Dwelling Units per Acre

Core Field

Dwelling Units per Acre (DUpAC)

• Associated Fields: DUpAC_SPEC, DUpAC_OVE, DUpAC_CALC1, DUpAC_CALC2,

  DUpAC_CALC3, DUpAC_EFF, DUpAC_ESVAL

• Value Referenced In: N/A

This field catalogs the maximum allowable dwelling unit density, in terms of dwelling units per acre. This allows a standardized comparison of density across zones where residential development is allowed by-right.

Estimation

DUpAC is populated for approximately 20% of the zones in the Zoning Atlas where residential development is allowed by-right.

Where dwelling units per acre was not specified in the Bylaw or Ordinance, MAPC was able to approximate it for an additional 70% of zones using three different formula fields:

• DUpAC_CALC1: If both MAXDU and MINLOTSIZE are specified, dwelling units per acre are estimated by calculating the number of lots that could be constructed on an acre (43,560SF/MINLOTSIZE) and multiplying this number by the maximum dwelling units for each of those lots, MAXDU. This calculation yielded an estimate for approximately 40% of zones.

• DUpAC_CALC2: If FAR is specified, dwelling units per acre are estimated by calculating the maximum building square footage for a one-acre lot (43,560SF * FAR) and dividing this figure by the estimated SFpDU, 1,000SF. The calculation yielded an estimate for approximately 25% of zones.

• DUpAC_CALC3: If neither MAXDU, MINLOTSIZE, or FAR were specified, MAPC used the same estimation method as DUpAC_CALC1, but replaced specified values with estimated values: (43,560SF /MNLS_EFF) * MXDU_EFF. This calculated yielded an estimate for approximately 5% of zones.

The remaining 10% of the zones in the Zoning Atlas where residential development is allowed by-right have an estimate in the DUpAC_OVE field. In some instances, values are populated because the three formula fields did not yield an estimate; in others, the result in the formula fields was obviously inaccurate. One example of this is a zone that had a DUpAC_CALC1 value of over 80,000, due to a specified MINLOTSIZE of 1. In this instance, MAPC recorded the DUpAC_CALC2 estimate in the DUpAC_OVE field.