Sustainable parking garages? The notion of a sustainable parking structure may seem to be an oxymoron. But for a building type that has been long associated with a peculiar mode of personal conveyance—predicated upon internal combustion of petrochemically derived natural resources on a massive systemic basis (and all that this entails)— sustainability can and must be a critical factor in its design and operation. And certainly the inexorable imperatives of environmental necessity, supported by its attending social, economic, and political corollaries, are now all-too apparent, requiring fundamental changes in the way we approach the issue, as embodied in the green building movement.

So how can a parking garage contribute to sustainability? Interestingly enough, customary design criteria for parking garages have always involved aspects related to sustainable practices, albeit in the guise of functional and operational efficiencies and economies. Location, capacity, level of service, construction materials, and technology for garages can all be seen in a sustainable light. Typically, parking structures are built to support concentrations of other commercial or institutional activities, either proactively (to promote) or reactively (to alleviate) greater density, and they thereby leverage and allow for balanced urban-design economies of scale. Even the construction materials that are most often used for garages (steel and concrete) are recyclable and technologically efficient (composite, prestressed, post-tensioned, prefabricated, etc.), essentially doing more with less.

Beyond the basic attributes of form and function, getting to the next level of sustainability for parking garages means having to call upon more advanced and evolving technologies. Recent trends have included the increased use of more-sophisticated lighting controls and sensors to account not only for diurnal cycles, but also for transient daylighting conditions. There have even been parking structures that have introduced internal light wells to better utilize natural daylight. The use of rooftop- and façade-mounted solar panels has also grown, with PV films offering more options and greater design flexibility. Electric and hybrid car-charging stations within garages are proliferating, which, along with solar panels, could potentially offer supplemental revenue sources.

Parking access and revenue control systems (PARCS) are being augmented with space count and traffic-management technology configurations, allowing for even greater throughput efficiency and utilization. Radio-frequency identification and mobile payment are also contributing to this improvement trend. Ultimately, integrating these systems into a larger coordinated precinct- or city-wide sensor, count, and traffic monitoring, and management systems can significantly impact how livable and sustainable our urban centers can be.

Looking at the horizon of sustainability, we also find the concept of adaptive reuse and repurposing of parking structures. One possible scenario based on prudent and practical long-range planning, which is already utilized in institutions such as healthcare or higher education, is a flat-floored garage built proximal to core institutional functions. As the institution and its core expands, replacement and augmented parking is located to accommodate this growth, and the original parking structure may be readily and economically converted to uses more compatible and appropriate to the core zone. As with many enduring historic buildings, what is sustainable is the inherently sound underlying planning, design, and construction, all of which needs to remain responsive and flexible to change and circumstance in functional use.

Personal vehicles will always be part of our overall transportation mix, but they certainly can be accommodated intelligently and responsibly within a coordinated, balanced, flexible, and economically viable multimodal and intermodal transportation network, with the sustainable parking garage playing a key role.

Stanley Tang is a partner at BLT Architects in Philadelphia.