A member of Harvard’s Planning Board is predicting that 64 percent of the housing units in Devens, once development is complete, could qualify as affordable housing.

In calculations she shared with the Press this week, Planning Board member Michelle Catalina estimated that 234 of a predicted 365 units will fall into that category.

State law calls for 10 percent affordable housing in towns, as does Harvard’s master plan. The Devens Reuse Plan calls for Devens to be built out with 25 percent affordable housing, and it was in this context that Catalina used numbers from the Devens Economic Analysis Team’s Sept. 20 report to calculate possible outcomes of development at Devens, and especially at Vicksburg Square.

Catalina assumed 119 units of current housing on Devens: 37 affordable and 82 market rate. To the 119 units, she added the 246 units proposed by Trinity Financial to come to a total of 365 units of housing.

The Devens Reuse Plan specifies 282 units as the total housing that may be developed at Devens; the Trinity proposal would require a change to the reuse plan.

Of the 246 units proposed by Trinity, 197 are either low income housing or very low income housing, categories of affordable housing defined by the state as 60 percent of area median income or 30 percent, respectively. According to the 2010 United States Census, median household income was $62,885 in Worcester County in 2009. The 197 proposed affordable units plus the 37 current affordable units add up to 234 affordable units.

Catalina calculated that 234 as a percentage of the total housing predicted (365) would be approximately 64 percent.

Catalina said that it’s possible that either all or a part of Devens could eventually become a village in Harvard and pointed out that the current Harvard housing plan calls for affordable housing to be distributed evenly throughout the town.

Trinity’s proposal would accomplish the preservation of buildings and some relief from the state’s Chapter 40B planning statue, Catalina said. However, she also referenced a 2007 Urban Institute study, “Ten Principles for Developing Affordable Housing,” which warns against affordable housing configurations that are too isolating and in which residents are too uniformly low-income.