Dynamic Environment, Adaptive Comfort, and Cognitive Performance

Since the invention of airconditioning over 100 years ago a central research challenge has been to define the indoor environmental temperatures best suited for occupants. The first scientific approach to this question was framed in terms of optimising occupant thermal comfort, commonly expressed as a U-function, symmetrical around a single optimum temperature for any given combination of the remaining comfort parameters (ISO, 2005). The inescapable conclusion drawn from such logic in the minds of risk-averse design engineers is that the only strategy able to reliably deliver occupant comfort is HVAC applied to sealed-façade architecture. A rigorous scientific rebuttal of the “single temperature optimum” model of comfort came 30 years after PMV/PPD was first floated (e.g. de Dear and Brager, 1998; 2001). Known as the adaptive comfort model, a clear implication is that passive design solutions are capable of delivering comfortable internal environments across a broad swathe of climate zones, throughout most if not all of the year. But recently the “single temperature optimum” model has resurfaced, this time with its justification shifting away from the thermal comfort requirements of occupants towards their cognitive performance. Beyond the building science domain, in disciplines such as psychology and ergonomics, the prevailing wisdom regarding temperature effects on cognitive performance is an extended-U rather than an inverted U function. The gist of the model is that cognitive performance is relatively stable throughout the moderate temperature range, but it rapidly deteriorates at the boundaries of thermal acceptability where stress drains the performers’ attentional resources. The extended-U model has garnered broad acceptance across a range of disciplines with the notable exception of HVAC engineering and indoor air sciences. But the weight of research evidence tends to support the extended- rather than inverted-U model. In this paper the arguments regarding thermal effects on cognitive performance are critically evaluated

Nudging the adaptive thermal comfort model

The recent release of the largest database of thermal comfort field studies (ASHRAE Global Thermal Comfort Database II) presents an opportunity to perform a quality assurance exercise on the first generation adaptive comfort standards (ASHRAE 55 and EN15251). The analytical procedure used to develop the ASHRAE 55 adaptive standard was replicated on 60,321 comfort questionnaire records with accompanying measurement data. Results validated the standard's current adaptive comfort model for naturally ventilated buildings, while suggesting several potential nudges relating to the adaptive comfort standards, adaptive comfort theory, and building operational strategies. Adaptive comfort effects were observed in all regions represented in the new global database, but the neutral (comfort) temperatures in the Asian subset trended 1–2°C higher than in Western countries. Moreover, sufficient data allowed the development of an adaptive model for mixed-mode buildings that closely aligned to the naturally ventilated counterpart. We present evidence that adaptive comfort processes are relevant to the occupants of all buildings, including those that are air conditioned, as the thermal environmental exposures driving adaptation occur indoors where we spend most of our time. This suggests significant opportunity to transition air conditioning practice into the adaptive framework by programming synoptic- and seasonal-scale set-point nudging into building automation systems

Theory of Attractive Quality: Occupant satisfaction with indoor environmental quality at workplaces

To improve employees’ comfort, health and productivity, indoor environmental quality (IEQ) is one of the most significant aspects of concern in the workplace. In future office buildings, IEQ is not only to meet the basic requirement of hygiene and physiological needs but also to motivate and lift occupants’ satisfaction. This chapter will introduce the attractive quality theory as well as the Kano model and its application in the field of indoor environment science on occupant satisfaction with IEQ and the research methods at workplaces. The chapter will also discuss the limitation of the theory and future research needs to utilise and verify the Kano model

UTCI - why another thermal index?

Existing procedures for the assessment of the thermal environment in the fields of public weather services, public health systems, precautionary planning, urban design, tourism and recreation and climate impact research exhibit significant shortcomings. This is most evident for simple (mostly two-parameter) indices, when comparing them to complete heat budget models developed since the 1960s. ISB Commission 6 took up the idea of developing a Universal Thermal Climate Index (UTCI) based on the most advanced multi-node model of thermoregulation representing progress in science within the last three to four decades, both in thermophysiological and heat exchange theory. Creating the essential research synergies for the development of UTCI required pooling the resources of multidisciplinary experts in the fields of thermal physiology, mathematical modelling, occupational medicine, meteorological data handling (in particular radiation modelling) and application development in a network. It was possible to extend the expertise of ISB Commission 6 substantially by COST (a European programme promoting Cooperation in Science and Technology) Action 730 so that finally over 45 scientists from 23 countries (Australia, Canada, Israel, several Europe countries, New Zealand, and the United States) worked together. The work was performed under the umbrella of theWMO Commission on Climatology (CCl). After extensive evaluations, Fiala’s multi-node human physiology and thermal comfort model (FPC) was adopted for this study. The model was validated extensively, applying as yet unused data from other research groups, and extended for the purposes of the project. This model was coupled with a state-of-the-art clothing model taking into consideration behavioural adaptation of clothing insulation by the general urban population in response to actual environmental temperature. UTCI was then derived conceptually as an equivalent temperature (ET). Thus, for any combination of air temperature, wind, radiation, and humidity (stress), UTCI is defined as the isothermal air temperature of the reference condition that would elicit the same dynamic response (strain) of the physiological model. As UTCI is based on contemporary science its use will standardise applications in the major fields of human biometeorology, thus making research results comparable and physiologically relevant

Ventilation mode effect on thermal comfort in a mixed mode building

Between 2017 and 2018, we conducted a longitudinal field experiment in a mixed-mode ventilation building located in Wollongong Australia, with a particular focus on occupant thermal comfort and adaptive behaviour. This study investigated how different building operation modes i.e. air-conditioning (AC) and natural ventilation (NV), can have an impact on occupant perception of thermal comfort. Time-And-place matching of objective (physically measured indoor climate parameters, outdoor meteorological data, and building operational information) and subjective data (i.e. occupant survey questionnaires) enabled empirical investigation of the relationships between those parameters. The result of the analysis revealed that subjective perception of indoor thermal environment can be affected by different modes of building operation. Occupants were found to be more tolerant of, or adaptive to, the indoor thermal conditions when the building was in the NV mode of operation compared to the AC operational mode. The applicability of the adaptive comfort standard to the mixed-mode ventilation context was also discussed

Applying the adaptive model of comfort

This note is directed to one major aspect of the comfort of building occupants &ndash; namely, thermal comfort. Even though it may be difficult to isolate thermal sensations from the whole of comfort itself, humans have a strong physiological connection with their thermal environment. Our thermal perceptions and sensations often vary greatly, especially between our indoor and outdoor environments. We may be totally comfortable lounging under a shade cloth on a 35&deg;C day with a stiff breeze enveloping our body, but would never tolerate similar conditions indoors. Such divergent perceptions of the same thermal stimulus across differing contexts raise countless questions about just what the determinants of thermal comfort actually are, and how they may be managed against the demands for an environmentally responsive architecture. <br /

Reliability and repeatability of ISO 3382-3 metrics based on repeated acoustic measurements in open-plan offices

This paper investigates variability in the key ISO 3382-3:2012 metrics, based primarily on the repeatability and reliability of these metrics, using repeated measurements in open-plan offices. Two types of repeated measurements were performed in offices, Type1 (n=36), where the same path over workstations was measured from opposite ends, and Type2 (n=7), where two different measurement paths were measured. Overall, most of the Type1 results seem reasonable considering repeats were conducted in complicated room acoustic environments, while Type2 repeats would benefit from larger sample sizes in future studies. Some recommendations are outlined for the ISO 3382-3 methodology vis-a-vis Type1 and Type2 repeats, including future research directions that go beyond increased sample sizes. (This is an abridged version of the abstract. Please see the paper for the full abstract

Aplicabilidade dos limites da velocidade do ar para efeito de conforto térmico em climas quentes e úmidos

Este trabalho discute os limites dados para a velocidade do ar pelas normas ASHRAE 55 (2004) e ISO 7730 (2005). Para tal, realizou-se uma análise comparativa entre os valores-limite para a velocidade do ar definidos por essas normas e as respostas dos usuários em relação à preferência e aceitabilidade do movimento do ar obtidas em experimentos de campo realizados em Maceió/AL. Resultados indicam que ambas as normas especificam valores para a velocidade do ar inferiores aos desejados pelos usuários. Os resultados da preferência do movimento do ar indicam que significativa percentagem dos usuários demanda “maior movimento do ar”. Quando associada às respostas da aceitabilidade do movimento do ar, a insatisfação dos usuários ficou mais evidente, assim como a demanda por maior velocidade do ar. O mesmo movimento de ar, considerado como inaceitável em climas frios e temperados, é desejado pelos usuários em climas úmidos. Nesse contexto, a aplicabilidade de limites máximos para a velocidade do ar provenientes de estudos com características climáticas diferentes deve ser evitada. Tais limites devem vir de resultados de experimentos de campo em ambientes naturalmente ventilados, onde os usuários possam utilizar de oportunidades adaptativas para reestabelecer o conforto térmico. Futuras normas brasileiras devem focar em tais questões, visando limites de velocidade que correspondam à expectativa dos usuários em climas quentes e úmidos

Validation of the Fiala multi-node thermophysiological model for UTCI application

The important requirement that COST Action 730 demanded of the physiological model to be used for the Universal Thermal Climate Index (UTCI) was its capability of accurate simulation of human thermophysiological responses across a wide range of relevant environmental conditions, such as conditions corresponding to the selection of all habitable climates and their seasonal changes, and transient conditions representing the temporal variation of outdoor conditions. In the first part of this study, available heat budget/two-node models and multi-node thermophysiological models were evaluated by direct comparison over a wide spectrum of climatic conditions. The UTCI-Fiala model predicted most reliably the average human thermal response, as shown by least deviations from physiologically plausible responses when compared to other models. In the second part of the study, this model was subjected to extensive validation using the results of human subject experiments for a range of relevant (steady-state and transient) environmental conditions. The UTCI-Fiala multi-node model proved its ability to predict adequately the human physiological response for a variety of moderate and extreme conditions represented in the COST 730 database. The mean skin and core temperatures were predicted with average root-mean-square deviations of 1.35 ± 1.00°C and 0.32 ± 0.20°C, respectivel

Validation of the Fiala multi-node thermophysiological model for UTCI application

The important requirement that COST Action 730 demanded of the physiological model to be used for the Universal Thermal Climate Index was its capability of accurate simulation of the human thermophysiological responses across a wide range of relevant environmental conditions, such as conditions corresponding to the selection of all habitable climates and their seasonal changes, and transient conditions representing temporal variation of outdoor conditions. In the first part of this study available heat budget/two-node models and multi-node thermophysiological models were evaluated by direct comparison over the wide spectrum of climatic conditions. The UTCI-Fiala model predicted most reliably the average human thermal response which was showed by least deviations from physiologically plausible responses when compared to other models. In the second part of the study, this model was, therefore, subjected to extensive validation using results of human subject experiments for a range of relevant (steady-state and transient) environmental conditions. The UTCI-Fiala multi-node model proved its ability to predict adequately the human physiological response for a variety of moderate and extreme conditions represented in the COST 730 database. The mean skin and core temperatures were predicted with average root-meansquare deviations of 1.35 ± 1.00 °C and 0.32 ± 0.20 °C, respectively