Reference Guide
Plain-English definitions of PPN 002, TOMs, SROI, proxy values, natural capital and 40+ social value terms used in UK public sector procurement. Bookmark it — you'll be back.
The principle that social value commitments in a bid must deliver outcomes that would not have happened without the contract. Evaluators look for additionality to distinguish genuine impact from business-as-usual activity. If you were going to do it anyway, it doesn't count as social value.
The period of active maintenance following tree planting — typically 1–3 years for young trees. Aftercare includes watering, staking, formative pruning and protection from damage. Without it, newly planted urban trees have high mortality rates. Carbon Heroes' Young Tree Aftercare intervention covers this critical establishment phase, delivering approximately £560 of social value per tree per year.
A legal requirement under the Environment Act 2021 for most developments in England to deliver at least 10% more biodiversity than existed on the site before development. Measured using the Defra Biodiversity Metric. Distinct from social value scoring in tenders but increasingly referenced alongside it.
Carbon Heroes' AI-powered tool that generates bid-stage social value strategy, quantification, methodology notes, and submission-ready content in minutes. Designed for bid managers working under deadline pressure on UK public sector tenders.
A former UK government advisory body whose research and benchmarks — particularly on greenspace amenity valuation — remain widely used in natural capital assessments. Carbon Heroes uses the CABE-derived benchmark of £30 per m² for greenspace amenity value.
A document required under PPN 06/21 for suppliers bidding on UK central government contracts above £5 million. Sets out the supplier's current emissions, net zero target, and reduction pathway. Distinct from social value scoring but often assessed in the same tender.
The process by which trees and other vegetation absorb CO₂ from the atmosphere and convert it into biomass. Valued by Carbon Heroes at £245 per tonne of CO₂e sequestered, based on HM Treasury Green Book carbon values.
The stock of carbon held in a tree's biomass and associated soil at any point in time — distinct from sequestration, which measures the annual flow. Valued at £299.60 per tonne of CO₂e stored. Separating sequestration (flow) and storage (stock) avoids double-counting and reflects two genuinely different climate services.
A broad term for positive outcomes delivered to local communities through a contract — jobs, training, volunteering opportunities, improved amenities, greenspace. Often used interchangeably with social value in informal contexts, though social value has a more specific regulatory meaning in UK procurement.
The UK government department responsible for environmental policy, including air quality guidance and natural capital valuation frameworks. Defra's air quality damage costs underpin the £2.30 per gram proxy used by Carbon Heroes for air pollution removal by urban trees.
The ability to demonstrate that social value commitments made at bid stage will actually be delivered post-award. Evaluators increasingly score delivery assurance separately from the commitments themselves. Carbon Heroes provides delivery assurance through council-approved partners, with every tree geolocated in a proprietary registry.
The subset of social value outcomes relating to environmental improvement — carbon reduction, biodiversity, air quality, flood resilience, greenspace creation. Maps primarily to PPN 002 Mission 4 (Fighting Climate Change) and TOMs Theme 5 (Safeguarding the Environment).
The person or panel within a contracting authority responsible for scoring tender submissions. Understanding what evaluators look for — quantification, evidence, methodology, delivery plans — is the key to writing social value responses that score in the upper quartile.
An annual UK dataset that maps access to parks and greenspace at neighbourhood level, weighted by deprivation. Widely cited in social value assessments and health inequality research. Demonstrates that lower-income urban communities are systematically under-served for quality greenspace.
The UK government's guidance on how to appraise and evaluate policies, programmes and projects. The Green Book's supplementary guidance on carbon valuation (£245/tCO₂e for sequestration) and its adoption of WELLBY methodology are the primary evidence base for many social value proxy values used in procurement.
The monetised value of public access to greenspace — parks, planted areas, urban forests. Carbon Heroes applies £30 per m² based on CABE/Natural Capital benchmarks. This proxy captures amenity (the value people get from being near greenspace) separately from ecosystem services like carbon or flood resilience, which are valued through their own proxies.
A framework for evaluating the social impact of interventions using standardised proxy values. The IES volunteer value of £32.95 per hour is one of the proxies used in Carbon Heroes' methodology for quantifying the labour component of environmental volunteering.
The UK government's measure of relative deprivation at small-area level (LSOAs). Used in social value assessments to target interventions in the most deprived communities. Commitments that explicitly reference IMD deciles demonstrate geographic intentionality — which evaluators score highly.
The economic multiplier effect of spending within a local area. Carbon Heroes measures this using the LM3 (Local Multiplier 3) methodology at £1.40 per £1 of local spend — meaning each pound spent with local suppliers generates an additional 40p of economic value in the local economy.
A geographic unit used in English statistics, containing roughly 1,500 residents. LSOAs are the building blocks for IMD deprivation analysis and are the level at which social value targeting is most precise.
The evaluation standard introduced by the Procurement Act 2023, replacing MEAT. Under MAT, social value is part of the definition of what makes a tender advantageous — not an optional extra. This shift means social value scoring is embedded in evaluation by default.
One of Carbon Heroes' five intervention types. Annual care for established urban trees (year 4+), delivering approximately £560 of social value per tree per year. The highest return-on-investment of any nature-based intervention — minimal cost, highly scalable, and protects the council's existing tree asset base.
The evaluation standard used under previous procurement regulations. MEAT focused primarily on cost and quality; social value was layered on via PPN 06/20 and then PPN 002 but was not inherent to the standard. Now superseded by MAT under the Procurement Act 2023.
A section of a tender response that explains how the supplier will deliver what they are committing to. In social value terms, a strong method statement includes the methodology behind the numbers, the delivery partners, monitoring and reporting mechanisms, and a timeline.
The stock of natural resources — trees, soils, waterways, biodiversity — that provides services to people and the economy. Natural capital valuation puts monetary figures on those services (carbon storage, air filtration, flood management, amenity) so they can be compared with other forms of investment.
One of Carbon Heroes' five intervention types. Sponsorship of one new urban tree plus three years of aftercare, delivered through council-approved partners. Delivers approximately £3,000 of social value over three years. Every tree is GPS-tagged, sponsor-specific, and geolocated in the Carbon Heroes registry.
Reference codes for specific measures within the National TOMs framework. Examples: NT18 (local SME subcontracting), NT19 (local direct employees), NT82 (carbon reduction), NT86 (biodiversity and ecosystem services). NT codes are how evaluators map a supplier's commitments to the framework.
The current UK government policy requiring social value to be evaluated in all central government procurement above £138,760. Replaced PPN 06/20. Introduces the Social Value Model with 5 Missions and 33 Strategic Reference Measures (SRMs). The primary regulatory driver for social value in UK public sector tenders.
A UK procurement policy note requiring suppliers bidding on central government contracts above £5 million to provide a Carbon Reduction Plan. Complements PPN 002 but is focused specifically on carbon, not broader social value.
The UK legislation that reformed public procurement, effective from 2024. Key changes include the shift from MEAT to MAT, placing social value within the core evaluation standard rather than as an add-on policy.
A monetised figure assigned to a non-market outcome so it can be quantified in financial terms. For example, £245 per tonne of CO₂e sequestered is a proxy value for the climate benefit of carbon removal. Proxy values are drawn from established frameworks (Green Book, CABE, IES, Defra) and are the building blocks of social value quantification in bids.
A leading international consultancy specialising in social value research and health economics. Carbon Heroes has partnered with Simetrica-Jacobs to develop a rigorous proxy value for quantifying the health and fiscal benefits of air pollution removal by urban trees.
The positive impact that a contract or organisation delivers to the economy, society and environment beyond its core commercial purpose. In UK public procurement, social value is scored and weighted in tender evaluations under PPN 002 and the Procurement Act 2023.
The UK legislation that first required public sector commissioners to consider social value when awarding contracts. Initially applied only to services contracts and was more of a 'have regard to' duty than a scoring requirement. PPN 06/20 and PPN 002 built enforcement mechanisms on top of it.
The framework introduced alongside PPN 002, structuring social value around 5 Missions: (1) Generate Employment for Those Who Face Barriers, (2) Grow the Pipeline of Future Talent, (3) Increase Supply Chain Resilience, (4) Fight Climate Change, and (5) Reduce Inequality.
A ratio expressing the social value generated per £1 invested. For example, an SROI of 3.24x means £3.24 of social value for every £1 spent.
One of the 33 specific measures within the PPN 002 Social Value Model. SRMs sit under the 5 Missions and provide the granular scoring criteria evaluators use. Environmental interventions map primarily to SRMs under Mission 4.
The ability of urban trees and green infrastructure to catch, absorb and slow rainfall before it enters the drainage system. A mature tree can intercept 1–3 m³ of rainfall per year.
Drainage solutions designed to manage surface water runoff close to where it falls — including rain gardens, permeable pavements, swales, and trees. CIRIA guidance recognises urban trees as a SuDS component.
A dense, fast-growing micro-forest of approximately 200 m², planted using the Miyawaki method with native species. One of Carbon Heroes' five intervention types. Delivers approximately £103,000 of social value per site.
Annual care and maintenance of an existing Tiny Forest site. One of Carbon Heroes' five intervention types, delivering approximately £28,000 of social value per year per site, with ongoing community engagement and volunteering built in.
The National TOMs Framework, maintained by the Social Value Portal, is the most widely used social value measurement framework in UK procurement. Organised into 5 Themes: Jobs, Growth, Social, Environment, and Innovation.
The top 25% of scores in a competitive tender evaluation. Used by Carbon Heroes to describe the scoring ambition for social value responses built with BidBooster.
The phenomenon where urban areas experience significantly higher temperatures than surrounding rural areas. Urban tree canopies reduce the effect by 2–8°C through shading and evapotranspiration. Increasingly relevant as a life-safety issue following the UK's 2022 heatwave.
A measure adopted by HM Treasury's Green Book for valuing changes in subjective wellbeing. One WELLBY represents one person experiencing a one-point improvement in life satisfaction for one year. Carbon Heroes uses an IES-derived wellbeing proxy (£16 per volunteer hour) as part of its methodology.
One of Carbon Heroes' five intervention types. One year of active care for recently planted young trees (years 1–3), delivering approximately £560 of social value per tree per year. Protects the council's investment in new planting and prevents the 'plant and forget' risk that leads to high early mortality.
BidBooster generates your entire environmental social value section — strategy, quantified outcomes, methodology note, and audit-ready bid content — in minutes.