Compartmentalization and Ventilation System Impacts on Air and Contaminant Transport for Multifamily Buildings

Provision of acceptable indoor air quality in multifamily buildings (MFBs) depends on the interior air
flows that impact dilution of contaminants, cross-contamination between units and building energy use.
The airtightness of interior partitions and design of ventilation systems in MFBs determine the flows
across building partitions. These flows change the total ventilation rate for the building and individual
units, and impact the mixing of air and contaminants between apartment units or with common spaces.
This study examines the changes in air flow and contaminant transport in MFBs using combined
CONTAM/EnergyPlus models. Key parameters were systematically varied, including climate, apartment
airtightness, and mechanical ventilation system type. Simulations were performed for mid-rise buildings
with and without an enclosed common corridor, and a 20-story high-rise building. Contaminants
simulated in the analysis were PM2.5, formaldehyde, water vapor, and CO2. Key results of this work are
that current airtightness requirements in ASHRAE 62.2 sufficiently limit transport of key contaminants,
independent of the type of ventilation system across all three building typologies, and significantly
reduce energy use in colder climates. The results of this work are intended to assist codes and
standards bodies in setting appropriate airtightness limits and ventilation system design guidelines for
MFBs.