INVESTIGATION OF THE THERMAL COMFORT AND PRODUCTIVITY IN JAPANESE MIXED-MODE OFFICE BUILDINGS

This study investigates the overall comfort and productivity of Japanese office workers in mixed-mode office buildings. The indoor thermal environment is adjusted using the air-conditioning in Japanese office buildings to maintain thermal comfort and productivity. Thus, it is necessary to research thermal comfort and productivity to understand how occupants prepare themselves to be at a comfortable temperature and perform their daily tasks under mixed-mode (MM) and free-running (FR) modes. Environmental parameters such as air temperature, relative humidity, and so on were measured in 17 Japanese office buildings with the help of digital instruments, and thermal comfort transverse surveys were conducted for two years in Tokyo, Yokohama, and Odawara of Japan. The data were collected every once a month for a day visiting each building with the measurement instruments, together with the questionnaires. Almost 3000 votes were collected. This paper evaluates the overall comfort discussions followed by how the occupant could achieve their productivity. The occupants were found to be thermally comfortable and productive in the office. The most suitable comfortable temperature range for MM mode was found to be 22–26 °C and 23–25 °C for FR mode. The workers' productivity range is defined by the globe temperature range of 21–27 °C for MM and 20–27 °C for FR mode. The findings should be useful to suggest that whenever new office buildings are designed, these factors always need to be taken into consideration

The range and shape of thermal comfort and resilience

The adaptive approach to thermal comfort shows that there is not a single comfortable temperature. A wide range of the temperatures which occur in indoor environments can be found acceptable to building occupants depending on their individual experiences and circumstances. This paper extends the approach introduced in a recent paper [1] to learn the lessons which can be drawn by looking in detail at the relationship between indoor and outdoor temperatures in buildings. By reviewing the records of indoor and outdoor temperatures from field surveys in a variety of climates and cultures, the paper explores the limits to the acceptable indoor temperature range, and its relationship to the concurrent outdoor temperature. In doing this the paper builds on past findings adding some related lessons derived from surveys from many parts of the world – especially Japan, Pakistan, Nepal and Europe. The ways in which the shape of a cloud can be interrogated are explored as well as the effect of emergencies on the range of acceptable temperatures in buildings

Field Survey of Thermal Comfort and Sleep Quality in the Bedrooms with Different Cooling Strategies in Malaysia

This study aims to determine the indoor comfort temperature before sleep and after wake up in air-conditioning (AC) mode with different adaptive cooling strategies. Two units of guest rooms on the university campus were used with a total of 20 participants. The arbitrary-controlled AC setting (case 1) and control of thermostat setting by 3∘C higher than case 1 with installing of cool bed padding (case 2) were employed as cooling strategies in this study. The measurement parameters were indoor and outdoor air temperatures, globe temperature, relative humidity, air velocity, and AC electricity consumption. The questionnaire survey has also been distributed twice a day for “before going to bed” and “after waking up” during measurement simultaneously. It was observed that thermal sensation vote (TSV) indicated for both cases were within -1 ≤ TSV ≤ 1 and respondents might accept the present condition for both cases. Mean thermal preference (TP) in both cases either “before going to bed” and “after waking up” was found mostly close to “0 no change” (0.1 ≤ TP ≤ 0.3) for all cases. Overall comfort (OC) ranged between 4.7 and 4.9 for both cases, indicating for “comfortable.” However, air movement sensation (AMS) shows respondent felt weak airflow inside the room for all ventilation strategies. The skin moisture sensation (SMS) shows value pointed to neutral feeling for all cases. The comfort temperature obtained by Griffiths’ method was approximately 24∘C and 25∘C that for case 1 and case 2, respectively. Meanwhile, most of the respondents experienced calmness during sleeping and satisfied with their sleep in both cases. Sleep efficiency index (SEI) shows case 2 was higher rather than case 1. It seems the second adaptive cooling strategy might effective for reducing AC energy consumption by about 32% and increase 2% of SEI without affecting respondents’ thermal comfort.     Keywords: thermal comfort, sleep quality, air-conditionin

Investigation of Indoor Thermal Environments in a Two-Story Corner Terrace House in Malaysia

An effective passive cooling strategy is essential for reducing energy consumption in a residential building without ignoring thermal comfort. Therefore, a field measurement on the thermal performance of a corner terrace house in Kuala Lumpur was conducted to reveal the effectiveness of free running (FR) with four different approaches – no ventilation, full ventilation, day ventilation, and night ventilation. The measurement was done for all bedrooms and family area on the first floor. Also, mixed mode (MM) consisting of natural ventilation, mechanical ventilation with ceiling fan, and cooling with an air-conditioner that represents the actual condition of this house was also measured at living and dining area on the ground floor for comparison. The results reveal that FR from all approaches recorded a mean indoor air temperature of approximately 31 ∘C. The actual thermal condition of the house with MM on the ground floor was recorded at 30 ∘C, 1 ∘C lower than FR approach on the first floor. When compared with relevant international standards on predicting indoor comfort temperature based on outdoor temperature, FR was approximately 5 ∘C higher than predicted temperature based on American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 55 (2017), 3.4 ∘C higher than European Standard EN15251 and 1.5 ∘C higher than adaptive thermal comfort equation (ACE) for hot-humid climate. In comparison, MM performed better and was closer to relevant international standards, especially ACE for the hot-humid climate. As a conclusion, FR is not suitable for a hot-humid climate such as Malaysia to achieve a comfortable indoor thermal environment without any assisted ventilation use in MM

Comfort temperature in air conditioned office buildings: case study of Indonesia and Singapore

Air-conditioning system has been a basic feature in many office buildings, especially in tropical climate where buildings are exposed to solar radiation all year round. However, air conditioning is a leading source of energy consumption. Efficient energy consumption is highly desirable for commercial, for-profit entities occupying offices. A field study in two countries; Indonesia and Singapore, has been conducted to investigate office building occupants’ thermal comfort. In 2015, questionnaire survey as well as physical parameter measurements were collected from each country. Analysis shows that occupants of air-conditioned building with window-opening behaviour has higher comfort temperature, compared to cooling mode only. The results of this study could be used to better understand comfort temperature in tropical countries

Investigation of Thermal Comfort at Different Temperature Settings for Cooling in University Building / Mohd Sabri Mustapa ...[et al.]

This paper presented the results of a study conducted on thermal comfort in a postgraduate office of the Malaysia Japan International Institute of Technology (MJIIT, UTM, Kuala Lumpur). The aim of the study was to verify the thermal comfort associated with different air conditioning (AC) thermostat set point temperatures in the cooling (CL) mode. The relevant temperature set points were 20 °C, 24 °C, and 28 °C, as well as the Japanese so-called 'cool biz mode' set point of 28 °C. The thermal sensation vote (TSV) in relation to these CL modes were –0.4, 0.0, 0.8, and –0.1, respectively. These results indicated that at the CL mode of 28 °C, the occupants felt slightly warmer compared to the CL modes of 20 °C, 24 °C, and the cool biz mode. The results of the linear regression analysis indicated the thermal comfort range as 25.3 °C to 26.2 °C, which was close to the range of 25.6 °C to 26.1 °C indicated by employing Griffiths' method

Investigation of thermal adaptation and development of an adaptive model under various cooling temperature settings for students’ activity rooms in a university building in malaysia

The use of an air conditioner (AC) becomes essential, particularly in a hot and humid climate, to provide a comfortable environment for human activities. The setpoint is the agreed temperature that the building will meet, and the use of the lowest setpoint temperature to accelerate the cooling of indoor spaces should be avoided. A comprehensive field study was conducted under various cooling temperature settings in two student activity rooms in a university building in Malaysia, so as to understand respondents’ characteristics and behavior toward AC usage, to estimate the comfort at various indoor temperatures, to develop an adaptive model of thermal comfort in AC spaces, and to compare the comfort temperature with related local and international indoor thermal environmental standards. The findings indicated that water intake and clothing insulation affected personal thermal comfort. Moreover, the mean comfort temperature for respondents was 24.3 °C, which is within an indoor thermal comfort zone of 23–27 °C. The findings suggest that the preference of occupants living in a hot and humid region for lower temperatures means that setting temperatures lower than 24 °C might underestimate the indoor comfort temperature. Additionally, an adaptive relationship can be derived to estimate the indoor comfort temperature from the prevailing outdoor temperature

Considering the impact of situation-specific motivations and constraints in the design of naturally ventilated and hybrid buildings

A simple logical model of the interaction between a building and its occupants is presented based on the principle that if free to do so, people will adjust their posture, clothing or available building controls (windows, blinds, doors, fans, and thermostats) with the aim of achieving or restoring comfort and reducing discomfort. These adjustments are related to building design in two ways: first the freedom to adjust depends on the availability and ease-of-use of control options; second the use of controls affects building comfort and energy performance. Hence it is essential that these interactions are considered in the design process. The model captures occupant use of controls in response to thermal stimuli (too warm, too cold etc.) and non-thermal stimuli (e.g. desire for fresh air). The situation-specific motivations and constraints on control use are represented through trigger temperatures at which control actions occur, motivations are included as negative constraints and incorporated into a single constraint value describing the specifics of each situation. The values of constraints are quantified for a range of existing buildings in Europe and Pakistan. The integration of the model within a design flow is proposed and the impact of different levels of constraints demonstrated. It is proposed that to minimise energy use and maximise comfort in naturally ventilated and hybrid buildings the designer should take the following steps: 1. Provide unconstrained low energy adaptive control options where possible, 2. Avoid problems with indoor air quality which provide motivations for excessive ventilation rates, 3. Incorporate situation-specific adaptive behaviour of occupants in design simulations, 4. Analyse the robustness of designs against variations in patterns of use and climate, and 5. Incorporate appropriate comfort standards into the operational building controls (e.g. BEMS)

Determinant Factors of Electricity Consumption for a Malaysian Household Based on a Field Survey

Electricity-saving strategies are an essential solution to overcoming increasing global CO2 emission and electricity consumption problems; therefore, the determinant factors of electricity consumption in households need to be assessed. Most previous studies were conducted in developed countries of subtropical regions that had different household characteristic factors from those in developing countries of tropical regions. A field survey was conducted on electricity consumption for Malaysian households to investigate the factors affecting electricity consumption that focused on technology perspective (building and appliance characteristics) and socioeconomic perspective (socio-demographics and occupant behaviour). To analyse the determinant factors of electricity consumption, direct and indirect questionnaire surveys were conducted from November 2017 to January 2018 among 214 university students. Direct questionnaire surveys were performed in order to obtain general information that is easily answered by respondents. On the other hand, some questions such as electricity consumption and detailed information of appliances must be confirmed by the respondents' parents or other household members through an indirect questionnaire survey. The results from multiple linear regression analyses of the survey responses showed that appliance characteristic factors were the main variables influencing electricity consumption and house characteristics were the least significant. Specifically, air conditioners, fluorescent lamps, and flat-screen TVs emerged as appliances with the most significant effect on electricity consumption. Occupant behaviour factors had a more significant influence than socio-demographic factors. The findings in this study can be used by policymakers to develop electricity-saving strategies in Malaysia

Investigation on Summer Thermal Comfort and Passive Thermal Improvements in Naturally Ventilated Nepalese School Buildings

Students require a comfortable thermal environment for better academic learning and health in general. In Nepal, the majority of school buildings are constructed using local materials, but little consideration is provided to the thermal environment required for comfort. Therefore, this study demonstrates the advantages of using passive design measures through a simulation that can be used either in the early stages or as a retrofit to determine how the building performs in terms of comfort and the thermal environment. First, the thermal environment of school buildings and thermal comfort of students were evaluated through field surveys. Subsequently, a simulation was performed to investigate the operative temperatures in the classroom of a school building in Kathmandu. DesignBuilder software was used to create the base model and the simulated operative temperature was validated using the measured globe temperature. Subsequently, passive strategies, such as natural ventilation, insulation, and thermal mass, were applied and analysed. The field survey showed that the indoor globe and outdoor air temperatures were correlated, and the students perceived a hotter environment and preferred a cooler environment. Within this context, the average comfort temperature was 26.9 °C. The simulation results showed that the operative temperature was reduced to below 27 °C with a maximum reduction of 3.3 °C due to the integrated design impact, which is within the comfortable limit required during school hours. This study helps to design Nepalese school buildings in a better way by considering passive design strategies during architectural design to make classrooms more thermally comfortable