Spa carbon measurement becomes useful only when the number can be traced back to operating decisions. A new peer-reviewed paper presents SPA-DEC, a dynamic calculator that combines metered energy and water with normalised estimates for activities such as waste, procurement and staff travel. It allocates those emissions to a defined visit across Scopes 1, 2 and 3. A Spa Business report brought the research to the sector’s attention, and the original study was published on 22 July 2026.
The study is important, but its headline averages are not a league table. Its two 2024 cases produced approximately 5 kilograms of carbon dioxide equivalent for a standard four-hour visit at a large facility and 3.5 kilograms for a standard 1.5-hour visit at a small facility. The services, duration, boundaries, energy systems and data completeness differ. The authors explicitly caution that the results are not normalised for service breadth and should not be interpreted as a direct ranking of sustainability.
For spa owners and directors, the opportunity is therefore larger than displaying a per-visit figure. It is to build a repeatable chain from meter and invoice to allocation rule, uncertainty, intervention and carefully bounded communication. A calculator, publication, partnership, scenario or directory listing does not prove complete environmental performance, verified reductions, certification, award merit or a universally comparable benchmark.
What the SPA-DEC study actually establishes
SPA-DEC links high-frequency operational data to a defined visitor stay. Metered inputs can include electricity, gas, on-site energy and water. Non-metered activities can be gathered less frequently and normalised across annual visitors. Open-hour emissions are allocated according to occupancy during a visit, while closed-hour loads such as overnight circulation and preparation are shared across the day’s visitors.
The paper applies that method to a large Romanian wellness resort and a smaller UK university sports-park wellness zone using 2024 data. A University of Surrey release identifies the sites as Therme Bucharest and the University of Surrey Sports Park. That institutional announcement is useful for identities and partnership context; the peer-reviewed paper remains the primary record for method, results and limitations.
The study also models each site’s observed energy configuration against a counterfactual grid-and-gas scenario. It reports that on-site renewable energy avoided about 32.9% of metered emissions at the large facility and 14% at the small one in 2024. Those are modelled differences against specified counterfactuals, not direct proof that all emissions fell by those percentages, and not forecasts for another property.
The research was produced through a Knowledge Transfer Partnership between the University of Surrey and Therme Group, co-funded by UKRI through Innovate UK. Its competing-interests statement says some authors work for the organisations operating the cases, two hold Therme management positions, and Surrey received Therme funding for work intended for commercialisation. Disclosure does not invalidate peer review; it is part of the context a careful operator should retain when assessing readiness, claims and independent assurance.
Spa carbon measurement begins with a declared boundary
A per-visit number answers a bounded question. Before selecting software, write that question plainly: emissions associated with which property, services, operating period, visitor duration and included activities? Define the organisational boundary, the reporting year, the visit unit, opening and closed hours, and how shared hotel or leisure loads are divided.
The Greenhouse Gas Protocol’s Corporate Standard provides requirements and guidance for organisational greenhouse-gas inventories, complemented by its Scope 2 and Scope 3 standards and guidance. SPA-DEC maps its inputs across direct emissions, purchased-energy emissions and other value-chain emissions. A per-visit service model still needs rules for allocating whole-property emissions to the spa and individual guest journey; a scope label alone does not resolve that allocation.
Record exclusions beside the result. SPA-DEC excludes visitor transport because of variability and limited operator control, and excludes food and beverage for separate treatment. Construction, major refurbishment and equipment replacement are not calculated by default, although known values may be added. The model is modular, so different users can include different sources. That flexibility helps adoption but makes boundary disclosure essential.
Carbon dioxide equivalent is also one environmental indicator. The paper notes that greenhouse-gas accounting does not measure other impacts such as water depletion, eutrophication or particulate emissions. A carbon figure should never be retitled as a complete environmental footprint.
Build the measurement ladder before the dashboard
Start with a source map. List incoming electricity, fuel, water and refrigerants; pool heating, pumping, filtration and air handling; treatment-room and laundry loads; waste streams; purchased goods; inbound logistics; contractor activity; staff travel; and any shared hotel, restaurant or fitness infrastructure. Assign an owner, unit, frequency, system of record and quality status to each source.
Then create a meter register. For every meter, record the asset served, calibration or verification status, reading interval, time zone, missing-data rule and relationship to the utility bill. A building main meter cannot reveal whether a change came from pool temperature, air handling, guest-room occupancy or kitchen activity. Submetering should follow decisions the team can actually make, rather than proliferating sensors without owners.
Non-metered categories require the same discipline. Procurement estimates derived from spend can be materially uncertain because a monetary category may include products with different emissions. Keep the factor source, currency and price year, category mapping, supplier evidence and estimation method. Label estimates as estimates. Replace the most consequential ones with physical quantities or supplier-specific evidence when proportionate.
Finally, reconcile. Energy totals should connect to invoices; visitor counts should connect to the access system; waste data should state whether weights are measured or converted from volume; and allocation totals should return to the facility inventory. Document gaps instead of silently filling them.
A per-visit number is an allocation, not a direct meter reading
A meter records consumption over a period. It does not know which guest used the heat retained overnight, the pool filtration running before opening or the ventilation serving several zones. A per-visit footprint is constructed by assigning shared emissions according to declared rules.
SPA-DEC’s open-and-closed-hour distinction responds to a real distortion. If all hourly emissions were divided only by people present at that moment, a quiet-hour guest could inherit an excessive share of fixed loads. The method allocates open-hour emissions using occupancy and visit timing, then spreads closed-hour overhead across the day’s visitors. Annually aggregated categories are divided across annual visitors.
That is a reason to publish the functional unit next to the result. State the visit duration, reporting period, included zones, visitor definition and treatment of closed hours. Explain cancellations, staff use, members who enter twice, hotel guests using multiple services, children, carers and non-spa pool users. Small choices can change the denominator and therefore the result without changing total emissions.
Use the allocated number to ask better questions, not to claim that each guest physically caused an identical amount. Some loads vary with attendance; others are fixed or stepwise. Lowering attendance can increase the figure per visitor even when total consumption falls, while higher attendance can lower it without improving equipment efficiency. Track absolute emissions and relevant intensity measures together.
Compare within a property before comparing across spas
The most defensible early comparisons hold boundaries stable: the same property over time, actual operation against a documented scenario, or one intervention against a verified baseline. These can show whether overnight circulation settings, heat recovery, ventilation control, pool covers, temperature policy, renewable supply or maintenance changed the measured pattern.
Cross-property comparisons need aligned boundaries, service definitions, visit durations, emission factors, energy accounting and data-quality thresholds. The two study sites are deliberately different, so their 5 and 3.5 kilogram averages do not establish that one is “greener.” The paper says the per-visit unit reflects both efficiency and amenities delivered.
The same discipline applies to Spa Awards research. An active listing such as Thermae Bath Spa or Peninsula Hot Springs provides directory context, not access to its meters, a verified footprint, nomination, judging or result. Comparable assessment would require current evidence from each property under a common method.
Use uncertainty as an improvement queue
The study’s cases cover one calendar year. It notes incomplete submetering and inventory detail, especially for Scope 3; sensitivity in spend-based procurement estimates; and an assumption of homogeneous visitor behaviour. Multi-year evidence would improve understanding of seasonal patterns and the stability of estimates.
An operator should preserve those limitations in the result. Create a data-quality score for coverage, frequency, source, assurance and estimation. Run sensitivity tests on uncertain factors and allocations. Prioritise improvement where uncertainty could reverse a decision, materially change a public claim or dominate the footprint.
This turns an apparent weakness into governance. If refrigerant loss dominates but records are incomplete, improve the leak and service log. If laundry is blended into hotel consumption, install or reconcile a useful submeter. If procurement is mostly spend-based, begin with high-spend or high-impact categories. A perfect inventory is not required before action, but material uncertainty must not be hidden.
Turn spa carbon measurement into an operating decision
Each material result should create a decision record: observed pattern, boundary, confidence, likely driver, proposed intervention, responsible owner, guest and safety constraints, capital and operating cost, verification window, and rebound risk. Carbon reduction cannot override pool-water safety, thermal comfort, ventilation, accessibility or treatment quality.
Separate maintenance from investment. Correct schedules, setpoints, leaks, controls and handovers first where evidence supports it. Then compare capital options using consistent scenarios: heat recovery, pumps, building controls, renewable supply, fabric improvements or plant replacement. Include embodied emissions when material and available, as well as equipment life and operational consequences.
Link the work to existing commissioning. The Journal’s guide to thalassotherapy spa operations shows why water source, treated pool, treatment inputs, claims and coastal assets need connected evidence. Carbon measurement should sit beside those controls, not collapse them into one sustainability score.
After implementation, measure against the pre-declared baseline and time window. Check whether the operational change persisted, whether weather or occupancy explains part of the movement, and whether another impact increased. Record an inconclusive result honestly.
Green claims need more than a dashboard
The UK Competition and Markets Authority’s Green Claims Code guidance says environmental claims should be truthful and accurate, clear, free of material omissions, fairly compared, lifecycle-aware and substantiated. Operators elsewhere should confirm their own law, but the evidence discipline travels well.
A defensible claim identifies what changed, compared with what, over which period, under which boundary, using which method and assurance. “Metered pool-plant electricity fell by X% against the weather-adjusted 2025 baseline” is narrower than “carbon-neutral spa,” although it still requires supporting evidence. Avoid turning a scenario into an achieved reduction, a selected category into a full footprint, or a partner-developed tool into independent certification.
Keep calculation, review and communication roles distinct. Material claims deserve competent technical and legal review. Archive the method version, factors, evidence and approval alongside the published wording so the claim can be updated or withdrawn when conditions change.
What does this mean for spa and wellness professionals?
Spa directors need a shared operating file with engineering, finance, procurement, housekeeping, treatment and communications—not a sustainability dashboard owned by one person. Define boundaries before targets, retain absolute totals beside per-visit intensity, and make uncertainty visible.
Facilities teams should meter decisions, not decoration. Finance and procurement should strengthen physical and supplier evidence for material Scope 3 categories. Marketing should communicate only the bounded result that the evidence supports. Awards researchers should distinguish publication, adoption, measured change, independent assurance and merit.
The immediate professional value of SPA-DEC is methodological: it demonstrates a transparent way to connect time-resolved operations and annual categories to a visit. Whether a particular operator can adopt a tool directly, integrate it with existing systems or obtain comparable results still depends on data, boundaries, competence and review.
A 90-day measurement plan
Days 1–30: define and reconcile
Name an accountable owner and a cross-functional group. Write the property, service and reporting boundaries; define the visit unit; list inclusions and exclusions; map meters and non-metered sources; document factors; and reconcile the most recent complete period to bills, access counts and finance records. Freeze public claims until their evidence is mapped.
Days 31–60: test allocation and uncertainty
Choose open- and closed-hour rules, shared-property allocations and visitor-count treatments. Calculate a baseline with version control. Test alternative reasonable assumptions. Identify the sources, factors and denominator choices that drive the result or uncertainty. Ask an independent competent reviewer to challenge boundaries, double counting, omissions and scenario logic.
Days 61–90: act and verify
Select a small number of interventions tied to observed hotspots. Protect water quality, ventilation, accessibility, staff conditions and guest experience. Predefine the verification period and success measures, including absolute emissions. Approve only narrow communications that explain their basis and limitations. Keep a decision log for inconclusive findings and the next data improvements.
What remains unproven
The research does not establish a universal carbon benchmark for spas, a complete lifecycle footprint, a reduction at any unstudied property, or environmental superiority between the two cases. One year cannot prove a long-term trajectory. Modelled avoidance against a counterfactual is not the same as a measured year-on-year reduction.
The paper and institutional release do not prove that every operator can deploy the calculator without integration, governance or assurance work. Nor do they establish that a per-visit display changes guest behaviour, that offsetting is appropriate, or that the calculated number supports an absolute “sustainable” or “carbon-neutral” claim.
Finally, publication in a peer-reviewed journal and appearance in industry news are not Spa Awards nominations or results. The value lies in testing the method against declared evidence and using it to improve operations.
Frequently asked questions
Is carbon per spa visit a directly measured value?
No. Meters measure facility consumption over time. A visit value applies emission factors and allocation rules to open-hour loads, closed-hour overhead and non-metered categories. Its meaning depends on the stated duration, boundary, visitor definition and data quality.
Can two spas compare their per-visit numbers?
Only after aligning services, boundaries, durations, factors, allocations, exclusions and evidence quality. Within-property trends under a stable method are generally more defensible. A lower intensity can also result from denominator changes, so absolute emissions and operating context remain necessary.
Does a calculator result justify a green claim?
Not by itself. The claim must match the measured category, baseline, period and evidence; disclose material boundaries; avoid broader lifecycle implications; and meet applicable consumer and advertising law. Independent review may be necessary for material public claims.
