CompAIR Full Description / FAQ

What goes into the CompAIR Volatile Ingredients Calculator?

The calculator requires the following inputs, and provides guidance to help you find them in the product literature.

  • % weight of solids
  • % weight of water
  • product density
  • standard coverage
  • coats required

How does the calculation work?

For each product, the calculator provides the weight of Volatile Ingredients released by coating a standard area. Wet-applied products are basically made of three things: water and volatiles that evaporate, and solids that stay behind. We first calculate the product’s % volatiles by counting what is left after you remove the water and solids. It’s also important to take into account how large an area each unit of product can cover, and how many coats are needed. Below, we’ve written the equation two ways to help make the calculation easier to follow. The first equation shows how the calculator takes data from product literature. The second equation shows the same calculation broken down to clarify how the units cancel to get the final answer. The equations are color-coded to show which sections are the same in each.

Equation 1: Formatted as entered from product literature

(100% - wt% solids - wt% water) × product density × coats required = weight volatiles
standard coverage area

Equation 2: Formatted to show units explicitly

wt. volatiles × wt. product × vol. product × coats required = weight volatiles
wt. product vol. product coverage area 1 area

How does the Volatile Ingredient Calculator treat chemicals with different health hazards?

The known health hazards of Volatile Ingredients in building products span a huge range from headaches and dizziness to cancer and reproductive toxicity, and most have not been fully studied. Even though these Volatile Ingredients have different toxicity profiles, this calculator treats them all equally since it’s uncommon for product literature to list the specific chemicals used. In cases where product literature does identify specific Volatile Ingredients, the Pharos Chemical and Material Library can be consulted to find their listed hazards.

What is the difference between Volatile Organic Compounds (VOCs) and Volatile Ingredients?

VOCs have many overlapping definitions, depending on who you ask. In the context of building materials, VOCs are commonly defined as chemicals that are released into the air during the application and curing of a product, and that contribute to smog formation. Their use in building products is regulated by a number of international, national, and regional bodies.

Volatile Ingredients is a broader category that includes all compounds that are released into the air during the application and curing of a product, regardless of whether they contribute to smog formation. We feel it’s important to account for all compounds because there are hazardous Volatile Ingredients that are exempt from VOC reporting, including the carcinogens perchloroethylene and methylene chloride and the reproductive/developmental toxicant acetone. The inclusion of chemicals like these makes Volatile Ingredients a better measure of human health impacts.

What if the products use different standards to measure and report VOCs?

While there are multiple standards that will provide different results, our approach sidesteps this sticky question by calculating the volatile content by subtracting the solids and water from the total.

Is the CompAIR volatiles ingredient calculator different from Regulatory VOC (VOC of Coating) or Actual VOC (VOC of Material)?

Yes, the CompAIR volatiles ingredient calculator is different from Regulatory VOC and Actual VOC in two ways:

  1. All calculators begin by determining the mass of volatiles in a certain volume (e.g. g/L), each using its own formula. In some cases, these formulas will produce the same result.
  2. Only CompAIR goes on to include the coverage area and number of coats.

The following examples are based on the spreadsheet calculator provided by the South Coast Air Quality Management District (SCAQMD). They show how each calculator can give different results based on the formulation of the wet-applied product.

Example 1: 10% VOCs Example 2: 20% VOCs Example 3: 40% VOCs Example 4: 20% VOCs + 20% exempt VOCs
Density Material, g/mL 1.2 0.99 0.982 0.99
Non-Volatile (NV, solids), wt% 32.3 30.0 60.0 35.2
Water, wt% 57.7 50.0 0.0 24.8
Exempt Compounds, wt% 0 0 0 20
VOC Coating1, g/L 393 393 393 393
VOC Material2, g/L 120 198 393 198
Volatile Ingredients, g/L 120 198 393 396
# coats 2 2 2 2
standard coverage area, m2/L 4 4 4 4
Volatile Ingredients, g/m2 60 99 196 198

Are semi-volatile compounds (SVOCs) included?

Like VOCs, these compounds also evaporate under ambient conditions, but more slowly, and they can also cause health problems. For example, it may take months or years rather than days for the bulk of the material to leave. As with VOC’s, there is no universal definition of semi-volatile compounds (SVOCs). Many phthalates used in paints and adhesives are considered SVOCs. These are most likely to be included as solids in the product literature, and so will not be considered by the Volatile Ingredient Calculator.

What if there are missing data points?

For some products, all of the required information for the volatiles calculation may not be available on product literature. When using a manufacturer’s website to obtain technical literature, look for professional websites, such as those for contractors, architects and designers. Other publicly available sources for data points, particularly percent weight of water, include disclosure tools such as HPD and Declare. Products listed by Declare can be found on their website. Products with HPDs can be found using the Pharos Building Product Library (BPL), for Pharos subscribers, on manufacturer websites, and the SmithGroup’s HPD library. Users may also find missing data points on other versions of product literature hosted on retailer websites, such as Home Depot, Lowes, and Menards. When data points are not publicly available, we encourage users to follow up with the manufacturer for more information.

Why does the volatile content vary widely?

Depending upon a manufacturer’s comfort with disclosure, product content and some technical information may be considered confidential business information and may be reported using wide ranges. Wide ranges in data may also be used in order to represent a number of products on one source rather than a single product. Wide ranges in data points will likely result in wider ranges in calculated outputs from CompAIR, which may make product comparisons less clear. HBN recommends using the source(s) that report with the greatest precision (ex. the smallest range) and/or de-prioritizing sources that report data for more than one product (ex. MSDSs may cover multiple products).


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