Investigation of the Moisture Buffering Potential of Magnesium Oxide...
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Investigation of the Moisture Buffering Potential of Magnesium Oxide Board
Transcript of Investigation of the Moisture Buffering Potential of Magnesium Oxide...
Investigation of the Moisture Buffering Potential of Investigation of the Moisture Buffering Potential of Magnesium Oxide Board
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.
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). 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.
Whole-Building Performance Research Laboratory (WBPRL)
Overview of Test Facilities
Occupancy Simulation System
TRIAD MAGNETICS F-401U
TRANSFORMER
OMRON G3NA-205B SOLID
STATE RELAY
AALBORG PSV-D SOLENOID
VALVE DRIVER
TRIAD MAGNETICS WSU240-1000 DC POWER SUPPLY
FTDI-USB-RS485-PCBA CONVERTER
ADAM-4024 CONTROLLER
Occupant simulation system control box
Humidification system components of the occupant simulator system
MethodologyMethodology
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
Field Verification of Moisture Production
Laboratory Calibration of Occupant Simulator Units
NORTH BUILDING (Painted Gypsum)
SOUTH BUILDING (Painted MAGO Board)
PARAMETERS: Indoor Temp, Relative Humidity
COMPARE
ANALYZE MOISTURE BUFFERING POTENTIAL
PARAMETERS: Indoor Temp, Relative Humidity
Phase I: Laboratory Calibration of the Phase I: Laboratory Calibration of the Occupant Simulator Units
Calibration Procedure
Determination of pump refill water level trigger
Laboratory setup for calibration of the indoor simulation units
Run #1: Linear fit of cumulative weight loss over time for occupancy simulator unit 1
y = 100.97x - 0.386
y = 89.837x + 1.6631R² = 0.9989
y = 88.664x + 1.9943R² = 0.9986
y = 85.26x + 4.8729R² = 0.997
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100
Cum
mul
ativ
e W
eigh
t L
oss
(g)
y = 100.97x - 0.386R² = 0.9991
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10
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30
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Cum
mul
ativ
e W
eigh
t L
oss
(g)
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)
Phase II: Field Verification of the Moisture Production Rate of the Moisture Production Rate of the
Occupant Simulator Units
Experimental Setup of WBPRL
RH-T’s
RH-T’s
POLY LINING OF THE CEILING,
OCCUPANT SIMULATOR
UNITS
RADIANT HEATER
RH-T’s
THE CEILING, FLOOR AND
WALLS
Field verification of the moisture production rate in the north and south building: Indoor temperature comparison
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22
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24
Tem
pera
ture
(oC
)
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2/3 17:00 2/3 23:00 2/4 5:00 2/4 11:00
Tem
pera
ture
(oC
)
SB Indoor Temp NB Indoor Temp
Field verification of the moisture production rate in the north and south building: Relative humidity comparison
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80
90
100
Rel
ativ
e H
umid
ity
(%)
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60
2/3 17:00 2/3 23:00 2/4 5:00 2/4 11:00
Rel
ativ
e H
umid
ity
(%)
SB Indoor RH NB Indoor RH
Comparison of the Laboratory derived and field derived calibration rates of the occupant simulator units
SouthBuilding Occupant
Simulator 1
SouthBuilding Occupant
Simulator 2
NorthBuilding Occupant
Simulator 1
NorthBuilding Occupant
Simulator 2
Calibrated Rate [g/hr] 90 141 70 126
Actual Rate [g/hr] 120 189 102 185
Phase III: Field testing of the moisture buffering potential of painted Magnesia buffering potential of painted Magnesia
board
Experimental Setup of WBPRL
Ceiling Fan
Poly Lining
Ceiling Fan
RH-T’s
Occupant Simulator
Unit
Radiant Heater
Poly Lining Of Ceiling And Floor
RH-T’sRH-T’s
Radiant Heater
Occupant Simulator
Unit
Poly Lining Of
Ceiling And Floor
South Building: MAGO BoardNorth Building: Gypsum Board
Test case #1: Relative humidity comparison of both buildings exposed to normal moisture production and normal ventilation rate
60
70
80
90
100
Rel
ativ
e H
umid
ity
(%)
0
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50
4/11 4:00 4/11 10:00 4/11 16:00 4/11 22:00 4/12 4:00
Rel
ativ
e H
umid
ity
(%)
MAGO_RH Gypsum_RH
Test case #2: Relative humidity comparison of both buildings exposed to normal moisture production and low ventilation rate
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60
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100
Rel
ativ
e H
umid
ity
(%)
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4/25 15:00 4/25 21:00 4/26 3:00 4/26 9:00 4/26 15:00
Rel
ativ
e H
umid
ity
(%)
MAGO_RH Gypsum_RH
Test case #3: Relative humidity comparison of both buildings exposed to high moisture production and normal ventilation rate
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100
Rel
ativ
e H
umid
ity
(%)
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4/16 4:00 4/16 10:00 4/16 16:00 4/16 22:00 4/17 4:00
Rel
ativ
e H
umid
ity
(%)
MAGO_RH Gypsum_RH
Test case #4: Relative humidity comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate
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e H
umid
ity
(%)
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5/3 4:00 5/3 10:00 5/3 16:00 5/3 22:00
Rel
ativ
e H
umid
ity
(%)
MAGO_RH Gypsum_RH
Test case #4: Ventilation Rate comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate
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45V
enti
lati
on R
ate
(CF
M)
0
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5/4 14:00 5/4 20:00 5/5 2:00 5/5 8:00 5/5 14:00
Ven
tila
tion
Rat
e (C
FM
)
MAGO_CFM_Rate Gypsum_CFM_Rate
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.• 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
Phase IV: Investigation of the moisture buffering potential of unpainted Investigation of the moisture buffering potential of unpainted
Magnesia board
Experimental Setup of WBPRL
Ceiling Fan
Poly Lining
Ceiling Fan
RH-T’s
Occupant Simulator
Unit
Radiant Heater
Poly Lining Of Ceiling And Floor
RH-T’sRH-T’s
Radiant Heater
Occupant Simulator
Unit
Poly Lining Of
Ceiling And Floor
South Building: MAGO BoardNorth Building: Gypsum Board
Test case #1: Relative humidity comparison of both buildings exposed to normal moisture production and normal ventilation rate
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Rel
ativ
e H
um
idit
y (%
)
MAGO_RH
Gypsum_RH
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8/14 4:00 8/14 10:00 8/14 16:00 8/14 22:00 8/15 4:00
Rel
ativ
e H
um
idit
y (%
)
Test case #2: Relative humidity comparison of both buildings exposed to normal moisture production and low ventilation rate
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70
80
90
100
Rel
ativ
e H
umid
ity
(%)
MAGO_RH
Gypsum_RH
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7/14 4:00 7/14 10:00 7/14 16:00 7/14 22:00 7/15 4:00
Rel
ativ
e H
umid
ity
(%)
Test case #3: Relative humidity comparison of both buildings exposed to high moisture production and normal ventilation rate
60
70
80
90
100
Rel
ativ
e H
umid
ity
(%)
MAGO_RH
Gypsum_RH
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20
30
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50
60
8/26 0:00 8/26 6:00 8/26 12:00 8/26 18:00 8/27 0:00
Rel
ativ
e H
umid
ity
(%)
Test case #4: Relative humidity comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate
60
70
80
90
100
Rel
ativ
e H
umid
ity
(%)
MAGO_RH
Gypsum_RH
0
10
20
30
40
50
9/3 3:00 9/3 9:00 9/3 15:00 9/3 21:00 9/4 3:00
Rel
ativ
e H
umid
ity
(%)
Test case #4: Ventilation Rate comparison of both buildings exposed to normal moisture production and RH controlled ventilation rate
25
30
35
40
45
Ven
tila
tio
n R
ate
(CF
M)
MAGO_CFM_Rate
Gypsum_CFM_Rate
0
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10
15
20
25
9/3 3:00 9/3 9:00 9/3 15:00 9/3 21:00 9/4 3:00
Ven
tila
tio
n R
ate
(CF
M)
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 surfaceboard 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.
