1. Mikael Salonvaara, Miao Yang and Jensen Zhang
A Study of Air, Water and VOC transport through Building Materials with the Dual Chamber System
Mikael Salonvaara, Miao Yang and Jensen Zhang

2. Simulation models and material properties
Advanced simulation models need material property data
Transport and storage for Heat, Air, Moisture and Pollutants (VOC)
Availability of data is currently poor
Test methods are time consuming ► Accelerated methods
Numerous compounds exist, not all can be measured ►Similarities approach to estimate properties without measuring
Different test methods exist even for the same property
Transient, Steady-State
Chamber, cup-methods

3. Dual Chamber method Current system is to deliver
Air permeability
Water vapor diffusion coefficients
VOC diffusion coefficients
Sorption data
Same system is used for all compounds
Can be used for individual or simultaneous measurements of water vapor and VOC diffusion

4. Dual Chamber system Determine diffusion coefficient of materials
Chamber A
Chamber B
RH/T Sensor
Pressure
sensor
Specimen frame
Two chambers, each ≈ 1 ft x 1 ft x ½ ft

5. System Schematics
T, RH (in/out)

6. Principle of the dual chamber method
Deff effective diffusion coefficient, m2/s
Vi air flow rate of Chamber i, m3/s
Dx thickness of specimen, m
A test specimen area, m2
Fick’s Law:
At steady state:
VA*(CA,inlet – CA) = VB*(CB-CB,inlet)
Note! It is not necessary to achieve steady-state; acceleration is possible

7. Measuring of air permeability
Insert air at known rate, measure pressure difference P

8. Measuring of air permeability
Q=k*p

9. Measuring of water vapor and VOC permeability
Insert air at known rate and humidity, measure humidity at inlets and outlets
Use both flows in analysis
Chamber A to material: 1
Material to Chamber B: 2
T, RH A,out
T, RH B,out
Pv 1 2
T, RH A,in
T, RH B,in

10. Acceleration in testing diffusion coefficient
Method development by simulation
Flow from material to Chamber B
Flow from Chamber A to material

11. Test method verification using water vapor
Results: Permeance of gypsum board
Dual chamber
42 Perms
Dry cup method
44 Perms

12. OSB (Oriented Strand Board)
Water vapor permeance test results
Literature data (cup method) vs. Dual Chamber (2 weeks test)
Permeability,
kg/msPa
Permeance,
Perm

13. Effective diffusion coefficients and air permeabilities with Dual Chamber system
Ratio of diffusion coefficients
Gypsum/OSB =
Decane: 25
Water vapor: 20

14. Testing of multi-layered structures
Testing of single vs. multi- layered structures
SBPO (Spunbonded polyolefin)
Weather resistive barrier
SBPO + 3 5/8” air + SBPO
SBPO + 3 5/8” fiberglass + SBPO

15. Multilayered structure - results
SBPO, resistance for water vapor and decane equals to
0.035 m of still air (H20)
0.029 m of still air (decane)
SBPO m air + SBPO
Measured total resistance = 2 x single SBPO + air = m
Air cavity resistance equals to m of still air ( x 0.029=0.021)
Air is probably moving
SBPO m fiberglass insulation + SBPO = m
Air cavity resistance equals to m of still air
Water vapor resistance of fiberglass insulation is about 1.3 times that of still air
True parameters for CHAMP modeling

16. Conclusions and future work
Dual Chamber method can produce permeance data for air, water vapor and VOCs
Results so far have been comparable to those from other methods with less time spent for testing
On-going and future work
Validation of the method is still on-going
Similarities between compounds will be investigated to give insight whether or not all VOCs need to be measured
Reactions between compounds are to be investigated
Ozone initiated secondary emissions