Mikael Salonvaara, Andreas Nicolai, Hui Li, Jensen Zhang Overview of CHAMP – Combined Heat Air Moisture and Pollutant Transport Simulation Model Mikael Salonvaara, Andreas Nicolai, Hui Li, Jensen Zhang and John Grunewald

Modeling objectives Develop An integrated computer simulation environment for assessing the Combined Heat, Air, Moisture and Pollutants Transport in a whole building system (CHAMP) Mathematical models and computer simulation tools for the assessment of the long-term energy, indoor environmental quality (IEQ), and durability performance of building envelope systems Fast CHAMP simulation models for real-time predictive control of building environmental systems Benchmark and validate the simulation models by conducting small and full-scale laboratory experiments, and field tests Apply models to analyze the effects of IAQ control options and building envelope design on individual exposure, energy efficiency and durability

Envelope Model Model development Model implementation In-material diffusion and sorption; coupled moisture, VOCs Effects of leakage (air) flows Boundary conditions Model implementation 2-D heat, air, moisture and VOC program in C++ Development of a user interface and ‘helper tools’ Shared database development Coupling with other models Model benchmarking Parametric study and sensitivity analysis (trend and uncertainties) Determination of transport properties of building materials Comparison with full-scale experimental data and existing models Comparison with field performance

CHAMP Building Envelope Model Overview Heat, Air, Moisture and Pollutant (VOC) transport and sorption Multilayered assemblies (walls, roofs, components) C++, 2D (will be extended to 3D)

CHAMP Building Envelope model Simulation of one and two-dimensional multilayered structures, components and materials… Walls (exterior, interior) Furniture, … exposed to natural climates Indoor climate Temperature, humidity, pressure, VOC concentrations Outdoor climate Temperature, humidity, pressure, wind speed and direction, solar radiation, counter radiation (sky, clouds, surfaces), rain User defined conditions

IAQ & Energy Performance of Building Systems long wave radiation solar radiation temperature (Extinction: Adsorption, Dispersion, Reflection) heated cellar garage cooking, laundry Emissions warm roof cold roof humidity wind rain air pressure cloud covering diffusion transmission convection air tightness air leakage (rot, mold) Coupled Heat thermal bridge (surface condensation, mold) Air temperature relative humidity transmission ventilation convection air exchange Moisture air leakage Pollutant Simulation thermal bridge imperfect sealing (salt efflorescence) capillary flow diffusion ground water ground water

Model equations Equations are included for Material properties Heat conduction Air transport in porous materials and cavities (carrying heat, vapor, VOC) Water vapor diffusion, liquid transport VOC diffusion Material properties Sorption Transport properties Liquid phase Vapor phase

Equations - Diffusion Water vapor diffusion

Model Parameters/Material Characterization Moisture storage property (sorption, water retention) VOC sorption similarly but at low concentrations

VOC sorption VOC sorption is commonly presented with partition coefficients i.e. Cm = Kma  Ca Kma is strongly dependent on temperature (e.g. doubles every 10K) Water vapor sorption w = f(RH = pv/pv,sat) Much less dependent on temp. Usually only one curve used New concept for VOCs Cm = f(RC) = Kma  Ca,sat  RC RC = Ca/Ca,sat Evidence in literature data Sorption of benzene in soil Henry’s law constant at 50C = 10x at 14C …etc.

User Interface – Input and Output Processing User interface creates an ascii data file

Tool - Material Property Inspector Visualize material properties and check anomalies

Post-Processing User can select outputs (points, fields, flows) and intervals Internal chart engine and conversion tool to Tecplot

Example: Investigation of 2 VOC Sorption Models Cm = Kma  Ca (KMA model, no temp. effects) Cm = f(RC) = Kma  Ca,sat  RC (RC model) Simulation of a light-weight wood frame wall exposed to exterior and interior climate with air infiltration through the wall Air infiltration rate 0.036 m3/m2h (small) Indoor conditions constant 20C, 50% relative humidity Weather: Syracuse – Comparison of months January July Assumed initial conditions High concentration of toluene in OSB

Light-Weight Wood-Frame Wall OSB Fiberglass insulation Gypsum board Air leakage from top outside to bottom indoor side How much VOC is transported indoors by diffusion and airleakage? Air leakage through wall is shown with arrows. Indoor air is on the right. Outdoor air is on the left.

Total VOC Flux to Indoor Climate

Full-Scale Experimental Validation Air flow characterization VOC emissions with airflow through wall assembly

Test Wall with Instrumentation Supply Top wood Supply S7 Roof space Return OSB S5 S2 S4 Gypsum board RH28 RH29 VOC injection port Facing of insulation Insulation S1 S3 VOC sampling port S6 Return Bottom wood Floor space Pressure sensor T/RH sensor Climate chamber (Outdoor) Test wall IEQ chamber (Indoor)

VOC Emissions to IEQ Chamber +10 Pa pressure difference Emission factor (g/m2h)

What is Next? Model availability Develop user group First release version of CHAMP, August 2006 Available to everyone interested Develop user group Feedback Collaborative development possibilities Shared database development Material properties Experimental data Analyzed properties Applications to specific emission problems Formaldehyde from office furniture and composite wood products Moisture/mold control in critical building envelope structures Outdoor to indoor pollutant transport