Abstract
This article details the pilot buildings for the Recirculate It project in Norway, which use return air recirculation. The buildings include an office building with a climbing center, a glass atrium cantina, a multifunctional museum, a chicken processing plant, and two shopping malls with adjoining office spaces. They face distinct indoor air quality (IAQ) challenges, such as humidity control, microbial contamination risks, and various air pollutants. For example, the climbing hall generates high dust levels at certain times, while other buildings struggle with odour dispersion.
Most pilot buildings have recirculation dampers with varying degrees of regulation, though few feature automatic recirculation adjustments. Air quality is monitored in exhaust flows, seldom in supply, and outdoor air quality is rarely used for control. Strategies rely on process knowledge, pollutant sources, and schedules rather than direct IAQ monitoring, except for CO₂, temperature, and sometimes humidity.