12.2: Duration and Extent of Building Infrastructure
Building statistics often differentiate between commercial, residential and other types of buildings. Table \(\PageIndex{1}\) shows the 2003 distribution of commercial buildings in the United States with regard to size, use, and energy sources. The total inventory includes 4.6 million buildings. Not surprisingly, the number of buildings in each size category declines as size increases. Nearly all commercial vehicles have electricity, and most have other energy sources
Table \(\PageIndex{1}\) - Characteristics of Commercial Buildings in the United States 2003
Source: Statistical Abstract of the United States, 2008, Public Domain, ‘Commercial Buildings Summary,’ Table 968. https://www.census.gov/library/publi...n-housing.html
The numbers of housing units in the United States is shown in Table\(\PageIndex{2}\). The numbers of residential buildings would be smaller than the number of housing units since there are multi-unit buildings. Of the 124 million housing units in 2005, 76 million (or 61%) are single unit houses (Census, 2008). The numbers of housing units has been increasing over time, reflecting growth in population and a decline in the average size per household. The fraction of homes owned by residents has been increasing over time to 60% in 2005.
Table \(\PageIndex{2}\) - United States Housing Units 1980-2005
Source: Statistical Abstract of the United States, 2008, Public Domain, ‘Total Housing Inventory for the United States,’ Table 947.
https://www.census.gov/library/publi...n-housing.html
Buildings tend to relatively long-lived types of infrastructure, with averages of 50 to 100 years not uncommon. Many buildings are demolished not due to deterioration, but due to functional obsolescence: building needs may change and replacing a building may become advantageous. The US Internal Revenue Service prescribes a depreciation lifetime of 20 years for farm buildings, 27.5 years for residential rental property and 39 years for nonresidential real estate (Treasury - https://www.irs.gov/pub/irs-pdf/p946.pdf ). Figure \(\PageIndex{1}\) shows the reported age of US commercial buildings in 2012, with a median building age of 32 years. Within any building, components may be replaced more frequently, such as HVAC or roof replacements.