Magnesium Oxide Board

Transcription

1 Investigation of the Moisture Buffering Potential of Investigation of the Moisture Buffering Potential of Magnesium Oxide Board

2 Introduction Excess humidity is one of the main factors affecting building envelope failures. Additionally, it creates a favorable environment for mold growth on the interior finish of the building envelope which pose respiratory health risks to occupants. Controlling indoor humidity within an acceptable range is therefore important. Indoor humidity control is typically achieved by ventilation, however, excess ventilation negatively impacts the building energy performance. By employing interior finishes with moisture buffering potential; the ability of materials to absorb excess moisture when the indoor humidity is high and vice versa, indoor humidity control can be achieved passively thereby reducing the ventilation energy requirements. More benefits attributed to this moisture buffering phenomenon are: reduction of building latent heat load, cooling load and equipment size. Knowing that the moisture buffering potential varies for different materials, that of Magnesia board; a relatively new product, is not known and is investigated in this research project.

3 Research Scope The objective of this project was to investigate the moisture buffering potential of Magnesia board under different operation scenarios. This involved monitoring two identical side-by-side buildings while measuring the indoor air temperature and relative humidity to evaluate the moisture buffering potential. These two test buildings are called the Whole-Building Performance Research Laboratory (WBPRL). One of the buildings is set as a reference building and the second one as a test building. The interior of the reference building is finished with gypsum panels; the most common interior finish, and the test building will be finished with the magnesia board. Both buildings are exposed to the identical indoor hygrothermal loads generated by an in-house developed Indoor simulation system. The different operation scenarios are designed to access the effect of finishing, occupancy density, ventilation rate and control strategy and a combination.

4 Whole-Building Performance Research Laboratory (WBPRL) Overview of Test Facilities

5 Occupancy Simulation System AALBORG PSV-D SOLENOID VALVE DRIVER TRIAD MAGNETICS F-401U TRANSFORMER OMRON G3NA- 205B SOLID STATE RELAY TRIAD MAGNETICS WSU DC POWER SUPPLY FTDI-USB- RS485-PCBA CONVERTER ADAM-4024 CONTROLLER Occupant simulation system control box Humidification system components of the occupant simulator system

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7 Methodology

8 Laboratory Calibration of Occupant Simulator Units Field Verification of Moisture Production TEST #1: Normal Moisture Production and 15cfm TEST #2: Normal Moisture Production and 7.5cfm TEST #3: High Moisture Production and 15cfm TEST #4: Normal Moisture Production and RH control NORTH BUILDING (Painted Gypsum) SOUTH BUILDING (Painted MAGO Board) PARAMETERS: Indoor Temp, Relative Humidity COMPARE PARAMETERS: Indoor Temp, Relative Humidity ANALYZE MOISTURE BUFFERING POTENTIAL

9 Phase I: Laboratory Calibration of the Occupant Simulator Units

10 Calibration Procedure Determination of pump refill water level trigger Laboratory setup for calibration of the indoor simulation units

11 Run #1: Linear fit of cumulative weight loss over time for occupancy simulator unit Cum mmulative Weight Loss (g) y = x R² = y = x R² = y = x R² = y = 85.26x R² = Time (hr) Trial #1-1st quarter Trial #1-2nd quarter Trial #1-3rd quarter Trial #1-4th quarter Linear (Trial #1-1st quarter) Linear (Trial #1-2nd quarter) Linear (Trial #1-3rd quarter) Linear (Trial #1-4th quarter)

12 Phase II: Field Verification of the Moisture Production Rate of the Occupant Simulator Units

13 Experimental Setup of WBPRL OCCUPANT SIMULATOR UNITS RH-T s RH-T s RADIANT HEATER POLY LINING OF THE CEILING, FLOOR AND WALLS RH-T s

14 Field verification of the moisture production rate in the north and south building: Indoor temperature comparison Tempera ature (oc) /3 17:00 2/3 23:00 2/4 5:00 2/4 11:00 SB Indoor Temp NB Indoor Temp

15 Field verification of the moisture production rate in the north and south building: Relative humidity comparison Relative Hum midity (%) /3 17:00 2/3 23:00 2/4 5:00 2/4 11:00 SB Indoor RH NB Indoor RH

16 Comparison of the Laboratory derived and field derived calibration rates of the occupant simulator units South Building Occupant Simulator 1 South Building Occupant Simulator 2 North Building Occupant Simulator 1 North Building Occupant Simulator 2 Calibrated Rate [g/hr] Actual Rate [g/hr]

17 Phase III: Field testing of the moisture buffering potential of painted Magnesia board

18 Experimental Setup of WBPRL Ceiling Fan Ceiling Fan RH-T s Radiant Heater Poly Lining Of Ceiling And Floor RH-T s Radiant Heater Poly Lining Of Ceiling And Floor Occupant Simulator Unit North Building: Gypsum Board Occupant Simulator Unit South Building: MAGO Board

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20 Test case #1: Relative humidity comparison of both buildings exposed to normal moisture production and normal ventilation rate Relative Hum midity (%) /11 4:00 4/11 10:00 4/11 16:00 4/11 22:00 4/12 4:00 MAGO_RH Gypsum_RH

21 Test case #2: Relative humidity comparison of both buildings exposed to normal moisture production and low ventilation rate Relative Hum midity (%) /25 15:00 4/25 21:00 4/26 3:00 4/26 9:00 4/26 15:00 MAGO_RH Gypsum_RH

22 Test case #3: Relative humidity comparison of both buildings exposed to high moisture production and normal ventilation rate Relative Humidity (%) /16 4:00 4/16 10:00 4/16 16:00 4/16 22:00 4/17 4:00 MAGO_RH Gypsum_RH

23 Test case #4: Relative humidity comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate Relative Humidity (%) /3 4:00 5/3 10:00 5/3 16:00 5/3 22:00 MAGO_RH Gypsum_RH

24 Test case #4: Ventilation Rate comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate Ventilati ion Rate (CFM) /4 14:00 5/4 20:00 5/5 2:00 5/5 8:00 5/5 14:00 MAGO_CFM_Rate Gypsum_CFM_Rate

25 Conclusion No measureable difference in moisture buffering performance between the gypsum and magnesia board. This is attributed to the interior surface coating of both interior finishes. To put in perspective, the permeability of ½ gypsum wall board is 51 perms, according to ASHRAE HOF, priming and coating gypsum has the potential to drop the permeability to about 10 perms. Falls under the category of Class II vapor retarders. The same could be said about the magnesia board, hence the similarity in moisture buffering performance of both interior finishes. In Phase IV of this research project both interior finishes will be tested without the interior primer or paint coating for maximum moisture buffering potential

26 Phase IV: Investigation of the moisture buffering potential of unpainted Magnesia board

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28 Experimental Setup of WBPRL Ceiling Fan Ceiling Fan RH-T s Radiant Heater Poly Lining Of Ceiling And Floor RH-T s Radiant Heater Poly Lining Of Ceiling And Floor Occupant Simulator Unit North Building: Gypsum Board Occupant Simulator Unit South Building: MAGO Board

29 Test case #1: Relative humidity comparison of both buildings exposed to normal moisture production and normal ventilation rate MAGO_RH Gypsum_RH Relative Humidit ty (%) /14 4:00 8/14 10:00 8/14 16:00 8/14 22:00 8/15 4:00

30 Test case #2: Relative humidity comparison of both buildings exposed to normal moisture production and low ventilation rate MAGO_RH Gypsum_RH Relative Humid dity (%) /14 4:00 7/14 10:00 7/14 16:00 7/14 22:00 7/15 4:00

31 Test case #3: Relative humidity comparison of both buildings exposed to high moisture production and normal ventilation rate MAGO_RH Gypsum_RH Relative Humid dity (%) /26 0:00 8/26 6:00 8/26 12:00 8/26 18:00 8/27 0:00

32 Test case #4: Relative humidity comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate MAGO_RH Gypsum_RH Relative Humid dity (%) /3 3:00 9/3 9:00 9/3 15:00 9/3 21:00 9/4 3:00

33 Test case #4: Ventilation Rate comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate MAGO_CFM_Rate Gypsum_CFM_Rate Ventilation Rat te (CFM) /3 3:00 9/3 9:00 9/3 15:00 9/3 21:00 9/4 3:00

34 Conclusion/Further Work Magnesia board showed similar moisture buffering capability to gypsum in that the discrepancies in the relative humidity comparisons Considering the similar moisture buffering behavior different surface characteristics of both boards, gypsum is more receptive to mold growth as a substrate Reason: Gypsum is paper faced compared to the hard and smooth magnesia board surface That being said, the experimental setup was designed to investigate the maximum buffering potential and it was found to be significant when compared with the previous phase Following, both boards will be coated with high permeable paint to investigate its impact on the moisture buffering.