Corvinus students examined the digital carbon footprint of hotel websites

Travel is usually preceded by an extensive digital preparation phase. We compare destinations and accommodation providers, view images and videos, read reviews, check prices, and then move through the stages of the online booking process. According to an international study, travellers spend an average of more than five hours engaging with travel-related online content during the 45 days before booking and visit 141 travel-related pages. 

Digital platforms also require energy and have an indirect carbon footprint. Operating websites requires servers, data transmission networks, and the phones and computers that process and display their content. Research on the environmental impacts of tourism has so far focused primarily on transport, accommodation operations, food services, and supply chains, while digital activities before and after travel have received less attention. 

Led by the Department of Tourism in cooperation with four departments 

The small-scale research project was carried out at the Institute of Sustainable Development at Corvinus University of Budapest under the leadership of the Department of Tourism. The Department of Sustainability Management and Environmental Economics, the Department of Economic Geography and Urban Development, and the Department of Agricultural Economics also contributed to the work. 

Students analysed real corporate services and digital interfaces that were publicly accessible. Among the student contributors, the work of Virág Mikolás, Luca Schenker, and Zoltán Vass deserves particular recognition. 

The project provided an opportunity to connect tourism, sustainability, digital technologies, and an ESG perspective. The students did more than explore theoretical questions. Using a consistent methodology, they produced measurable findings that can also be interpreted at company level. 

The full digital guest journey was examined 

The study analysed the websites of 43 five-star hotels in Hungary as they appeared in April 2026. The same predefined digital guest journey was followed for each hotel. It included the homepage, the image gallery, the list of available rooms, and the booking page for a selected room. 

The study used Carbon.Crane technology to quantify the environmental impacts of digital services. Based on the data volume of images, videos, text, and technical elements on each page, the tool estimates the energy required for server-side operations, data transmission, and user devices. The related emissions can then be calculated from this energy use by applying the carbon intensity of Hungary’s electricity system. 

The same settings and system boundaries were applied to every website, making the results comparable. The measurement did not assess the hotels’ overall sustainability performance, service quality, or ESG maturity. It examined only the technical energy and carbon efficiency of the digital guest journeys available at the time of the study. 

A difference of more than eighteenfold 

The carbon footprint of the four-page digital guest journeys ranged from 0.89 to 16.45 grams of carbon dioxide equivalent. The difference between the lowest and highest measured values was 18.4-fold, while the sample median was 3.24 grams. 

The length of the booking process alone does not explain these differences. A shorter digital journey may still be data intensive if it loads large images, videos, external services, or unnecessarily large technical elements. The carbon footprint is therefore jointly determined by the number of pages, the volume of data, and the technical design of the website. 

On average, homepages and image galleries had the highest carbon footprints among the page types examined. Galleries also offered substantial optimisation potential, since the file size of high-resolution or insufficiently compressed images can often be reduced without any visible loss of quality. 

Potential reduction of nearly one fifth 

The combined, emissions-weighted reduction potential of the 43 websites was 18.2 percent. This means that nearly one fifth of the digital emissions examined could be avoided through the technical optimisation of images alone. 

The result covers only the opportunities identified in images. The additional effects of videos, fonts, program code, external tracking and marketing solutions, and a simplified booking journey are not included in the 18.2 percent figure. 

To illustrate the scale of the impacts, the project participants also applied a standardised modelled reference level of traffic. Under this scenario, each hotel was assumed to receive one million complete four-page digital guest journeys per month. The modelled annual emissions of the 43 digital guest journeys totalled 2,158 tonnes of carbon dioxide equivalent. Image optimisation could save 393 tonnes of emissions and nearly 1,699 megawatt-hours of electricity use each year. 

These figures do not represent the hotels’ actual annual digital emissions or real visitor traffic. The purpose of the modelling was to show how differences of only a few grams per page can accumulate into a substantial environmental impact when the same interfaces are accessed by hundreds of thousands or millions of users. 

A sustainable guest experience begins with the first click 

Optimising digital guest journeys does not replace the decarbonisation of transport, building energy use, hotel operations, or supply chains. It does, however, represent an area for action that can be measured directly and influenced relatively quickly. 

Reducing data volumes can lower environmental impacts while also producing faster loading times and a better user experience. The same technical improvement can generate savings for every subsequent page view without requiring changes to guests’ travel habits or to the content of the service. 

“Assessing sustainable tourism requires us to examine the guest’s entire journey, including what happens online before departure and after returning home. The project connected an environmental impact that has so far remained relatively invisible, but is measurable and can be influenced in the short term, with an ESG perspective. The students therefore analysed not only theoretical questions, but also real corporate services using actual data and advanced measurement technology,” said Dr László Kökény, Head of the Department of Tourism at Corvinus University of Budapest. 

The digital assessment forms part of a broader Corvinus research project examining ESG preparedness in the Hungarian tourism sector. One of its central messages is that assessing sustainable tourism requires consideration of the guest’s entire journey. This includes not only what happens at the destination, but also digital activities before departure and after returning home. 

“It is striking that, while we search for ways to meet growing energy demand, we can easily overlook the opportunities hidden in oversized elements within existing interfaces and applications. Yet these improvements can generate savings and may also create a business advantage through a better user experience and improved conversion rates,” said György Huszics, Co-founder and CEO of Carbon.Crane. 

Most of tourism’s carbon footprint is still generated in the physical world. By the time a guest departs, however, the data have already travelled a long way. Sustainable tourism must therefore consider the efficiency of guest clicks alongside guest nights. 

Methodological note 

The WebPage Carbon Scanner is a tool designed to examine individual websites and is based on Carbon.Crane’s Website Carbon Monitor measurement technology. The conformity of the Website Carbon Monitor with the requirements of the MSZ EN ISO 14067:2019 standard was assessed by Bureau Veritas, an independent certification body. The Carbon.Crane WebPage Carbon Scanner is a version of the Carbon.Crane Website Carbon Monitor measurement platform that has been optimised for examining individual websites. During measurement, the system automatically navigates the website under review, records the data traffic, and identifies the resources that determine it, including images, videos, fonts, style sheets, and scripts. Based on the collected data, it calculates the energy demand associated with using the website across the entire delivery chain. This includes the energy requirements of backend systems, network data transmission, and end-user devices. It then converts this energy demand into carbon dioxide equivalent emissions using country-specific or region-specific electricity emission factors. The methodology allows calculations to be performed using parameters tailored to the purpose of the assessment. In the present study, the model assumed a returning visitor rate of 25 percent and therefore did not include repeated downloads of resources available from the browser cache. The calculations applied an emission factor for Hungary’s electricity mix. When estimating the optimisation of visual content, the algorithm draws on the analysis and comparative assessment of several thousand real web images and on a benchmark developed from these data. This enables a reliable estimate of the achievable reduction in file size and the associated potential reductions in energy use and emissions.