ventilation

Under the influence of biological hazards including COVID-19, it is required sufficient ventilation to decrease the infection risk in the indoor area. In particular, the natural ventilation with window opening is recommended in rooms with inadequate ventilation. However, the ventilation rate, energy loss, and indoor thermal environment with window opening in air-conditioned room varies hourly with given environment. In addition, opening windows in winter causes serious problems such as deterioration of the indoor thermal environment and reduction of absolute humidity.

Deep Energy renovation (DER) adopts a whole building approach and achieves much larger energy savings than shallow energy renovations that typically only included a small number (one or two) of upgrade measures. DER includes the installation of high levels of insulation, uses renewable energy technologies and minimises uncontrolled air leakage by achieving air permeability levels no greater than 5 m3/h.m2 to achieve building energy ratings (BER) of at least A3.

This paper reports preliminary analysis from a large field study of 100 university classrooms in Central Texas. Lecture classrooms and auditoriums were sampled for three consecutive weekdays in the 2019 – 2020 academic year. Carbon dioxide (CO2) concentrations, used as a marker for both ventilation and exposure, and temperature were measured in the general room area and when able, the supply airstream. HVAC control data that relates to ventilation was also saved for comparison.

Ventilation and source control (e.g. using low volatile organic compound (VOC) emitting materials) are two recommended approaches to control indoor air pollution and VOC’s in particular. Decisions on how to minimize exposure can be supported by indoor air chemistry modeling, since the relationships between VOC’s, their precursors, and building ventilation is so complex. For example, modeling could be used to examine the impact of altering building ventilation.

Many differences exist between countries in the requirements and regulations for ventilation of dwellings, offices, classrooms and other spaces. Sometimes the variation of the ventilation requirements for the same building type between countries is more than a factor of five. There are strong drivers, e.g., climate change, to reduce energy consumption for HVAC and therefore these variations are worth examining. Before reducing ventilation rates, it is critical to understand the reasons behind them.

The Book of Proceedings of the 42^nd AIVC - 10^th TightVent - 8^th venticool Conference: "Ventilation Challenges in a Changing World" held in Rotterdam, Netherlands on 5-6 October 2022