Global collaboration is the cornerstone of scientific advancement. Frontiers in Built Environment has organized a series of special edition Research Topics, with the goal of highlighting the latest advancements in Indoor Environment across the globe, showcasing the academic excellence and high-quality work of internationally recognized researchers. These collections aim to shed light on the recent progress made across the entire breadth of the Indoor Environment field, and reflect on the future challenges faced by researchers across borders. Please note, contributions to the collection are by invitation only. Other Research Topics in this series: • <a href="https://www.frontiersin.org/research-topics/48895/global-excellence-in-indoor-environment-north-america" target="_blank">Global Excellence in Indoor Environment: North America</a> • <a href="https://www.frontiersin.org/research-topics/52210/global-excellence-in-indoor-environment-south-america" target="_blank">Global Excellence in Indoor Environment: South America</a>

University of Trento

University College London

R2M Solution

Department of Architecture, Design and Media Technology, Aalborg University

Frontiers in Built Environment

Indoor Environment

Frontiers in Energy Research

Frontiers in Mechanical Engineering

Global Excellence in Indoor Environment: 'Europe'

In recent decades, a new generation of “green indoor” spaces has fulfilled the latest regulations and guidelines for a carbon-neutral society. Their targets are reachable through certifications embracing sets of measures and the adverse effects on occupants. Notwithstanding this, it has constituted a significant step forward in building design. However, the challenges given by climate change and the ecological crises lead to the need for new disruptive approaches to indoor design and function, enhancing human health and adopting regenerative design” at the forefront of buildings’ conception. Besides the positive energy-performance attributes, the creation of a Regenerative Indoor Environment utilizes appropriate construction technologies and systems, to reinforce human health, and enhance users’ experience. This regenerative paradigm shift foresees putting ecosystems at the centre and the users’ psycho-physiological wellbeing, thus magnifying their collaboration. Despite regenerative design gaining some attention, a framework towards its implementation promoting the actual performances of the indoor environment is still missing, and designers do navigate among guidelines with no apparent performance indicators to be achieved, technologies to be implemented, or methodologies for post-occupancy evaluations. These three levels, constituting a stepwise methodology, are addressed by the authors within the sections of this paper, and validated as an example of the office buildings’ typology. i) What characterizes a Regenerative Indoor Environment? ii) What technical solutions underpin the realization of a Regenerative Indoor Environment? iii) What methods or standards are crucial for its evaluation? With these premises, the paper contributes to supporting the creation of a regenerative indoor’ design, by sampling and outlining regenerative indoor performances to be obtained, describing the adequate tools to implement them, as well as by displaying approaches and solutions for their final verification.

In recent decades, a new generation of &#x201c;green indoor&#x201d; spaces has fulfilled the latest regulations and guidelines for a carbon-neutral society. Their targets are reachable through certifications embracing sets of measures and the adverse effects on occupants. Notwithstanding this, it has constituted a significant step forward in building design. However, the challenges given by climate change and the ecological crises lead to the need for new disruptive approaches to indoor design and function, enhancing human health and adopting regenerative design&#x201d; at the forefront of buildings&#x2019; conception. Besides the positive energy-performance attributes, the creation of a Regenerative Indoor Environment utilizes appropriate construction technologies and systems, to reinforce human health, and enhance users&#x2019; experience. This regenerative paradigm shift foresees putting ecosystems at the centre and the users&#x2019; psycho-physiological wellbeing, thus magnifying their collaboration. Despite regenerative design gaining some attention, a framework towards its implementation promoting the actual performances of the indoor environment is still missing, and designers do navigate among guidelines with no apparent performance indicators to be achieved, technologies to be implemented, or methodologies for post-occupancy evaluations. These three levels, constituting a stepwise methodology, are addressed by the authors within the sections of this paper, and validated as an example of the office buildings&#x2019; typology. i) What characterizes a Regenerative Indoor Environment? ii) What technical solutions underpin the realization of a Regenerative Indoor Environment? iii) What methods or standards are crucial for its evaluation? With these premises, the paper contributes to supporting the creation of a regenerative indoor&#x2019; design, by sampling and outlining regenerative indoor performances to be obtained, describing the adequate tools to implement them, as well as by displaying approaches and solutions for their final verification.

A framework to support the design of a regenerative indoor environment

Over the past decades there has been a strong evidence of a temperature rise across the world that has led to a growing concern of more extreme weather patterns and regular seasonal heat waves globally. As such, building occupants are at a continuously growing risk to overheating exposure inside the premises throughout the warm season of the year. This study investigates the utilization of cooling pad technology as a potential solution to enhance cooling efficiency. Compared to traditional cooling methods, the implementation of cooling pads leads to significant reductions in temperature and enhanced humidity control, while consuming relatively lower amounts of energy. The study contains a comprehensive analysis of the climatic conditions in Latvia, focusing on temperature and humidity variations throughout the year over the last decade in three cities–Riga, Daugavpils and Liepaja, that extensively represent the scope of climatic variations across Latvia, featuring coastal and continental climate patterns. This study aims to evaluate the effectiveness and suitability of cooling pad technology in Nordic climate, focusing on three Latvian cities. The novelty of the study lies in its analysis of cooling pad technology’s effectiveness in Nordic climatic conditions in addressing the increasing cooling demand. The paper examines the fundamental principles behind cooling pad technology, its impact on chiller performance, and its ability to optimize the cooling process. The utilization of cooling pad technology as an effective means to enhance cooling efficiency across the building stock to improve occupant comfort level and IEQ is highlighted. The results demonstrate 5.47% COP increase during average summer temperature conditions, and 17.78% COP increase in peak summer temperature conditions after implementation of cooling pads. This study contributes to the existing knowledge on cooling technologies, offering practical recommendations for the implementation of cooling pad systems use in Latvia and across the wider Nordic region, which is experiencing the gradual rise in summer temperature and humidity level.

Over the past decades there has been a strong evidence of a temperature rise across the world that has led to a growing concern of more extreme weather patterns and regular seasonal heat waves globally. As such, building occupants are at a continuously growing risk to overheating exposure inside the premises throughout the warm season of the year. This study investigates the utilization of cooling pad technology as a potential solution to enhance cooling efficiency. Compared to traditional cooling methods, the implementation of cooling pads leads to significant reductions in temperature and enhanced humidity control, while consuming relatively lower amounts of energy. The study contains a comprehensive analysis of the climatic conditions in Latvia, focusing on temperature and humidity variations throughout the year over the last decade in three cities&#x2013;Riga, Daugavpils and Liepaja, that extensively represent the scope of climatic variations across Latvia, featuring coastal and continental climate patterns. This study aims to evaluate the effectiveness and suitability of cooling pad technology in Nordic climate, focusing on three Latvian cities. The novelty of the study lies in its analysis of cooling pad technology&#x2019;s effectiveness in Nordic climatic conditions in addressing the increasing cooling demand. The paper examines the fundamental principles behind cooling pad technology, its impact on chiller performance, and its ability to optimize the cooling process. The utilization of cooling pad technology as an effective means to enhance cooling efficiency across the building stock to improve occupant comfort level and IEQ is highlighted. The results demonstrate 5.47% COP increase during average summer temperature conditions, and 17.78% COP increase in peak summer temperature conditions after implementation of cooling pads. This study contributes to the existing knowledge on cooling technologies, offering practical recommendations for the implementation of cooling pad systems use in Latvia and across the wider Nordic region, which is experiencing the gradual rise in summer temperature and humidity level.

Examining the efficacy of cooling pad technology to address increasing building cooling demand in Latvia

The COVID-19 pandemic has shown that infection prevention actions need to be more efficient in public indoor environments. In addition to SARS-CoV-2, the cause of COVID-19, many pathogens, including other infectious viruses, antibiotic-resistant bacteria, and premise plumbing pathogens, are an invisible threat, especially in public indoor spaces. The indoor hygiene concept for comprehensive infection prevention in built environments highlights that the indoor environment should be considered as a whole when aiming to create buildings with increased infection prevention capacity. Within indoor environments, infections can indirectly spread through surfaces, air, and water systems. Many methods, such as antimicrobial technologies and engineering solutions, targeting these indoor elements are available, which aim to increase the hygiene level in indoor environments. The architectural design itself lays a foundation for more efficient infection prevention in public buildings. Touchless solutions and antimicrobial coatings can be applied to frequently touched surfaces to prevent indirect contact infection. Special ventilation solutions and air purification systems should be considered to prevent airborne infection transmissions. Proper design and use of water supply systems combined with water treatment devices, if necessary, are important in controlling premise plumbing pathogens. This article gives a concise review of the functional and available hygiene-increasing methods—concentrating on indoor surfaces, indoor air, and water systems—to help the professionals, such as designers, engineers, and maintenance personnel, involved in the different stages of a building’s lifecycle, to increase the infection prevention capacity of public buildings.

The COVID-19 pandemic has shown that infection prevention actions need to be more efficient in public indoor environments. In addition to SARS-CoV-2, the cause of COVID-19, many pathogens, including other infectious viruses, antibiotic-resistant bacteria, and premise plumbing pathogens, are an invisible threat, especially in public indoor spaces. The indoor hygiene concept for comprehensive infection prevention in built environments highlights that the indoor environment should be considered as a whole when aiming to create buildings with increased infection prevention capacity. Within indoor environments, infections can indirectly spread through surfaces, air, and water systems. Many methods, such as antimicrobial technologies and engineering solutions, targeting these indoor elements are available, which aim to increase the hygiene level in indoor environments. The architectural design itself lays a foundation for more efficient infection prevention in public buildings. Touchless solutions and antimicrobial coatings can be applied to frequently touched surfaces to prevent indirect contact infection. Special ventilation solutions and air purification systems should be considered to prevent airborne infection transmissions. Proper design and use of water supply systems combined with water treatment devices, if necessary, are important in controlling premise plumbing pathogens. This article gives a concise review of the functional and available hygiene-increasing methods&#x2014;concentrating on indoor surfaces, indoor air, and water systems&#x2014;to help the professionals, such as designers, engineers, and maintenance personnel, involved in the different stages of a building&#x2019;s lifecycle, to increase the infection prevention capacity of public buildings.

Methods for infection prevention in the built environment—a mini-review

Optimal controllers can enhance buildings’ energy efficiency by taking forecast and uncertainties into account (e.g., weather and occupancy). This practice results in energy savings by making better use of energy systems within the buildings. Even though the benefits of advanced optimal controllers have been demonstrated in several research studies and some demonstration cases, the adoption of these techniques in the built environment remains somewhat limited. One of the main reasons is that these novel control algorithms continue to be evaluated individually. This hampers the identification of best practices to deploy optimal control widely in the building sector. This paper implements and compares variations of model predictive control (MPC), reinforcement learning (RL), and reinforced model predictive control (RL-MPC) in the same optimal control problem for building energy management. Particularly, variations of the controllers’ hyperparameters like the control step, the prediction horizon, the state-action spaces, the learning algorithm, or the network architecture of the value function are investigated. The building optimization testing (BOPTEST) framework is used as the simulation benchmark to carry out the study as it offers standardized testing scenarios. The results reveal that, contrary to what is stated in previous literature, model-free RL approaches poorly perform when tested in building environments with realistic system dynamics. Even when a model is available and simulation-based RL can be implemented, MPC outperforms RL for an equivalent formulation of the optimal control problem. The performance gap between both controllers reduces when using the RL-MPC algorithm that merges elements from both families of methods.

Optimal controllers can enhance buildings&#x2019; energy efficiency by taking forecast and uncertainties into account (e.g., weather and occupancy). This practice results in energy savings by making better use of energy systems within the buildings. Even though the benefits of advanced optimal controllers have been demonstrated in several research studies and some demonstration cases, the adoption of these techniques in the built environment remains somewhat limited. One of the main reasons is that these novel control algorithms continue to be evaluated individually. This hampers the identification of best practices to deploy optimal control widely in the building sector. This paper implements and compares variations of model predictive control (MPC), reinforcement learning (RL), and reinforced model predictive control (RL-MPC) in the same optimal control problem for building energy management. Particularly, variations of the controllers&#x2019; hyperparameters like the control step, the prediction horizon, the state-action spaces, the learning algorithm, or the network architecture of the value function are investigated. The building optimization testing (BOPTEST) framework is used as the simulation benchmark to carry out the study as it offers standardized testing scenarios. The results reveal that, contrary to what is stated in previous literature, model-free RL approaches poorly perform when tested in building environments with realistic system dynamics. Even when a model is available and simulation-based RL can be implemented, MPC outperforms RL for an equivalent formulation of the optimal control problem. The performance gap between both controllers reduces when using the RL-MPC algorithm that merges elements from both families of methods.