There’s no getting around the fact that automobiles are among the leading causes of pollution. There are tens of millions of cars and trucks on American roads contributing significant amounts of greenhouse gases to the atmosphere.

The question facing policy makers, scientists, and engineers is how to reduce the impact that our vehicles have on the environment. In Washington, the discussion revolves around how high to raise fuel efficiency standards and whether to offer tax credits to those who drive hybrids and alternative fuel vehicles. And on the drawing boards of auto industry engineers and environmental scientists, new ideas for vehicles that run on hydrogen fuel cells, solar power, and other alternative fuels are being pursued.

Martin Stein

But the need for new approaches for addressing this problem is urgent. While we wait for the introduction of new policies and technologies, we must find ways to minimize the impact of cars and trucks on the environment. An important part of the solution can be found through parking. By developing parking resources more strategically, and doing a better job of managing parking structures, parking owners and their designers can have a beneficial impact on the environment.

When it comes to parking sustainability begins with a facility’s design. There are a number of sustainable design approaches that can be applied, both when the structure is being developed and as part of a retrofit.

For instance, by including sufficient entry and exit lanes in a facility, designers can assure that cars don’t sit in traffic idling while waiting to enter or leave the structure. In fact, idling vehicles are a significant source of pollution. When cars sit waiting to enter or leave a parking structure, they unnecessarily emit carbon monoxide into the environment, which, of course, contributes to the growing amount of greenhouse gas that is introduced into our air every day. This can also pose health hazards to parking staff who work in enclosed spaces in which cars are idling.

However, these greenhouse gases can be minimized by assuring that there are sufficient entrances and exits to keep traffic flow moving during peak hours. Parking designers must be able to accurately predict peak traffic flows within the structure and design entry/exit schemes that can meet peak demand. Often, the inclusion of reversible lanes can help keep vehicles moving. During peak entry times, the reversible lane can be used as an entrance, while during common exiting times they can be changed over to exit lanes. This is a simple and cost-effective way to meet entry/exit requirements in an efficient and cost-effective manner. It is relatively simple to add reversible lane technology in both new structures and existing facilities.

There are also sustainable design approaches that can be built into the structure itself. For instance, by creating facades with large openings to let in natural light, and by including central light cores, designers can reduce the need for round-the-clock interior lighting. Minimizing the need for interior lighting reduces the amount of electricity that is required to operate the facility.

Some parking designers are even including green roofs on their facilities to reduce their carbon footprints. Green roofs absorb a portion of the heat that is created in and around the structure, and they also include vegetation that can help cleanse the surrounding air.

There are also management approaches that parking owners can implement to be better environmental stewards. Since the most effective way to reduce vehicle emissions is to keep cars moving in and out of the facility, parking owners should utilize technologies that facilitate exiting. For instance, pay-on-foot technologies permit people to pay for parking before they get into their cars to leave. This keeps parkers from having to wait in long lines to leave the structure. Also parking structures can use credit card readers at exits, since credit card transactions can be much faster than cash payments.

But why should parking owners and managers care about these “green” initiatives? It’s nice to be a good environmental steward, but isn’t a business’ primary concern the bottom line? The good news is that more often than not, these sustainable practices are also good business practices. Providing shorter entry and exit queues is a great customer service practice. And relying on natural light instead of electric lighting can save owners thousands of dollars each year in lighting costs. And of course, reducing emissions within a parking facility provides a healthier workplace for staff. For parking owners, being “green” is also good for the bottom line.

Martin Stein is the president of the National Parking Association.
He can be reached at or 202-296-4336.