Wellness travel crossed $1 trillion in 2024, and Therme Group and the University of Surrey have published SPA-DEC, the first peer-reviewed calculator that measures the carbon footprint of a single spa visit in real time.
The wellness trip has become one of travel’s most dependable growth stories. People are booking weekends around thermal baths, sauna circuits, and hydrotherapy pools, and planning longer stays at destination spas built for rest and recovery. Wellness tourism crossed the $1 trillion mark in 2024 and is projected to reach $1.4 trillion by 2027, and it is one of the fastest-growing corners of a $6.8 trillion wellness economy.
All of that heat and water carries a cost that has been hard to pin down, though. A spa keeps its pools warm overnight, runs saunas and steam rooms through the day, and filters, treats, and reheats the water, drawing energy whether the building is full or nearly empty. Until now the industry had no standard way to say what a single visit does to the atmosphere.
That is the gap a new tool from Therme Group and the University of Surrey is meant to close. On July 22, the two partners, with co-funding from Innovate UK, published the Spa and Wellness Dynamic Emissions Calculator, known as SPA-DEC, in the peer-reviewed journal Communications Sustainability. It is, the authors write, the first standardized method for measuring the carbon footprint of an individual spa or wellness visit in real time, and it gives operators a common basis to track, benchmark, and lower emissions.
The study attaches real numbers to the experience. A typical visit produced about five kilograms of carbon dioxide equivalent at a large wellness resort in Bucharest and roughly 3.5 kilograms at a smaller sports-park spa run by the university, the two sites where the calculator was validated. On-site renewable energy narrowed both figures in 2024, cutting per-visit emissions by about 33 percent at the larger facility and around 14 percent at the smaller one, so where a spa buys its power matters nearly as much as how much it uses.
How SPA-DEC measures the carbon footprint of a spa visit
The calculator combines live metered readings of energy and water use with normalized figures for waste and staff travel, then divides a facility’s total emissions across every visit, covering all three scopes of the Greenhouse Gas Protocol. Because it runs on live data, it can also show how emissions rise and fall by the hour or the season.
“Life cycle assessment is a fundamental tool for engineering systems design and decision-making,” Professor Jhuma Sadhukhan, of the University of Surrey’s Centre for Environment and Sustainability, said in a statement. “However, a spa visit’s life cycle assessment does not follow the standard approach and needed out-of-box thinking. Working out how to divide a whole building’s emissions fairly, including some of them in real time, between the people using it is what makes this work significant and real-world application-oriented, as it can be adopted to a wide range of facilities in the tourism sector to assess and mitigate emissions.”
Wellness travel is facing a carbon reckoning
The tool arrives as travelers increasingly ask what their trips cost the planet, and as the sector it measures keeps growing. Spas grew 14.6 percent between 2023 and 2024 and thermal and mineral springs 11.1 percent, which puts more heated water into service every season.
For Therme Group, which operates large-scale wellness resorts, the calculator turns broad sustainability goals into a daily number. “Our SPA-DEC is a world-first. The wellness industry has now a carbon footprint calculator of its own: peer-reviewed, real-time, bottom-up and dynamic, going beyond anything that existed before, and the methodology for a true carbon intelligence tool,” Dr. Robert Hanea, founder and chief executive of Therme Group, said in a statement. “It empowers spas, wellness centers and even theme and amusement parks, small and large alike, to manage carbon as an asset and build agile sustainability strategies, factoring carbon into daily operations.”
The research grew out of a Knowledge Transfer Partnership between Therme Group and the University of Surrey, co-funded by Innovate UK, with Surrey leading the methodology and the company supplying operational data from its facilities.
“This publication evidences the quality and credibility of the innovative SPA-DEC tool, a practical output from a Knowledge Transfer Partnership that will deliver both commercial impact and sustainability benefits,” Dr. Shona Campbell, of Innovate UK Business Connect, said in a statement. “This achievement highlights the value of the collaboration between an ambitious business and an expert academic team.”
SPA-DEC follows a companion tool for aviation, the Air Travel Passenger Dynamic Emissions Calculator, or ATP-DEC, published last year in Communications Earth & Environment, with further calculators for accommodation, food and beverage, and business events in development. Together they point toward a single science-based way to measure the carbon behind a wellness trip, from the flight to the hotel to the hours spent in the water.
“To minimise carbon impact, spas should aim to move towards cleaner, renewable energies, such as solar panels,” Steve Harding, founder and chief executive of Showerkap, told European Spa Magazine. “Simple measures such as adopting better maintenance of taps, pipes and toilets can reduce wastage, creating environmental gains and financial savings.”
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