Case Study: Consulting Engineering

Veterinary Diagnostics Laboratory

North Dakota State UniversityFargo, North Dakota

North Dakota State University Chooses Geothermal to Save Energy

The modern, highly efficient North Dakota State University Veterinary Diagnostics Lab was designed to provide the university and surrounding areas with the resources to support veterinary science research and advancement. The new facility offers expanded laboratory and office space and features significant layout enhancements for safety and efficiency. Furnished with top-of-the-line technology and equipment, the laboratory provides testing and diagnostic services for veterinarians, animal owners and producers, and the public health sector. CMTA provided mechanical and fire protection engineering services for the Diagnostics Lab, as well as designed a geothermal heating and cooling system to aid in energy efficiency, carbon reduction, and lower operating costs.

The Challenges

  • Design state-of-the-art diagnostics laboratory to support veterinary science research
  • Prioritize occupant health and wellness with significant ventilation required for lab buildings
  • Achieve significant energy efficiency and carbon reduction goals
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When I look at the new lab, I see a modern, well-designed facility that will not only meet the current needs of the livestock industry and companion animal owners in North Dakota and the surrounding region, but also is sufficiently flexible to adapt to future animal health challenges. Created with Sketch.

Brett Webb

NDSU Veterinary Diagnostics Laboratory Director

The Solutions

This state-of-the art, single story facility offers a wide array of forensic services and functions. Approximately 4,000 SF are allocated for office space, while the remaining 23,400 SF serve as laboratory space for forensic functions, including necropsy, accessioning, and specialized wet lab spaces. The building also contains approximately 350 SF of BSL-3 certified lab space, ten fume hoods, two-grossing stations, 6-tissue cabinets, and one large necropsy table. The facility offers toxicology, bacteriology, virology, molecular diagnostic, clinical and anatomic pathology, parasitology, and serology testing services. Testing is supported by an impressive 2-ton crane capacity combined incinerator that aids staff in moving and disposing of larger specimens efficiently. The laboratory is fully accredited by the American Association of Veterinary Laboratory Diagnosticians.

Laboratory buildings require significant ventilation. The supply airstream for offsetting the required exhaust and conditioning of the building is 100% outside air. The building’s main energy efficiency features are the use of a geothermal wellfield, an energy recovery run-around loop between the exhaust and outside air, a laboratory ventilation control system, and a low ambient chilled water heat recovery system. The building’s Climate Zone 7 location, along with the large outside air component, results in a heating dominant load profile—a significant challenge for a 100% geothermal project. Therefore, the final system selection is a hybrid model geothermal system coupled with a high-efficiency natural gas hot water boiler plant. The geothermal wellfield is designed to provide all cooling needs and a significant portion of the heating needs. All domestic hot water is heated with high-efficiency natural gas water heaters to support significant facility washing needs.

The labs and offices in the building are designed to make the thermal conditions comfortable for occupants. Comfortable wintertime Climate Zone 7 spaces require special attention. A combination of radiant ceiling panels, fin tube radiation, and in-floor heat increase local comfort in sequence with ventilation hot water reheat coils to provide warm and comfortable spaces. Ventilation in the lab spaces is maintained at a minimum of six air changes per hour, as recommended by ASHRAE Classification of Laboratory Design Levels LVDL-3. Ventilation rates are increased with the operation of fume hoods or other local exhaust sources. Unoccupied laboratory ventilation rates are maintained at 3 air changes per hour which is less than the standard, recommended 4 air changes per hour. The change was recommended and validated by the owner to increase operational efficiency in unoccupied spaces.

The laboratory exhaust ductwork is under negative pressure within the building, with redundant exhaust fans on the roof. The fan discharges and exit velocities are designed to prevent possible entrainment of exhaust air into the fresh air intake. The entire building is set up with a room pressure cascade that progresses from the office spaces (most positive) to the labs to confine contaminants to the space in which they are generated. The BSL-3 Lab space is designed with an independent ventilation system including an air handling unit and exhaust system. A pressure cascade and HEPA filter system capture contaminants to the space along with provision in the ventilation system for sterilization. Office areas are ventilated with the laboratory supply air ventilation system, which is essentially operating as a Dedicated Outside Air System (DOAS).

Hybrid Geothermal HVAC System

The HVAC system utilizes geothermal heating and cooling for the entire building, with the wellfield sized at 308 wells drilled 220 feet deep. The integrated 6-pipe heat recovery chiller is the focal point of the HVAC system, consisting of seven, 50-ton modules integrated into a single system. The modular design improves the system’s capability to load match and provides a level of redundancy. The system is designed with an N+1 redundancy factor to increase reliability. The unit can create chilled and hot water directly, without the use of the geothermal wellfield system as the demand exists. Excess energy from heat rejection in the cooling mode or heat absorption in the heating mode is transferred to the geothermal wellfield loop as demand requires. Laboratory buildings typically have a high level of reheat required in the summer as a function of maintaining humidity levels and cooling requirements. During this time, the 6-pipe chiller provides heat as a waste byproduct and the building requires no additional energy input for reheating. The combined Coefficient of Performance (COP) is nearly ten at design conditions and greater at part load conditions, interfering only when one portion of electrical energy input moves ten portions of heating and cooling energy.

The Results

Due to NDSU's prioritization of energy efficiency and sustainability, the building's energy consumption, utility costs, and carbon footprint were reduced. The hybrid geothermal strategy over the more traditional natural gas boiler and air-cooled chiller option reduces site annual carbon emissions by approximately 206 Metric Tons of CO2e/yr, or about 18%. Implementing innovative solutions in a challenging climate zone, CMTA was proud to partner with NDSU on this unique project that supports the university, the surrounding community, and the environment.

NDSU Vet Diagnostics Lab

What does this data mean?
Baseline: AIA 2030 Annual Energy Use Goal
Actual: The measured energy use of this project