Case Study: Consulting Engineering
Located two blocks from the White House on the Foggy Bottom campus, Thurston Hall is George Washington University’s (GW) largest freshman residence hall, housing 825 students, faculty in residence, and residential life staff. The 100-year-old building has seen many uses in its lifetime but had previously had no comprehensive renovations. CMTA served as the MEP engineer for this 200,000 square foot complete interior overhaul.
From an energy efficient standpoint, it’s going to meet some of the highest standards out there. From a health standpoint, brand new systems will address some of the concerns of the air handling around campus and nationally.
The building’s new central courtyard design brings the rhythms of Washington, D.C. into the heart of the building. With the intent to draw students out of their rooms and into modern common areas, the design integrates academic and social experiences around a lively central spine with views, clear orientation, and collaboration space. Breaking down the building’s density through a variety of light-filled, flexible spaces, the renovation creates clear orientation around a new three-season atrium. The program includes a multi-purpose area, food service, and penthouse student space that offers natural light and city views.
Except for the recently installed condensing boilers, all building systems were completely removed, allowing GW the chance to focus on sustainability, health, and wellness goals. The building features Dedicated Outdoor Air Systems (DOAS) with energy recovery, a rainwater collection system for domestic greywater, and Building Integrated Photovoltaics (BIPV). The lower-level dining service incorporates energy-saving strategies, including water source refrigeration and demand-controlled ventilation. An active circadian lighting system was used for interior spaces that have no viable daylighting options. The project is targeting LEED Platinum certification.
The project scope also included high efficiency water-source heat pumps (WSHP) in all spaces. A two-pipe heat pump loop serves all the WSHPs for space conditioning. This network of piping allowed other forms of water-cooled equipment to tie into the heat pump system, including the kitchen walk-ins, IT variable refrigerant flow risers, the domestic hot water pre-heating loop, and the heat pump chiller, which provides dual-temp water to the DOAS units and kitchen makeup air units. The balance of equipment adding and removing heat from the same loop prevents the cooling towers and boilers from having to supplement with additional loads throughout the year.
Additionally, like many century-old buildings, the pre-renovated building had poor indoor air quality (IAQ) due to inadequate ventilation and infiltration issues. Pollutants in the ambient air in metro DC are higher than the national average, so it was critical to incorporate enhanced ventilation and filtration techniques into the renovation. The IAQ improvements were driven by the rooftop DOAS units, which provide ventilation directly to each residential space, while two additional units serve the dining and kitchen areas. The rooftop units, which include MERV 13 filters, provide constant dehumidified 70°F air, delivered 24/7. Compared to the pre-renovation levels measured in 2019, the post-renovation levels revealed drastically reduced levels of pollutants such as Sulfur Dioxide, Nitrogen Dioxide, Ozone, and Particulate Matter.
The renovated design reduces the building’s operational carbon footprint by nearly 35% compared to the ASHRAE 90.1-2010 baseline. Not only does this meet the University’s carbon goals, but it also complies with potential future BEPS carbon taxes. This is an annual savings of around 1,600 MT eCO2, or the amount of carbon sequestered by 1,900 acres of forest. Furthermore, the design team significantly reduced the building’s embodied carbon by reusing most of the existing concrete structure. Much of the new embodied carbon was limited to new walls, finishes, and other architectural elements.
Similarly, the building requires significantly less water from baseline use due to several water-saving strategies. The rainwater harvesting system provides non-potable water for public restrooms in the dining hall, as well as 100% of the water required for building irrigation. Indoor water use is reduced by 40% by implementing low-flow faucets, showerheads, and water closet slashes. A side stream sand filter and conductivity meter installed on the condenser water system maintain a conductivity of 200 μS/cm. The additional filtration maximizes the cooling tower cycles of concentration which minimizes the required domestic makeup water, further aiding in the building’s environmental impact.
CMTA was proud to help George Washington University renovate a residence hall that is critical to the first-year experience for many students. The building’s new central courtyard design promotes connection and collaboration, while also maximizing daylighting and lowering and reducing the building’s energy consumption. The renovated Thurston Hall is not only energy efficient, but it also prioritizes occupant health and wellness and reduces the University’s operational carbon footprint.
