Analysis of alternative ventilation strategies for existing multi-family buildings using CONTAM simulation software

Abstract

In many existing high-rise multi-family buildings, a pressurized corridor ventilation system is used to meet outdoor air ventilation requirements. However, this system often has poor performance, leading to under- or over- ventilation in different parts of a building. This study examines three ventilation strategies including: the base case, which is a traditional pressurized corridor ventilation system, a direct-to-suite ducted ventilation system, and a suite-based HRV ventilation system. A building model was constructed in CONTAM using features of a typical post-war multi-family building in Toronto, Canada. All three strategies were simulated using CONTAM under both summer and winter conditions. The resulting outdoor airflow delivery rates to the suites and corridor pressure differentials were compared to assess the effectiveness of each strategy. The results show that the suite-based HRV strategy is able to provide adequate ventilation airflow to individual suites in both summer and winter. In the traditional pressurized corridor system and the direct-to-suite ducting system, the airflows delivered to the suites located at the top of the building are higher than those delivered to the suites located at the bottom of the building. This uneven airflow distribution is more pronounced in winter when stack effect impacts the ventilation system more significantly.

High‐rise residential building ventilation in cold climates: A review of ventilation system types and their impact on measured building performance

“…The lowest floor did not receive sufficient outdoor air in any of the studied buildings, regardless of the season. 50,54 On the contrary, as a result of stack effect, the top floor generally received sufficient outdoor air in the studied buildings 54 with the most outdoor air delivered during the winter season, 50,54 when stack effect is most prominent.…”

“…One study discussing centralized ventilation strategies noted that occupants were frustrated they could not control their suite ventilation and directly linked control to greater occupant satisfaction. 54 When occupants do not have enough control of their environment, they seek alternative means to control their thermal comfort. For example, 25% of residents opted to leave the corridor door open at least once a day to allow more cool air to enter the suite and 14% continued this behavior in the winter.…”

“…Figure 8 presents the results from the subset of studies that evaluated outdoor air delivery rates in suites [47][48][49][50][51][52][53] and corridors, 50,54 and Figure 9 presents the results from studies that evaluated outdoor air delivery rates in living rooms 53,55 and bedrooms. 41,53,55,56 Figure 8 shows the minimum, maximum, and average ventilation or combined ventilation and infiltration rates measured within suites and corridors.…”

“…[21][22][23][24][25] • Commonly under-delivers the required amount of outdoor air and provides inconsistent amounts of outdoor air from floor to floor and suite to suite (when on the same floor). 50,54 • IEQ tends to suffer-reports of poor IAQ, 63 thermal discomfort, 73 and acoustic discomfort, 26 which were all related to outdoor air delivery or lack thereof.…”

“…Figure8shows that pressurized corridor ventilation systems are currently underperforming in Canada50,54 as the outdoor air delivered is typically insufficient to meet ASHRAE Standard 62.2…”