The Variable Dynamics Unit (VDU) for high performance roof top units comprised of heating and cooling heat pump “blades” addresses energy efficiency and resilience of rooftop air conditioning units (RTU) used in commercial buildings in the U.S. The VDU is constructed in a modular form that reduces the total amount of working fluid used in operation. This concept is a prime candidate for prototyping and evaluation in situ because the unit will have secondary building benefits not captured in standard RTU testing (i.e., decreased heat gain, reduced maintenance costs, and fewer connection failures [such as leaks or air infiltration]). The project team will measure and quantify the advantages found in the VDU over incumbent technologies. The VDU will also meet Integrated 20-Energy Efficiency Ratio (20-IEER) laboratory testing. The approach taken in this project is to develop a working prototype that answers key engineering questions related to the technology and then move to produce units for in situ field validation. This project will be developed in close coordination with demonstration sites and ESTCP requirements.

Georgia Institute of Technology proposes to build an equivalent RTU that is designed, manufactured, installed, operated, and serviced in a similar fashion to how modern technology companies approach the design of “super computers” by utilizing arrays of commodity hardware. The Variable Dynamics Unit contains arrays of commodity-ducted mini-split heat pump components which are “ganged up” and “controlled in various arrangements” in order to provide space conditioning (heating/cooling) which leads to a lower initial installed cost with increased energy efficiency (20-IEER).

Comprised of heating and cooling heat pump blades from commodity components, this solution will demonstrate a solution that will advance installation energy resilience by increasing the energy efficiency of installation facilities, among other advantages. Specifically, the VDU will display the following purported benefits:

• Decrease energy costs by reducing heating, ventilation, and air conditioning energy use by up to 50% compared to incumbent RTUs.
• Increase ease of access associated with managing/running the technology due to its modular component design.
• Enhance resilience by remaining operational during disturbances using control solutions that reduce capacity rather than going completely offline.
• Utilizing cyber security controls developed by Pacific Northwest National Laboratory.
• Reduce maintenance costs and repair downtime through the technology's plug-and-play design, along with greater accessibility/availability of underlying commodity components.

(Anticipated Project Completion - 2026)