Design Topic: Building Square Footage (Net Floor Area vs. Gross Floor Area)

The design enrollment and educational plan influence the space summary program which ultimately drives the size of the building. When referring to the building square footages, the terms Gross Floor Area (GFA) and Net Floor Area (NFA) are often used.

The NFA includes the area of program spaces only, for example: classrooms/teaching spaces, offices/admin spaces, cafeteria/kitchen, athletics, etc.

The GFA is the sum of the total area of all spaces including building components, such as: wall thicknesses, stairs/corridors, mechanical & electrical spaces, toilet rooms, storage, etc.

The space summary template commonly referred to for school projects recommends a size and count of spaces to determine the NFA by category (core academic, special education, art, music, etc.). It also compares the areas of the existing and proposed spaces, while using the MSBA guidelines as a reference point. Because the building is not limited to NFA spaces, the GFA is used for estimating/cost information purposes.  

During the Feasibility Study Phase, dimensional floor plans are not yet created due to the preliminary nature of the design. As a result, the space summary template uses a Net-to-Gross Ratio which is an industry standard multiplier that increases the NFA to GFA.

The current space programming summaries for the new building and addition/renovation approaches currently reflect the following:

Net Square Footage (NSF)Gross Square Footage (GSF)Ratio of NSF to GSF
Existing AHS Facility *206,813 sq ft315,200 sq ft1.52
“Courtyard” approach (addition/renovation)298,043 sq ft500,635 sq ft1.68
“Campus 2” approach (new building) with renovated Collins Center307,423 sq ft478,948 sq ft1.56
“Campus 2” approach (new building) with new theater inside school 298,473 sq ft460,261 sq ft1.54

* Based on today’s space standards, the capacity of the existing high school is 1,400 students, although over 1,700 students attend.  

As shown above, there is an increase in the NFA/GFA between the existing high school and the proposed site approaches for many factors including: alleviating current overcrowding, allowing for future growth, and meeting educational needs.