Higher Education

Binghamton University Nuthatch Hollow

Nuthatch Hollow is a 75-acre environmental learning and research preserve at Binghamton University and the campus selected Pathfinder to provide mechanical, electrical, plumbing engineering and energy modeling for a new 3,450 sq. ft. environmental classroom and research facility that strives for Living Building Challenge and Passive House (PHIUS) certification.


The design seeks to minimize and control ventilation and includes operable windows and window closure switches that deenergize the HVAC system when the windows are open. Demand Control Ventilation will provide ventilation air to each occupied zone matched to occupancy and controlled by a CO2 sensor. Two energy recovery ventilators will be provided to condition the ventilation air and provide recovery energy from an exhaust fan serving the composting toilet.

Mechanical systems are "right sized" to minimize electrical power by the all-electric system. The HVAC system incorporates variable refrigerant flow (VRF) technology with the added advantages of improved part load performance, higher COPs and EERS, multiple zone control from a common condensing unit, and integration inside the energy recovery ventilator. The PV inverters, battery packs and building exhaust discharge are being co-located inside a shed with the VRF condensing unit to reclaim waste heat to improve low ambient performance.

Air movement is important for occupant comfort, and in a tight building constructed to meet Passive House requirements the challenge is to do so passively, when possible, with operable windows and minimal fan energy under heating or air conditioning. Large-diameter, high volume fans operate at lower energy use due to improved blade design and integration of ECM motors, variable speed control and airflow reversing. Coupled with VRF technology these fans significantly reduce fan energy.

Each space is controlled individually with space sensors and control devices with a wide dead band between heating and cooling set points. The building management system (BMS) monitors occupancy and controls system operation and space temperatures for occupied and unoccupied conditions.


Electrical design features a photo-voltaic system that will capture energy in an array of solar panels as direct current, providing 105% of the energy required by the building. Estimated annual energy consumption is 14,375kW, and the 14kW system will generate an average of 15,505 kWh per year with a range of 14,925 kwh (103.8%) to 15,982 kWh (111.1%).

The University is a leading research facility for batteries. The building will be used as a battery research testing platform. Initially, the battery storage system will be (2) 5kW lithium ion battery packs.

The design uses LED lighting, vacancy sensors, and utilizes daylight harvesting where natural light is present such as glass walls, windows and skylights.


The water supply for the building is an existing domestic well and water use in the building will be minimized by the use of a composting toilet and ultra low automatic faucets in lavatories, the laboratory, and a kitchen sink. Total anticipated water use is calculated at less than 70 gallons per day.

Domestic water from the well will be sanitized via a UV lamp system and stored in the well head tank prior to distribution. Tank pressure will activate the well pump and UV lamp system.

Rainwater will drain to grade, and there will be some rainwater catchment to bio-retention areas. There will be a leach field for grey water from the kitchen and laboratory sinks, the limited black water liquid waste from the composting toilets, and the condensate water from the condensate pan under the cooling coils.

Grey water will be separated from black water and run through a filtering system in the basement of the building. During months when frost is not a factor grey water will be run to an irrigation distribution bed below demarcated planting beds. When frost is a factor the greywater will be directed to the black water leach field.

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