Minimum parking requirements are regulations that mandate the minimum number of off-street parking spaces that new construction must provide, based on the type and usage of the building. Established primarily to ensure sufficient parking capacity during peak demand, these regulations aim to prevent street parking overcrowding, parking neighborhood spillover, and traffic congestion.
Originating in the 1920s and expanding rapidly in North America after World War II due to rising car ownership and suburban growth, these requirements are now also common in many other countries. They vary by country, city, land use, and building size, with commercial and institutional uses typically requiring more parking than do residential developments.
However, minimum parking mandates also have unintended negative effects. They significantly increase construction costs for housing, retail, and other urban projects, straining affordability for occupants and users of alternative transportation modes. These requirements can contribute to increased traffic congestion, air pollution, and urban sprawl, because they encourage development in outer areas with lower land costs.
Large surface parking areas have additional adverse environmental effects. The asphalt and concrete needed for these spaces require substantial energy for production, and asphalt continues to leak toxic chemicals into the ground over time. Additionally, these impermeable surfaces hinder rainwater from recharging groundwater and create runoff that carries pollutants, such as oil, heavy metals and other contaminants into waterways and into aquatic ecosystems.
Moreover, paved parking areas absorb and retain heat, thereby raising ambient temperatures in urban areas. This can result in increased energy use for air conditioning and worsen air quality, disproportionately affecting vulnerable populations such as elderly or low-income residents — just as such residents are disproportionately affected by the higher costs of housing resulting from minimum parking requirements.
Multi-story parking lots can help mitigate some of the environmental problems associated with large surface lots, including toxic runoff, groundwater blocking, and urban heat islands. However, they can be more expensive to provide unless land values are exceptionally high.
In response to growing environmental concerns and the rising costs of housing, many cities are beginning to reassess minimum parking requirements, in some cases eliminating them entirely. This is frequently accompanied by measures to improve public transportation and promote walking. Moreover, a small but growing number of countries and cities have even started implementing maximum parking requirements.