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Occupants of highly glazed buildings often suffer from thermal discomfort during the mid-seasons when no shadings are used in such buildings, especially when inertial heating systems are used. The present study is devoted to evaluating the impact of long solar beam exposure on the internal thermal discomfort in glazed spaces when heating is implemented through a floor system. A comprehensive experimental study is carried out using an experimental bi-climatic chamber which is fully monitored and controlled, allowing realistic simulations of the dynamic movement of the sun patch on a heated slab. The findings show that a period of discomfort as long as 8 h can occur, and persist far after the sunbeam exposure stops. During this period, the heating slab's surface temperature, considered from an average point of view, can attain 34°C while the indoor temperature reaches 26°C. Simulations conducted using a previously developed model display a good fit with the measurements. [ABSTRACT FROM AUTHOR]

This case study is aimed at transient simulation of floor heating systems. There is comparison of surface floor temperatures and heat fluxes changes of different systems over time. The first studied system is a dry floor heating system which consists of system boards made from insulation material, spreader plates, and it is covered by cement fiber boards. The second examined system is heavy wet concrete floor heating system whose heating power is set identically as heating power of dry floor heating system. Mean temperature of heating water is investigated. All simulations, both time steady-state and transient, are performed in software CalA. Reduction of duration and computational performance of simulation is achieved by creation of a surrogate model. The surrogate model evinces identical surface temperatures and heat fluxes. Total number of computational grid is reduced and therefore lower number of equations is solved. Results show that dry floor heating system has faster response than concreate floor heating system. It is caused by lower weight and lower thermal capacity of this system. [ABSTRACT FROM AUTHOR]

The new type water floor (NTWF) is a device that combines the heating function with interior decoration to effectively supply heat indoors through low-temperature hot water circulating in the channels. This article investigates the thermal performance of the NTWF and indoor thermal comfort experimentally and performs a numerical simulation. The experimental results indicate that two groups in parallel with eight channels provide the optimal combination, and the indoor temperature can be maintained within the range from 19.4 °C to 24.9 °C in different operating conditions. Under the premise of meeting the heating demand, the average supply water temperature of the NTWF is 3–7 °C lower than that of a conventional floor. The simulation results show that the predicted mean vote (PMV) for the indoor environment is –0.19, and only 6.2% of the occupants feel discomfort. In conclusion, the NTWF can improve the indoor thermal comfort effectively with low energy consumption and a short construction period. It has excellent prospects for future development in practical engineering. [ABSTRACT FROM AUTHOR]

A hybrid system with a floor-ceiling heating system (FCH) and a mixing or displacement ventilation system (MV or DV) is a potential advanced heating, ventilation, and air conditioning system in the modern buildings. To date, very few studies focused on the indoor thermal environment and air distribution for FCH + MV or FCH + DV. Therefore, in this article, the effect of double heated surface temperature on indoor thermal environment and air distribution in a simulated office room with FCH + MV or FCH + DV were studied. Vertical distributions of air temperature and velocity and globe temperature in the occupied zone and horizontal distributions of contaminant concentration in the breathing zone were measured when floor and ceiling surface temperatures ranged from 25.0 °C to 29.5 °C. Vertical air temperature difference, turbulence intensity, difference between operative temperature and air temperature, and air distribution effectiveness were calculated and compared for all test conditions. The results showed that the vertical air temperature differences were all less than 0.5 °C with both positions for FCH + MV and were 4.0 °C to 4.9 °C with sitting position and 4.3 °C to 5.3 °C with standing position for FCH + DV. The turbulence intensities were from 12.5% to 17.5% with sitting position and from 12.8% to 17.1% with standing position for FCH + MV and were all within the range of 10% for FCH + DV. The differences between operative temperature and air temperature were all no more than 0.5 °C with both positions for FCH + MV and FCH + DV. The air distribution effectiveness was close to 1.0 with FCH + MV and between 1.04 and 1.21 with FCH + DV. The results in this article are relevant to the design and operation of an FCH integrated with an MV or DV. [ABSTRACT FROM AUTHOR]

Abstract In order to optimize structural design and balance heat distribution of the raised floor heating system heated by a burning cave, an unsteady heat transfer process of the raised floor was analyzed and discussed. An unsteady heat transfer model of the raised floor heating system was established to solve the problem of inner natural convection by air coupled with radiation and conduction heat transfer between two floor surfaces by computational fluid dynamics (CFD). Moreover, heating intensity, structural size and position of the heat source (burning cave) impact on the heat transfer performance and heating effect were discussed, which can provide a theoretical basis for parameter matching and structure optimizing. The results indicate that the best position of burning cave is under the center ground of a rural house, where the reasonable heat intensity of the burning cave is about 200 W/m2. The calculated temperatures and velocities are in reasonable agreement with measurements on the model house, which can provide a basic data support for the engineering practice of raised floor heating system. Highlights • An unsteady heat transfer model for a raised floor heating system was established. • Temperature and velocity fields inside the raised floor were simulated. • Reasonable design and approaches of heat transfer were discussed and confirmed. [ABSTRACT FROM AUTHOR]

Abstract In response to the policy of energy-saving and air pollution management, Beijing is vigorously promoting the work of decreasing coal-fired heating and using clean energy in the countryside. Considering the feature of energy efficiency and environmental protection, air-source heat pump has been used for residential heating in north China. To evaluate the heating performance of different heating terminals used in 'Coal-to-electricity' heat pump heating systems, the experimental study was conducted in a test house with different heating terminals, including cast-iron radiator, radiant floor heating, new bimetal radiator and small temperature difference fan-coil unit. The heating capacity, system COP, indoor temperature distribution and economic comparisons of ASHP combined with different heating terminals are abstained. The result shows that the test room with radiant floor heating has the best thermal comfort than other heating terminals under the same hot water temperature conditions, while the operating cost of new bimetal radiator, STD fan-coil unit and radiant floor heating are 25%, 28% and 43% higher than that of cast-iron radiator, respectively. From the aspect of thermal comfort and energy efficiency of heating system, the cast-iron radiator is not recommended to be used in 'Coal-to-electricity' project. [ABSTRACT FROM AUTHOR]

In this study, experimental and comprehensive multidimensional numerical models are developed for the analysis of the thermal behavior of an anhydrite slab floor heating system (FHS). Three different modeling approaches are employed, including a one dimension (1D) Modelica ® method based on an object-oriented approach, a two dimension (2D) finite difference method (FDM), and a three dimension (3D) finite volume method (FVM), using the ANSYS/Fluent ® software. The comparison between the numerical results and the measured data is performed for the inlet and outlet water temperatures, the average slab surface temperature, the depth local temperatures, and the average total heat flux. Experiments and simulations were in agreement regarding the thermal response of the FHS in accordance to the well-known 2D FDM. A multi-objective sensitivity study is then performed, based on a design of experiments method (DoE) in order to analyze the effects of the design and physical control factors and their interactions on the average surface temperature and the thermal time constant. A full factorial design, generating 128 simulations based on our validated 2D FDM model is used to construct polynomial meta-models using the aforementioned thermal parameters. As a result, the water volume flow rate and the inner diameter are the most influential factors on the surface temperature, whilst the thermal time constant is shown to be considerably influenced by the slab thickness, density, and specific heat, as well as their interactions. The elicited results may be exploited in order to help practicing building engineers to optimize the FHS, and to enhance its energy performance. [ABSTRACT FROM AUTHOR]

In cold climates, the electrical power demand for space conditioning during certain periods of the day becomes a critical issue for utility companies from an environmental and financial point of view. Shifting a portion or all the demand to off-peak periods can help in reducing the peak demand and stress on the electrical grid. To predict the required energy that needs to be stored, predictive supervisory control strategies such as Model Predictive Control (MPC) have been developed, by which the future operating modes of storage systems can be preplanned. However, control strategies like MPC requires a building model and an optimization algorithm. Their development is time-consuming and also requires high implementation cost. This paper is aimed at developing a new simplified predictive controller to manage an electrically heated floor for shifting and/or shaving the building peak energy demand. The function of the developed controller is to increase the rate of energy storage during off-peak hours and to decrease it during peak periods, while maintaining occupants’ thermal comfort. To achieve this goal without using a detailed building model, a simplified solar predictive model, using available online weather data has been proposed. The controller approach is based on a learning process; it takes building responses of previous days into consideration. The developed algorithm was applied on two models of a single-storey building, with and without basement. Results show a significant decrease in thermal discomfort, average applied powers during peak periods and mid-peak periods. The approach has also proven to be financially attractive to both supplier and consumer. [ABSTRACT FROM AUTHOR]

This article examines the ondol--the cooking stove--cum--heated floor system conventional to Korean dwellings--as a site of contestation over forest management, fuel consumption, and domestic life in colonial Korea. At once a provider of heat essential to survival in an often frigid peninsula and, in the eyes of colonial officials, ground zero of deforestation, the ondol garnered tremendous interest from an array of reformers determined to improve the Korean home and its hearth. Foresters were but one party to a far-reaching debate (involving architects, doctors, and agronomists) over how best to domesticate heat in the harsh continental climate. By tracing the contours of this debate, this article elucidates the multitude of often-conflicting interests inherent to state-led interventions in household fuel economies: what the author calls the politics of forest conservation in colonial Korea. In focusing on efforts to regulate the quotidian rhythms of energy consumption, it likewise investigates the material underpinnings of everyday life--a topic hitherto overlooked in extant scholarship on forestry and empire alike. [ABSTRACT FROM AUTHOR]

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The usage of floor heating is increasing in low-energy buildings as it enables efficient applications of low-exergy level heat sources as well as provides a uniform distribution of air temperature and low air velocities in heated spaces. The aim of this study was to analyse the effects of floor heating on the dispersion of gaseous pollutants emitted at the floor level, considering that carpets and flooring materials can be sources of such pollution. Mixing ventilation with high-level wall grille air supply and in-ceiling four-way air supply was tested numerically and experimentally in the full-scale chamber at the air change rate of 2 h−1. Three positions of a heated dummy in relation to the pollution source, cold surface and air supply diffusers were analysed. Both experiments and CFD predictions revealed the overall positive effect of floor heating on ventilation effectiveness and personal exposure. Floor heating increased pollutant removal effectiveness by 5% and reduced personal exposure by 22% on average. [ABSTRACT FROM AUTHOR]

A hybrid system with a radiant heating system and a mechanical ventilation system, which is regarded as an advanced heating, ventilation and air-conditioning (HVAC) system, has been applied in many modern buildings worldwide. To date, almost no studies focused on comparative analysis of the indoor air distribution and the thermal environment for all combinations of radiant heating systems with mechanical ventilation systems. Therefore, in this article, the indoor air distribution and the thermal environment were comparatively analyzed in a room with floor heating (FH) or ceiling heating (CH) and mixing ventilation (MV) or displacement ventilation (DV) when the supply air temperature ranged from 15.0℃ to 19.0℃. The results showed that the temperature effectiveness values were 1.05–1.16 and 0.95–1.02 for MV + FH and MV + CH, respectively, and they were 0.78–0.91 and 0.51–0.67 for DV + FH and DV + CH, respectively. The Predicted Mean Vote values were from 0.24 to 0.45 and from 0.11 to 0.43 for MV + FH and MV + CH, respectively, and from 0.01 to 0.23 and from −0.41 to 0.10 for DV + FH and DV + CH, respectively. Hence, MV + FH had the largest temperature effectiveness and Predicted Mean Vote, and DV + CH had the smallest values. In addition, the vertical air temperature differences for MV + FH and MV + CH were all within the comfort zone according to ISO 7730, but exceeded the comfort zone for DV + FH and DV + CH when the supply air temperature was less than 17℃ and 19℃, respectively. The air distribution effectiveness values for MV + FH and MV + CH were close to the recommended value for MV in the ASHRAE Standard 62.1, and those for DV + FH and DV + CH were slightly less than the recommended value for displacement ventilation. The results in this article are relevant and useful in the process of selection and design of a hybrid system with a radiant heating system and a mechanical ventilation system in practice.Practical application: The supply air temperature is one of key parameters for the design and operation of a hybrid system with a radiant heating system and a mechanical ventilation system. The results in this article may contribute to the design and operation of a hybrid system when taking in account the indoor air quality and thermal comfort. [ABSTRACT FROM AUTHOR]

Heat output and uniformity of surface temperature distribution are primarily concerned by designers and users of radiant floor heating. The testing approach, testing conditions and calculation of the heat output at each stage of program are different among the test standards. In this paper, a mathematical model to calculate surface temperature and heat output of radiant floor heating system was proposed. Measured data from experiments was used to validate the proposed model. Based on this simulation model, four current test standards in China, Europe, America and Japan were simulated. The simulation results show that the heat output of the same sample is different under the four test standards. Meanwhile, simulations were carried out at various non-heating surface temperatures. The results indicate that the non-heating surface temperature has a significant impact on the heat output of the radiant floor. The differences in the simulations of heating capacity vary from 2% to 7%. Hence, a parameter, the temperature difference between average water temperature of test sample and area weighted average temperature of non-heating surfaces, is introduced to revise the heat output characteristic equation based on the Chinese test standard. [ABSTRACT FROM AUTHOR]

Recent years, most cities in China suffer from ambient particulate matter pollution, especially in winter. The absence of fresh air system in most northern heating buildings in winter results in the poor indoor air quality. This work aims to deal with the particle dispersion in a ventilated and floor-heated indoor environment by using experimental measurements and computational fluid dynamics (CFD) methods. Two ventilation systems were considered, i.e., top & down supply. Firstly, experiments were conducted to validate the velocity and particle concentrations by CFD simulation. Secondly, unsteady particles (with the diameter of 1 μm) dispersion was simulated with different inlet velocities (i.e., 0.3, 0.4 and 0.5 m/s) and floor temperatures (i.e., 293, 298, 303 and 308 K) in a ventilated and floor-heated chamber. Lagrangian method was employed for particles tracking. It is found that the higher the inlet velocity, the faster particle concentration decayed. For the same inlet velocity, particles in the chamber were removed faster with the increase of floor temperature. When the inlet velocity was 0.5 m/s and the floor temperatures were 293 and 308 K, it took 391s and 200s respectively for normalized concentration decreasing to 0.1. The number of particles deposited on the floor decreased with the increase of the inlet velocity and the floor temperature. This study also identifies that when the floor temperature was 308 K, the removing time is reduced by 15% for normalized particle concentration with the down-supply ventilation mode. These findings would be facilitating for the future design of ventilation and heating systems. [ABSTRACT FROM AUTHOR]

Floor heating has become more and more popular due to its comfort and energy efficiency nowadays. However, there is no specific testing device and evaluation system for the wood floor materials. In order to fill the gap, we proposed a method of wood materials used for floor heating. First, the preheated wood samples from Betula platyphylla, Fraxinus mandshurica, B.alnoides and Quercus mongolica, which could be used for floor heating, were set at the middle of the bottom of the testing cylindrical cavity, as heat source. After setting up the initial values and boundary conditions of the model, the temperature distributions at different periods were analyzed by FLUENT. The results of temperature distribution were compared and evaluated. The results show that, the method can accurately demonstrate the temperature distribution for different wood samples, and be used to evaluate the heat storage performance of different wood floor materials, which is of great significance to standardize the products and market for wood floor industry in our country. [ABSTRACT FROM AUTHOR]

The hot summer and cold winter zone (HSCW) plays a significant role in residential energy consumption in China because of climate, policy, and social-economic factors. Accordingly, occupant heating behaviors and associated social-psychological factors are essential elements in understanding energy consumption. This study presents a new investigation on the demographic factors, building characteristics, and social-psychological motivations influencing current heating patterns and future heating intentions among 904 residents in the HSCW zone in China. Most residents surveyed selected the city-scale central-heating system as their future heating pattern, which might lead to a high level of energy consumption. Among demographics, family income was the main factor influencing residents’ current heating patterns, followed by number of children and building age. Additionally, thermal comfort was one of the most frequent motivations for adopting specific heating patterns in our sample. Although residents were generally concerned about the environmental impacts of energy use, they could have been unaware that their current and future heating patterns could cause high levels of energy consumption. This study provides multifaceted insight in occupant research by investigating the link among occupant heating patterns, climate zone, and behavioral motivations, which should be considered by building designers, policymakers, engineers, and energy educators. [ABSTRACT FROM AUTHOR]

In order to evaluate the performance of a solar-groundwater heat pump (SGHP) unit associated with radiant floor heating, a experimental installation was designed and established, the performance was measured and compared with the conventional central heating system(CCHS). The results shown that the new system has an energy-saving rate of 30.55% compared with the CCHS. The floor heating systems can save energy 18.96% compared with the traditional radiator. In the present experiment, the solar energy contribution rate was about 24%. Taking the basic energy (primary energy) consumption as a benchmark, the SGHP can reduce energy consumption by 30.55% compared with the traditional regional boiler room heating system. As the solar fraction increases from 0% to 100%, the COP of heat pump units and overall system are increased 6.44% and 19.34%, respectively [ABSTRACT FROM AUTHOR]

The thermal properties of wood-plastic composites (WPCs) and typical heating floor substrates heated by an electrothermal film were studied. Their effects on human feelings and the human autonomic nerve system were also investigated. The temperature changes of the specimens during heating and cooling were analyzed with an infrared thermal imager. People's subjective feelings of touching different materials were analyzed with a semantic differential (SD) technique, and their electrocardiography was recorded with a multi-channel physiological signal acquisition system. The thermal conductivity, temperature variation, tactile impression, and heart rate variability of WPCs and other heating floor substrates were investigated. The WPCs presented a markedly lower thermal conductivity and superior tactile impression compared with ceramic tile, which has a similar density to WPCs. There was a negative correlation between the scores of the warm-cool feeling and the density of the heating floor substrates under room temperature (19 °C ± 1 °C), and a positive correlation when heated (33 °C ± 1 °C). The thermal conductivity and heat storage capacity of WPC were higher than those of solid wood. Electric heating composite floors with a high comfort level and good thermal properties could be manufactured by combining WPCs and solid wood. [ABSTRACT FROM AUTHOR]

This paper deals with a numerical and experimental study of energy performance as well as an economic study of a solar under floor heating system for a traditional bathroom (Hammam). Prior to this, the solar under floor heating system was designed via a parametric study conducted by means of dynamic simulations for the solar collectors area and inclination, the storage tank, the piping materials, the pumps mass flow rates, the temperature regulation and the thickness of the active slab. Moreover, two configurations with or without thermal storage were compared. The Hammam was monitored via air temperature and humidity measurements as well as IR thermography. Good agreement between simulation and experimental results was found with 94% of the discrepancies less than 1 °C. Numerical results show that the system without thermal storage allows the Hammam's operative temperature to reach the desired one. The latter ranges between 30 °C and 37 °C for sunny days in winter, while the system with thermal storage leads to at least 10 °C operative temperature lower compared to system without thermal storage. In addition, the thermal storage system allows having quasi-constant floor temperature that depends on the storage volume, as it avoids large day/night temperature fluctuations thanks to its thermal inertia. Nevertheless, the solar floor heating system configuration with storage tank does not achieve the desired floor surface temperature of the Hammam. Furthermore, it was stated that the best configuration, which leads to an operative temperature of around 35 °C inside the Hammam, is that with cross-linked polyethylene serpentine tubes (PEX) inserted in a concrete slab of 5 cm thickness, 4 m 2 water solar collectors with 80 kg h −1 mass flow rate and temperature regulation difference of 5 °C. On the other hand, the studied solar floor heating system exhibits high to excellent energy performance depending on the use of the Hammam and auxiliary heating is almost not needed for a rational use. Furthermore, the economic feasibility of the solar floor heating system of the Hammam indicates that the annual heating energy consumption is reduced by at least 72%. Moreover, the annual energy savings are about 950 MAD (around 97 USD) and 690 MAD (around 70 USD) respectively compared to the electric and gas heating systems. The payback period of the solar system is then around 6 and 8 years respectively. Over the lifetime of the solar system, which is assumed to be 15 years, its cumulative reduction of the CO 2 emissions is up to 10 tons. [ABSTRACT FROM AUTHOR]

Increasing building energy efficiency is one the most cost-effective ways to reduce emissions. The use of thermal insulation materials mitigates heat loss in buildings, therefore minimising heat energy needs. In recent years, several papers were published on the subject of foam alkali-activated cements with enhanced thermal conductivity. However, on those papers cost analysis was strangely avoided. This paper presents experimental results on one-part alkali-activated cements. It also includes global warming potential assessment and cost analysis. Foam one-part alkali-activated cements cost simulations considering two carbon dioxide social costs scenarios are also included. The results show that one-part alkali-activated cements mixtures based on 26%OPC + 58.3%FA + 8%CS + 7.7%CH and 3.5% hydrogen peroxide constitute a promising cost-efficient (67 euro/m3), thermal insulation solution for floor heating systems. This mixture presents a low global warming potential of 443 KgCO2eq/m3. The results confirm that in both carbon dioxide social cost scenarios the mixture 26 OPC + 58.3 FA + 8 CS + 7.7 CH with 3.5% hydrogen peroxide foaming agent is still the most cost efficient. [ABSTRACT FROM AUTHOR]

In the present study, energy and exergy analyses of two commonly used heating systems, including floor heating and skirting board heating, were investigated in a room. For this purpose, first the energy analysis of each heating system was carried out using an in-house computer code along with the computational fluid dynamics (CFD) method. The room temperature distributions as well as the energy efficiencies of the both heating systems were found and compared with each other in the same conditions. Second, the exergy analyses of the both systems were evaluated. Then, the exergy destructions of these two systems were obtained and discussed. Results showed that with equally generated heat flux in the both systems, the total thermal efficiency of the skirting board heating system was 8% more than that of the floor heating system. However, the skirting board heating system could not provide good thermal conditions in the room, especially when there was a window on the room's walls. The exergy analysis also showed that the thermodynamic second law efficiency of the thermal skirt system was 4% higher than that of the floor heating system. Although the exergy destruction between the supplied hot water and the room air in the skirting board heating system was more than that of the floor heating system (i.e., 40%), the overall exergy performances of these two systems were still close to each other. Furthermore, it was concluded that the floor heating system followed more closely the criteria of thermal conditions in comparison with the skirting board heating system. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have the potential to maintain thermal comfort of occupants while reducing the energy consumption due to their high energy storage capacity. In this paper, thermal performance of active heat conduction–enhanced shape-stabilized phase change material (HCE-SSPCM) encapsulated boards, fitted with active hot/chilled water pipes were investigated for side-wall cooling and for incorporation in an under-floor heating system. Numerical model based on finite difference method was developed to study the effect of HCE-SSPCM on annual heating/cooling energy consumption saving and indoor air relative temperature fluctuation rate reduction. Our study shows that there exists an optimal location for HCE-SSPCM according to thermal resistance value of each layer and ambient conditions. The recommended thickness and thermal conductivity of HCE-SSPCM wallboard were 30–60 mm and 1–1.5 W·m−1·K−1. Compared to the room without HCE-SSPCM boards, the maximum annual heating energy consumption saving would be 16.2%. Indoor air relative temperature fluctuation rate for heating would be reduced by 41.3%. The maximum annual cooling energy consumption saving would be 4.53%. Indoor air relative temperature fluctuation rate for cooling would be reduced by 56.2%. Our research provided scientific evidences for application of PCMs to reduce energy consumption in residential buildings without sacrificing indoor thermal comfort. [ABSTRACT FROM AUTHOR]

Low operating cost, comfort, sustainability, and environmental footprint are the key elements of robust space heating (SH) system. In quest for higher efficiencies, it is not always possible to meet all of these demands where environmental footprint often gets secondary attention. This paper presents a novel SH system which is capable of meeting all of the aforementioned elements while simultaneously proving SH and domestic hot water (DHW). The system comprises a geothermal sourced heat pump (HP) featuring "hot gas water" (HGW) technology which delivers higher efficiency. This paper gives a thorough thermodynamic assessment of the system covering component based first and second law analysis and provides test results based on two case studies at a house (W10IW35) and a renovated building (W10/W45). The results show that a theoretical efficiency gain by 11.02% is achievable where the source temperature is 10 °C and the water temperature for floor heating is 35 °C. For the same system, with the same source temperature but with a supply temperature of 45 °C for SH, an efficiency gain of 17.91% is achievable. From experimental testing of the system using the test stand at GeoTherma, 4.73% efficiency gain with water temperature of 35°C and 3.59% efficiency gain with water temperature of 45 °C were obtained. Economic analysis results showed that savings of up to 10% on an annual basis is possible with HGW technology installed in an average family house, whereas it gets 4.36% for a small hotel with a payback time period of about 9 yrs. [ABSTRACT FROM AUTHOR]

We investigated whether hypothermia in newborn piglets could be reduced by applying different thermal aids. The experiment was performed on 150 newborn piglets from 24 sows. Right after birth, the piglets were moved to a wire mesh cage for the first 2 h of life where they experienced 1 of 7 different combinations of flooring (solid vs. slatted) and treatments: control, with no additional thermal aids on a solid floor (n = 26) or a slatted floor (n = 26); built-in floor heating (n = 31) or floor heating as a radiant floor plate on solid floor (FloorPlate; n = 19); radiant heater above a solid floor (RadiantC; n = 22) or a slatted floor (RadiantSlat; n = 18); and provision of straw on a solid floor (Straw; n = 8). Piglets' rectal temperature was measured both continuously and manually every 10 min for the first 2 h after birth using a thermal sensor inserted in the rectum of the piglets. The rectal temperature curve was analyzed for differences in the slope of the drop in rectal temperature and the deflection tangent of the curve. Furthermore, differences in average rectal temperature, minimum rectal temperature, rectal temperature 2 h after birth, and time with rectal temperature below 35°C were analyzed. All statistical analyses were performed using a mixed model. All thermal aids/heat solutions resulted in a less steep drop in rectal temperature, a faster recovery, and, for the smaller piglets, also a greater average rectal temperature (except for built-in floor heating) and less time with rectal temperature below 35°C. The most efficient thermal aids to reduce hypothermia in newborn piglets were Straw and RadiantC. Furthermore, Straw, RadiantC, and FloorPlate also eliminated the effect of birth weight on some of these indicators of thermoregulatory success. Otherwise, FloorPlate and RadiantSlat showed an intermediate outcome for most measures. With no heating, piglets on a solid floor experienced more severe hypothermia than piglets on a slatted floor. In conclusion, several types of thermal aids can reduce hypothermia in newborn piglets, but some are more efficient and can partly eliminate the effect of birth weight on hypothermia. These results are especially important in countries where breeding for large litter sizes has resulted in a reduction in average birth weight of the piglets and, thus, creates a greater demand for an early, adequate thermal environment to secure piglet viability. [ABSTRACT FROM AUTHOR]

A systematic development of an electrically heatable cement-based composite, prepared by admixing a few volume percent of chopped carbon fibres without a need of adding further heating elements, is reported. The optimal volume content of carbon fibres is determined to range from 1 to 2 volume percent, if 3 mm long and 7 μm thick carbon fibres are being used. By applying an electrical current to the composite material, a temperature rise suitable for heating rooms and walls can be induced. Mechanical tests show that the flexural strength of carbon fibre reinforced composite is not decreasing during electrical heating at 60 °C for 4 weeks. For electrical heating purposes, graphite or silver is found to be the best electrode material. [ABSTRACT FROM AUTHOR]

Three space heating systems (floor heating with different floor covering resistances, radiator heating with different working temperatures, warm-air heating with and without heat recovery) were compared using a natural gas fired condensing boiler as the heat source. For the floor heating systems, the effects of floor covering resistance on the whole system performance were studied using two heat sources; a natural gas fired condensing boiler and an air-source heat pump. The heating systems were also compared in terms of auxiliary exergy use for pumps and fans. The low temperature floor heating system performed better than other systems in terms of exergy demand. The use of boiler as a heat source for a low-exergy floor heating system creates a mismatch in the exergy supply and demand. Although an air-source heat pump could be a better heat source, this depends on the origin of the electricity supplied to the heat pump. The coefficient of performance (COP) of the heat pump has a critical value (2.57 in this study); it is beneficial to use a heat pump instead of a boiler only when the COP is above this critical value. The floor covering resistance should be kept to a minimum, in order not to hinder the performance of the floor heating and the whole system. The exergy input to auxiliary components plays a significant role in the overall exergy performance of systems, and its effects become even more significant for low temperature heating systems. [ABSTRACT FROM AUTHOR]

Wall heating is an alternative method for residential heating that is used in a limited part of Europe. The goal of this study was to show the feasibility of this method for the Nordic market and to provide a comprehensive picture of wall heating and its functionality compared to traditional methods, i.e. radiators and floor heating. The study was conducted using a literature review, calculations, and a survey. Simulations were made using the computer software EnergyPlus (US Department of Energy). Results showed that placement of wall heating panels in interior walls results in a lower heat loss than placement in outer walls, and that wall heating can have equal or better energy-efficiency compared to floor heating and conventional radiators. Wall heating provides a more comfortable indoor climate, in regard to dust allergies, and there is no need to remove air from each individual heating panel. A disadvantage is the need for hidden installation, which creates a problem for a safe water installation and difficulties in the attachment of fixtures. Also, the wall heating system has difficultly in handling cold drafts. Though wall heating could compete with floor heating and radiators, its disadvantages are sufficient to explain why the system is not yet used in Sweden. [ABSTRACT FROM AUTHOR]

This paper presents a high spatial resolution based method for design and operation of a low temperature district heating system and evaluates its feasibility and energy and exergy performance through case comparison. Selected case area is existing district in North Japan. The district heating system design and operation follows a bottom-up approach. The study scope takes into account the demand side, distribution and supply side where biomass CHP (combined heat and power) plant is selected as main supply source. Radiating floor heating system model is used to estimate building temperature requirement. Results indicate that low temperature heating is infeasible for non-residential buildings in North Japan at high loads. Improving building insulation decreases heating quality demand considerably. Low temperature district heating performs better than medium temperature, especially in terms of exergy efficiency, however requires a bit larger pipe diameter indicating cost trade-off between installation and operation cost. Implementing cascade configuration based on quality level of building energy demand results in highest system performance. Lower network temperature provides least net primary energy consumption primarily due to higher electricity generation of CHP plant. This transcends to favourable system exergy efficiency of low temperature operation due to high quality of electricity, increasing the exergy of the product. [ABSTRACT FROM AUTHOR]

Thermal performance experiments were carried on a new floor heating device in a thermal environmental chamber in order to provide design reference for engineering application. The new floor heating device can achieve heating demand with lower heat medium water temperature when compared with traditional floor radiant heating coil pipe. The device can combined with low grade thermal energy utilization system for high efficient heating. [ABSTRACT FROM AUTHOR]

Solar or solar assisted heating and cooling systems are becoming widespread to reduce CO2 emissions. Efficient radiant space heating and cooling systems can be used to decrease the energy bills and improve occupant thermal comfort in buildings. This study uses the TRNSYS program, for the modeling and simulation of solar assisted radiant heating and cooling of a building with the domestic hot water supply, to examine the effects of various parameters on energy consumption. Calculations are performed for a typical meteorological year (TMY) and ten attached houses in Istanbul, Turkey with hot water and chilled water storages on a six minute time step basis. Graphs showing variations of the room temperature and room relative humidity indicate satisfactory thermal comfort. Daily average COP of the absorption cooling system is improved by suitable choice of the type and size of the collectors. Sizes of the hot water and chilled water tanks are also important parameters; their roles are shown by their effect on the discarded portion of the heat from the collectors and the energy amount supplied by the auxiliary heater. It is concluded that the presented model for a solar assisted radiant heating and cooling of ten attached houses, with the domestic hot water supply, natural gas fueled auxiliary heater, hot water and chilled water storage tanks have considerable advantages; these should be maximized by optimizing the sizes of the solar collectors and storage tanks using a simulation program. [ABSTRACT FROM AUTHOR]

The ground-coupled heat pump (GCHP) system used to provide space heating for an office room is a renewable technology with a high performance. The experimental measurements are used to test the performance of a GCHP system integrated with the radiator or radiant floor heating system for an office room. A comparative analysis of the main performance parameters (energy efficiency and CO 2 emissions) is performed for the two heating systems. Additionally, two numerical simulation models of useful thermal energy and the system coefficient of performance (COP sys ) in heating mode are developed using the TRNSYS (Transient Systems Simulation) software. Finally, the simulations obtained using TRNSYS software are analysed and compared to the experimental data, resulting in good agreement and thus the simulation models are validated. [ABSTRACT FROM AUTHOR]

Anecdotal evidence suggests that many residents of severely cold areas of China who use floor heating (FH) systems feel warmer but drier compared to those using radiant heating (RH) systems. However, this phenomenon has not been verified experimentally. In order to validate the empirical hypothesis, and research the differences of human physiological and psychological responses in these two asymmetrical heating environments, an experiment was designed to mimic FH and RH systems. The subjects participating in the experiment were volunteer college-students. During the experiment, the indoor air temperature, air speed, relative humidity, globe temperature, and inner surface temperatures were measured, and subjects' heart rate, blood pressure and skin temperatures were recorded. The subjects were required to fill in questionnaires about their thermal responses during testing. The results showed that the subjects' skin temperatures, heart rate and blood pressure were significantly affected by the type of heating environment. Ankle temperature had greatest impact on overall thermal comfort relative to other body parts, and a slightly cool FH condition was the most pleasurable environment for sedentary subjects. The overall thermal sensation, comfort and acceptability of FH were higher than that of RH. However, the subjects of FH felt drier than that of RH, although the relative humidity in FH environments was higher than that of the RH environment. In future environmental design, the thermal comfort of the ankles should be scrutinized, and a FH cool condition is recommended as the most comfortable thermal environment for office workers. Consequently, large amounts of heating energy could be saved in this area in the winter. The results of this study may lead to more efficient energy use for office or home heating systems. [ABSTRACT FROM AUTHOR]

In this paper new draft standard prEN 15316:2-2014 was tested against detailed dynamic simulation and an operative temperature corrections were developed in order to enable fair comparison of heat emitters to provide equal thermal comfort for occupants. Simple one room model with different number of external envelope elements and two occupant positions were used to analyze operative temperature effects. Operative temperature corrections and comparative analyses with the tabulated values of the standard were conducted with two low energy reference building simulation models in two climates. The use of the operative temperature set-point increased the temperature variation in the case of radiator heating by 0.2–0.3 K and decreased it in the case of floor heating by 0.1 K. However, in the case of floor heating the occupant location effect provided an additional increase of 0.1 K which compensated the operative temperature effect, i.e. no correction is needed for floor heating. For the radiator heating the operative temperature variation of 0.25 K is to be added, but this increase falls well within the safety margin of about 0.35 K of existing tabulated values. The comparison of the emission efficiency of the radiator and floor heating revealed equally efficient by the PI controller. [ABSTRACT FROM AUTHOR]

Computational Fluid Dynamics (CFD) simulations were used to study the indoor climate in a low energy building in northern Sweden. The building's low heat requirement raise the prospect of using a relatively simple and inexpensive heating system to maintain an acceptable indoor environment, even in the face of extremely low outdoor temperature. To explore the viability of this approach, the indoor climate in the building was studied considering three different heating systems: a floor heating system, air heating through the ventilation system and an air heat pump installation with one fan coil unit. The floor heating system provided the most uniform operative temperature distribution and was the only heating system that fully satisfied the recommendations to achieve tolerable indoor climate set by the Swedish authorities. On the contrary, air heating and the air heat pump created a relatively uneven distribution of air velocities and temperatures, and none of them fulfills the specified recommendations. From the economic point of view, the air heat pump system was cheaper to be installed but produced a less pleasant indoor environment than the other investigated heating systems. [ABSTRACT FROM AUTHOR]

In this article, black-box models of the residential heating, ventilation and air conditioning (HVAC) system are developed. The data of the input and output of the system is measured and the models of the energy recovery ventilator (ERV), air handling unit (AHU), buffer tank (BT), radiant floor heating (RFH) and ground source heat pump (GSHP) are developed using the system identification techniques in Matlab ® . The developed models include models based on multiple-input and multiple-output (MIMO) artificial neural network (ANN), transfer function (TF), process, state-space (SS) and autoregressive exogenous (ARX) ones of each HVAC subsystem (ERV, AHU, BT and RFH). The gray-box models of the same HVAC subsystems were developed in [1] which are also compared with the black-box models developed in this article. The models were compared visually and analytically. Ranks of the models were calculated based on their relative performance. It was found that the ANN outperforms the other modeling methods followed by the ARX, TF, SS, process and gray-box models respectively. [ABSTRACT FROM AUTHOR]

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The aim of this paper is to present results of measurement of hot-air floor heating system. The energy from fireplace directly heats the house near to the chimney and partly is distributed by the special ventilation under the floor in the whole heated room. The main principle is based on specially designed accumulative floors, consisting of a set of special chambers, which enable to heated air from the fireplace to flow through them. The layer of concrete floor is installed on the surface of these chambers. Hot-air can be intensively distributed around the house with time shift, but the air flow is not uniform and some places are warmer or colder. The results of measurements in the building showed that the accumulation in the floor compensates temperature differences. The result of proper application of this type of heating is a stable thermal comfort and saving of heating costs. Based on the results of measurements, practical recommendations for the design, installation and use of these types of heating were summarised in the conclusions. [ABSTRACT FROM AUTHOR]

The present study explores efficient integration approaches of photovoltaic-thermal systems coupled with corrugated transpired solar collectors (building-integrated photovoltaic-thermal, BIPV/T), Heating, Ventilation and Air Conditioning (HVAC) systems and thermal storage devices, to enable optimal collection and utilization of solar energy in high performance buildings. The objective is to (a) develop models that capture the relevant system dynamics and are computationally efficient for subsequent use within model-predictive control (MPC) algorithms; (b) evaluate the energy saving potential of the integrated system and the predictive controller in comparison with baseline operation strategies. An open plan office space at Purdue’s Living Laboratory is used as test-bed, in which the BIPV/T system preheats ventilation air, while also, it is coupled with the building through an air-to-water heat pump and a thermal energy storage (TES) tank that serves as the heat source for the radiant floor heating (RFH). A detailed energy prediction model developed in TRNSYS is considered as a true representation of the building and it is used to identify the parameters of low-order linear time-invariant state-space models. Both gray-box and subspace state-space system identification (4SID) methods are investigated. A simulation study is performed using TMY3 data for West Lafayette, IN during the heating period. The results show that implementation of a deterministic MPC algorithm for the optimal set-point trajectory of the TES tank can reduce the electrical energy consumption of the heat pump by 34.5%. For the BIPV/T configurations tested, the energy saving of the integrated solar system can be up to 45% compared to the baseline operation of the radiant floor heating. The study also investigates the impact of forecast uncertainty for the horizontal solar irradiance on the performance of the predictive controller, with the results showing considerable impact on thermal comfort conditions when the prediction error is higher than 38%. [ABSTRACT FROM AUTHOR]