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Total Volatile Organic Compound (TVOC) Measurement for LEED/Green Building Evaluation

May 27th, 2009

LEED Testing


Total Volatile Organic Compounds (TVOC) may be evaluated when building designers/managers are pursuing the Leadership in Energy and Environmental Design Green Building Rating System for New Construction (LEED-NC) EQ Credit 3.2. The latest LEED-NC guidance document specifies that the maximum allowed concentration of TVOC measured in a building (post construction, pre-occupancy) is 500 µg/m3; the guidance also mentions using the sampling/analytical methods in the US EPA Compendium of Methods for the Determination of Air Pollutants in Indoor Air. However, none of these sampling and analytical methods address TVOC in particular, and thus the existing methods must be modified. In addition, TVOC is not defined (in terms of boiling point range, etc.) in the latest LEED-NC guidance and therefore is left open for interpretation; historically, many definitions of “TVOC” exist in literature.

For TVOC measurement, the analytical technique used must always reference one compound for calibration purposes. All compounds detected are then assumed to have the same response factor as the calibration compound. For instance, handheld instruments are most often calibrated using isobutylene or methane, and laboratory-based methods may reference TVOC as hexane (C6), toluene, or some other chemical species.

In practice, indoor air quality practitioners may use several different techniques for evaluating TVOC in buildings. Each sampling & analytical method has its own benefits and drawbacks, cost implications, and applicability.

Handheld “Real-Time” Instruments

Handheld photoionization detectors (PIDs) and flame ionization detectors (FIDs) are common tools used for site investigation. PIDs contain a UV lamp of a particular energy (e.g. 10.6 eV or 11.7 eV); any chemical species with an ionization potential at or below this energy will be detected. FIDs require a fuel gas (hydrogen) to burn hydrocarbons in a small flame, ionizing the chemical species which are present; thus any chemical species with a C-H bond (hydrocarbons) will be detected (including lighter end C1-C3 hydrocarbons, which may not be considered part of a TVOC definition). This type of instrument is typically calibrated by running a “zero” (blank/clean air) and “span” (known concentration of calibration gas, isobutylene for PIDs and methane for FIDs) measurement—essentially a one point calibration forced through zero. While each of these instruments respond to a wide range of compounds and yield a “total” value, the detection limits of these instruments are typically in the range of 0.1-0.5 ppmV (as methane for FID, as isobutylene for PID), and therefore may not be suitable for the low-level TVOC assessment required for LEED. However, ultra-sensitive PIDs currently exist in the marketplace, with manufacturers claiming detection limits in the low ppbV range and accuracies within 20 percent. Costs to rent this type of equipment range from approximately $50-$100/day, plus any costs for associated equipment (calibration gases, dataloggers, etc.).

Charcoal Tubes

NIOSH/OSHA methods such as NIOSH 1500 or OSHA 07 use small coconut shell charcoal tubes and personal sampling pumps to sample for VOCs in air. Traditionally, these methods were written to address workplace exposure issues, and the reporting limits of these methods are typically in the ppmV (mg/m3) range. Air is drawn through the tubes with a pump at a known flow rate for a known amount of time, with the compounds of interest adsorbing on to the charcoal media. Back at the laboratory, the charcoal in the tubes is then chemically desorbed with a small volume (1-2 mL) of solvent such as carbon disulfide. A small microliter amount of that solvent extract is then injected into a gas chromatograph (GC), typically equipped with a flame ionization detector (FID). Since only a very small portion of the sample (approximately equivalent to 1/1000th of the volume of air sampled) is being analyzed, the sensitivity of the analysis is only moderate (although completely adequate for traditional workplace exposure monitoring). The laboratory analysis will determine the total mass of contaminants captured and report it as “TVOC as Toluene” (or other chemical species); concentration is calculated by dividing the mass by the total volume of air pulled through the tube. When using this technique to evaluate TVOC for LEED, it may be necessary to increase the sampling flow rate and/or sampling duration to lower the detection limit below 500 µg/m3. Costs for this type of analysis range from approximately $65-125 per sample.

Thermal Desorption Tubes

Thermal desorption tube for TO-17

Methods such as EPA Method TO-17 (1999), EPA IP-1B (1990) and/or NIOSH 2549 (1996) use stainless steel thermal desorption tubes (packed with one or multiple sorbent materials) and a personal sampling pump to sample for VOCs in indoor/ambient air. In general, thermal desorption methods were written to detect low concentrations of VOCs in indoor/ambient air, with reporting limits typically in the low ppbV (µg/m3) range. Air is drawn through the tubes with a pump at a known flow rate for a known amount of time, with the compounds of interest adsorbing on to the sorbent media. The tube is then thermally desorbed and the entire amount of all compounds of interest is transferred to the GC column for analysis.

For this analysis, the GC is equipped with a mass spectrometer for the detector (GC/MS), allowing for qualitative and/or quantitative identification of all species present (based on retention time and matching of the sample spectrum against a NIST library). Since the entire sample may be consumed, the sensitivity of this analysis is 100-1000 times greater than the traditional (solvent desorption) charcoal tube approach. The laboratory analysis will determine the total mass of contaminants captured and report it as “TVOC as Toluene” (or other chemical species); concentration is calculated by dividing the mass by the total volume of air pulled through the tube. Costs for this type of analysis are in the range of $125-$250/sample.

Table 1 presents a summary of pros and cons for the solvent desorption (traditional charcoal tubes) and thermal desorption approaches.

Table 1. Solid Sorbent Sampling: Solvent Desorption vs. Thermal Desorption for TVOC


Solvent Desorption

Thermal Desorption

Analytical Methods

  • NIOSH 1500,  OSHA 07
  • EPA TO-17, NIOSH 2549, EPA IP-1B

Typical Sorbent Used

  • Coconut shell charcoal
  • Tenax, Carbon Molecular Sieve, Carbopack, and/or various combinations thereof

Analytical Detector

  • Flame Ionization (FID)
  • Mass Spectrometry (MSD)

Concentration Range

  • high ppbV – ppmV
  • high pptV – low ppbV

Amount Analyzed

  • Only analyze a portion of total sample extract
  • (~ 1/1000)
  • Entire sample may be analyzed for greater sensitivity


  • Reanalysis possible
  • Wide dynamic range
  • Lower reporting limits
  • Qualitative ID of compounds comprising TVOC is possible


  • Difficult to account for desorption efficiency when evaluating TVOC 
  • Difficult to choose one appropriate desorption solvent when evaluating TVOC
  • Reanalysis may not be possible depending on analytical system
  • Limited dynamic range

Passive Sorbent Samplers

Passive sampling technology has long been used to monitor workplace/indoor air exposures (both personal monitoring and area samples). A sorbent material is contained in some convenient form (e.g. clip on badge, tube with diffusive cap, etc.) and air passively enters the sampler without the use of a personal sampling pump. Compounds of interest are adsorbed onto the sorbent media, in the same manner as active sorbent sampling (either traditional charcoal tubes or thermal desorption tubes). Different types of passive samplers exist; some types utilize solvent desorption and some types utilize thermal desorption.

One main limiting factor for passive samplers is the uptake rates for various compounds of interest. Current technology such as the Radiello sampler allows for high diffusivity/effective flow rates, while also allowing for a sensitive GC/MS thermal desorption analysis.

Costs for passive sorbent samplers vary widely, depending on the analytical technique used (either solvent or thermal desorption).

Table 2 presents a summary of the pros and cons associated with passive sorbent sampling and active sorbent sampling (using a personal sampling pump).

Table 2. Solid Sorbent Sampling: Active Sampling vs. Passive Sampling


Active Sampling

Passive Sampling


  • Can sample large volume of air in a relatively short time period
  • Potentially lower reporting limits with shorter sampling duration
  • No pump needed, unobtrusive, simple to deploy


  • Potential logistical issues with pumps (battery failure, pressure drop, etc.)
  • Limited by uptake rates/effective flow rate of passive media


EPA Method TO-15 (and IP-1A) utilizes evacuated stainless steel canisters to collect whole air samples for VOC analysis. Canisters will be fully evacuated by the analytical laboratory so that when the canister valve is opened, air enters the canister without the use of a pump. A flow controller may be put inline to restrict the flow entering the canister so that the canister fills over a longer time period (i.e. four hours for LEED sampling). Since only an aliquot of the total volume collected is analyzed, re-analysis and/or dilutions are possible from the same sample canister. Similar to the thermal desorption techniques, the analysis is via GC/MS, allowing for qualitative and/or quantitative identification of target compounds. Costs for this type of analysis are in the range of $125-$250/sample.

Figure 1 summarizes the types of compounds that will be detected by whole air sampling (i.e. canisters) and solid sorbent sampling, and which compounds may be detected via either technique.

Figure 1. Compounds Detected via Whole Air Sampling (Canisters) vs. Solid Sorbent Sampling

LEED figure 1


Many analytical choices exist for measurement of TVOC for LEED projects. Practitioners must make an educated choice, consulting with their laboratory personnel where applicable, to decide which TVOC method may be most appropriate for their project. When deciding which sampling/analytical method to use, consideration must be given to the sample analysis/equipment rental costs, time frame/turnaround time needed, the building owner’s interest in having detailed chemical indoor air quality information, as well as which building materials (e.g. paints, carpet glues, finishes, cabinetry, etc.) are used. Also, if qualitative information is desired about which specific compounds comprise the TVOC value (e.g. for troubleshooting purposes if a building continues to fail to meet the 500 µg/m3 criteria), a GC/MS technique (thermal desorption or canisters) must be used. Until TVOC is defined more specifically, and/or until specific analytical methods are given in the LEED documentation, practitioners will have a wide range of options available to meet this credit requirement.

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24 Responses to “Total Volatile Organic Compound (TVOC) Measurement for LEED/Green Building Evaluation”

  1. Jon Says:

    How accurate are the handheld sensors? I know of an instance where cologne was setting off the detector on a LEED project when they were measuring for VOCs levels. Are false positives a common occurrence?


  2. Alyson Fortune, Columbia Analytical Says:

    Jon, you would have to refer to the various manufacturers specifications for accuracy information for handheld equipment. But your other comment about cologne being detected in a VOC scan for LEED work is a good point. Proper VOC sampling protocol would include not wearing cologne, not using or storing solvents/gasoline/etc. near sampling locations. Typically the methods used for LEED TVOC evaluation are sensitive enough to pick up cologne/personal care products/etc. and thus you could obtain unrepresentative results that are biased high from these additional sources. If you choose to perform a GC/MS analysis to evaluate TVOC, you would have qualitative information about which VOCs comprise the TVOC value and you could identify when this phenomenon occurs.

  3. Dave Dahlstrom, CIH Says:

    I realize that your interest is in selling lab services and I know fromw experience that Columbia is a very relialable laboratory and does great work; but, I have to say that the TVOC level of 500 ug/m3 is totally without scientific basis and virtually meaningless when it comes to health impacts. It is unfortunate that special interest filled organizations can pervert “best science” in a way that alludes to false health dangers in the basically uninformed. It is also a shame that a quality firm like Columbia would not provide a responsible scienfic perspective to an obviously irresponsibly established “limit”.

  4. Alyson Fortune, Columbia Analytical Says:

    Hello Dave,

    Thanks for bringing up some good points related to this article. Our laboratory agrees that the “limit” of 500 ug/m3 appears to be founded on outdated information, and we agree that the entire Credit 3.2 should be revised appropriately. Hopefully that is something that the AIHA’s Green Building Working Group will successfully address with USGBC. In the meantime, this limit exists; therefore, the purpose of our article was to simply advise practitioners of the various methods that are available. Our lab has also begun compiling data comparing TVOC values obtained from different sampling/analytical techniques (preliminary results were presented at AIHce 2009 in Toronto)—as you can imagine, each method yields slightly different results and detects different combinations of compounds. Again, it is our intention to spark a discussion among the LEED community as to which chemical tests are necessary and/or relevant for indoor air in LEED buildings.

  5. dareen Says:

    hi , i want to know if possible the mass spectrum for gasoline, names of major peaks & the substitutionary peaks in GC-MS.thx in advance

  6. Alyson Fortune, Columbia Analytical Says:

    Hello Dareen,
    As you most likely know, gasoline is not one compound, but a very complex mixture of hydrocarbon compounds; the mixture varies based on crude oil source, geographic region, formulation/grade, etc. Thus, there is not one mass spectrum for gasoline–each compound within the gasoline mixture will have a mass spectrum associated with it. In addition, gasoline “weathers” when exposed to the environment, further changing its composition as certain components in the mixture biodegrade over time. That being said, some of the major peaks we see in indoor/ambient air samples impacted by gasoline are: isooctane, cyclohexane, n-hexane, toluene, m&p-xylene, o-xylene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and benzene. Depending on the age of the gasoline and what oxygenate was used (e.g. MTBE, ethanol), you may see those compounds as well. Hope this helps!

  7. James Says:

    You mentioned that there is no clear definition set for “TVOC”. What is the range used to quantitate the amount of TVOC’s present in a particular sample? How does this range differ when using sorbent tubes vs. canisters? Cheers.

  8. Maryam Azad, Columbia Analytical Says:

    According to the LEED-NC guidance document the TVOC range is not specified. The TVOC range can vary depending on the sampling and the analytical method used. Sorbent tubes are more desirable for heavier compounds with higher boiling points (~80°C -380°C, volatile to semi volatile) where as canisters are preferred for lighter compounds with lower boiling points (~-40°C to ~170°C, very volatile to volatile).

  9. Kamal David Says:

    I’m very interested in the IAQ related TO15 analysis. How many compounds does this analysis cover? Can the results be compared to a particular PEL? If not is there a Cal OSHA or Cal EPA compound listing that shows the regulation by compound (just like the PEL registry)?

  10. Alyson Fortune, Columbia Analytical Says:

    EPA Method TO-15 is a performance based method, meaning that it may be used for any volatile organic compound, provided its method performance (i.e. calibration, sensitivity, etc.) meets the required quality control specifications. Thus, there is no compound list required by the method, and the compound list may vary from laboratory to laboratory. You may view our standard list of 75 compounds on our website here: Additional compounds are available upon request.

    Results from EPA TO-15 indoor air samples may be compared to a variety of guidelines, depending on the sampling situation, data quality objectives, and most importantly the local, state, or Federal agency overseeing the work. Since you mention Cal OSHA and Cal EPA, one example specific to California are the California Human Health Screening Levels (CHHSLs) published by Cal EPA in January 2005.

  11. N. Chong Says:

    It is stated in the TVOC article for LEED testing that both the thermal desorption and canister methods cost about $125-$250 per sample. Can you give a more detailed pricing for each method (i.e. EPA TO-17, IP-1B, TO-15, IP-1A, and NIOSH 2549) and the comparison among these methods in terms of compounds analyzed, accuracy, and detection limits? What information is given in the analytical report? Does it have just a TVOC value or a breakdown of compounds identified and their respective concentrations?

  12. Alyson Fortune, Columbia Analytical Says:

    All the thermal desorption and canister methods you mention utilize gas chromatography/mass spectrometry (GC/MS) as the analytical technique; therefore, both a TVOC value and a breakdown of compounds identified may be reported. With regards to the breakdown of compounds, if the laboratory has calibrated for the compound of interest, they may report a concentration. Otherwise, the compound is a Tentatively Identified Compound (TIC) and an estimated concentration can be given (assuming a response factor of one).

    As for reporting limits (“detection limits”), for the sorbent tube methods (EPA TO-17, IP-1B, and NIOSH 2549), a reporting limit is given in total mass/tube. Concentration unit reporting limits will depend on the volume of air that is pulled through the tube. For canister reporting limits, these will take into consideration the volume of air analyzed from the canister and whether or not the laboratory pressurizes samples upon receipt. However, overall, the reporting limits in canisters tend to be more “fixed” than reporting limits using sorbent tubes since they are independent of the total volume collected.

    All the items you ask about are perfect examples of the data quality objectives that must be discussed with your analytical laboratory PRIOR to sampling.

  13. Zoia Shedaia Says:

    Dear all,
    could you please be so kind to tell me haw many ppm will be 500 µg/m3 of TVOCs ?
    Best Regards

  14. Alyson Fortune, Columbia Analytical Says:


    The conversion from ug/m3 to ppbV (or ppmV) involves the molecular weight of the chemical species. Therefore, for a generic term such as Total Volatile Organic Compounds (TVOC), you cannot accurately convert the units. You could make some assumption as to an average molecular weight, or use the molecular weight of a common midrange VOC such as toluene, but again, this would just be an estimation. You can go to our Air Testing FAQ page for more information on the conversion:

  15. Rob Thomas Says:

    I wonder if you could help? We’ve got (in the UK) a remediation project underway at an abandoned pesticide factory. This site is close to a number of villages, and the odours are very noticeable. I’ve been looking into how the company are measuring the VOCs in the immediate area around the site and found that they are using passive tenax air diffusion sampler tubes. These have been strapped to a number of lamposts in the street, where they are left for 28 days. The tubes themselves look very similar to the thermal desorption tubes shown on your website. My question is – these tubes are not connected to any pumps or similar, so how can you estimate the volume of air sampled in the tube?
    Hope you can help

  16. Alyson Fortune, Columbia Analytical Says:

    Hi Rob,

    For passive diffusion samplers, sampling rates are often determined experimentally for various compounds of interest. So, knowing the sampling duration and using the sampling rate you can assume a certain volume of air sampled. Many sampling rates have been established and published by the manufacturer for sampling media such as the radiello (distributed by Sigma Aldrich), SKC Ultra, etc. Also, the MDHS 80 method has many sampling rates published for Perkin Elmer tubes (including Tenax).

  17. Eric Rosenblum Says:

    Is there an original source for the 500 ug/m3 threshold limit for TVOCs? Is it based on a health endpoint or an analytical method?



  18. Alyson Fortune, Columbia Analytical Says:

    Hi Eric,

    Great question! To the best of our knowledge, there is no health basis for the 500 ug/m3 TVOC limit–it is likely more based on typical concentrations seen in the indoor environment. The 500 ug/m3 value can be traced back to a State of Washingron Depamnent of General Administration Indoor Air Quality specification from a 1989 document. Obviously, the largest flaw in the 500 ug/m3 limit is that it does not give any limits of any individual VOCs, so a building with 450 ug/m3 of benzene (comprising the TVOC) would technically pass the criteria.

  19. Louie Cheng Says:

    I’m just getting into LEED testing now and the EPA Compendium specified by GBC only describes two methods for VOC testing: TO-1A and TO-1B. Yet, I see a lot of discussion about additional methods, such as TO-15 and TO-17 and there are even some companies that test using handheld PID.

    1. Who makes the final decisions regarding the acceptability of test results? Is that up the the LEED reviewer who looks at the overall certification documentation submitted by the project manager?

    2. Are other methods acceptable besides TO-1A and 1B, and if so, what is the justification or reference that allows it?

    3. I am considering purchasing a handheld PID that, like your article describes, has a resolution down to the PPB level. The EPA compendium describes PID for use as a screening tool — does this suggest that it might be acceptable?


  20. Alyson Fortune, Columbia Analytical Says:

    Hi Louie,

    You are correct, the GBC has information about the lesser used EPA Compendium of Methods for the Determination of Air Pollutants in Indoor Air (a.k.a. the “IP” compendium), of which IP Methods IA (canisters) and IB (sorbent tubes) are relevant to LEED VOC testing. A much more widely used compendium is the EPA Compendium of Methods for the Determination of Toxic Organic Compounds in
    Ambient Air (a.k.a. the “TO” compendium), of which TO-15 (canisters) and TO-17 (sorbent tubes) are relevant. Most likely because the IP versions are nearly identical to the TO versions, and the TO methods are much more widely offered by commercial laboratories, many LEED practitioners have used the TO series.

    As for your question of who exactly makes a final decision on the acceptability of test results, that is a great question to which I am unsure of the answer. I suspect it is up to the LEED reviewer, and that in most cases, that person is less familiar with the technical differences between different analytical methods/techniques–thus that is why you see many projects accepted with using alternate methods such as OSHA07, handheld PIDs, etc.

    In our laboratory’s opinion, the analytical technique that will capture the VOCs which are most relevant to LEED projects (e.g. emissions from carpets, adhesives, building materials, etc.) involves solid sorbent tubes which are analyzed via thermal desorption GC/MS. A few years ago, we conducted some side by side testing using multiple techniques (canisters, thermal desorption tubes of various types) in a facility pursuing LEED accreditation. Active TO-17 samples ended up capturing VOCs that were missed in other sampling approaches, such as texanol (from latex paints) and various glycol ethers. On a side note, another advantage of using TO-17 for the TVOC evaluation is that 4-PCH may be determined from the same sample.

    The bottom line is, we still see LEED practitioners performing a variety of techniques to meet the TVOC measurement criteria in EQ 3.2. Our laboratory can perform the various analytical methods and advise you on the pros and cons of each. Best of luck!

  21. BJ Duerson Says:

    Bold to state the 500 ug/m3 limit. I have looked for other guidelines but have only found this number. Yet in many of instances, enough employees have raised a concern thus involking the guideline provided by ANSI/ASHRAE 62.1-2007. Why has there not been a number set? Or at least a number for carcinogenic compounds (ex: formaldahyde)? Thanks for you help!

  22. Alyson Fortune, ALS Environmental Says:

    Hi BJ,

    Thanks for your comment–we were not trying to be “bold”, so-to-speak…but just trying to state the guidelines that are being followed currently, and the 500 ug/m3 guidance is in the LEED program. As far as other screening values for other constituents, I have also frequently seen maximum allowable concentrations used that are derived from the Chronic Reference Exposure Limits as published by the California EPA, Office of Environmental Health Hazard Assessment. This approach is taken in the more recent ASHRAE 189.1 document which specifically addresses indoor air quality in green buildings. It combines the “TVOC” approach with also monitoring for individual VOCs expected to be related to building materials.

  23. Brandon Says:

    How accurate toluene equivalent concentrations compared to actual concentrations? My understanding that toluene equivalents are calculated based on peak areas in which case I’d expect huge variations…

  24. admin Says:

    Hi Brandon,

    For the TVOC analysis, we use a mass spectrometer (MS) as a detector, so the response is pretty close to equivalent for most compounds, i.e., the area for 10ng of benzene and 10ng of dodecane are about the same.

    This is not true for an flame ionization detector (FID), since the response is proportional to the number of carbons and is affected by functional groups. Therefore, using the toluene response to quantify all the peaks is not that far off using MS.

    For an FID analysis, it would depend on the types of compounds in the sample. If the majority of your sample compounds were oxygenated or halogenated, the result would be biased low compared to toluene.

    Thank you,

    Nicole Pannone
    ALS Environmental Simi Valley Laboratory

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