The indoor climate in schools and offices has come into focus in recent years, especially after the COVID-19 pandemic. A good indoor climate is crucial for both health, learning and productivity. In the period 2022–2025, Europe has experienced a number of new trends in measuring and improving indoor climate. Below, the most important trends and developments in three main areas are reviewed: the use of IoT devices to measure indoor climate, improving indoor climate through behavioral changes, and technological solutions for a healthier indoor climate. Examples of initiatives and projects with a special focus on the school sector are given, and future development opportunities are outlined.
A significant trend since 2022 is the widespread use of IoT-based sensors to monitor indoor climate in real time. Schools across Europe are now installing CO₂ meters and other indoor climate sensors, which provide teachers and students with insight into air quality. These sensors typically measure CO₂ levels , temperature , humidity and often also noise levels and lighting conditions at the same time. Data is sent wirelessly (e.g. via WiFi or LoRaWAN) to the cloud or local dashboards, where it is visualized for users. The purpose is to identify poor indoor climate early and support rapid action – for example, airing out if the CO₂ level becomes too high.
Several countries have launched national initiatives to roll out IoT indoor climate monitoring in schools. In 2022, the Netherlands decided to make CO₂ sensors mandatory in all classrooms. The background was the pandemic and a desire for healthier air; despite thousands of devices installed, around 40% of schools still lacked sensors in all rooms. The government allocated 17 million euros to ensure that all around 9,000 school buildings had CO₂ meters installed before the next school year. The measure is intended to help schools monitor ventilation and reduce the risk of infection, as research shows a close link between CO₂ levels and the risk of airborne infection. The UK also rolled out CO₂ meters on a large scale: In 2021–2022, 300,000 sensors were distributed to schools in England to improve ventilation in classrooms. A British research team developed guidelines for teachers on how to use the monitors, which are color-coded (green/yellow/red) according to CO₂ levels. These “CO₂ traffic lights” make it easy to see when air quality is poor (above ~1500 ppm CO₂), so that you can respond by opening windows or doors.
In parallel, many citizen science projects have emerged where IoT devices are used to collect indoor air quality data in schools. For example , the UK has launched the SAMHE (Schools' Air quality Monitoring for Health and Education) project, where almost 1000 schools received free indoor air quality meters installed in 2022–2023. The sensors (AirGradient One) measure, among other things, CO₂, temperature, humidity and VOC, and the data is displayed on a web platform for teachers and students. Students actively participate by conducting experiments and learning about air quality, and the project aims to both raise awareness and provide data for research into indoor air quality in schools. Similar initiatives are seen in other countries; in Portugal, a “SchoolAir” IoT framework has been developed with do-it-yourself sensor modules in classrooms that measure CO₂, particles, humidity and temperature and send data to a local hub and a central cloud. The preliminary results showed frequent CO₂ exceedances during teaching hours, which supports the need for such measurements. The trend is clear: IoT indoor climate sensors have become commonplace in schools , and data from them is used both locally (to improve daily ventilation) and strategically (for research and planning). Offices are also seeing an increasing spread of smart indoor climate sensors connected to building management. Many companies are installing multi-sensor units that continuously monitor the workplace's CO₂, temperature, sound and light, to optimize the working environment and document the indoor climate, e.g. in connection with well-being certifications.
Technology alone will not solve indoor climate challenges – everyday behaviour and habits also play a big role. An important trend in the school sector is an increased focus on changing the behaviour of students and staff to get fresher air, less noise and better comfort. Many initiatives now combine technical measurements with “nudging” and education, so that good indoor climate practices become part of everyday life.
A key element is better ventilation habits . In several countries, teachers and students are encouraged to ventilate during breaks and regularly during classes – preferably every 20 minutes, where possible. The new CO₂ meters support this by giving a clear signal when it is time to open the windows. A number of schools have installed smart lamps or traffic lights that glow red when CO₂ concentrations are high, motivating students to ventilate the room . Such simple behavioral nudges can make a noticeable difference: measurements show that CO₂ levels drop significantly as soon as the class gets into the habit of responding to the alarm and ventilating.
Information and student involvement is another important aspect. In Denmark, the Danish Center for the Educational Environment (DCUM), with support from Realdania, has developed teaching materials and guides that integrate indoor climate into teaching. Students learn about how, for example, ventilation, cleaning and noise levels affect the indoor climate, and what they can do to improve it. DCUM also lends indoor climate meters (IC meters) to schools so that students can measure CO₂, temperature, humidity and noise in the classroom and experiment with solutions . For the youngest students, a card game “Indeklimakampen” has been developed, where they solve indoor climate problems in the form of a game. These initiatives create a cultural change : when students understand the importance of fresh air and appropriate noise levels, their behavior changes. DCUM points out that better indoor climate not only provides fresher air, but also calmer and less tired students – which in turn benefits the learning environment and the working environment for teachers.
Changing the use of space and interior design is also a behavioral approach to improving indoor climate. In Glostrup Municipality in Denmark, they have experimented with spreading students across several areas during the school day. By setting up common areas with seating niches and workstations, groups of students can be sent out to work independently, while the rest stay in the classroom. This has two effects: The noise level in the class decreases, and the CO₂ load per room is reduced when there are fewer people in the room. The result is both a better acoustic environment and lower CO₂ concentrations – solely through a change in behavior in the use of the building. Another behavioral measure is more frequent cleaning and chemical caution . A new Danish analysis highlights that simple measures such as more thorough cleaning can reduce dust and off-gassing from surfaces, which noticeably improves air quality. Likewise, choosing whiteboard pens, glue, paint, etc. with low VOC emissions and limiting perfumes and sprays in the classroom can reduce chemical pollution indoors.
Behavioral changes are also seen outside the building itself. Several European cities have introduced “School Streets” – campaigns where school roads are closed to traffic during school start and end times, to reduce children’s exposure to exhaust fumes. A British study found that such campaigns, combined with information efforts aimed at parents and the local community, could reduce outdoor NO₂ levels at schools by up to 23%. This is important, as cleaner outdoor air provides a better starting point for the indoor climate through natural ventilation. The study concludes that community efforts and behavioral campaigns can make a real difference to school air quality – especially when combined with technological solutions such as ventilation systems or air purifiers.
Overall, in 2022–25 there is a growing recognition that human behavior must be considered together with technology to achieve good indoor climate. Especially in schools, where resources for large technical installations may be limited, rapid improvements have been seen through awareness, education and better habits . This “soft” approach is considered necessary here and now, until more permanent solutions are in place. Nordic neighboring countries such as Norway and Sweden have traditionally had a greater focus on indoor climate, which is reflected in better air quality – something Denmark is now trying to catch up with through behavior and information. In the future, behavioral measures are expected to continue side by side with new technologies.
In addition to behavior and sensors, technological solutions are crucial for lasting improvements in the indoor climate. Especially in older buildings without adequate ventilation, investments are now being made in everything from mechanical ventilation systems to intelligent control systems and air purifiers. A common theme for 2022–2025 is that these solutions must be thought of together with energy considerations and automation, so that the indoor climate is improved in a sustainable way.
Mechanical ventilation with heat recovery is becoming standard in new buildings and renovations. Many schools in Europe that were built before modern ventilation requirements are now being retrofitted with ventilation systems to ensure air exchange without constantly opening windows. For example, schools in Germany received large subsidies after 2021 to install ventilation systems or improve existing HVAC filters as part of the COVID effort. However, there are financial and practical challenges in installing full systems everywhere at once. Therefore, in several cases, combination solutions such as hybrid ventilation are seen , where natural ventilation (via windows or slot valves) is supplemented by mechanical exhaust units. A Danish development project called NOTECH has, for example, tested a new ventilation concept for classrooms based on controlled natural ventilation that meets the requirements of the building regulations but uses minimal mechanics. The results were promising in terms of keeping CO₂ below 1000 ppm and limiting drafts through intelligent control of the air supply.
Another important technological track is air purification and filtration . During the pandemic, many schools invested in mobile HEPA air purifiers as a quick solution to poor ventilation. In Germany, state support programs were implemented for the purchase of HEPA air purifiers for classrooms without mechanical ventilation. These devices can remove >99% of airborne particles, including aerosols with viruses, and have been shown to reduce particle concentrations in classrooms. Studies have shown that mobile air purifiers can reduce particles (and thus potential infection) by over 50% compared to no action. However, they should be seen as a supplement – they do not add fresh air or remove CO₂, so they are best combined with some ventilation. UV-C light in ventilation systems and advanced filtration materials are also technologies being tested to neutralize bacteria and viruses, but they are not yet widespread in mainstream schools. In office buildings, on the other hand, electrostatic filters and activated carbon filters are more frequently seen integrated into HVAC systems to remove fine dust and VOCs from indoor air, driven by both health and comfort requirements (as well as certifications such as WELL and RESET Air).
Perhaps the most exciting development is the integration of IoT, automatic control and AI in building operations. Modern building automation not only switches ventilation on and off, but also optimises according to indoor climate conditions and energy needs in real time. Since 2022, there has been a greater focus on AI-based control of the indoor climate – i.e. algorithms that learn the building’s usage patterns and proactively adjust heating, cooling and ventilation. A pioneering example is a school in Loir-et-Cher in France , which was one of the first to implement a full “smart building” system with wireless sensors in all rooms and AI control via the cloud. The school installed battery-free temperature sensors and motion sensors in each room as well as automatic controls on the radiators. At first, the system was regulated manually via a local system, but after an upgrade, all data is sent to an Azure cloud, where Engie’s Vertuoz platform with machine learning now controls the heating and ventilation per room . If a room is empty, the temperature is automatically lowered, and in full classrooms approx. 19°C constantly. At the same time, ventilation is adjusted as needed to ensure air quality. The AI has learned how different parts of the building react (e.g. south-facing rooms become warmer) and proactively adjusts according to comfort and low energy consumption goals. The result has been better thermal comfort and over 20% energy savings annually for the school. This illustrates the potential of AI control: you can achieve a healthier indoor climate and save energy by intelligently adjusting operations.
Similar approaches are gaining ground in office buildings, where “smart offices” use IoT sensors and AI to balance ventilation, lighting and HVAC according to actual occupancy. For example, several companies have integrated motion sensors, CO₂ meters and thermostats into a system that automatically ventilates extra during meetings with many participants and dims systems in empty zones. A current trend is also the development of digital twins of buildings – virtual models that, fed with sensor data, can simulate and optimize indoor climate conditions. According to industry reports, IoT-based building automation is growing rapidly in Europe (around 20% annually), spurred by both energy requirements and the desire for healthier workplaces. The EU’s Buildings Directive EPBD (revised 2024) calls for stricter requirements for smart building management systems in all large buildings, precisely in order to achieve the nearly zero-energy goals. This will also drive more schools and offices towards installing smart indoor climate control in the coming years , as energy efficiency and indoor climate go hand in hand.
In addition to ventilation and air quality, light and acoustics are also important parameters where technology is used. In some European schools, dynamic lighting (Human-Centric Lighting) has been introduced, which automatically changes light intensity and colour tone during the day to mimic daylight and improve students’ concentration. Noise levels can be tackled with acoustic ceiling tiles or even electronic systems: some classrooms have tested noise feedback systems, where a microphone measures the sound level and provides visual feedback (e.g. a light that turns red when there is a lot of noise) to make the class quiet down. This combines technology and behavioural nudging and has shown a reduction in unnecessary noise.
In general, public authorities are seen to be supporting technological indoor climate solutions through new standards and subsidies. Belgium adopted a law on indoor climate in publicly accessible spaces at the end of 2022, which requires risk analyses and action plans for air quality, as well as the visible installation of CO₂ meters in the premises. The law also introduces a certification and labelling system so that buildings can receive an IAQ label (similar to energy labels) that informs users that air quality is being measured and controlled on an ongoing basis. France has required regular monitoring of indoor climate (CO₂ and formaldehyde) in schools and daycare centers since 2018, and in 2021 the limit values were tightened in line with the WHO's new recommendations. These measures put pressure on schools and offices to implement technical solutions , whether ventilation improvements or IoT monitoring, to comply with the standards.
The past three years have brought indoor climate high on the agenda, and this development is expected to continue. In the coming years, we will likely see further integration of sensors, behavior and automation into holistic indoor climate solutions. For schools, the classroom of the future could be equipped with self-regulating systems , where windows automatically open and close as needed based on CO₂ sensors, and where students can see their classroom’s indoor climate score (e.g. a simple A–G rating) via an app and thus be involved in keeping it green. AI is likely to play a greater role – not only in controlling HVAC, but also in predicting indoor climate problems. For example, AI could predict that “tomorrow classroom 7 will be too hot in the afternoon given the weather forecast and number of students”, and thus provide preventive cooling or ventilation. Such predictive controls are a new area of innovation, using weather data, calendars (when rooms are used) and machine learning to continuously fine-tune the indoor climate.
Energy efficiency and indoor climate optimization will become even more interconnected. The EU's green transition and stricter climate targets mean that buildings must be nearly energy-neutral by 2030. This means that schools and offices must be renovated with a focus on insulation AND ventilation – a challenge that can only be solved by smart technology, so that healthy indoor climate is not sacrificed to save energy. Demand-controlled ventilation is expected to become standard: sensors detect exactly how many people are present and adjust the air change accordingly. This already exists, but will spread to more buildings – including smaller offices and all classrooms – as sensor technology becomes cheaper and requirements are tightened. We can also expect more standardization around indoor climate data: perhaps schools will have to report CO₂ levels and temperature conditions annually as part of building operations, which will create a market for new solutions for automatic indoor climate documentation .
On the innovation front, work is being done on new materials and methods. Indoor climate-friendly building materials – such as paint, floors and furniture that actively break down pollutants – are being developed. For example, there are paints that can absorb formaldehyde from the air, and curtains with special coatings that filter dust. Green plants are also part of the future: studies indicate that strategically placed plants in a room can significantly reduce certain VOCs (volatile organic compounds) (one study found up to a 73% reduction in VOCs with plants). That is why pilot projects are being seen where classrooms are equipped with indoor “green walls” to improve air quality and acoustics naturally. These nature-based solutions can complement technological efforts.
For schools specifically, the authorities' requirements will probably be tightened, which opens up opportunities for innovation. In Denmark, for example, there is discussion of introducing a binding CO₂ limit value for classroom air and an obligation to take action if the indoor climate is poor. If such rules are introduced, the market will demand simple plug-and-play solutions – for example, a box that both measures, displays and automatically ventilates a classroom. Here, companies can develop new products such as the next generation of ÅBN's indoor climate sensors that not only measure but also actively control (e.g. wirelessly activate a ventilation flap or send a message to a central unit). Small portable sensors or wearables could also become a trend: students with asthma could wear a personal air quality meter that alerts when there is a high CO₂ or allergen level – and data could be aggregated to help the school adapt the indoor climate for vulnerable groups.
In offices, well-being certifications (WELL, Fitwel, etc.) are expected to drive innovation towards even healthier working environments. This can include everything from advanced lighting and sound scenarios (e.g. automatic adjustment of brightness and background noise according to circadian rhythms) to individual control options (employees can adjust the temperature at their workstation via smartphone). Artificial intelligence can be used here to unify preferences – i.e. learn from employee feedback which conditions provide the greatest satisfaction, and adjust the building accordingly.
In conclusion, the indoor climate area has undergone rapid development 2022–2025 , where digitalization , awareness and innovative solutions go hand in hand. Europe's schools and offices are on the path to becoming healthier environments through a combination of IoT monitoring, engaged users and intelligent systems. The future offers exciting opportunities to combine these for the benefit of both people and the climate - an area rich in potential for further product development and innovation.
Sources:
Realdania & DCUM – The “Schools Indoor Climate” campaign and studies of indoor climate in Danish schools realdania.dk realdania.dk realdania.dk realdania.dk .
FRI (Association of Consulting Engineers) – Report on the indoor climate of schools with proposals for CO₂ limits etc. frinet.dk frinet.dk .
EU and national guidelines: Belgian Indoor Climate Act 2022 health.belgium.be , WHO & EU air quality targets air-label.com air-label.com , Dutch and UK initiatives for CO₂ meters in schools dutchnews.nl theguardian.com .
IoT and sensor technology: Product description of IoT multi-sensor (CO₂, temp., humidity, sound, light) iotfactory.eu ; Amsterdam Smart City pilot (SensorTeam) amsterdamsmartcity.com amsterdamsmartcity.com ; SchoolAir Project (Portugal) mdpi.com .
Behavior and education: DCUM's materials and lending of IC meters godtarbejdsmiljo.dk , Glostrup and municipal experiences (Realdania case) realdania.dk , University of Surrey study on behavioral campaigns sciencedaily.com sciencedaily.com .
Technological solutions: Engie/Vertuoz AI management in French school news.microsoft.com news.microsoft.com ; QleanAir on HEPA filters in German schools qleanair.com qleanair.com ; Imperial College on CO₂ monitoring and ventilation efficiency imperial.ac.uk imperial.ac.uk ; Neuroject on smart buildings and EU trends neuroject.com neuroject.com .
Projects and research: SAMHE (UK) citizen science sei.org sei.org , Masseeksperimentet 2021 (Denmark) results realdania.dk realdania.dk , University of Surrey literature review (technology vs. behavior) sciencedaily.com sciencedaily.com , as well as various scientific studies of indoor climate in schools (referenced in the above sources).
Are you still interested in knowledge about your indoor climate? Find similar articles below or check out our entire indoor climate universe here:
