Patients Know Best (PKB) has been Net Zero since 2021, utilising a combination of carbon reduction initiatives alongside the procurement of genuine carbon removal credits to remove the carbon footprint we directly contribute to the environment.

Whilst we’ve been calculating our carbon footprint since 2021, we have established the 2023 calendar year as the new baseline year for our Carbon Reduction Plan. This decision was made because we shifted our approach to improve our modelling by incorporating more granular data analysis, improving data quality and availability, and using the best available evidence to ensure estimates of our emissions remain robust. This shift includes the introduction of Greenly as our new Carbon Accounting Partner, who have supported us to track our carbon footprint using activity-based metrics instead of financial-based costing. This has improved the accuracy of our carbon footprint and sets the new benchmark for carbon accounting for years to come.

We list our previous carbon footprints for transparency, but similarly to NHS England, we have encountered an increase in our footprint based upon more accurate tracking of our carbon footprint through activity and financial spend rather than solely due to an increase in activity. In 2021, we produced 105t CO2e, rising to 163t CO2e in 2022.

As a remote company that doesn't have physical offices, provide company cars or directly purchase electricity, our scope 1 and scope 2 emissions are 0t CO2e. Within Scope 3, we have business travel and commuting emissions, in which we include teleworking. Our other Scope 3 categories include purchased goods and services, capital goods, fuel and energy related activities not included in Scope 1 or Scope 2, upstream transportation and distribution. Our largest areas of emissions are ‘Digital’, which includes cloud and software licences, and ‘Services purchases’, which includes insurances and intellectual services.

By accurately accounting for our carbon emissions, we are able to establish comprehensive emission reduction targets. Our current operational policies already align with and address many of the reduction actions recommended by Greenly for our industry. This foundation demonstrates our strong commitment to sustainable practices.

Our emission reduction targets are:

• 50% reduction in emission intensity per revenue by 2030
• 90% reduction in emission intensity per revenue by 2045

Both targets relate to all material scope 3 emissions.

1. Sustainable Meeting Venues (Addressing Carbon from Commute)

Commitment to Low-Carbon Meetings: As a fully remote organisation, we mandate that all team meetups utilise venues with direct, easy access to public transportation. This policy minimises reliance on private vehicles, directly reducing the associated carbon impact of employee travel.

2. Extending Equipment Lifespan (Addressing Embodied Carbon)

Extended Hardware Lifecycle Management: We are committed to maximising the lifespan of all IT assets to reduce embodied carbon emissions associated with manufacturing new devices. Our policy dictates that, wherever economically viable, hardware (laptops, equipment) must be retained, maintained, and repaired for a minimum of five years. Furthermore, all functional surplus equipment is centrally managed by the People team for internal reuse or spare parts, ensuring zero viable hardware goes to disposal.

3. Prioritising Rail Over Air (Addressing Business Travel Emissions)

Rail-First Travel Mandate: To achieve significant reductions in our business travel footprint, we enforce a policy to prioritise rail travel over flying or driving for all trips where a viable train journey of six hours or less is available. This promotes rail—a low-carbon, productive travel mode—as the standard for domestic and short-haul international missions.

4. Future Reduction Strategy

We will continue our assessment and evaluation of our suppliers against their net zero ambitions and transparency in terms of their measurement, reporting and plans to reduce their own emissions. CO2 emissions are a core factor of our purchasing decisions, particularly concerning cloud hosting providers and their associated locations, given the high environmental impact of this sector. For example, cloud hosting accounted for a significant percentage of our 2024 footprint at 23.15%, rising from 21.65% of our 2023 footprint. We utilise Google Cloud Platform as our hosting provider, a company which continues to promote sustainability and is the most transparent in terms of their own footprint, with a net-zero ambition for 2030.

Whilst we strive to reduce our carbon footprint as much as possible, there remain essential sources of emissions that we cannot fully eradicate. Therefore, our focus is on full carbon removal rather than simple offsetting. Carbon removals are considered the gold standard because they permanently extract existing CO2 from the atmosphere, directly addressing historical emissions. This mechanism is critical for achieving Net Zero targets and genuinely reversing climate change. In sharp contrast, most carbon offsetting projects primarily focus on avoiding future emissions. While this slows the rate of climate change, it does not decrease the total amount of CO2 currently in the atmosphere.

To date, we have chosen to invest in schemes which directly tackle the carbon we're responsible for. This included carbon sequestration/removal through biochar and investments in bio-oil in 2021, enhanced weathering in 2021/22 with aforestation to bridge the gap until carbon removal for enhanced weathering and bio-oil.

We’re pleased to now be partnering with Cur8 on our carbon removal projects, a UK-based high-integrity platform backed by Google Ventures that aggregates scientifically vetted carbon removals rather than low-quality offsets. By rejecting roughly 95% of projects and bundling durable solutions into diversified portfolios, they ensure permanent sequestration.

We partnered with Cur8 to invest in Varaha High Tech Biochar Telangana (Puro) and Avonmouth Facility to remove the entirety of our 2024 footprint.

Located in Telangana, India, the Varaha project converts corn husk waste into high-quality biochar using centralised gasification. This process offers superior control and efficiency compared to traditional kilns, while also capturing syngas for energy. The resulting biochar is certified by Puro for over 100 years of durability, with an expected stability of over 1,000 years. By mixing the biochar with manure and distributing it to local smallholders, the project combines scalable carbon removal with significant social impact—improving soil fertility and water retention for the farming community.

OCO’s Avonmouth facility utilises a low-energy process to permanently capture biogenic CO2 within construction-grade aggregates. Sourced from farm biogas production, the CO2 is injected into a mixture of water and reactive fly ash residues to produce stable carbonate minerals, effectively manufacturing limestone. This mineralised product is then blended with cement and other residues to create building aggregates that serve as a cement substitute. The resulting material stores carbon in an extremely durable form, remaining stable for thousands of years—well beyond the lifespan of the infrastructure it helps build.

Our carbon removal portfolio is strategically diversified by technology, with 89.95% invested in biochar credits and the remaining 10.05% allocated to biogenic CO2 capture.

The graphs below illustrate the details of the credits we have purchased. The portfolio is also diversified by durability and location: 90% of our credits guarantee a carbon storage lifespan of 100 years, with the remaining 10% offering long-term durability of 1,000 years. Crucially, the associated carbon is removed from the biosphere immediately upon purchase. Geographically, 90% of these credits are allocated to projects in Asia, and 10% are allocated to projects in Europe.

The largest portion of our historical removals comes from biochar, a method that locks carbon into a stable soil amendment while solving critical local waste challenges. This includes investment in Exomad Green for 284t CO2e. This project in Riberalta, Bolivia, intercepts forestry residues that would otherwise be burned, preventing immediate emissions and reducing wildfire risks. The resulting biochar is distributed to indigenous communities to improve soil fertility, directly supporting local agriculture.

Further investment in Wakefield Biochar removed 147t CO2e and Douglas County removed 94t CO2e. In the USA, these projects focus on repurposing waste biomass. Wakefield utilises FSC-certified waste pine bark to create soil conditioners that reduce the need for chemical fertilisers. Meanwhile, the Douglas County project in Colorado is the first county-owned facility of its kind, specifically designed to process slash from wildfire mitigation efforts turning a dangerous fuel load into a climate-positive resource.

We’ve also explored alternative methods of carbon removal, including Enhanced Weathering, when we purchased 24t CO2e from UNDO, a project based in Scotland that permanently locks away carbon by accelerating natural geological processes. UNDO spreads crushed basalt rock, a byproduct of local quarrying, onto agricultural land. As rainwater interacts with the rock dust, it captures CO2 to form stable bicarbonate minerals. Beyond carbon removal, this process releases essential nutrients like magnesium and potassium into the soil, offering tangible agronomic benefits to local farmers without land-use change. This carbon removal is expected to be delivered in the summer of 2026 (with the full delivery of removals expected by 2040).

Another method we explored was Bio-oil, when we secured 3t CO2e from Charm Industrial. This engineered removal method uses fast pyrolysis to convert waste biomass into a carbon-rich bio-oil. Instead of being used as fuel, this oil is injected deep underground into geologically secure salt caverns or depleted oil wells, permanently sequestering the carbon for millennia. This approach bypasses the biological carbon cycle entirely, ensuring the CO2 cannot re-enter the atmosphere through decomposition or burning. This carbon removal is expected to be delivered in the summer of 2026.

Finally, in previous years we adopted a bridging strategy using Afforestation to cover the time gap between the purchase and delivery of the high-tech removals listed above, we purchased 27t CO2e from the TIST program in Uganda. While tree planting is a shorter-term storage solution compared to rock weathering or bio-oil, TIST acts as an essential bridge, ensuring immediate climate action while the more durable technologies scale up. This community-led initiative empowers smallholder farmers to plant trees on degraded land, providing them with direct payments and sustainable resources like fruit and fuel, ensuring the project delivers high social value alongside its carbon benefit.