The potential of the adaptive thermal comfort concept in longterm actively conditioned buildings for improved energy performance and user wellbeing

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\u27s 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

The ambivalence of personal control over indoor climate - how much personal control is adequate?

Literature sets personal control over indoor environmental conditions in relation to the gap between predicted and actual energy use, the gap between predicted and observed user satisfaction, and health aspects. A focus on building energy performance often leads to the proposal of more automated and less occupant control of the indoor environment. However, a high degree of personal control is desirable because research shows that a low degree (or no) personal control highly correlates with indoor environmental dissatisfaction and sick building syndrome symptoms. These two tendencies seem contradictory and optimisation almost impossible. Based on current efficiency classes describing the effect of room automation systems on building energy use during operation, fundamental thoughts related to thermophysiology and control, recent laboratory experiments, important lessons learnt from post-occupancy studies, and documented conceptual frameworks on the level of control perceived, we discuss the ambivalence of personal control and how much personal control is adequate. Often-proposed solutions ranging from fully automated controls, over manual controls to dummy controls are discussed according to their effect on a) building energy use during operation and b) occupants perceived control. The discussion points to the importance of adequate personal control. In order to meet the goals for nearly zero energy buildings and for a human-centric design, there is the need to establish design procedures for adequate personal control as part of the design process

Guidelines to bridge the gap between adaptive thermal comfort theory and building design and operation practice

Adaptive thermal comfort guidelines have been developed within the work of Annex 69: “Strategy and practice of adaptive thermal comfort in low energy buildings”. The guidelines have been established based on a framework for adopting adaptive thermal comfort principles in building design and operation developed by the authors. The guidelines target building practitioners, addressing the critical interrelated role building planners, building operators and occupants play. A successful adaptive thermal comfort design, in which design for human thermal adaptation is foreseen, planned, and carefully embedded in the design and operation intent, is based on broad knowledge and understanding of the multiple quantifiable and non-quantifiable factors influencing human perception, as well as human building interaction. Adaptive building design follows a user-centric integrated design approach and therefore it is critical to consider the occupants’ and the operators’ role in buildings already in the design phase. This paper focuses on three main challenges identified earlier and how these are addressed in the guidelines, i.e. i) updating prevailing knowledge about human thermophysiology and adaptation, ii) developing a procedure for design of adaptive opportunities, and iii) providing guidance for operational planning and operation of adaptive buildings. The challenge for future research remains to assess the magnitude of how specific design decisions affect particular adaptive mechanisms

Thermal conditions in indoor environments: Exploring the reasoning behind standard-based recommendations

Professionals in the building design and operation fields typically look at standards and guidelines as a reliable source of information and guidance with regard to procedural, contractual, and legal scope and requirements that are relevant to accountability issues and compliance necessities. Specifically, indoor environmental quality (IEQ) standards support professionals to bring about comfortable thermal, air quality, acoustic, or visual conditions in buildings. In this context, it appears essential to regularly examine the IEQ standards’ applicability and scientific validity. The present contribution focuses on common thermal comfort standards in view of the reasoning and includes evidence behind their recommendations and requirements. Thereby, several international and national thermal comfort standards are examined via a structured matrix to assess basic parameters, design and performance variables targeted by the standards, suggested value ranges, and both general and specific evidence from the scientific literature. Finally, this paper discusses findings and points to the identified gaps in the chain of evidence from the results of scientific studies and the recommendations included in the thermal standards. As such, the present contribution has the potential to inform future developments regarding transparent and evidence-based thermal standards

The role of user controls with respect to indoor environmental quality: From evidence to standards

There are important reasons to offer building users the possibility to adjust indoor-environmental conditions. For one thing, people sharing the same indoor environment, may have different needs, requirements, and preferences. The same set of conditions would thus not satisfy everyone. Moreover, even an individual user's preferences can change considerably, given fluctuations in the state of their disposition and health, as well as their physical and cognitive activities. After a brief discussion of available information and evidence concerning the importance of user controls in buildings, the present contribution focuses on the reflection of the user control topic in indoor-environmental quality standards. To this end, a selection of common indoor-environmental quality standards and guidelines is reviewed. The results suggest that, whereas some standards and guidelines refer to user control related issues in a general manner, there is a paucity of more specific guidance in methods and means for incorporation of user control considerations in the building design and operation process

The colours of comfort:From thermal sensation to person-centric thermal zones for adaptive building strategies

Thermal comfort research has been traditionally based on cross-sectional studies and spatial aggregation of individual surveys at building level. This research design is susceptible to compositional effects and may lead to error in identifying predictors to thermal comfort indices, in particular in relation to adaptive mechanisms. A relationship between comfort and different predictors can be true at an individual level but not evident at the building level. In addition, cross-sectional studies overlook temporal changes in individual thermal perception due to contextual factors. To address these limitations, this study applied a longitudinal research design over 8 to 21 months in eight buildings located in six countries around the world. The dataset comprises of 5,567 individual thermal comfort surveys from 258 participants. The analysis aggregated survey responses at participant level and clustered participants according to their thermal sensation votes (TSV). Four TSV clusters were introduced, representing four different thermal sensation traits. Further analysis reviewed the probability of cluster membership in relation to demographic characteristics and behavioural adaptation. Finally, the analysis at individual level enabled the introduction of a new metric, the thermal zone (Zt), which in this study ranges from 21.5°C to 26.6°C. The thermal sensation traits and person-centric thermal zone (Zt) are a first step into the development of new metrics incorporating individual perceived comfort into dynamic building controls for adaptive buildings