Brown Field Municipal Airport Land Use Compatibility Plan

APPENDIX DMETHODS FOR DETERMINING CONCENTRATIONS OF PEOPLEWithout clearly measurable occupancy numbers, other sources must be relied upon to estimate thenumber of people expected to use a proposed development.Survey of Similar UsesOne option is to conduct a survey of similar uses already in existence. However, gathering data in thismanner can be time consuming and costly. Also, unless the survey sample is sufficiently large and thesurvey is conducted at various times, inconsistent numbers may result. Except for uncommon uses forwhich occupancy levels cannot be estimated through other means, surveys are most appropriate assupplemental information.Maximum OccupancyA second option for estimating the number of people that would be on a site is to rely upon dataindicating the maximum occupancy of a building measured in terms of occupancy load factor—thenumber of square feet per occupant. The number of people on the site, assuming limited outdoor orperipheral uses, can be calculated by dividing the total floor area of a proposed use by the occupancy loadfactor. The challenge of this methodology is to establish realistic figures for square footage per occupant.The number varies greatly among uses and, for some uses, changes over time.A commonly used source of maximum occupancy data is the standards set in the California BuildingCode (CBC). The chart reproduced as Table D-1 indicates the occupancy load factors for various typesof uses. The CBC, however, is intended primarily for purposes of structural design and fire safety andrepresents a legal maximum occupancy in most jurisdictions. A CBC-based methodology consequentlyresults in occupancy numbers that are higher than typical maximum use in most instances. The numbersalso are based on usable floor area and do not take into account corridors, stairs, building equipmentrooms, and other functions that are part of a building’s gross square footage. Surveys of actualoccupancy load factors conducted by various agencies have indicated that many retail and office uses aregenerally occupied at no more than 50% of their maximum occupancy levels, even at the busiest times ofday. Therefore, the Handbook indicates that the number of people calculated for office and retail uses canusually be divided in half to reflect the actual occupancy levels before making the final people-per-acredetermination. Even with this adjustment, the CBC-based methodology typically produces intensities atthe high end of the likely range.D–2Brown Field Municipal Airport Land Use Compatibility PlanJanuary 25, 2010