Ceiling Heating System Research Articles

Experimental Investigation of Mean Radiant Temperature Trends for a Ground Source Heat Pump-Integrated Radiant Wall and Ceiling Heating System

Mean radiant temperature (MRT) is one of the six primary factors that determine thermal comfort in a given thermal environment. In this study, the average radiant temperature was determined using a calculation method based on the surrounding surface temperatures and view factors. The present study specifically investigated the use of calculated radiant temperature, compared to measured radiant temperature, for predicting the mean vote (PMV) and percentage of dissatisfied (PPD) comfort parameters. The method was validated by the experimental measurements via the black sphere thermometer at five different reference points in a test room, including radiant panels on the ceiling and walls. By using global thermometer measurements, the proposed approach achieved a high degree of compatibility and an accuracy of 0.17 °C, which was the difference between calculated and measured values. The results demonstrated the reliability of the procedure using view factors and surrounding surface temperatures to calculate the radiant temperature in the designated test room; here, a straightforward method for evaluating the thermal conditions of an office room and determining the optimal location of an air temperature sensor in PMV-controlled radiant systems was also proposed. This study contributes to the increasing field of research on thermal comfort and offers knowledge that is beneficial for the design and optimization of indoor environments.

Heating Ceiling System Efficiency in Different Climate Zones

Abstract There are many benefits of building construction with prefabricated thermo active ceilings technology, and the most highlighted are: short lead time, ease of installation, low price, lack of taking up space in a room and additionally the possibility of working in heating and/or cooling mode. An analysis was carried out to illustrate the factors that influence the thermal output of a ceiling heating system in residential buildings located in 5 climate zones in Poland and 2 in Ukraine. The thermal loads were determined for the entire building, designed in accordance with the regulations in force in each country, for the flats and particular rooms (considering the heat exchange between the flats according to PN-EN 12831:2006). An average heating medium temperature of 34°C was assumed. The results were compared with the achievable heating capacity of the ceiling system, which results from the difference between the heating medium temperature and the indoor room temperature. It was investigated that the system achieves the calculated output in all climate zones in Poland, while it will not be sufficient in Ukraine. This is due to both less stringent building thermal protection regulations and different indoor design temperature values, resulting in a higher average temperature in the flat. When analysed on a room-by-room basis, it became apparent that in all considered locations there were rooms for which the heating capacity was insufficient. In the climate zones I to IV in Poland, the problem concerns only bathrooms, where in this case quite often the surface heating can be combined with a supplementary electric radiator. In the V climate zone in Poland and both in Ukraine, the solution to the power shortage under design conditions may be: building construction according to a higher energy standard, increasing the supply temperature (with the limitation of maximum ceiling surface temperature to 35°C for living spaces) or using additional heating elements not only in bathrooms. A novel part of the article discusses calculated power shortages in relation to climate change and the external design temperatures suggested by sources other than the standard.

Influence of the Heating System on the Indoor Environmental Quality—Case Study

This aim of this paper is to explore the specific indoor environmental quality factors under different heating conditions in a meeting room of an administrate building located in Kosice. In terms of thermal comfort, a system with radiant ceiling heating provides more favorable results. Low relative humidity was recorded for both heating systems, which could be due to insufficient air conditioning settings. The results of measuring CO2 concentrations were almost identical for both systems and did not exceed the recommended limit value of 1000 ppm. The increase in CO2 concentrations was mainly related to the presence of employees in the monitored room. On none of the monitoring days, whether in the case of a mechanical heating system or a radiant ceiling heating system, the average 24 h concentration of PM10 did not exceed the legally permissible limit of 50 µg/m3. The presence of selected volatile organic compounds in the room has not been demonstrated due to effective ventilation by air conditioning. The results of the evaluation were comparable and smaller fluctuations in values can be attributed to other factors, such as the presence of persons in the monitoring room or the overall heating as well as ventilation and air conditioning (HVAC) systems.

Experimental study on energy consumption and thermal environment of radiant ceiling heating system for different types of rooms

This paper investigates energy consumption and thermal environment performance of a radiant ceiling heating system serving different types of rooms in the same building. Four types of rooms with different functions, namely restaurant, office, flight control room, and conference room, were chosen in this study. Energy consumption and thermal environment parameters were measured in different rooms, including the heating energy consumption intensity, indoor air temperature, surface temperature of the building envelope, air temperature stratification, and vertical temperature gradient. The results show that the heating energy consumption intensity is about 19.63 W/m2, which is about 30% lower than the heating index recommended in the regional standard. The heating indexes per unit area of the restaurant, office, flight control room, and conference room are 33.41, 17.36, 18.91, and 20.32 W/m2, respectively. The unit volume heating energy consumption of the flight control room, which is a large space, is significantly lower than that of the office, which is a small space. Moreover, there are also differences regarding the indoor thermal environment of the different types of rooms. Factors such as solar radiation, outdoor cold air infiltration, and indoor occupancy rate are the main factors that influence the indoor thermal environment. In general, the energy consumption level of radiant ceiling heating systems for larger spaces is lower, and the indoor thermal environment is better. Therefore, radiant ceiling heating systems are more suitable for larger rooms.

A comprehensive approach to analyze the discrepancies in heat transfer characteristics pertaining to radiant ceiling heating system

Radiant heating/cooling systems are being popular thanks to their ability of regulating the living-environment with the use of low temperature heating and high temperature cooling. In this work, an artificial neural network investigation is carried out to predict heat transfer characteristics over a heated radiant ceiling. Experimental tests consisting of 28 case studies, obtained through varying supply water temperature, are conducted. A computational method, including the Boussinesq approach using k-ɛ RNG model, is also employed to increase the number of case studies in order to use them in artificial neural networks investigation that applies Levenberg-Marquardt training function. Thus, total data number have been increased from 28 to 74 by a simulation software. Estimations of artificial neural networks method are compared with experimental data, and seen that the outputs are compatible with each other, where most of deviations are within the range of ±15%. According to this result, experimental data can be increased by a numerical simulation software and evaluated by one of the artificial intelligence techniques, successfully. In conclusion, the heat transfer coefficients to use in the radiant ceiling heating applications are proposed as 0.9 W/m2 K, 5.3 W/m2 K, and 7.0 W/m2 K for convective, radiative, and total heat transfer coefficients, respectively.

Duty Cycle of a Radiant Ceiling Heating System under Extremely Cold-Temperature Conditions: A Theoretical Assessment

Duty Cycle of a Radiant Ceiling Heating System under Extremely Cold-Temperature Conditions: A Theoretical Assessment

Experimental Evaluation of Radiant Heating Ceiling Systems Based on Thermal Comfort Criteria

Low-temperature radiant heating systems can be considered as suitable candidates for the refurbishment of old heating systems. These systems are proven to save energy, however, their drawback is their impact on the creation of radiant temperature asymmetry and local thermal discomfort, especially in old buildings where the temperatures of surfaces (for example external walls with a low level of insulation and large windows) are low. This study aims to evaluate the potential application of low-temperature radiant ceiling heating systems (28–38 °C) in old and energy-renovated buildings, based on subjective experiments and thermal comfort criteria such as thermal sensation, comfort, satisfaction, and sensation asymmetry votes. Later, in the Discussion section, the guideline for the radiant temperature asymmetry for the warm ceiling presented in ASHRAE Standard-55 is corrected for relatively low air temperatures and different surface temperatures corresponding to “about neutral” conditions for winter clothing. Findings of this research show that the radiant ceiling heating system operating at low temperatures (33–38 °C) can provide fairly neutral thermal sensation and satisfactory comfort at the majority of body-parts, if the building envelope satisfies advanced building energy-efficiency regulations. Additionally, the experimental analyses imply that limitation of 5% suggested by ASHRAE-55 for the percentage of dissatisfied occupants feeling uncomfortable due to overhead radiation can be elevated to 10%.

Downdraft Assessment of the Office Buildings with Radiant Ceiling Heating System

Downdraft Assessment of the Office Buildings with Radiant Ceiling Heating System

An experimental investigation devoted to determine heat transfer characteristics in a radiant ceiling heating system

Investigations on heated ceiling method can be considered as a new research area in comparison to the common wall heating-cooling and cooled ceiling methods. In this work, heat transfer characteristics of a heated radiant ceiling system was investigated experimentally. There were different configurations for a single room design in order to determine the convective and radiative heat transfer rates. Almost all details on the arrangement of the test chamber, hydraulic circuit and radiant panels, the measurement equipment and experimental method including uncertainty analysis were revealed in detail indicating specific international standards. Total heat transfer amount from the panels were calculated as the sum of radiation to the unheated surfaces, convection to the air, and conduction heat loss from the backside of the panels. Integral expression of the view factors was calculated by means of the numerical evaluations using Matlab code. By means of this experimental chamber, the radiative, convective and total heat-transfer coefficient values along with the heat flux values provided from the ceiling to the unheated surrounding surfaces have been calculated. Moreover, the details of 28 different experimental case study measurements from the experimental chamber including the convective, radiative and total heat flux, and heat output results are given in a Table for other researchers to validate their theoretical models and empirical correlations.

Optimization of thermal insulation of a house heated by using radiant panels

Radiant panels are known to be energy efficient sensible heating systems and a suitable fit for low-energy buildings. The main goal of this paper is to optimize the thermal insulation layers of house heated by using the radiant heating systems. This work is conducted to study four radiant systems: floor-heating system, wall-heating system, ceiling-heating system and newly developed floor-ceiling heating system located in a net-zero-energy house in Kragujevac, Serbia. The operation of these panels is simulated by software EnergyPlus. For the optimization of the optimal length of the thermal insulation software GenOpt is used.

Experimental study of radiation and free convection in an enclosure with a radiant ceiling heating system

Participation of the radiation and free convection in the heat transferred from the ceiling surface of a room to other internal surfaces has been investigated in this study. A model enclosure representing a room was constructed and equipped with a radiant ceiling heating system. In order to have a thermal map over both internal and external surfaces of the enclosure, 108 elements were specified over the walls, floor and ceiling of the enclosure. Temperatures at both sides of the elements were measured using an infrared thermometer and k-type thermocouples under steady state heat flow condition. Using the measured temperatures, conductive heat transfer through the compartment elements was first calculated. A model based on the net-radiation method was employed to compute the radiation exchanges between internal surfaces of the elements. Convection participation was also specified using radiation and conduction for each element. Based on the results, more than 90% of the heat is transferred by the radiation from the heated ceiling to the other surfaces of enclosure. The participation of the radiation increases slightly as the ceiling temperature is increased.