Calculating your parking Facilities Oversell Factor


A crucial factor often comes into play in determining the project’s sustainability in providing adequate and sufficient parking for its tenants, patrons and visitors. This factor is “overassignment,” or “oversell,” parking industry terms for maximizing parking resources. Overassignment takes into account that not every tenant employee is at work each and every day, taking up a parking space. There are a myriad of reasons why employees are not present on any given day, from illness to jury duty, vacations, off-site assignments, working from home (which is more and more prevalent in today’s world of technological remote access), personal days off, staggered work schedules, etc. The parking industry has long recognized that at least 20% of employees with parking permits are not present on any one particular day. Essentially, if a parking lot has 100 parking spaces, there can be up to 120 parking permits issued without worry of running out of parking spaces. In many instances, the percentage can be as high as 40%, and even up to 60%, depending on the type of business in an office building (entertainment- related and law firms have high “out of the office” ratios, as do tenants that are heavily influenced by business travel, to cite several examples).

The best manner in which to ascertain a property’s actual overassignment factor is to determine both the overall quantity of tenant parkers and the quantity of those parkers present at peak demand – which is, at either 10:00 am or 2:00 pm on Tuesdays or Thursdays.

Let’s set up an example where we determine a property’s overassignment factor. Here’s our make believe property – Pacific View Office Towers has a garage with 4,500 parking spaces. The building has 1,500,000 RSF, and is presently 90% occupied, with 1,350,000 RSF leased. There are 4,000 monthly parkers. An occupancy survey is performed and 3,333 monthly vehicles are parked at peak. This results in a 20% overassignment factor – 4,000 / 3,333 = 1.20.

What this means for the property is that, despite having issued 4,000 parking permits for a garage that has the room for 4,500 vehicles, property management can issue up to 5,400 total parking permits and not have to worry about exceeding capacity with the current tenant mix. 4,500 X 1.20 = 5,400