Capacity

Three definitions of capacity affect considerations of Brookline’s MBTA-CA compliance. By default, capacity is calculated assuming that one unit of housing capacity requires 1000 square feet, slightly greater than the size of a typical two-bedroom apartment.

Theoretical capacity is the number of units that could be built on a parcel if it were empty. EOHLC uses theoretical capacity to determine compliance.

Incremental capacity subtracts the floor area of what is already built from the theoretical capacity. When the Select Board and the planning department consider the number of units incentivized by changes to our zoning code, they consider incremental capacity.

Practical capacity further reduces incremental capacity by incorporating economics of building new units. For example, consider a parcel that allows four stories but already contains a two-story commercial building. Despite the incremental capacity to build two more floors, if adding two stories isn’t profitable then the parcel’s practical capacity is zero.

Because many factors affect the economics of building new units, practical capacity is hard to calculate and every parcel might have a different formula. However, practical capacity shows how many additional housing units are likely to be built if allowed by the zoning code.