Lab Validation of Next-Generation RTUs: DOE's Challenge Method of Test and Performance Results

As energy and economic priorities reshape the commercial building sector, rooftop units (RTUs) must advance beyond traditional designs to deliver reliable, adaptable performance under diverse operating conditions. To accelerate this transformation, the U.S. Department of Energy (DOE) launched the Commercial Building HVAC Technology Challenge, a collaborative initiative engaging manufacturers to develop next-generation rooftop heat pump units capable of meeting ambitious performance targets across multiple climate zones. Eight leading manufacturers participated in the Challenge, designing and building prototype RTUs that align with DOE's advanced specifications. This paper details the comprehensive laboratory validation process for these prototypes, which included the development of a new Method of Test (MoT) to evaluate both steady-state and dynamic performance characteristics. Additionally, a Control Verification Procedure (CVP) - based on load-based testing methodology-was implemented to assess native control strategies under field-representative conditions, ensuring that units can maintain optimal operation in real-world scenarios. The standardized testing framework provides a consistent approach for verifying heating and cooling performance, part-load operation, backup heat response, and integrated control functionality. Results from these evaluations offer critical insights into performance trends, control behavior, and system resilience under varying conditions. Key findings highlight lab validation outcomes and lessons learned, which inform opportunities for future improvements and support readiness for widespread commercial deployment. By establishing robust testing protocols and validating prototype performance, the Challenge sets the stage for scalable, high-performing HVAC solutions that advance market transformation and contribute to long-term energy and cost savings.