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The adaptive thermal comfort concept has been developed over many years and proven in numerous field studies (e.g. Webb 1964, Nicol and Humphreys 1973, Auliciems 1981b, de Dear et al. 1997, McCartney and Nicol 2002, Manu et al. 2016), showing that people are satisfied with a wide range of thermal conditions. Prerequisite is that people are provided with means to make themselves comfortable, that they know which opportunities they have, that it is socially acceptable to use these opportunities and that they are willing to use them (Hellwig, 2015). However, the overall understanding of how to design for such opportunities enabling the occupant to make themselves comfortable in relation to climate and building type, thus how to convert the adaptive thermal comfort concept into building design and concepts for operating buildings, is still limited. There are still common misunderstandings in the interpretation of the adaptive comfort approach among building planners and operators e.g. regarding the amount of control, the seriousness of this topic or the level of information needed by occupants for which reason guidance (e.g. CIBSE 2010, Cook et al. 2020) and knowledge transfer (e.g. Hellwig and Boerstra 2017, 2018) is absolutely essential. Consequently, there is still a gap between scientific research and real-world-application, which this report aims to diminish.In line with the activities within IEA EBC Annex 69 Subtasks A, B, and C, the present report includes four main sections, addressing the above listed identified challenges and barriers to the adoption of the adaptive thermal comfort in practice by explaining the adaptive thermal comfort principles, by illustrating the benefits from applying the adaptive principles in buildings, through guidance on how to implement the adaptive principles in the design and operation of buildings, especially providing guidance on how to design for adaptive opportunities. The Appendices contain additional information on standards, checklists for stakeholders in the design and operation of buildings as well as documentation and lessons learnt from the buildings investigated within this Annex 69 Subtask C. This report is formulated with the help of frameworks (Hellwig et al. 2019, Hellwig et al. 2020) developed to facilitate the adoption of adaptive principles in the design and operation of buildings. We aim to provide the knowledge on a general level of understanding, so that it is possible to apply the knowledge in different types of building usage, different climate zones and occupant groups. However, the majority of examples used in this report stems from office buildings, which is mainly rooted in the fact that the majority of research studies focussed on this type of building. Nevertheless, we have supplemented this report with examples from other building types. The target group of the guidelines in this report are building planners (architects, engineers, sustainability certification consultants/councils) and building operators (facility managers, operators, owners, and tenants). Furthermore, the guidelines in this report are intended as critical sources and guidance to educate future building professionals and stakeholders.The report includes four main sections, as outlined below.Section 2 summarises the three adaptive comfort principles, i.e. physiological, behavioural and psychological adaptation. The section follows with a discussion on the effectiveness of the adaptive principles and on the order of activation of adaptive responses. It ends with a brief account on the development of adaptive models.Section 3 describes the benefits from applying the adaptive principles in buildings, including energy savings, resilience to climate change, improved usability and thermal satisfaction, as well as improved health and well-being.Section 4 presents the developed framework for adopting the adaptive comfort principles in design and operation of buildings. The main elements of the framework are described, i.e. the building context, adaptive responses and actions, the building planning and design, –the adaptive opportunities design, and the operational planning and operation. Each of these subsections includes guidelines to facilitate the integration of adaptive principles. Section 4 ends with considerations and recommendations for adopting adaptive comfort in conditioned buildings, including advice for facilitating free-running mode in building operation as often as possible and ways to integrate the use of the adaptive principles in permanently or long-season conditioned spaces.AppendicesAppendix 1 summarises information on adaptive models used in international and national standards, as well as examples of models developed by research in various locations and climates.Appendix 2 provides checklists of parameters that can help stakeholders implement measures to ensure the availability of adaptive opportunities in buildings.Appendix 3 is a collation of case studies with practical learnings from adaptive buildings investigated in Annex 69 Subtask C.Appendix 4 lists publications, presentations and workshops related to Activity B2 of IEA EBC Annex 69.Authors of main report on guidelines, Appendix 1, 2, 4 worked out in Subtask B, Activity B2Lead: Runa T. Hellwig, Aalborg University, DenmarkCo-lead: Despoina Teli, Chalmers University, SwedenContributors:Marcel Schweiker, Karlsruhe Institute of Technology, GermanyRodrigo Mora, British Columbia Institute of Technology, CanadaJoon-Ho Choi, University of Southern California, USARajan Rawal, CEPT University, IndiaM.C.Jeffrey Lee National Taichung University of Science and Technology, TaiwanWang Zhaojun, Harbin Institute of Technology, ChinaFarah Al-Atrash, German Jordanian University, JordanAuthors of Appendix 3 Documentation of buildings investigated in Annex 69, Subtask CLead: Richard de Dear, University of Sydney, AustraliaCo-Lead: Stephanie Gauthier, University of Southampton, UK; Jungsoo Kim, University of Sydney, AustraliaContributors (in alphabetical order): Farah Al-Atrash, German Jordanian University, JordanLeonidas Bourikas, University of Southampton, UK Bin Cao, Tsinghua University, ChinaJoon-Ho Choi, University of Southern California, USAChungyoon Chun, Yonsei University, KoreaHeidi Creighton, Buro Happold Engineering, USAPaul Cooper, University of Wollongong, AustraliaJérôme Damiens, Tsinghua University, ChinaRichard de Dear, University of Sydney, AustraliaStephanie Gauthier, University of Southampton, UKRuna T. Hellwig, Aalborg University, DenmarkWenjie Ji, Tsinghua University, ChinaXinyu Jia, Tsinghua University, ChinaJungsoo Kim, University of Sydney, AustraliaSuhyun Kwon, Yonsei University, KoreaKyeongsuk Lee, University of Southern California, USA

Within the IEA EBC Annex 69 on Strategy and Practice of Adaptive Thermal Comfort in Low Energy Buildings (http://annex69.org/), we are conducting an international questionnaire study related to thermal comfort scales. Our objective is the analysis of influences on the perception of thermal comfort scales. In particular, we are looking at the effect of the current thermal state, peoples climatic background, and level of adaptation on the relationship between thermal sensation, thermal comfort, and thermal acceptance.

Human environmental perception and occupant behaviour are driven by a multitude of factors, including demographics and preferences. The type and amount of information/data able to be collected is increasing manyfold in recent times and includes very personal data such as heart rate, skin temperature, and emotional reactions to the environmental conditions experienced. There are potential benefits, which may arise in getting access to such information/data for research on multi-domain influences, active interfaces and operation/control purposes. An important question regarding the availability of such data for building operation is the extent to which people are willing to share their personal information. With this project a discrete choice experiment is designed in order to reveal information on this question.

Within the IEA EBC Annex 69 on Strategy and Practice of Adaptive Thermal Comfort in Low Energy Buildings (http://annex69.org/), we are conducting an international questionnaire study related to thermal comfort scales. Our objective is the analysis of influences on the perception of thermal comfort scales. In particular, we are looking at the effect of the current thermal state, peoples climatic background, and level of adaptation on the relationship between thermal sensation, thermal comfort, and thermal acceptance.

This review table entails a collection of papers with relevance to the topic of occupants' role in buildings' energy performance gap.

Within the IEA EBC Annex 69 on Strategy and Practice of Adaptive Thermal Comfort in Low Energy Buildings (http://annex69.org/), we are conducting an international questionnaire study related to thermal comfort scales. Our objective is the analysis of influences on the perception of thermal comfort scales. In particular, we are looking at the effect of the current thermal state, peoples climatic background, and level of adaptation on the relationship between thermal sensation, thermal comfort, and thermal acceptance.

Technological progress in conditioning practice combined with prevailing thermal comfort criteria, created stable, tightly controlled indoor temperature bands. Research shows indoor temperatures to be increasing in the heating period, leading to higher building energy use than planned. Field studies provide proof that occupants not in control of their indoor climate are more dissatisfied and report problems in wellbeing. Widening temperature bands could be an effective measure leading to energy conservation, increasing satisfaction and, as shown recently, helping to mitigate health problems related to our way of life. The adaptive approach to thermal comfort postulates that people's thermal comfort perception adapts to the indoor and outdoor climatic conditions they normally experience. However, according to standards, the adaptive model is applicable only to passively conditioned (free-running) buildings, even though the adaptive principles may well apply also to actively conditioned buildings. Our review found studies demonstrating positive health effects and energy conservation potential in permanently or seasonally conditioned buildings. On this basis, the potential of the adaptive approach and translations into concrete design or operation solutions for actively conditioned buildings are discussed in this paper. We conclude that the adaptive concept offers a potential for indoor climate control in actively conditioned buildings in the temperate and cold climates.

Occupants’ thermal response is influenced by their sensitivity to temperature variations, i.e. the rate of change in occupants’ thermal sensation per unit change in indoor temperature. Thermal sensitivity is commonly taken as constant (Griffiths constant) in the calculation of occupants’ comfort temperature. This constant is based on small differences found between buildings’ ventilation modes [naturally ventilated (NV) vs. air conditioned (AC)]. However, recent research found significant differences depending on building type, ventilation mode, age, gender and climate. This paper reviews thermal sensitivity within the same building type and main ventilation mode using longitudinal surveys and monitoring data from school buildings, two in the UK (U1 and U2) and one in Sweden (S1). Results show that in two of the schools (U1 and S1) children were half as sensitive as in school U2 and the difference is statistically significant. A similar result with slightly different thermal sensitivities was derived from comparison by clusters derived from the classrooms’ indoor temperatures. This outcome suggests that building ventilation mode (AC/NV), which is typically considered the main determinant of occupants’ thermal experience and often the only building information recorded in field surveys, is inadequate to explain this important occupant response factor.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The influence of a classroom's indoor environment on children's health, performance and comfort is a concern that receives increasing attention. Many schools experience problems with inadequate indoor air quality and climate. Investigations of the indoor air quality (IAQ) in schools have been often non-systematic, which can lead to costly ad-hoc remediation actions. It is therefore important to develop a holistic approach to the assessment of IAQ in schools. This paper presents a field study on the indoor air quality and thermal environment conditions of elementary schools in Gothenburg, Sweden. The focus of the paper is on the methodology to investigate the IAQ using both objective measurements and subjective assessment of the perceived IAQ. The indoor environmental measurements include indoor air quality and thermal comfort parameters for which guideline values exist. Finally, a questionnaire was developed to evaluate the perception of the classroom's thermal environment and air quality by young children. The paper presents the study protocol and diagnostics approach for IAQ in classrooms. Examples of results from the first 10 investigated classrooms are presented.

Thermal discomfort is one of the main triggers for occupants’ interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses.

One of the major challenges of building industry today is to provide indoor spaces allowing the occupants to make themselves comfortable while achieving low energy consumption. Considering the observed increasing temperatures and a more extreme climate, this becomes even more urgent and difficult to accomplish. It is therefore necessary to rely on approaches than contribute to sustainable building design, such as the adaptive approach to thermal comfort which postulates that people are not passive recipients of their environment but adapt behaviourally, physiologically and psychologically. The concept of adaptive thermal comfort was formulated many decades ago and has been validated in numerous field studies. Temperature thresholds based on adaptive models have been included in international and national standards. However, the overall understanding of how to translate the adaptive principles into design practice and concepts for operating buildings is still limited. Subtask B of IEA Annex 69 addresses this gap: "Strategy and practice of adaptive thermal comfort in low energy buildings". The subtask aims to develop guidelines for low energy buildings that include the principle of adaptive comfort. This paper discusses the challenges and gaps identified in using the principles of adaptive thermal comfort in building design and operation and outlines the contents of the imminent guideline.

In temperate climates, one passive design solution is to increase the heat capacity of building fabric. This design principle aims to reduce heating demand in winter and over-heating in summer; it is also coupled with more stable indoor air and radiant temperature. This may suggest that by exposing thermal mass, occupants may feel more comfortable. Although previous research based on simulations have studied this relationship, there is a lack of empirical evidence. This paper reviews the results an EU-funded research project, smart controls and thermal comfort (SCATs) to ascertain the impact of building fabric on occupants’ perceived comfort. Between 1997 and 2000, twenty-six office buildings from five different countries (France, Greece, Portugal, Sweden and UK) were surveyed using a transverse questionnaire, a longitudinal questionnaire and environmental monitoring. This paper analyses the transverse questionnaires responses (N=451), in particular answers to questions on thermal perception, thermal preference and overall comfort. Results show a statistically significant relationship between building fabric heat capacity and subjective comfort (thermal perception χ2(1)=3.78, p=0.05 and overall comfort χ2(1)=4.37, p