Tracking Building Performance at Portland International Jetport
Jim Stanislaski
Portland International Jetport was the second commercial airport terminal in the United States to achieve LEED Gold certification. Image © Robert Benson
Numbers and data have historically been the currency of engineers. But designers are now being asked to quantify how their designs bring value to clients and communities. At Gensler, we need to get comfortable talking about our projects in increasingly quantitative terms. Are our designs better than our competitors? How do we know for sure?
In this enlightened era of green building, performance matters and numbers can be a beast. Our clients have a thirst for data. They expect our designs to yield quantitative value that can be measured and tracked over time. LEED still matters, but a green building certification isn’t good enough. Like us, our clients have developed finely tuned greenwashing antennae and are capable of separating the posers and proselytizers from the projects with real and measurable environmental benefits. This is a story about a Gensler client committed to sustainability and how that client has used data to abet design performance.
The Gensler-designed Portland International Jetport was the second commercial airport terminal in the United States to achieve LEED Gold certification—San Francisco International Airport's Terminal 2 was the first. The project has been a success at many levels: a happy client, a community well-served, a context-sensitive design solution, and a functionally efficient building for passengers and airlines. It has received several sustainable design awards, most recently at the “Airports Going Green” conference in Chicago this month.
It also has the largest geothermal heating and cooling system in Maine. The system consists of 120 wells located 500 feet below ground and uses 15 sensors and meters to track a range of data points—high and low temperature loops, BTUs generated by the underground well field, and energy usage—that can be monitored via a user-friendly dashboard.
Of course such numbers are academic if not analyzed and used to improve performance. With this in mind, a Gensler design team looked at nine months of data gathered from the geothermal system’s sensors, as well as historical weather data for Portland, to get a better sense of how the system would perform during that region’s notoriously cold winters. The result? We found some surprises and learned a few lessons that can now be used by the client and design team to make a good system even better.
1. Energy costs did not drop immediately.During the first nine months of the geothermal system’s operation, the Portland Jetport saw natural gas costs go down by $108,200. Operating the system required 1.31 million KWhrs in total electricity, resulting in a net cost increase of $2,355 to operate the system (on our 125,000 SF building, this is low enough to be considered cost neutral). We expected the “fuel swap” from natural gas to electricity, but didn’t expect a cost increase due such a high number of KWhrs. The current low cost of natural gas, due in part to the fracking boom taking place across the United States, is partly why we missed our energy savings projections out of the gate. As the price of natural gas rises, the savings should increase over the long term.
2. Operational savings were surprising.In the three years since the terminal opened, the natural gas fired rooftop cooling tower was never run (other than for occasional testing it to ensure it still worked). This means the geothermal system covered 100 percent of the airport’s cooling load since 2011. This also means lower maintenance costs and longer service life of the rooftop equipment. The terminal still needs a cooling tower for potential peak loads during any usually hot summers as a back-up, but the fact that it hasn’t been used yet is quite astounding.
3. Everything has a learning curve.Because the client is monitoring the geothermal system’s various attributes, they are learning how to operate the system in a way that maximizes energy savings and emissions reductions. For example, in the shoulder seasons (spring and fall), the client noticed a ground temperature “stasis:” the water being pumped between the ground and the building was almost the same temperature. With this in mind, we realized electrical costs could be reduced if we used the chiller in lieu of the geothermal system during these temperate months. This is a great example of how a client that is committed to understanding how its building functions under different conditions can save money and reduce energy use.
4. Emissions reduction projections were spot on.On-site greenhouse gas emissions reductions are right where we predicted them to be. The project has succeeded in significantly reducing Carbon Dioxide (CO2) and Nitrogen Oxide (NOx) emissions—reducing the latter was especially important since NOx is one of the most damaging of the greenhouse gases. Changing the primary fuel source to electricity has also played an integral role in reducing emissions. Although Maine still burns a lot of natural gas in their electrical power plants, the state burns very little coal and has higher percentages of hydroelectric and other renewables compared to other parts of the country.
Image © Gensler
We know natural gas costs won’t stay low forever, and with its geothermal system the Portland Jetport is well suited to save significant energy costs and greenhouse gas emissions for the long haul. They have invested themselves in learning how to operate the system for maximum value and environmental benefit and that is extremely commendable.
In this case, the new terminal’s beauty is not skin deep: It is deep underground, invisible to passengers, quietly working every day to make Portland’s air and water a little cleaner.
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Jim Stanislaski AIA, LEED AP will go to great lengths to explain how airports are a great place to illustrate innovation in sustainable design. A co-chair of the Boston Society of Architects Committee on the Environment, Jim believes in the power of design to craft a more sustainable world. Contact him at jim_stanislaski@gensler.com. |
Reader Comments (2)
Great to read about the details of the underground system of wells, and I like the image of the building and its roots extending far below the surface for energy and warmth.