SPACEWALK™ is a Gruen Gruen + Associates (GG+A) proprietary three-dimensional spreadsheet-based computer model used to estimate the demand for nonresidential development in a region based on changes in employment by sector. Projections of employment change are converted into projections of demand for office, manufacturing, warehouse and retail space based on the space use characteristics of occupational groups within economic sectors. The final step in the determination of space demand from employment projections is the multiplication of the number of workers expected to occupy space by the number of square feet of space needed to accommodate each worker.