Search Results (9)

This paper considers microclimate to be one of the main contributors to thermal comfort in educational buildings. The influence of microclimate on well-being and productivity is considered. The role of microclimatic parameters is assessed from the perspective of building design, focusing on approaches to regulating these parameters. We also describe the formation of microclimate and the factors directly affecting it. The state of the microclimate of classrooms of an educational institution was analyzed, providing estimates of people’s real thermal sensations. The microclimate was assessed by the Fanger method. The PMV and PPD comfort indices were calculated for this purpose. The calculations were carried out thrice, i.e., based on the data obtained by using measuring equipment, based on the data from the survey and based on a SolidWorks model. Calculations in the program were carried out to validate the measured values and visualize the process of the distribution and localization of comfort indices. The results confirm that the indoor microclimate was generally favorable, and the PMV values obtained from the survey of people’s real sensations of thermal comfort were higher than the calculated PMV values. It was established that the PMV and PPD values corresponding to the largest deviations from the norm were as follows: −0.74/17% (PMV/PPD) for the calculation based on the real values of microclimatic parameters and 0.70/15.3% (PMV/PPD) for the calculation based on people’s thermal sensations. For applying the Fanger method for thermal comfort analysis in an educational institution in St. Petersburg, we upgraded the procedure, introducing a questionnaire survey. The mean PMV values calculated by the Fanger method were 0.16 lower than the PMV values obtained by the survey. Full article

With the growing interest in radiant heating and cooling systems, driven by their improved efficiency and enhanced thermal comfort compared to air systems, there is an increasing need to develop a more accessible method for designers to understand the implications of radiation heat exchange between the human body and radiant panels. To address this, a novel angle factor calculation model, named the HNU Angle Factor Model, was developed, taking into account the spatial arrangement and geometric relationship between the human body and radiant panels. The angle factors obtained using the HNU Angle Factor Model exhibited good agreement with the results obtained with Fanger diagrams and the contour integral method, with average relative differences of 8.1% and 10.0% for 140 cases, respectively. Furthermore, placing a radiant panel on the floor while maintaining its fixed size can contribute to the creation of an even and efficient thermal environment for individuals in both seated and standing positions. By implementing the HNU Angle Factor Model in practical engineering applications, more effective utilization of radiant systems can be achieved, as it provides an evaluation of the heat transfer between the human body and radiant panels. Full article

Heating, ventilation, and air conditioning (HVAC) system performance research has received much attention in recent years. Many researchers suggest a set of appropriate fuzzy inputs that can be used to design fuzzy rules-based smart thermostats or controllers that can respond to demand-controlled ventilation, which in turn optimizes HVAC energy usage and provides satisfactory indoor temperatures. Previous research has focused on limited input parameters, such as indoor occupancy status, ambient temperature, and humidity constraints, which cannot efficiently and precisely manage thermal comfort. Hence, this study proposes a novel fuzzy controller with additional input parameters to keep indoor thermal comfort consistent with the corresponding number of occupants. The process employs an automatic fuzzy rule generation method to simplify the task of generating rules in the fuzzy inference system (FIS) using Mamdani FIS. A design-builder is used for modeling the HVAC systems. Local weather data were used to conduct simulations via EnergyPlus. The thermal comfort analysis using the Fanger model for three different scenarios shows that the proposed FIS controller can successfully respond to the indoor comfort variation in all possible scenarios and ensure a satisfactory comfort level. The proposed method demonstrates up to 50% energy savings if occupants do not worry about comfort. Full article

This research explores the energy behaviour of a traditional house on the Mediterranean coast of south-eastern Spain. The objective of the work is to determine the optimal passive strategies for rehabilitating a traditional house, improving its energy savings and comfort, considering the characteristics of the warm semi-arid Mediterranean climate. The main novelty of this article is that it demonstrates that the limits imposed by current regulations, based on globalised climate strategy approaches, undermine the energy efficiency capacity that passive solutions in vernacular architecture already employed. The methodology used consists of a systematised multi-objective study of various energy rehabilitation strategies. Four strategies were studied: raising the thermal insulation of enclosures, improving thermal insulation and solar control glazing with movable shading devices, increasing the size of windows and introducing the use of natural ventilation enhanced by ceiling fans. The results show that simultaneous improvement of these parameters reduces cooling and heating requirements by up to 87%, reducing the energy consumption of air conditioning systems. Indoor temperatures are also maintained within the comfort limits set by regulations for 91% of hours per year without the need for air conditioning systems. This results in a passive energy-efficient and comfortable house almost all year round. This work offers an alternative solution to the comfort standards of current Spanish regulations and demonstrates the need to adapt Fanger’s analytical method for comfort estimation. The research concludes that the comfort criteria of current energy regulations should be modified to better adapt the design criteria to the dry Mediterranean climate. Full article

Since P.O. Fanger proposed PMV, it has been the most widely used index to estimate thermal comfort. However, in some cases, it is challenging to measure all six parameters within indoor spaces, which are essential for PMV estimation; a couple of parameters, such as Clo or Met, tend to show a large deviation in accuracy. For these reasons, several studies have suggested methods to estimate PMV but their accuracies were significantly compromised. In this vein, this study proposed a way to reduce the dimensions of parameters for PMV prediction utilizing the machine learning method, in order to provide fast PMV calculations without compromising its prediction accuracy. Throughout this study, the most influential features for PMV were pinpointed using PCA, Best Subset, and the Gini Importance, with each model compared to the others. The results showed that PCA and ANN achieved the highest accuracy of 89.70%, and the combination of Best Subset and Random Forest showed the fastest prediction performance among all. Full article

The number of migrants increases globally due to natural disasters, global warming, and war conflicts. Inefficient and unsustainable construction approaches for migrant shelters have resulted from improper planning and design systems regarding lifespan, materials and techniques, and socio-cultural aspects. Therefore, the study aim has an incentive to assess the impact of the morphological, siting, and layout of zones and shelters for the long-term displacement prototypes considering sustainability concepts from social context, affordability, adaptability, low-impact construction materials, and techniques. Furthermore, applying the dynamic simulation IDA ICE 4.8 tool was cardinal to justify the comprehensive reported outcomes based on the bottom-up construction method after assessing energy and thermal comfort performance in seven cases. The energy performance assessment regarding heating reveals the superiority of the compact layout plan system, while the open-layout plan system is superior for electric cooling assessment. Concerning thermal comfort performance for the number of accepted hours category, the open-layout plan system is superior. Fanger indicators for thermal comfort assessment demonstrated the superiority of the horizontal-compact layout plan scheme. The carbon dioxide (CO₂) concentration level assessment shows that the open-yard layout cases have better results than other systems. To conclude, sustainable prototypes for displaced people should involve several aspects such as lifespan, socio-cultural and affordability, thermal performance and energy-efficient, and environmental impact. The beneficiaries from the methods and the results of this study would be firstly the Syrian refugees in the Middle East context, then various places and involved people affected by the displacement issue globally. Full article

The concept of the mean radiant temperature (T_mrt) allows the study of radiative exchanges between a human and its environment. It presupposes that the radiant effects on the person of the actual environment, which is generally heterogeneous, and the virtual environment, which is defined as homogeneous, are identical. ISO 7726 specifies the required accuracy in T_mrt as input of rational thermal indices, outdoors ±5 (K). T_mrt accounts for the radiant heat absorbed by skin/clothing from the shortwave (SW) and longwave (LW) spectral bands. Most of the radiant components are isotropic. However, there are anisotropic SW components; namely the direct irradiance and under clear or partly obstructed skies a significant circumsolar fraction (f_cs) in the diffuse irradiance. Both originate from the close proximity of the solar disk. This study highlights the effect of f_cs on T_mrt. In the scope of human biometeorology a standing body posture is standard. For unidirectional irradiances its radiant cross-section varies dependent on the solar altitude. Active radiometry in deriving T_mrt is based on measured irradiances. One method is the Klima-Michel-Modell (KMM) that uses readily available measurements from standard meteorologically radiant observations. KMM references Fanger’s area projection factors that are derived from precise measurements of real humans. Thus, KMM serves as reference in evaluation of further methods. One is the six-directional instrument (T_{mrt,r,6−Dir}). Slightly simplifying a standing human, it represents a subject as a rectangular solid. T_{mrt,r,6−Dir} is derived based on measured irradiances incident on the vertical and horizontal planes. In passive radiometry the energy balance equation of a black globe thermometer is solved that leads to T_mrt,Tg,BG. f_cs significantly impacts T_mrt with noticeably reduced values for high and increased for low solar altitudes. Hence, accounting for f_cs is essential for the accuracy of T_mrt. For KMM an extension to an existing algorithm is provided in order to include f_cs into the T_mrt calculation that results in T_mrt,r,KMM. For T_{mrt,r,6−Dir} the radiant cross-section of the solid depends to a minor extent on its azimuth relative to the solar azimuth. As a result T_{mrt,r,6−Dir} slightly scatters compared to T_mrt,r,KMM. However, it remains within ±2 (K). T_mrt,Tg,BG compared to T_mrt,r,KMM complies only at night with the ISO 7726 bin of ±5 K. T_mrt,Tg,BG significantly overestimates T_mrt,r,KMM during the daytime, because of its greater SW absorptance compared to skin/clothing and to a smaller extent because the standing posture is represented by a sphere. Particularly in sunny conditions, T_mrt,Tg,BG is subject to considerable variance. Thus, outdoors during the daytime, T_mrt,Tg,BG is unable to serve as an appropriate input for the calculation of rational-based thermal indices. Full article

For evaluating the thermal comfort of occupants, human factors such as clothing thermal insulation (clo level) and metabolic rate (Met) are one of the important parameters as well as environmental factors such as air temperature (Ta) and humidity. In general, a fixed clo level is commonly used for controlling heating, ventilation, and air conditioning using the thermal comfort index. However, a fixed clo level can lead to errors for estimating the thermal comfort of occupants, because clo levels of occupants can vary with time and by season. The present study assesses a method for predicting the clo level of occupants using a thermoregulation model and an infrared (IR) camera. The Tanabe model and the Fanger model were used as the thermoregulation models, and the predicted performance for high clo level (winter clothing) was compared. The skin and clothing temperatures of eight subjects using a non-contact IR camera were measured in a climate chamber. In addition, the measured values were used for the thermoregulation models to predict the clo levels. As a result, the Tanabe model showed a better performance than the Fanger model for predicting clo levels. In addition, all models tended to predict a clo level higher than the traditional method. Full article

Designing and constructing near zero energy buildings (NZEBs) is a challenge not only from a structural point of view, but also from the point of view of ensuring appropriate climate comfort for users. The standards describing how to ensure comfort were created in times when the challenges of building ZEB/NZEB were not yet explored and energy issues were not as important as they are today. Therefore, the assessment of the thermal and climatic comfort of people living and working in such buildings requires a new or revised approach to the methodology of thermal comfort assessment. In this article, the authors present the results of a thermal comfort study based on measurements and thermal sensory tests. Testing was carried out in an experimental office building (passive standard). The main goal of the experiment was to compare the thermal comfort measurement method based on the ISO-Fanger model with the actual comfort results obtained by the panellists in the model office condition. The tests allowed the lowest operating temperature providing thermal comfort (predicted mean vote (PMV) = 0 and −0.5) to be determined. Sensory tests were conducted using three types of questions. The results were compared to the other researchers’ findings. It was noted that the panellists showed better thermal comfort sensation at lower temperatures than would result from the traditional Fanger distribution, so the authors proposed the experimental function of percentage of dissatisfied (PPD) = f(PMV). The authors hope that it contributed to the actual state of knowledge as a “small and specific scale” validation of the existing thermal comfort model. The results also revealed that the method of heating has an influence on the subjective thermal sensation. Full article