In skimming through the recent articles on the Sustainable Cities Collective, I came across one that featured a story about an Austrian “Smart Buildings Program” at the University of Applied Sciences in Salzburg. One of the projects for students was probing the design for the most efficient supermarket, effectively built to Passivhaus standards–which any American architect will tell you is ambitious for a retail entity that relies so heavily on cooling. Given that our country’s food system is highly carbon-intensive, a study for how its sale and distribution can be more ecological responsive is certainly worthwhile.
Reports tell of student groups targeting many variables that come to mind quickly: lighting, refrigeration, heating and cooling systems, building envelope and infrastructure for electric vehicles. This collection of what is ultimately technological upgrades can hypothetically account for a 50% reduction in energy use for a store with the possibility of going to grid-neutral by adding in some renewables for power generation. At a certain point, however, these techniques could be tools for any building to be more sustainable. LED light fixtures and heat recovery systems are options open to architects and contractors everywhere.
So then we need to ask is this really the most sustainable supermarket that we can imagine–knowing that sustainability has to be thought of as more than just a technological fix to a wasteful lifestyle. Sustainability is a mentality of balance and dynamic equilibrium that encompasses cultural norms. It is great to see any building use increased efficiency in order to push net energy usage down, but at some point the real transition in creating a “sustainable” supermarket might have to be larger in scope and cultural participation.
Building Better is Building Smaller
One question would certainly be whether or not a sustainable supermarket is actually a smaller one? Buying food in bulk is a relatively new cultural trend–facilitated by the growing size of food stores from regular outlets all the way up to trend of “club” stores like Sam’s, BJ’s and Costco. Growth in space also translates into a growth in options. According to the Food Marketing Institute, a U.S. supermarket carries an average of 43,844 items in 2013. While it’s true that these bulk purchases can usually render the shopper with more food for a lower price, there are numerous secondary costs–environmental and monetary costs–that come with expanding our buying appetite for food.
The energy consumption of the store is an easy place to start. More aisles, more lighting and more frozen-food sections all point to more energy use. Perhaps this is the area that technology is most apt to dampen the problem, but the problem is not restricted to the building at the point of sale. As noted by author David Owen, our growing purchasing patterns for food trickle over into larger cooling and storage needed at home. Whether it is the growing size of cabinets, pantries, or ballooning refrigerators, all of it points to resources spent on keeping more food in the home at any given time. As written about on Intercon before, despite the fact that our fridges are getting more efficient, they’re also growing in size and often joined by other supplementary means of cooling like a wine fridge or basement chest freezer to bring a net increase of energy.
But that’s not the end either. The larger problem is the buying of more food than we can readily use. Owen’s explains that our penchant for buying and storing more food often lead to us throwing more food out. Whether it is leftovers that are never eaten or food that simply sits in its chilled state until it edges past its expiration date, we throw away more food in this country than we used to. As noted by the Washington Post:
“In 2012, the most recent year for which estimates are available, Americans threw out roughly 35 million tons of food, according to the Environmental Protection Agency. That’s almost 20 percent more food than the United States tossed out in 2000, 50 percent more than in 1990, and nearly three times what Americans discarded in 1960, when the country threw out a now seemingly paltry 12.2 million tons.”
Larger stores hinge on more parking, which brings in more impervious blacktop to create heat islands that raise ambient temperatures when it’s nice out and increase stormwater runoff when the sun isn’t shining.
Local, Walkable Stores
Speaking of parking, how about all of that driving? No matter how efficient the store at the end of the trip is, there is a large amount of energy poured into car trips back and forth to the supermarket. A truly sustainable food outlet would most likely be one that more people can use without a car at all.
Near my Astoria apartment, I have two food stores that are open 24 hours a day within 3 blocks. In fact neither store has a parking lot at all because no one drives to the store to pick up food. They are in addition to the numerous convenience stores and bodegas that dot the landscape to fill smaller, faster needs of local residents.
Even though Astoria and the rest of New York City set a high bar for walkability, they are pointing towards a model that diminishes car use and promotes accessibility for walkers and bikers. With all of the (many) other cultural benefits to a walkable environment aside, reducing total vehicle miles traveled can bring just as much of a reduction as cutting the building’s energy use in half. Let’s look at some numbers:
According to a document on the Environmental Protection Agency’s website, these are some figures that outline the standard profile of an American grocery store as of June 2011:
- Store Size: 46,000 square feet
- Annual Electricity Consumption Intensity: 51 kilowatt hours per square foot
- Annual Electricity Consumed 2,346,000 kilowatt hours per year
- Electricity Use Emission Factor (U.S. Average) 1.30 pounds of CO2eq per kilowatt hour
- Annual CO2eq Emissions from Electricity Consumption 3,049,800 pounds of CO2 per year
Looking again at the EPA’s website, we can find an average carbon emission per gallon of gasoline burned of 8,887 grams of CO2, or 19.6 pounds. Add to that the ±5 pounds required to extract refine and deliver the gas to a gas tank and it is around 24.5 gallons. We will take the new CAFE standard of 27.5 mpg and an average distance of about 7 miles between an American home and the food store. Assuming two trips to the store a week, a single household could rack up 728 miles and 26.5 gallons of gas creating 649 pounds of carbon dioxide.
With these numbers it would take approximately 2,350 customers to not travel to the store by car every year to equal the 1.5 million pounds saved by reducing the store’s energy usage by 50%. Using FMI’s numbers, an average supermarket can host over 2,200 customers a day. If a store can eliminate 4,700 car-traveling customers a year, it is the equivalent of taking the store off the grid. The exact numbers aren’t as important as understanding that comparing the two sides of resource consumption render them in completely different orders of magnitude. As a result, I would argue that the two stores near my apartment, housed in old buildings with no LED lighting, are still more sustainable than the most cutting edge, suburban counterpart in existence.
Pursuing the integration of best-practices in industry tech is a good pattern, but should be the work of more consistently updated code structures in order to push for continuous improvement in energy consumption, but these still represent changes that seem like bigger strides than they actually are–at least in comparison to what is available to us.
Sustainability needs to be viewed through lens other than technological improvement, especially at the community scale. Municipalities, especially smaller cities and towns, should be looking into planning decisions that promote higher densities and alternative transit that make smaller stores in walking distance economically viable. Like everything else, the most efficient supermarket is not necessarily the one doing the most for the planet it’s on or the culture of the community it serves.