To determine non-residential projects and square feet built, a list of proposed non-residential projects was generated from proposed building plans through the Chester County Planning Commission. For projects built prior to 2019, to determine the year of construction for the proposed projects, the list was cross-referenced with assessment data. As assessments are made upon the completion of a project, and new buildings cause increases in assessment, the year of construction was assigned for projects with clear significant increases in assessment during a given year. Next, historic Google aerial imagery was used to confirm projects with changes in assessment, as well as for those without. Years were estimated for projects clearly built but with gaps in the available years of aerial imagery. All remaining projects were assumed unbuilt prior to 2019.

For 2019 new non-residential building data, a list of projects deemed unbuilt thrugh the prior to 2019 process, along with new project proposals submitted in 2018-2019 were sent to municipalities for status review. Finally, site visits were completed to ascertain status of any projects that did not receive municipal review.

For projects over 10,000 square feet, Google aerial imagery was cross referenced with the approved building plans to obtain updated building square feet added.

Building type was obtained through submitted plan data, and updated as needed. Projects with more than one building type were counted as .5 of a project.