Question

• What is the difference between Simple vs Detailed calculation methods / recommendations?
• How do simple vs detailed differ in Mitigate / MICA?
• When to use Detailed vs Simple calculation methods?

Answer

You will use Simple vs Detailed calculation methods based on several surrounding factors of the drying chamber. It is typical for Simple Calculation Factors to be used for residential properties and Detailed Calculation Factors to be used for commercial properties, however this will depend on the nature of the property and whether the drying process necessitates adding additional calculation factors.

Simple Calculation Factors

Initial dehumidifier capacity is calculated using the formula discussed below:

1. Step 1: Calculate the cubic feet (ft3) of air in the area being dried by multiplying its length x width x height.
2. Step 2: Determine the Class of the water-damaged environment.
3. Step 3: Using the ICRC initial dehumidification capacity for Simple Calculation table below, select an appropriate factor and calculate the minimum dehumidification capacity for initial setup of a closed drying system.
   1. Refrigerant Pint Method: Divide the factor into the cubie footage of the area being dried. This yields the total number of pints of dehumidification capacity needed initially to begin the drying project. Example: 1500 sf Class 2 water project @ 12,000 f3 ÷ 50 pints (LGR) =240 pints per day at AHAM rating.
   2. Desiccant CFM Method: Multiply the cubic footage of the affected area by the factor, then divide the result by 60. This yields the total CFM of process air nceded initially to begin the drying project. Example: 1500 square foot Class 2 project with 8' ceiling; at 12,000 cubic feet x 2 ACH - 60 = 400 Process CEM.

Detailed Calculation Factors

Calculating the drying capacity using the detailed calculation requires the understanding of several factors related to the structure and surrounding weather conditions. Below is a description of the factors considered by the detailed calculation methods. 

• Build-Out Density: impacts the ability to create lower vapor pressure air in all areas of the space as well as the amount of affected wall material that may need to be addressed
  • Very open: as in a factory, warehouse, convention center, large ballroom, sports complex, box store or theater,
  • Fairly open: as in a school with large classrooms or open office areas (e.g., open space with cubicles), department store.
  • Average: as in most homes, traditional office buildings or hotels
  • Very dense: as in an executive office suite with many small (e.g., 10' x 10°) offices and few open common areas, medical offices, or dormitory.
• Building construction and finishes: impacts the drying of the structure and contents.
  • Standard: Standard material and construction, such as: primarily carpet/pad over concrete or plywood subfloor or commercial glue-down, single-layer drywall, little to no insulation in interior walls and construction is standard; either wood or metal framing, mostly painted walls and builder-grade wood or vinyl baseboards.
  • High-end/Complex: High-end materials and complex construction such as: extensive carpet over heavy pad, multiple layer or high density wall assemblies, insulation and/or sound-attenuation may be present in interior walls, construction includes some fire-rated walls, complex assemblies (e.g., multiple layer flooring systems, chase walls) and higher-end finishes (e.g., vinyl wall-coverings, architectural-grade paneling, and wood trim details).
• Class of Water Intrusion: the estimated evaporation load used when calculating the initial humidity control requirements
• HVAC Impact: can impact the project if system is present, operable, and can be beneficial to the drying process
  • Beneficial: the system is present, operable, and will help maintain conditions favorable to the drying process.
  • Non-Beneficial: the system is not present, not operable or will not assist in maintaining conditions favorable to the drying process.

• Prevailing weather: impact will vary significantly from one climatic region to another and from one season to the next. Such variations may require that restorers use different equipment and techniques when drying similar wet structures during different times of ycar, or in different regions.

  1. Estimate the expected impact. Examples provided are approximate:

     1. Favorable: anticipated to aid drying (e.g., less than 40 gpp or 43°F DP)

     2. Neutral: anticipated to have minimal impact on drying (c.g., between 40 and 60 gpp, or 43° and 53°F DP)

     3. Unfavorable: anticipated to hinder drying (c.g. above 60 gpp, or 53°F DP).

  2. Estimate the building envelope's ability to keep the outside conditions from adversely influencing the drying environment (i.e., infiltration):

     1. Tight: drying conditions can be controlled without significant influence by the outdoors

     2. Moderate: drying conditions will be influenced somewhat by the outdoors

     3. Loose: drying conditions will be significantly influenced by the outdoors.