Multizone airflow models for calculating infiltration rates in commercial reference buildings

Sixteen reference building models were created in the multizone airflow and contaminant transport program CONTAM in order to support physically based airflow calculations, as well as indoor air quality analyses, that are not possible using the existing EnergyPlus input files of these buildings. The EnergyPlus models were created for assessing new technologies and supporting the development of energy codes in pursuing building energy efficiency improvements. These models employed an oversimplified approach to infiltration in which infiltration rates were input as constant values. A number of additional inputs had to be defined for the CONTAM models to realistically account for airflow, including the addition of several building zones. Annual airflow simulations were performed in CONTAM for six of the sixteen reference buildings. There are clear relationships between the infiltration rates calculated by CONTAM and weather, which are not exhibited in the EnergyPlus results. In addition, the building envelope airtightness values assumed in either approach have a major impact on calculated infiltration rates. The results of this study provide a baseline for subsequent use of these models to investigate design approaches and technologies that are intended to reduce building energy consumption, improve indoor air quality, or both.

► Development of CONTAM models of DOE reference buildings for airflow analyses.
► Annual airflow simulations using CONTAM for six reference buildings in Chicago.
► Envelope airtightness values assumed have major impact on outdoor air change rates.
► Infiltration calculated by CONTAM affected by weather.
► Models can be used to compare approaches for reducing energy and improving IAQ.