADUs.

Instead, Somerville needs the ADU zoning to require a minimum number of permanently affordable units on ADU eligible lots. For example, 20% of the dwelling units from five and above rounded to the nearest whole number need to be affordable. Thus, a lot with five dwelling units would have at least one be affordable; a lot with eight dwelling units would have two be affordable.

Somerville’s Backyard Cottage under current zoning fits the Affordable Homes Act definition of an ADU. But lot splitting needs to be prohibited to curtail luxury housing,  and ADU zoning needs to meet the Affordable Homes Act Gross Floor Area limit of 900 sq. ft.

New ADUs need to be all-electric. Electrifying buildings to replace oil and natural gas  will mitigate greenhouse gas emissions, an additional important Somerville goal. Buildings produce 65% of Somerville’s greenhouse gas emissions, as recognized by SomerVision 2040 and Somerville’s Climate Forward Plan, which seek by 2040 to reduce them by 80% (pp. 18-20) from the 2014 level. Therefore, newly constructed ADUs need to be all electric.

Keeping Somerville green and livable. Greening Somerville to reduce adverse health impacts from excessive temperature and to mitigate air pollution are also Somerville’s goals. Density also adversely affects privacy and open spaces, so Somerville needs to keep setbacks and manage building siting to keep existing  larger trees and provide for sufficient tree planting space, air flow and view sheds. A tree canopy can lower the temperature by as much as 10 degrees Fahrenheit in what would otherwise be a high temperature neighborhood. Housing  affordability and lowering neighborhood temperatures with urban trees are compatible partners that should be part of any ADU policy. Somerville  has been recognized as a Tree City USA by the Arbor Day Foundation. Let’s not lose that accolade. Do not plant affordable ADUs at the expense of trees and livability. Plan, plant and preserve them together.

So, back to the Planning Department’s drawing board!

Woll is a member of Davis Square Village and Davis Square Neighborhood Council

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