This blog was originally posted by Greater Greater Washington on May 11, 2020.
Written by Will Schick.

Much of our greenhouse gas, especially in cities, comes from buildings. To fight climate change, cities are pushing for buildings that don’t pollute. In the Washington region, a few are showing the path forward in urban and suburban areas.

In the District, for instance, buildings account for approximately 3/4 of all greenhouse gas emissions. Those emissions are produced by heating, cooling, and lighting buildings, as well as their construction. This number is far higher than globally (39%) or in the United States (40%), since cities have more buildings and less industry, mining, power plants, and so forth.

The District has imposed new rules for large buildings to reduce greenhouse gas emissions as much as possible.

The ultimate goal is a “net zero” building, which produces as much energy as it uses, on average. There are a few in our region, including the American Geophysical Union in DC, Discovery School in Arlington, and the Unisphere in Silver Spring.

The American Geophysical Union (AGU) recently renovated their building on Florida Avenue NW into a net zero building. AGU is a community of around 120,000 earth and space scientists from all over the world who study everything from oceans to natural hazards to the weather and the intricacies of black holes.

Janice Lachance, the Executive Vice President of Strategic Leadership and Global Outreach for AGU said that there was a “direct link” between her organization’s mission and “the decision to make this a net zero building.”

“Net zero” is different in cities and suburbs

There are some challenges that come with being a structure in an urban environment. During construction of their current site, Lachance and her team decided to visit several different net zero energy buildings in suburban Virginia. That’s when they discovered that achieving net zero in an urban environment could be more challenging than in suburbia because of the lack of space.

She remembers asking one administrator of a suburban net zero building about how they would react to an unanticipated spike in energy use. Lachance laughed when she received the answer: “Oh, I just buy a couple more solar panels and throw them up on the roof.”

For Lachance, it was a lesson in efficiency. In cities, “there’s only so much space that you have for the things that generate energy,” she said.

That’s not the only challenge: the AGU building faced considerable hurdles getting historic preservation approval for its renovation as well, particularly for the solar panels.

This spring and summer AGU will install 719 solar panels on their roof, making use of every possible square inch (some of those panels will be positioned vertically on their southern wall).

By contrast, the Discovery School in Arlington, which is Virginia’s first net zero energy building, has 1706 solar panels installed on their roof. The Discovery School spans 97,588 square feet while the AGU building has slightly less space at 62,000 square feet.

But the key to achieving net zero for both structures has as much to do with reducing energy use as it does on solar energy.

Within the AGU building, you’ll find that lights are set to motion monitors, that computer monitors are on low power and that people take the stairs when they can.

The Discovery School uses 100% LED lighting, which helps to reduce overall energy consumption.

Other innovative ways large buildings can reduce energy

Like the AGU building and the Discovery School, the “Unisphere” project in Silver Spring, Maryland couples solar with innovative design methods to make the building as energy efficient as possible.

Both AGU and the Unisphere project feature “electrochromic” windows. These are coated with various tints that react to the changing position of the sun, keeping down the demand for heat in winter by allowing more sun in, and for cooling in summer by blocking it out.

Commercial and residential buildings of the future could feature such windows as a way to reduce overall energy consumption.

Windows are also a key feature of the Discovery School, where one third of their wall space is windows, which increases natural light and also helps energy efficiency.

Each one of these buildings also rely on other energy-saving strategies involving everything from the use of geothermal heating to sophisticated ventilation systems.

The AGU building for instance, uses a direct current (DC) system within their building instead of alternating current, which requires conversion to DC power and wastes potential energy every time something is plugged in like a laptop or phone.

In the basement of the AGU building, there’s a heat exchanger that repurposes sewage into a source for heating and cooling, by redirecting thermal energy that comes from separating solids from liquids.

Then there’s the HVAC system, which uses cooling panels and water pipes throughout the building. A filtration system makes use of plants that grow up walls to help with air quality.

How do the calculations for “net zero” work?

So, here’s where things get a bit complicated. According to Christine Gibney, AGU’s net zero operations specialist, there are “about forty different definitions” of the term “net zero energy.” This, she said, has to do with how energy production and use is accounted for — for instance, it can come from either on-site sources, or from off-site sources. Then, there are competing industry standards that each have a slightly different definition of the term.

The AGU building generates all the energy it uses. Building managers work with the standards set by the New Buildings Institute to ensure that the total energy they’ve consumed on a 12-month basis equals the amount they generate. The purpose behind doing this is to show that creating such a structure is possible, even given the limitations of being in an urban environment.

Eventually, as cities inch toward their goals of becoming carbon neutral and environmentally friendly, residential buildings and homes will likely need to follow suit and develop ways to reduce their energy consumption and also contribute to the grid.

The lessons offered by the experience of the large scale buildings such as AGU, the Discovery School, and Unisphere show the importance of adopting solar and give us some ideas as to what homeowners and other businesses should think about when planning for their future: more energy efficient windows, upgraded HVAC systems, LED lighting, and solar — which the District has recently made available for free to low-income homeowners.

“Net-zero” for large-scale buildings also comes at a hefty cost: according to Liza Lester, AGU’s manager of public information, they received some financial assistance from the District in the form of $37.4 million in tax-free bonds. However, many smaller homes and businesses can make relatively small changes to get themselves closer, at least, to net zero.