moisture assessment
DESCRIPTION
Moisture Assessment. WEATHERIZATION ENERGY AUDITOR SINGLE FAMILY. WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012. Learning Objectives. Moisture Assessment. By attending this session, participants will be able to: - PowerPoint PPT PresentationTRANSCRIPT
1 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Moisture AssessmentWEATHERIZATION ENERGY AUDITOR SINGLE FAMILY
WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012
2 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
By attending this session, participants will be able to:• Analyze the symptoms of moisture problems in houses.
• Identify moisture sources.
• Explain moisture terms and concepts.
• Demonstrate how to measure relative humidity.
• Demonstrate how to use a psychrometric chart.
• Apply moisture control strategies.
• Use moisture assessment tools.
Learning ObjectivesMOISTURE ASSESSMENT
3 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Symptoms #1
Excessive window condensation
Photo courtesy of PA WTC
MOISTURE ASSESSMENT
4 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Symptoms #2
Frost on underside of roof sheathing
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
5 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Symptoms #3
Mold on interior surfaces
Photo source: PA WTC Photo
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
6 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Symptoms #4
Peeling Exterior Paint
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
7 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Standing Water in Basements
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
Symptom #5
8 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
• Foundations
• Unvented space heaters
• Unvented dryers
• Disconnected ventilation fans
• Drying wood indoors
• Excessive mechanical or passive humidification
Moisture Sources
These water stains are a result of fan venting into the attic.
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
9 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Sources of Water VaporMOISTURE ASSESSMENT
10 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
• Condensation: water vapor transformed to liquid water
• Evaporation: liquid water transformed to water vapor
• Absolute humidity (vapor pressure): the ratio of water vapor to a given volume of air
• Relative humidity (RH): the ratio of the amount of moisture in the air compared to amount of moisture that the air can hold
• Dew point: the temperature at which condensation occurs
Important Terms and ConceptsMOISTURE ASSESSMENT
11 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Measuring Relative Humidity
Sling Psychrometers• Two thermometers side by side• One is wrapped in wet wick (wet
bulb), the other is dry (dry bulb)• Spinning it around speeds
temperature stabilization• Plot wet bulb and dry bulb
temperature on psychrometric chart to determine dew point and RH
Photos courtesy of Bacharach
MOISTURE ASSESSMENT
12 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Dry bulb = 80°Wet bulb = 66°Dew point = 60°RH = 50%
Grains of w
ater per pound of dry air
MOISTURE ASSESSMENT
Psychrometric Chart #1
13 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
156
Psychrometric Chart #2
78
Grains of w
ater per pound of dry air
MOISTURE ASSESSMENT
14 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Grains of w
ater per pound of dry air
MOISTURE ASSESSMENT
Psychrometric Chart #3
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Grains of w
ater per pound of dry air
MOISTURE ASSESSMENT
Psychrometric Chart #4
16 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Grains of w
ater per pound of dry air
MOISTURE ASSESSMENT
Psychrometric Chart #5
17 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
• Warm, wet air contacting cold surfaces creates condensation instantly.
• Cold winter air typically contains very little moisture and therefore has a low RH. When that air is heated, the RH drops even lower.
• RH below 15% can lead to respiratory problems, failure of furniture glue and other problems.
RH: Things to RememberMOISTURE ASSESSMENT
18 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Attic Case Study
Floored Attic and First Condensing Surface
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
19 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Possible Causes• Moderate to high interior moisture source
• Attic surface temps are below the dew point of the indoor air
• Air leaks to attic
Control Strategies• Source control
• Air seal the attic
Attic Case – Causes & SolutionsMOISTURE ASSESSMENT
20 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Basement Case Study
Mold on cool interior corner
Symptom
• Condensation evident on basement walls
Reason
• Light to moderate interior moisture source
• Basement walls are below the dew point of the indoor air
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
21 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Control moisture sources.
Remove susceptible materials.
Educate occupants to:
• Mechanically dehumidify.
• Increase air flow in basement (fans).
• Close basement openings during hot humid periods.
Basement Case Study Solutions MOISTURE ASSESSMENT
22 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Symptoms• Wet wood• Condensation on
foundation surfacesPossible Reasons• High ground moisture
source• Warm humid air entering
vents from outside• Crawl space surfaces
are below the dew point of the outside air
Crawl Space Case Study
Water droplets of condensation on AC ducts.
MOISTURE ASSESSMENT
Photo courtesy of PA WTC
23 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
• Install a ground vapor retarder.
• Control moisture sources and remove susceptible materials.
• Consider converting to a conditioned crawl space.
Crawl Space Case Study Solutions
Conditioned crawlspace with air sealed and insulated walls.
MOISTURE ASSESSMENT
Photo courtesy of INCAP
24 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
Clear understanding of moisture management principles.• Senses - Visual inspection
o Evidence of condensationo Evidence of mold
• Communication Skillso Know what questions to asko Documentation is vital
• Wood Moisture Metero To make quantitative assessments on wood moisture content
• Psychrometero To determine real time RH levels
• Digital Camera
Tools of the TradeMOISTURE ASSESSMENT
25 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
PhotoSource: PA WTC
MOISTURE ASSESSMENT
Moisture Meters
Photos courtesy of PA WTC
26 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012 eere.energy.gov
• The first step in doing a moisture assessment is to look for visible signs of moisture and moisture sources in the house.
• Plotting the wet bulb and dry bulb temperatures on a psychrometric chart gives dew point and relative humidity.
• Understanding the effects of temperature and vapor pressure on RH can help identify solutions.
• Source control, air sealing, ventilation, and thermal improvements are important moisture mitigation strategies.
• Photos and diagnostic equipment help document existing conditions.
SummaryMOISTURE ASSESSMENT