Energy Efficiency Potential of Dedicated Outdoor Air Systems in Commercial Buildings

This Final Project Report summarizes the findings of PG&E’s Code Readiness Subprogram DOAS Field Research project, which collected dedicated outdoor air systems (DOAS) and variable refrigerant flow (VRF) system data from eight field sites. DOAS ventilation, which separates outdoor ventilation air delivery from space cooling and heating for thermal comfort, is a mature technology used extensively in Asia and in parts of Europe, but with relatively little market share in the US. DOAS, when coupled with VRF or hydronic heat pump space conditioning systems, can provide an efficient, cost-effective, all-electric alternative to the conventional mixed-air systems more commonly found in California nonresidential buildings. Understanding the true performance, cost, and benefit of DOAS in California climate zones is essential to know its role in California’s building codes and standards. PG&E’s Code Readiness Subprogram aimed to fill this data gap by collecting data from eight commercial buildings across five California climate zones. 

Throughout the project, the research team delivered eight unique publications including one Field Assessment, five case studies, and two targeted analysis reports. This Final Project Report is a culmination of all project findings and focuses on field observations of the real-world performance of DOAS and their controls, the cost-effectiveness of all-electric HVAC with DOAS in small to medium California nonresidential buildings (less than 150,000 sf) using building simulation, and an evaluation of Title 24, Part 6 (Title 24) energy code language. The research yielded key findings and recommendations in four categories; installation and verification barriers, cost-effective DOAS configurations through modeling analysis, Title 24 code language enhancements to support DOAS performance and compliance, and incentive and market transformation program recommendations.