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Step 3: From Estimates to Measurement

The imperative of understanding your Greenhouse Gas emissions and how that defines what’s possible.

June 8, 2022

By: Melissa Dakas, Terence Trefiak, Shawn Nelezen, & Patrick Clark


In previous steps, we recently discussed greenhouse gas (GHG) reporting frameworks, what they mean for your organization, and how they can help you meet your goals and standardize your reporting – while demonstrating your commitment to ESG for your community and shareholders. In this step, we’re going to talk about how important it is to fully understand your GHG emissions and some of the technologies that can help you accurately measure them.

Types of Emissions

Scope 1, 2 and 3 Emissions

A company’s GHG emissions can be divided into three scopes. Scopes 1 and 2 are most commonly calculated and reported, and they represent direct emissions from a company’s operations along with the indirect emissions from energy resources like electricity used in their operations. Scope 3 emissions are indirect emissions that occur in the value/supply chains of the reporting company. Fewer companies calculate Scope 3 emissions, which can be difficult to obtain and monitor.

Testing Methods and Technologies

Estimating GHG emissions has been primarily achieved using emission factors, which are representative values for the amount of a pollutant released to the atmosphere from a specific type of activity. Recent studies have shown that many published emission factors do not accurately represent actual quantities of GHG emissions. These emission factors can be averaged values while the real values can range widely or conservatively to ensure the actual emissions will almost always be lower. When a GHG inventory is based only on emission factors, it is difficult to demonstrate a reduction in emissions from improvements to equipment performance and operating practices. Often, a reduction in reported emissions is from minimizing the activity, completely eliminating the source, or from the divestment of assets.

To determine accurate, transparent GHG emissions, direct monitoring and measurement programs need to be deployed. As these more robust and accurate sampling and testing methods are developed, the sensitivity and overall accuracy of sampling and reporting have been steadily increasing. Where continuous, direct measurement isn’t possible, companies are implementing measurement programs to periodically measure a statistically significant/representative population of the emission sources and develop site and source specific factors that more closely align with reality. This allows for more accurate reporting and better information for making decisions around reductions. Here at Montrose, we have been at the forefront of these emerging technologies, which provide a perfect companion to older, more traditional methods.  Some of these technologies are listed below.

Fourier Transform Infrared Spectroscopy (FTIR)

FTIR is an analytical technique that has been applied to source monitoring. Extractive FTIR monitoring removes gas from the stack or duct, filters out particulate matter, and transports the gas through a sample line to a remote location for continuous, real-time analysis by an FTIR spectrometer.

This multi-component, real time measurement is a trusted technique for gaseous hazardous air pollutants (HAPs), volatile organic compound (VOC) emissions, and non-organic volatile compounds from stationary sources. FTIR can potentially identify and quantify any gas that absorbs infrared light, and the system can measure hundreds of HAPs.

Leak Detection & Repair (LDAR)

LDAR inspections of process components can be done using the traditional EPA Method 21 or newer technologies like Optical Gas Imaging (OGI), which offer more coverage with greater efficiency. There are a growing number of innovative approaches to fugitive emission management enabled by advanced equipment and technology, such as vehicle and drone-based detection/triangulation and real-time sensor arrays that offer immediate leak response.  Traditionally, leak rates are calculated using ppm readings and correlation emission factors that can significantly underestimate large leaks. There are technologies that can provide an actual direct measurement of the flow rate of each leak (e.g., hi-flow sampler, thermal mass and vane anemometer flow meters, and volumetric bagging).

Data QA/QC

All the sampling conducted is only as good as the data it collects. Our AirSense platform interfaces with multiple air, water, and soil data sources to provide an integrated environmental solution with advanced data analytics capabilities. Coupled with experienced and highly trained operators, such a capability greatly reduces data errors and provides more usable, actionable data.

What’s next?

We’ve touched on the types of emissions you need to be aware of and account for, as well as the various emerging technologies that can help you more accurately measure and react in a timely fashion. In our next step, we’ll talk about the power and importance of data, and how it can help you improve your decision-making capability. If you have any questions or comments about this step or anything else, just contact us below. We look forward to the continued conversation on this important topic, and we stand ready to assist you and your organization with getting on the path toward achieving your GHG reduction goals.

The 5 Steps to Making Your Company’s GHG Reduction Goals a Reality

Montrose CxO Blog_Step 3_Green


From Estimates to Measurement: The imperative of understanding your greenhouse gas emissions and how that defines what’s possible.


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