If your GP, a customer, or a deal team has asked about your Scope 3 emissions, you may have looked up the GHG Protocol and immediately felt overwhelmed. Fifteen categories. Upstream and downstream. Spend-based estimates. Primary data. It looks complicated.
It is less complicated than it appears, especially for office-based private companies. Most of the fifteen categories do not apply to your business, and the ones that do follow a relatively straightforward process. The harder part is getting the right internal data together, not the methodology itself.
If you have completed a Scope 1 and 2 inventory and someone is now asking about Scope 3, you almost certainly do not need to calculate all fifteen categories. For most office-based private companies in professional services or pharma, three to five account for the vast majority of the footprint. The rest are immaterial, not applicable, or something to address in a later reporting cycle. Not sure whether you need a carbon footprint or a full ESG strategy first? This post covers how to decide.
Here is how to think about it.
What the fifteen categories cover
The GHG Protocol splits Scope 3 into upstream and downstream.
Upstream is what comes into your business: purchased goods and services, capital goods, fuel and energy, transportation of inputs, waste, business travel, employee commuting, leased assets.
Downstream is what goes out: transportation of outputs, processing and use of sold products, end-of-life treatment, downstream leased assets, franchises, investments.
For a professional services company or pharma services firm, the downstream categories are almost entirely irrelevant. You are not selling physical products that get transported, processed, or disposed of. The downstream footprint is effectively zero.
Public company sustainability reports cover all fifteen categories because large manufacturers and consumer goods companies have significant downstream footprints.
Which categories actually matter
For most office-based private companies, five categories do most of the work.
Category 1: Purchased goods and services. Almost always the largest. Everything you buy to run the business: software, professional services, IT equipment, office supplies, marketing. Usually calculated using a spend-based method: your vendor spend multiplied by an industry emission intensity factor. The accuracy depends on how cleanly your spend data is categorized.
For a pharma services company, Category 1 typically includes CRO vendors, lab supply spend, and IT infrastructure. For a professional services firm, it is software subscriptions, subcontractor fees, and office supplies. In both cases, a well-categorized accounts payable export is the starting point.
Category 2: Capital goods. Emissions from producing the assets you buy: computers, servers, furniture, equipment. Smaller for most office-based companies, but worth including if capital expenditure is significant.
Category 3: Fuel and energy-related activities. Upstream emissions from producing the fuel and energy you already account for in Scopes 1 and 2. Smaller category, calculated using standard factors. For more on how Scope 1 and 2 work, see Scope 1 and 2 Reduction Strategies for Office-Based Private Companies.
Category 6: Business travel. Flights, trains, hotels, rental cars. Often one of the larger categories for professional services and pharma companies, and one of the harder ones to calculate. Requires expense data broken down by mode of transport and distance, not just total spend. A consulting firm with client-facing teams traveling weekly will find this category significant. A pharma company with regular site visits and clinical trial monitoring will too.
Category 7: Employee commuting and homeworking. Travel to and from work, plus home office energy use. Requires headcount by location and commuting patterns. Survey data fills the gaps.
Reviewing each category for materiality
Every category needs to be reviewed. The GHG Protocol requires you to assess all fifteen and document the rationale for any you exclude. Skipping a category without explanation is not acceptable.
Before starting your own materiality review, search for sustainability reports from two or three public companies in your sector and look at how they handle Scope 3. Most reports include a table showing each category, whether it was included or excluded, and a brief written explanation. If companies similar to yours consistently include Categories 1, 6, and 7 and exclude the downstream categories with documented rationale, that tells you something about what is considered material in your sector. For a pharma services company, look at how companies like IQVIA, Covance, or Syneos handle their Scope 3 disclosure. For a professional services firm, look at how mid-size consulting or advisory firms explain their category decisions. You are not copying their approach. You are using their methodology decisions as a sanity check on your own.
For most private professional services companies, the downstream categories will come out of the review as not relevant. A management consulting firm does not sell physical products that get transported, processed, or disposed of. A pharma services company providing CRO or regulatory consulting is in the same position. The rationale is legitimate and widely accepted, but it needs to be written down.
For categories you do include, spend-based estimates are acceptable under the GHG Protocol where primary supplier data is not available. A reasonable estimate with a documented methodology is the standard for a first inventory.
Why data quality is the real challenge
If you are working with an outside firm, they are applying the methodology. What they need from you is the data. That is where most inventories slow down or fall apart.
For Category 1, they need spend data categorized by vendor type. If your accounts payable system lumps everything into miscellaneous or uses internal codes that do not map to industry categories, the calculation requires manual cleanup and produces a less accurate result. For more on finance's role in providing the right data, see What CFOs and Controllers Need to Understand About ESG.
For Category 6, they need travel data broken down by mode of transport and distance. A report that combines all travel into a single line is not useful for an emissions calculation.
For Category 7, they need headcount by location and commuting patterns. Survey data works when direct data is not available.
The bottleneck is never the math. It is getting the right data out of your systems in the right format. Finance, HR, and operations all play a role. Getting them involved early makes the whole process faster and the output more accurate.
What a first Scope 3 inventory produces
At the end of the process, you have a number for each material category in metric tons of CO2 equivalent, methodology documentation, data sources, emission factors used, and written rationale for any exclusions.
That is what a GP, customer, or investor actually needs. For more on what GPs specifically ask for, see What PE Firms Look for in ESG Due Diligence. It is also the baseline for every subsequent year. Once the first inventory exists, future years are about updating the data, not rebuilding from scratch.
The first one is the hardest. Do it right and everything after is easier.
If you are working through a first Scope 3 inventory or trying to figure out what is actually required, get in touch or learn more about carbon footprint consulting and fractional ESG support.
Check out other blogs on private company ESG
If your GP, a customer, or a deal team has asked about your Scope 3 emissions, you may have looked up the GHG Protocol and immediately felt overwhelmed. Fifteen categories. Upstream and downstream. Spend-based estimates. Primary data. It looks complicated. It is less complicated than it appears, especially for office-based private companies.