American Geophysical Union Headquarters
2000 Florida Avenue, NW
General Contractor: Skanska USA Building, Inc.
Architect: Hickok Cole Architects
Engineer: Interface Engineering
Contract Amount: $4,962,000
Start Date: March 15, 2017
Completion Date: November 15, 2018
According to its website, the American Geophysical Union (AGU) “is dedicated to the furtherance of the Earth and space sciences, and to communicating our science’s ability to benefit humanity.” With over 62,000 members from 144 countries, the AGU is demonstrating this dedication in the renovation of its 25-year-old headquarters building in downtown Washington, D.C.
As AGU realized that their structure was aging, and a renovation was looming, the organization decided to take the lead as an integral part of the earth/science solutions it promotes. In addition to specifying a LEED Platinum rating, the AGU set an even loftier design and construction goal – to achieve Washington, D.C.’s first-ever “net zero” office building renovation.
This means that over the course of a calendar year, the building will generate as much energy as it pulls from the electrical grid. Mechanical systems, including HVAC and plumbing equipment, use a substantial amount of energy. Reducing energy usage of these mechanical systems is essential to helping the building achieve net zero status.
First-Ever Commercial Integration of Advanced Technologies
Regular air conditioning (A/C) systems reject heat in several ways, but primarily remove heat to the outside through air or water. In order to save money, as well as enhance energy efficiency, a municipal waste heat exchanger (MWHE) was specified in the AGU renovation design to reject heat from the building and facilitate the A/C process whenever cooling is required. Furthermore, this same system also absorbs heat from the sewer water in the winter to facilitate the heating process. This is the first time MWHE technology will be used in a commercial building project in the United States.
Instead of using a fan to blow hot air outside, or water through a cooling tower, a MWHE uses water in the sewer system where the water temperature usually ranges from the upper 40s to the mid-50s Fahrenheit. This is actually the ideal temperature range for both cooling and heating purposes. The process works for heating because, in winter, sewage water contains heat.
A wet well, 30 feet tall and nine feet wide, is where sewage water is brought into the heat exchanger using a pump and filtration equipment (to remove solids). Again, this is the first time this had ever been done in a U.S. commercial building renovation.
Bringing it all together, from a net zero standpoint, is a water-to-water heat pump that produces hot and chilled water to heat and cool the building. This type of heat pump relies on a closed glycol loop with the MWHE to either reject or absorb heat from the sewage loop. This is how they work together to heat and cool the building.
The radiant ceiling system starts with approximately 1,000 metal-based, cooling-only radiant panels which were supplied by a German manufacturer. These are mounted on a hanging grid, much like acoustical ceiling panels. In addition, 200 cooling-only radiant ceiling panels are embedded in the drywall ceilings and are not visible. Working in tandem with the radiant ceiling is a dedicated outdoor air system (DOAS) that provides all of the ventilation air in the building. Air is distributed throughout the building by 100 variable air volume (VAV) boxes.
Another innovative – and somewhat unusual – element of the building mechanical system is a “hy-phy” wall, a living plant wall that is responsible for funneling all of the DOAS exhaust air from the building. By exhausting interior air through the hy-phy wall, the living plants remove CO2 and other pollutants – which means the DOAS unit doesn’t need to spend extra energy to temper outside air. It can simply use return air and send it back to the building.
A final “green” feature of this top-to-bottom building renovation is the rainwater harvesting system, which collects and filters rainwater. This filtered rainwater is then used to irrigate plants as well as to flush toilets and urinals.
Specific Design and Installation Challenges
Above and beyond the fact that the AGU project is the first time that all of the above advanced, innovative technologies were integrated in one U.S. commercial structure, there were several specific challenges related to design and installation.
Our first major challenge related to coordination. The existing structure retained its metal decks and concrete floors, as well as structural steel beams and columns, but the engineering drawings did not reflect the actual beam conditions. To facilitate coordination and devise a solution for routing ductwork and piping, our Virtual Design and Coordination (VDC) team used our advanced Building Information Modeling (BIM) system to create 3D models of the true beam conditions (including openings) on all six floors. Guided by these models, the engineers were able to go back and redo the drawings.
Another big challenge was installing the pump equipment inside the wet well. Not only was this the first time our company had worked with this German-manufactured brand of filtration and pumping equipment, but this type of mechanical structure had never before been installed and aligned in a 30 x 9 underground concrete well. Getting it right required careful sequencing of the work from the site utility contractor.
Our team solved these challenges by getting the different trades together that were responsible for all of the components, researching answers to the problems, and then working together to overcome sequencing challenges of installation. For example, in the wet well, instead of relying solely on engineering drawings to determine proper placement of taps to and from the sewer system, and to and from the building, our field team and the utility contractor’s team performed actual field surveys of the existing infrastructure. This is how we ensured proper coordination of all line locations – two lines from the well to the building and two lines from the well to the sewer.
Our team also went above and beyond the usual scope of a mechanical system design and installation project by taking it upon ourselves to 3D remodel the structural steel beams.
Installation of the radiant heating panels went smoothly because we knew what to expect based on our prior successful first-time experience with this brand-new technology in 2015-16, during construction of the new American University Washington College of Law campus in Northwest Washington, D.C.
Our team overcame scheduling difficulties. We succeeded in coordinating and installing cutting-edge, foreign-made wet well equipment in a 30-foot-deep well – something that had never been done before in the United States. We demonstrated that we could pull sewage water from the D.C. water system into the building, use it for heating and cooling purposes, and then send it back into the sewer system.
When the time came to cool the building during the summer of 2018, the entire system was functional and operational. The 1,200 sensible-only radiant heating panels operated as designed and the DOAS component maintaining low humidity levels inside the building.
The key takeaway from this project is that Shapiro & Duncan prides itself on living on the cutting edge of mechanical technology. By purchasing, installing and integrating advanced equipment never before used in a commercial U.S. project, our efforts were key to helping the newly-renovated American Geophysical Union headquarters achieve not only a LEED Platinum rating – but also first-in-D.C net zero energy efficiency.