Greener Buildings Need Less Parking

automated parking It would be fair to say that the baseline of sustainability in building construction is rising. Whether it is due to improving technology, updated building codes or the slow but steady growth of consumer demand, we are in the process of making buildings tighter and smarter. At the same time, the nature of proactive lobbying in the beginning of the millennium has led to many of today’s common measures being attributes that are easy to fight for with limited resulting gains. For all the time spent on toggling technologies of a systems-oriented approach to sustainability, there are still simpler aspects of building design that could bring large lifecycle savings to resource use. One of them is parking.   

I was recently involved in the early stages of a large, mutli-family residential project. The details are relatively inconsequential outside of the fact that the site resides on the island of Manhattan. Though decidedly still in the beginning of the process, there are important programmatic decisions that will ultimately shape large aspects of the project and its energy footprint. The decision of whether to have parking and if so, how much, has energy repercussions on par with most other measures when it comes to a net reduction beyond a code-compliant building.

New York City is well aware of its problems with congestion and acknowledges that the streets can only hold so many cars at a time. Given that this particular site is zoned residential without a commercial overlay, there is no inherent parking requirement. On the contrary, the city caps the number of allowable spaces in response to a portion of new development–in this case 35% of the number of new residential units as a number of the new units were located within the retained portion of an existing structure. For this example, we can assume 19 new parking spaces for the building for a look into how that amenity relates to the energy footprint of the building.

Anyone who is buying newly constructed real estate in Manhattan can tell you it is a lifestyle of amenities. The premium of real estate is based just as much on what is within the walls you occupy as what is within walking distance. Of the things that people are apparently willing to pay lots of money for (views, terraces, walk in closets) a dedicated space to park a car may be one of the most highly valued. For commuters that wish to drive on the island, rates of $400-800 per month are commonplace, but upwards of $1000 are not hard to find. A parking space that a property owner can purchase for his own vehicle… well it’s a luxury few can afford that sends estimated values into the realm of hundreds of thousands of dollars. As a result, it’s not uncommon for those financing new construction to lobby for as much parking as possible. The ownership of this project site was no different.

Parking Footprint is Growing, not Shrinking

selldorf parking tower garage

200 11th Avenue Courtesy of Selldorf Architects

The focus on improving the mileage efficiency of cars could lead one to believe that their urban energy footprint is shrinking over time, but when it comes to urban centers like New York, the opposite is most likely true. As demand for this amenity rises (and its resulting cost) developers are going out of their way to only make parking accommodations more lavish in order to entice buyers into a higher asking price for a spot. A CBS News article reports that the average residential parking space could cost an additional $136,052.

Some could pinpoint the birth of this new generation of NYC parking accommodations on 200 11th Avenue, designed by Selldorf Architects. The west side tower incorporates a car elevator that allows for access to “sky garages,” a parking space right outside the apartment on each floor. But what started as the rare and unusual is quickly becoming more commonplace.

parking materials luxury

Courtesy of 443 Greenwich

Projects like the Tribeca Lofts at 443 Greenwich Street begin to re-imagine the garage experience, transforming it from a dark and simple service space that required little more than excavation and concrete into lavish interiors for resident rides. Brick floors paired with herringbone tile on vaulted ceilings bring an image of class to what was normally thought of as a utilitarian space, but all of these components come with a carbon cost of production, packaging, shipment, installation and maintenance. Like many amenities, parking garages are spaces with relatively little traffic, but significant material contributions in construction with systems such as ventilation and lighting that are consistently operating.

Sustainability & Cars?

In a time when sustainability is becoming more widely accepted in urban buildings, cars have been conveniently left out of most conversations or standards created to rate or quantify the “greenness” of a building project. While systems like LEED have historically given points to reserving parking spaces for alternative fuel or electric vehicles, the practice largely skirts the deeper question of how does the latent energy of cars and their operation relate to the sustainable foundations of a building.

Given that, in its current form, the infrastructure of producing and driving automobiles is widely accepted to be detrimental to the environment when compared with other transportation options, the next logical question could be: How much is adding parking spaces to a building offsetting the productive measures that are becoming more routine in architectural projects? When we compare the positive outcome of efforts to reduce things like energy use or water consumption, how do those gains compare with making it a little bit easier to drive–especially in an environment as dense as New York City?

To demonstrate an order of magnitude for the answer, we can look at a single, sustainable metric of energy use and compare that to the embodied energy used in creating and driving a car.

To start, we can use the site Metered New York as a resource for establishing a baseline for building energy use. The site is the creation of the Urban Green Council (the local NYC chapter for the USGBC) and serves as a collection point for the benchmarking data for water and energy that is now required by the city for large buildings throughout the five boroughs. The site puts the median energy usage for multi-family residential buildings built in the last 5 years at 112 kBtu per square foot. Applying that to a design size of roughly 200,000 zoning square feet, which excludes cellar and mechanical spaces, and the result is an estimated annual energy usage of  22.4 million kBtus–not an insignificant sum.

In order to demonstrate the lifecycle costs of an American car, I started with a 2010 study done by the Argonne National Laboratory studying the embodied energy within the production and assembly of modern vehicles (a copy can be found here). The conclusion of the study amounted to an average energy usage of 34,000 megajoules of energy to make a car or about 32,226 kBtu that weighed 3,377 pounds. When held against 22.4 million, that doesn’t seem like a bad place to start.

The average American car drives an average of 12,000 miles a year for ten years. If we use the EPA CAFE standards of a mileage of 27.5 miles per gallon combined with the 4,145 kBtu/mile of energy usage discerned in a previous article (here) it adds up to 49,800 kBtu per year for each car. The cumulative total amounts to 49,800 (of usage) + 3,223 (of embodied energy), or 53,023 kBtu of energy cost per vehicle every year. A few kBtu here and a few kBtu there and all of a sudden we’re talking about real energy.

When tallied for 19 cars, the total springs to just over 1 million kBtu of energy or around 4.5% of the annual energy usage for the building as a whole.  

While one could claim that urban residents most likely drive less than the national average of 12,000 miles per year, there are also a number of other factors that contribute to the latent energy of a car’s footprint on the site. One could start with the fact that many of the cars parked at a high end condominium would not be a standard, 4-door sedan weighing 3,400 pounds. Luxury SUVs carry even greater energy costs for production with less efficient mileage. This still discounts the energy and material needed to excavate down for an additional cellar level as well as the materials needed to construct a garage with 19 spaces including the automotive elevator to get them to and from the street. When all is said and done, it is not outlandish to think that the design team would need to employ proactive efforts to decrease the energy usage of a building by 5% just to break even from a relatively small number of on-site parking spots.

Redefining Green

As the nature of the architectural landscape in urban centers like New York continues to change, so too must our expectations for how we identify and credit sustainable efforts and results. New York enjoys a progressive energy code that continues to raise the bar for new construction–helping to raise the level of performance in new additions to the city’s built environment.

While more efficient heating and cooling systems may use less power to temper indoor environments, the size of apartments could be rising to satisfy a market increasingly made up of end high buyers. Advances in LED lighting will continue to permeate deeper into designs as code reduces the slack in design goals, but the array of amenity spaces that are quickly becoming the standard for enticing new residents, coupled with the provision of on site parking, could be depreciating the progress made on reducing the city’s carbon footprint.

Could it be outlandish to think that the approval of parking spaces for new development could be directly tied to design reductions in the use of energy and water on site? Given the market value of each space to prospective developers, could the city make more progress by having development teams “pay” for new parking spaces with design features that negate their contribution to net energy use?

Especially within the limits of a city containing such a mature ecology of alternative transit options, a more sustainable fabric has to begin to toggle the expectations of a new generation beyond just tweaking the technology of the status quo, but this is not only a problem restricted to metropolises. The sustainable initiatives of new headquarters of both Apple (here) and Google (here) have to be paired with their relatively remote locations and deference to large amounts of space for parking and commuting by car rather than locations close to existing centers of activity to promote, if not bolster, walkable environments.

We are fortunate to live in an exciting time where there has been an influx of effort to find ways of improving numerous buildings systems to reduce energy consumption. There are few traditional building components that do not have a more sustainable counterpart that can be easily replaced. Given that the status quo gives us a baseline so riddled with opportunities for improvement, it is easy to give more weight to a series of smaller technological improvements than they actually deserve in terms of how much of an impact they currently make. Plus, the concept of efficiency is attractive and easily marketable. But too much of the “green” movement revolves around the idea of allowing us to keep doing what we’re doing now, but simply using less energy and maybe saving a bit of money in the process. Looking outside of the realm of systematic upgrades to fundamental, programmatic changes shifts the opportunity for sustainable impact into a whole new gear.

Image Credit: