IAQ Models of Representative U.S. Homes
Residential exposure analysis with CONTAM
Andrew PersilyNational Institute of Standards and
TechnologyGaithersburg, MD
[email protected], 301 975-6418
NSF/UL 440 Environments & Products TeleconferenceMay 24, 2012
Topics for Today
• IAQ modeling with CONTAM
• “Suite of homes” CONTAM models of US dwellings
• Issues in modeling exposure
Building Airflow and Contaminant Transport Modeling
Macroscopic/MultizoneNetwork airflow analysis
Each zone: 1 node, 1 reference pressure, uniform temperature & concentration
e.g., CONTAM
Microscopic/CFDDetails of airflow and contaminant concentrations in a space
e.g., FDS, FLUENT, CFD0
CONTAM www.bfrl.nist.gov/IAQanalysis
CONTAM SketchPad
CONTAMW Inputs & OutputsEnvironmental FactorsWind Speed and DirectionWind Pressure CoefficientIndoor/Outdoor TempOutdoor Contaminants
FiltrationSteady State SimulationScheduled Flows, Sources
etc.Transient Simulations up to
One YearFirst Order Chemical
ReactionsData Libraries
Building and System DescriptionBuilding Zone ConfigurationBuilding Leakage CharacteristicsHVAC Airflow RatesDuct SystemsFilter Efficiencies
Contaminant InformationChemical Reaction DataContaminant Sink CharacteristicsContaminant Source StrengthOccupancy Schedules
Infiltration Rates
Interzonal Airflows
Pressure Drops across Openings
Contaminant
Concentrations
Exposure Levels
NIST “Suite of Homes”
HUD-funded effort to define a representative collection of houses based on U.S. building surveys (e.g., Census, DOE)– 209 dwellings that represent 80 % of the U.S. housing stock
Floor plans and CONTAM models available for
download
Variables used to define dwellings
Suite of Homes
Persily et al. 2006. A Collection of Homes to Representthe U.S. Housing Stock, NIST report NISTIR 7330.
Report, CONTAM files and floor plans: http://www.bfrl.nist.gov/IAQanalysis/case%20studies/cwcase_11.htm
Application “Suite of Homes”First statistically representative distribution of ventilation rates in U.S. homes
CONTAM models are being used for IAQ and exposure studies
Advantages: Established and documented; public domain; generates distribution instead of single value
Indoor CO exposure from emergency generatorsPersily et al. 2010. Indoor
Air. 20: 473-485.
Issues in modeling exposureBASIC QUESTIONSHow many dwellings: Which and why?Simulation duration: 24 h? Annual?Occupants: Number? Schedule?Contaminants: How many?
INPUTSWeather conditions: How many?Building tightness: Covered in suite modelsMechanical ventilation: Any? How much?Impose constant air change rate or calculate from leakage/weather?
Source strengths: Source areasRemoval mechanisms: Surface sorption? Air cleaning?
DATA MANAGEMENT AND ANALYSIS