Search results for "Thermal comfort"
showing 10 items of 68 documents
Indoor Comfort in School Buildings: The Case Study of Palermo
2014
Buildings primary energy consumption in developed countries accounts for about 40% of whole uses. Therefore, the European Union has released many regulations, concerning energy saving issues; particularly, it has enacted Directive 2002/91/EC regarding the energy performance of buildings, and its Recast Directive 2010/31/EU, that promotes the Nearly Zero Energy Building targets, introducing more strict parameters in this aim. Furthermore, the latter Directive asks Member States to include within their national plans measures aimed at supporting public authorities to become early adopters of building energy efficiency improvements. In the same time, Public Authorities should implement effecti…
Measurements of projected areas of seated and standing people of southern Italy based on a statistical analysis
2006
One of the most important components affecting the human thermal balance is represented by its radiative exchange with the surrounding surfaces. The projected area of the human body is an important parameter of these thermal exchanges. Unfortunately, although the anthropometric measures of people are characterized by significant differences among various populations, the experimental data currently available in the literature refers to a small group of people. Moreover, measurements are generally performed regardless of the statistical significance of the involved subjects with respect to the population to which they belong. In this study, a statistical study is introduced that is based on …
Multiobjective optimization of building energy consumption and thermal comfort based on integrated BIM framework with machine learning-NSGA II
2022
Detailed parametric analysis and measurements are required to reduce building energy usage while maintaining acceptable thermal conditions. This research suggested a system that combines Building Information Modeling (BIM), machine learning, and the non-dominated sorting genetic algorithm-II (NSGA II) to investigate the impact of building factors on energy usage and find the optimal design. A plugin is developed to receive sensor data and export all necessary information from BIM to MSSQL and Excel. The BIM model was imported to IDA Indoor Climate and Energy (IDA ICE) to execute an energy consumption simulation and then a pairwise test to produce the sample data set. To study the data set a…
A generalized model of human body radiative heat exchanges for optimal design of indoor thermal comfort conditions
2018
Abstract Human thermal sensation depends heavily on radiative exchanges between the human body and the surrounding environment. Because these exchanges play a crucial role in the thermal balance of the human body, about 35% of the process, human thermal sensation should draw the attention of planners when designing both indoor environments and equipment. The present study aims to contribute to this field by proposing a procedure for delineating the optimal comfort conditions for occupants in most of the articulate and realistic configurations of actual indoor environments. Specifically, this procedure enables accurate assessment of the radiant field surrounding a subject in a given indoor r…
A Proposed Methodology to Control Body Temperature in Patients at Risk of Hypothermia by means of Active Rewarming Systems
2014
Hypothermia is a common complication in patients undergoing surgery under general anesthesia. It has been noted that, during the first hour of surgery, the patient’s internal temperature (Tcore) decreases by 0.5–1.5°C due to the vasodilatory effect of anesthetic gases, which affect the body’s thermoregulatory system by inhibiting vasoconstriction. Thus a continuous check on patient temperature must be carried out. The currently most used methods to avoid hypothermia are based on passive systems (such as blankets reducing body heat loss) and on active ones (thermal blankets, electric or hot-water mattresses, forced hot air, warming lamps, etc.). Within a broader research upon the environment…
The calculation of the mean radiant temperature of a subject exposed to the solar radiation – A generalised algorithm
2005
Abstract The thermal sensation experienced by a subject in a confined environment is significantly affected by the radiative heat exchange between the human body and the surrounding surfaces: it contributes as far as 30% of the whole thermal exchanges of the subject. Besides, the presence of high-intensity radiation sources like, for example, the sun, may appreciably modify the radiant field to which people are exposed. As a consequence, this could alter notably the comfort conditions. In order of properly taking into account this issue, a simple analytical method is introduced in this work, that allows the easy evaluation of the thermal radiant field induced by the presence of the solar ra…
The spatial evaluation of the radiative human body heat exchanges: An effective contribution for limiting energy consumption and achieving better ind…
2018
Abstract Radiative heat exchanges inside buildings remarkably affect the thermal balance of the human body in confined spaces and the related thermal comfort sensations of people. The mean radiant temperature is an important component of this balance. Unfortunately, it is usually computed by means of too simplified relationships, which significantly influence the comfort evaluations. Such simplified approaches are also accountable for a less effective design of HVAC systems which, in turn, could result in high energy consumption in the climatization of buildings. However, an accurate evaluation of the mean radiant temperature, especially when high intensity sources are present in a given in…
Algorithms for the calculation of the projected area factors of seated and standing persons
1991
Moderate thermal environments, other than being affected by the mutual radiative heat exchange at low frequency among the internal surfaces, are often characterized by the presence of high intensity sources, that is, radiant sources showing a small area, a high emission temperature and a strongly directional beam. The sun's direct radiation can be considered to be among these radiant sources. In these cases, the computation of the mean radiant temperature and, consequently, the evaluation of the thermal comfort conditions, require knowledge of the “project area factor”, fp, of the subject. Moreover, the fp parameters are also applicable to derivation of the shape factors between subjects an…
Fifty Years of PMV Model: Reliability, Implementation and Design of Software for Its Calculation
2019
In most countries, PMV is the reference index for the assessment of thermal comfort conditions in mechanically conditioned environments. It is also the basis to settle input values of the operative temperature for heating and cooling load calculations, sizing of equipment, and energy calculations according to EN 16798-1 and 16798-2 Standards. Over the years, great effort has been spent to study the reliability of PMV, whereas few investigations were addressed to its calculation. To study this issue, the most significant apps devoted to its calculation have been compared with a reference software compliant with EN ISO 7730 and the well-known ASHRAE Thermal Comfort Tool. It has been revealed …
Energy Performance and Indoor Comfort of a 1930s Italian School Building: A case study
2021
Reducing energy consumption in the building tertiary sector, which accounts for a big share of the total energy use (and related CO 2 emissions) at European and Italian level, represent a strong element of safety for the EU-28. On the other hand, it is important to improve the, often overlooked, indoor comfort conditions of Italian schools since they have a significant impact on the well-being, productivity, health and safety of their occupants. Thus, it is appropriate to take into account the combination of both needs, also in light of the climate change scenario, in order to identify adequate improvement measures and justify such economic investment. This paper brings a contribution to th…