Em climas quentes e úmidos, é sabido que a velocidade do ar exerce um papel importante no conforto, promovendo as trocas térmicas entre nossa pele e o ambiente. Com isso em mente, o objetivo principal deste trabalho é avaliar o efeito de valores elevados de velocidade do ar (0,20-1,35 m/s) no conforto térmico de ocupantes em salas de aula com sistema de condicionamento híbrido (ar condicionado + ventiladores de teto), localizadas em uma região de clima quente e úmido. Para esse fim, questionários foram aplicados em alunos de graduação, simultaneamente às medições instrumentais ambientais (temperatura do ar, umidade relativa, temperatura de globo e velocidade do ar). Os resultados sugerem que, para as condições do experimento e em ambientes condicionados artificialmente, os usuários podem aceitar, e até preferir, a velocidade do ar acima de 0,90 m/s, se associada a valores de temperatura mais elevados (25 a 28 ºC) em climas quentes e úmidos.

The aim of this paper is to identify which method to assess thermal comfort is the most appropriate to be used in hybrid commercial buildings located in hot and humid summer climate. Three methods to assess thermal comfort were analysed: (1) ASHRAE 55 for determining acceptable thermal conditions in occupied spaces, (2) ASHRAE 55 for determining acceptable thermal conditions in naturally ventilated spaces and (3) Givoni's chart for hot and humid climates. Models with two geometries, two room sizes per geometry, two solar orientations and three window areas per model were analysed. Simulations were performed using the EnergyPlus programme, with the TRY climate file of Florianópolis. Thermal comfort was evaluated applying the simulations output data into the three methods. Thus, the amount of time (number of hours per year) in which the use of air-conditioning is necessary to bring thermal comfort for the users throughout the year was determined using each method. Such number of hours of use of air-conditioning was also compared with the pattern of use of air-conditioning observed in Florianópolis. The main conclusion is that the most suitable method for use in hot and humid summer climates is the method proposed by Givoni.

ASHRAE Standard 55 is widely used to assess thermal comfort in buildings worldwide. The main purpose of this paper is to evaluate the adaptive method application proposed by ASHRAE 55 in two different climates in Brazil. This method relates the conditions for comfort to the “prevailing mean outdoor air temperature”. The currently available version of the Standard allows for linear and exponential methods to calculate the “prevailing mean”, and both are tested to establish the acceptability zones. The results indicate that choosing any of the methods to calculate the prevailing mean outdoor air temperature gives similar results when the temperature amplitudes are small; but it can lead to different limits of acceptability, and consequently sum of discomfort hours, when significant day-to-day temperature variations are present. In addition, the results indicate that it is possible to find significant percentages of thermal acceptability from previous studies below the lower limit of acceptability proposed by the Standard. As a result, a “clo adjustment zone” is suggested.

The aim of this paper is to review the literature on human thermal comfort in the built environment. First an overview about the subject area is presented. This is followed by a review of papers published in the last 10 years that examine the various sub-areas of research related to human thermal comfort. Some remarkable works about both the Fanger's and adaptive thermal comfort models are also discussed. This review does not contain simulation works and/or experimental studies without subjective results of people. As a result of the literature review, 466 articles were classified and grouped to form the body of this article. The article examines standards, indoor experiments in controlled environments (climate chamber) and semi-controlled environments, indoor field studies in educational, office, residential and other building types, productivity, human physiological models, outdoor and semi-outdoor field studies. Several research topics are also addressed involving naturally ventilated, air-conditioned and mixed-mode buildings, personalized conditioning systems and the influence of personal (age, weight, gender, thermal history) and environmental (controls, layout, air movement, humidity, among others) variables on thermal comfort.

Currently, there is a rising trend for commercial buildings to use air conditioning to provide indoor thermal comfort. This paper focuses on the impact of prolonged exposure to indoor air-conditioned environments on occupants’ thermal acceptability and preferences in a mixed-mode building in Brazil. Questionnaires were administered while indoor microclimatic measurements were carried out (i.e., air temperature, radiant air temperature, air speed and humidity). Results suggest significant differences in occupants’ thermal acceptability and cooling preferences based on thermal history; differences were found between groups based on different physical characteristics (i.e., different gender and body condition). The findings also indicated a significant potential to implement temperature fluctuations indoors when occupants are exposed to air conditioning environments in warm and humid climates.

Quando se trata de conforto térmico em edificações condicionadas artificialmente, o modelo predicted mean vote/predicted percentage of dissatisfied (PMV/PPD) de Fanger, publicado em 1970, é o mais utilizado para prever e avaliar as condições térmicas internas. Este artigo apresenta dados de conforto térmico levantados em uma edificação de escritórios com sistema central de condicionamento de ar, localizada em Florianópolis, uma cidade de clima subtropical úmido. O objetivo da pesquisa é analisar e comparar os resultados de sensação térmica obtidos em estudos de campo (284 participantes) com os valores calculados de PMV/PPD provenientes do método analítico adotado pela ASHRAE 55 (2013). Questionários eletrônicos foram aplicados simultaneamente às medições das variáveis ambientais (temperatura do ar, umidade relativa, temperatura radiante média e velocidade do ar) durante 2014. Observou-se que, embora 91% dos ocupantes tenham avaliado o ambiente como confortável termicamente, o PPD médio apontou 16% de insatisfeitos termicamente. Constatou-se certa inadequação do modelo ao clima em questão, principalmente quando se considera o restrito intervalo de PMV entre ± 0,50 delimitado como confortável pela ASHRAE 55 (2013).

This paper aims to compare thermal comfort responses from office workers in both fully air-conditioned and mixed-mode buildings against both the analytical and adaptive models of thermal comfort of ASHRAE 55-2013. Occupants were asked to record their thermal perception in questionnaires delivered online while instantaneous instrumental measurements were taken in situ (air temperature, radiant temperature, air velocity and humidity). Three buildings were investigated in a temperate and humid climate, i.e., in Florianópolis, southern Brazil. Two buildings have mixed-mode operation and one building has central air-conditioning. Almost two thousand six hundred questionnaires were collected during field studies. Actual thermal sensation and acceptability votes were compared against two predictive models of thermal comfort: the analytical model and the adaptive model. The 80% and 90% acceptability limits of indoor operative temperature used in the adaptive model were calculated using the prevailing mean outdoor air temperature. The analytical model overestimated the cold sensation of users, mainly for natural ventilation mode, and did not properly predict the percentage of thermal dissatisfaction of users. The analytical model could be used only when air-conditioning is operating; and a wider range of indoor thermal conditions than recommended by ASHRAE 55-2013 is recommended to be adopted during air-conditioning operation. The application of the adaptive model seems to be inappropriate for fully air-conditioned buildings. This work was not conclusive about the use of the adaptive model when the air-conditioning is on in mixed-mode buildings due to few data collected in this mode of operation. Under natural ventilation operation in mixed-mode buildings, occupants adapted to temperature fluctuations as predicted by the adaptive model, however, occupants appear to be more tolerant to cool conditions. The adaptive model may be used in mixed-mode buildings, when the air-conditioning is not on.

This paper addresses thermal comfort conditions in office buildings with rudimentary mixed-mode environments controlled by occupants compared to fully air-conditioning in a humid subtropical climate in Brazil. Occupants from three office buildings with two different environmental control strategies (two with mixed-mode ventilation and one with permanent air-conditioning) assessed their thermal environment via “right-here-right-now” online questionnaires, while indoor climatic measurements were simultaneously carried out in situ. 2688 questionnaires from 617 occupants were collected. The results indicated that air-conditioning in mixed-mode (MM) buildings controlled by occupants was used permanently throughout the year without any season pattern, being specially connected to the peak outdoor air temperature. In addition, there was a strong tendency toward thermal discomfort due to excessive cold in MM buildings at times when air-conditioning mode was under operation, and hot discomfort during the naturally ventilated mode. When compared to fully-air conditioning buildings, there were similarities in terms of occupant thermal sensation and acceptability levels within the same intervals of Standard Effective Temperature (SET). The results obtained in this study could be useful as a framework for future studies, as well as a baseline for a Brazilian thermal comfort standard.

Thermal insulation from clothing is one of the most important input variables used to predict the thermal comfort of a building’s occupants. This paper investigates the clothing pattern in buildings with different configurations located in a temperate and humid climate in Brazil. Occupants of two kinds of buildings (three offices and two university classrooms) assessed their thermal environment through ‘right-here-right-now’ questionnaires, while at the same time indoor climatic measurements were carried out in situ (air temperature and radiant temperature, air speed and humidity). A total of 5,036 votes from 1,161 occupants were collected. Results suggest that the clothing values adopted by occupants inside buildings were influenced by: 1) climate and seasons of the year; 2) different configurations and indoor thermal conditions; and 3) occupants’ age and gender. Significant intergenerational and gender differences were found, which might be explained by differences in metabolic rates and fashion. The results also indicate that there is a great opportunity to exceed the clothing interval of the thermal comfort zones proposed by international standards such as ASHRAE 55 (2013) - 0.5 to 1.0 clo - and thereby save energy from cooling and heating systems, without compromising the occupants’ indoor thermal comfort.

The aim of this paper is to determine the comfort temperature for men and women in two office buildings, one operating under mixed-mode strategy (naturally ventilated and/or air-conditioned) and one fully air-conditioned. Thus, 116 field studies were performed from March 2014 to March 2016 involving 584 participants in two office buildings. In order to collect temperature, relative humidity and air velocity data, microclimate stations were installed in the offices. Data collected were submitted to statistical analysis: they were initially separated according to the type of building (mixed-mode or fully air-conditioned) and operating system, and then they were distributed according to gender. The comfort temperatures were estimated by means of linear regression and by using the Griffiths method. Results show that the Griffiths method is more suitable to express the comfort temperature for men and women. Overall, the comfort temperature was 24.0°C for females, and 23.2°C for males. In the mixed-mode building, comfort temperature was statistically higher for females than that for males (23.7°C and 23.0°C, respectively). In the fully air-conditioned building, significant differences were found for comfort temperature for females and males (24.2°C and 23.4°C, respectively). Furthermore, when the mixed-mode building operated under natural ventilation the comfort temperatures tended to be lower for both men and women when compared to the comfort temperature found in the same building during air-conditioning operation.