In the United States, surface parking lots alone cover more than five percent of all urban land, representing an area greater than the states of Rhode Island and Delaware combined. Unfortunately, when municipalities allow soil, vegetation, and trees to be replaced with parking lots and structures, negative environmental consequences follow. Using their capital budgets and land use authority to regulate development, municipalities are beginning to mitigate these adverse environmental impacts.

For example, urban heat islands occur when cities develop and replace natural surfaces and vegetation with asphalt, concrete, and other low albedo surfaces. These types of surfaces trap, absorb, and retain heat making it substantially warmer. Additionally, large surfaces, like asphalt parking lots, are unable to absorb rainfall and lead to runoff. Runoff from parking lots can contain high levels of pollutants, and with nothing to absorb and redirect the heavily polluted runoff, the runoff can end up in waterways. Finally, parking lots, spaces, and structures curtail the walkability of urban spaces. Pedestrians could reach their destinations more easily and quickly without having to walk across large parking lots and structures. Developing a community that is easily navigable on foot can help to minimize emissions and alleviate the effects of climate change.

To reduce the negative impacts parking has on the environment, municipalities can wield their state-delegated land use authority to make parking lots and structures more climate and environmentally friendly. For example, municipalities can require parking spaces to: be painted white, include more green infrastructure, use pervious materials, and not inhibit walkability.

Painting parking spaces white, or using asphalt-alternatives such as light-colored concrete blocks, increases the albedo of the surface, thus, mitigating the spaces’ contribution to urban heat. Albedo is the fraction of light that a surface reflects. It has a big impact on climate because it determines how much incoming solar energy or light will be reflected back to space. This change helps decrease temperatures, as well as heat-related illnesses and deaths. In certain locations, utilizing white-tinted asphalt can lower the temperatures by 25 to 30 degrees.

By properly incorporating vegetated landscaping parking spaces, parking lot designers can increase natural drainage, erosion, and stormwater management. Landscaping can also provide cooling shade. Similarly, pervious pavers allow rain to seep through and, instead of accumulating pollutants and running off, water can permeate through layers of soil, reducing the risk of flooding and surface water pollution.

San Rafael, California has parking regulations that require the top level of parking structures to utilize light colored/high albedo paving material (reflectance of at least 0.3), shade structures, photovoltaic carports, landscaped trellises, or trees to achieve at least fifty percent daytime shading.

Miami Beach, Florida land use boards are required to take the following factors into account when making decisions regarding development decisions within their jurisdiction: cool pavement materials or porous pavement shall be utilized, design of each project shall minimize the potential for heat island effects on-site, and resilient landscaping (salt tolerant, highly water-absorbent, native, or Florida-friendly plants) shall be provided.

Milwaukie, Oregon is doing a number of things to ensure the reduction of the urban heat island effect, carbon dioxide absorption, and stormwater management, and to break up expansive areas of pavement. Landscaping is required for all parking areas except single and low-density housing. Within 10 years, the trees planted must provide a minimum of 20 feet diameter shade canopy. For parking areas with more than 100 spaces on a site, there must be no more than 15 spaces in a row without an interior landscaped island. The implementation of permeable paving may be used to help lower the amount of surface water runoff and protect water quality.

The City of Overland Park, Kansas has created incentives for people who are developing new driveways and parking structures. The city may award up to a 20 percent increase in the maximum density for providing structured or underground parking. Parking structures shall be located underground (below-grade) or beneath the multi-family structure or integrated into the overall design of the structure. This can help make cities more walkable and sustainable. If a development uses a specified stormwater technique, there will be a development bonus. Pervious paving must be provided for at least half of all parking spaces. To receive a development bonus, the maximum credit shall be awarded for meeting the minimum area/volume requirements indicated and partial credit may be awarded on a prorated basis for providing less than the required area.

Municipalities implementing these parking incentives and regulations reduce urban heat island effect, improve stormwater management, reduce pollution, and create cities that are more climate-friendly and walkable.

This article is part of a series from the Land Use Law Center that explores how local governments can implement Climate Resilient Development (CRD) as defined in the Sixth Assessment Report of the IPCC. CRD requires innovative reform of land use planning and regulation by local governments. The series presents and analyzes numerous local laws and policies capable of adapting to and mitigating climate change to create equitable and sustainable neighborhoods, achieving “sustainable development for all.” 

Author: Jenna Faucheux, 1L Land Use Scholar