Ceiling Heating Research Articles

Experimental study on heat transfer characteristics of interior walls under partial-space heating mode in hot summer and cold winter zone in China

In this paper, in order to study the effect of heat transfer between households on good indoor thermal environment and building energy efficiency, the indoor thermal environment and heat consumption of the room with different laying forms of radiation end are compared in the case of no heating in the adjacent room through the field experimental test. It was found that whether the adjacent room is heated directly affects the surface temperature and total heat consumption of the inner wall. Compared with the heating adjacent room, when the adjacent room is not heated the indoor air temperature in the working area decreased by 3.4-4.7%, the internal wall surface temperature decreased by 3.0–7.4%, and the heat flux density of internal wall surface increased by 29.8–52.2%. The heating surface temperature was reduced by 2.3–3.7%, the heat flux density of the heating surface was increased by 15.3–16.3% for floor and ceiling heating, and the heat flux density was reduced by about 22% because of the large heat transfer to adjacent rooms through interior walls. The heating of the large heat transfer to the adjacent rooms through interior walls. The total heat supply to the room increased by 5.2–7.2%. Additional heat load calculation is supposed to be taken into consideration due to the large heat transfer between interior walls while neighboring rooms are not heated.

Diel variation of formaldehyde levels and other VOCs in homes driven by temperature dependent infiltration and emission rates

High time resolution monitoring of formaldehyde and other volatile organic compounds in the air of four homes in winter and summer revealed diel variation of VOC levels driven by infiltration and temperature dependent whole house emission rates. In unoccupied homes, these pollutants displayed a large diel concentration variation, with an afternoon maxima and early morning minima. VOC abundance lagged about 2 h behind changes in infiltration rates measured by a tracer release method, resulting in poor correlations between VOC concentration and air change rate. The data demonstrate that VOC abundance was not in steady state with respect to whole house emission rates. Formaldehyde and other VOCs displayed a positive correlation with indoor temperature in both winter and summer. Formaldehyde sensitivity to temperature ranged from 3.0 to 4.5 ppbv per °C, a useful metric for predicting the impact of heat waves and changing regional climate on indoor air quality. Gypsum wallboard used as radiant ceiling heating product in one home was identified as source of formaldehyde and potentially mercury.

Experimental study of radiator, underfloor, ceiling and air heater systems heat emission performance in TUT nZEB test facility

This paper reports the results of different heat emitter system measurements, which were carried out at the nZEB test facility near Tallinn University of Technology in early 2018. Radiators, underfloor heating, air heaters and radiant ceiling panels are studied as coupled with different control schemes ranging from ON-OFF to PI-type control. The objective is to assess and quantify the control accuracy and thermal comfort parameters among different configurations. Scheduled heating dummies are used to simulate internal heat gains within the otherwise unoccupied test rooms. Along with outdoor temperature variation, the heating demand is therefore constantly changing and the control systems are continuously adjusting the heat output to maintain the desired indoor air temperatures. Control accuracy is then determined from the temperature deviations against this set value. Air stratification within the room is assessed with vertical temperature gradient calculations from measured air temperatures at different heights. The operative temperature at the point of expected occupancy is calculated from surrounding air and enclosing surface temperatures. The quantified results provide a comprehensive comparison between the different system configurations, enabling further energy simulations in related software packages since these parameters directly influence the energy usage within a system.

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%.

Energy Demand Reduction in Nearly Zero-Energy Buildings by Highly Efficient Aluminium Foam Heat Exchangers

The capability periodically to store and release the latent heat of phase transition during melting and solidification of Phase Change Materials (PCMs) has been currently the main subject of interest with regard to cost reduction efforts for cooling, heating of interiors and Domestic Hot Water (DHW) necessary for the operation and maintenance of adequate thermal comfort in new modern as well as old renovated residential buildings. The main principle of PCMs facilities to reduce significantly the energy consumption in the building industry of the future is based on the ability of thermo-active heat exchangers to absorb and later to dissipate into the surroundings excessive heat which can be easily obtained from renewable sources (e.g. solar energy, geothermal heat, etc.) directly in a building or in its immediate vicinity. Smart interior tiling and furnishing systems can provide high energy efficiency by stabilizing the room temperature at a level ensuring sufficient thermal comfort basically governed by the thermal conductivity and heat exchange area between ceiling (respectively also wall and floor if necessary) heat exchangers (radiators) and the heat storage medium in the form of PCMs. Unfortunately, most conventional building materials, e.g. aerated concrete, bricks, gypsum, ceramic tiles, etc. are particularly characterized by very low thermal conductivity, which disadvantages them to be used for these purposes. However, highly porous metallic material such as aluminium foam prepared by powder metallurgy [10, 11] is on the contrary excellently heat conductive, which predisposes it to be used for light-weight design of supporting structure of very energy efficient indoor as well as outdoor thermo-active heat exchangers for building industry of the future. This contribution points to the possibility to apply aluminium foam for both the novel innovative roofing system to cover pitched roofs and the interior ceiling panels, with the minimum energy demands for maintaining the sufficient thermal comfort in future nearly Zero-Energy Buildings (nZEBs).

Downdraft Assessment of the Office Buildings with Radiant Ceiling Heating System

Downdraft Assessment of the Office Buildings with Radiant Ceiling Heating System

4床病室における放射空調をベースとした感染リスク低減に関する研究 （第3報）拡散範囲の可視化実験とCFD解析結果の比較

4床病室における放射空調をベースとした感染リスク低減に関する研究 （第3報）拡散範囲の可視化実験とCFD解析結果の比較

Performance of Radiant Heating Systems of Low-Energy Buildings

After the introduction of plastic piping, the application of water-based radiant heating with pipes embedded in room surfaces (i.e., floors, walls, and ceilings), has significantly increased worldwide. Additionally, interest and growth in radiant heating and cooling systems have increased in recent years because they have been demonstrated to be energy efficient in comparison to all-air distribution systems. This paper briefly describes the heat distribution systems in buildings, focusing on the radiant panels (floor, wall, ceiling, and floor-ceiling). Main objective of this study is the performance investigation of different types of low-temperature heating systems with different methods. Additionally, a comparative analysis of the energy, environmental, and economic performances of floor, wall, ceiling, and floor-ceiling heating using numerical simulation with Transient Systems Simulation (TRNSYS) software is performed. This study showed that the floor-ceiling heating system has the best performance in terms of the lowest energy consumption, operation cost, CO2 emission, and the nominal boiler power. The comparison of the room operative air temperatures and the set-point operative air temperature indicates also that all radiant panel systems provide satisfactory results without significant deviations.

Experimental investigation on heat gain reduction using a vinyl perforated ceiling

This paper is investigated the ceiling heat gain reduction by using the vinyl perforated ceiling. Two model houses are served to investigate with the ceiling area about 1.44 m2. The vinyl perforated ceiling made from the vinyl soffit panels, the original dimension as (W:33×H:300 ×t:0.1 cm). Three vinyl ceiling area ratios (vinyl perforated area/ solid vinyl area) were considered. The experiments have been carried out under the climatic conditions of Thailand. The performance of vinyl perforated ceiling was investigated experimentally and compared to a common ceiling (gypsum board). The results indicated that the vinyl perforated ceiling can reduce the ceiling heat gain and attic temperatures are 1-7 W/m2 and 1-4°C, respectively. The percentage of ceiling heat gain reduction is much sufficiently.

Effect of Supply Air Temperature on Indoor Thermal Comfort in a Room with Radiant Heating and Mechanical Ventilation

Abstract: The study presents the investigation of the effect of supply air temperature on thermal comfort in a room with floor heating (FH) or ceiling heating (CH) and mixing ventilation (MV) or displacement ventilation (DV). Vertical distributions of air temperature and velocity and globe temperature in the occupied zone were measured when supply air temperature varied from 15.0°C to 19.0°C. PMV-PPD, vertical air temperature difference and draught near the neck were calculated and compared for the four hybrid systems. The results showed that the PMV values were varied from 0.24 to 0.37 and from 0.11 to 0.27 for FH + MV and CH + MV and from 0.01 to 0.19 and from -0.41 to -0.12 for FH+DV and CH+DV. The vertical air temperature differences were less than 0.3°C with FH+MV or CH+MV, and from 1.9°C to 4.0°C and from 2.5°C to 4.2°C for FH+DV and CH+DV. The PPDs and draughts near the neck for the four systems were all less than 10%. The results in this paper can be used to facilitate the design and operation of a hybrid system with a radiant heating system and a mechanical ventilation system for both residential and commercial buildings.

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.

Comparison of indoor air distribution and thermal environment for different combinations of radiant heating systems with mechanical ventilation systems

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.

Prediction of the HVAC Energy Demand and Consumption of a Single Family House with Different Calculation Methods

In this study a comparative energetic analysis is investigated of a single family house with different calculation procedures. One of the methods that were used is the Ministry without Portfolio Decree No. 7/2006 for energy certification and MSZ-140-04 for energy demand calculations (by using WinWatt computer software) that are a widely used in the Hungarian practice by HVAC designers and experts. Passive House Planning Package (PHPP) is also more and more common used PC software in Hungary due to the continuously tightening energy requirements. To see the differences and imperfections between these methods the heating, cooling and ventilation system was designed of a given single family house and the annual energy consumption was investigated with these methods. To perform the investigation in more detailed three different heating systems were designed. In the first case the heat source is a condensing boiler operated with floor heating. In the other two cases the thermal systems are heat pumps with floor and ceiling heating. One of the heat pumps is an air-to-water system, the other one is a geothermal heat pump. The advantages of the heat pumps are that heating, cooling and domestic hot water energy is produced by only one equipment and efficiency. However comparing investment and operating costs for the heat pumps with gas boiler the payback time is very long based on this study. The investment costs, payback periods are investigated for the three different systems evaluating the results also with PHPP and WinWatt computer software tools in this study.

ENERGY DEMAND REDUCTION TO ENSURE THERMAL COMFORT IN BUILDINGS USING ALUMINIUM FOAM

The high energy efficiency of buildings can be achieved if energy needs are almost entirely covered by the supply of renewable energy sources obtained directly on the building or in its immediate vicinity. The technology providing efficient storage of the heat at a time of excessive sunlight is necessary if a returns of investment for the construction of small houses with zero energy balance should be less than 10 years. The regular alternation of day and night cycle resulting in continuously changing amount of sunshine falling on the building roof causes even though a small but very well usable potential. The concept presented in this contribution is based on the storage of energy obtained through the aluminium foam roof and facade cladding, which are capable of absorbing the desired, or even take away the excess energy to the surroundings if necessary. The energy effectively generated by this way is by means of piping system distributed by heating liquid medium/coolant to interior ceiling heat exchangers made of aluminium foam enabling due to filling by Phase Change Materials (PCMs) to store the energy required for heating/cooling for a period of at least several hours. This progressive technology, therefore, contributes significantly to reducing of energy demand and thus also the prices of future not only large buildings but also small family houses that are able to achieve the optimal thermal comfort by extremely low costs. Possibility to manufacture facade, as well as the interior panels of aluminium foam, is a good prerequisite for ensuring that these structural components could be in the nearest future made from fully recyclable aluminium alloys. This fact indicates large potential chance for long-term sustainable further development of above-mentioned advanced technologies.

Air distribution in a multi-occupant room with mixing or displacement ventilation with or without floor or ceiling heating

This study performed a comparative analysis of the air distribution in a multi-occupant room with mixing or displacement ventilation and the effect of adding floor or ceiling heating to each of them. The vertical distribution of indoor air temperature and velocity in the occupied zone and the horizontal distribution of indoor containment concentration in the breathing zone were measured for all six systems with a supply air temperature of 19.0°C and an air change rate of 4.2 h−1. The results showed that the mean vertical air temperature difference in the occupied zone varied from 0.1°C to 0.6°C; the mean local turbulence intensity varied from 12.0% to 14.1% with mixing ventilation with or without floor or ceiling heating, and the corresponding values were 1.5°C to 2.5°C and 7.3% to 9.8% with displacement ventilation with or without floor or ceiling heating. Mean air distribution effectiveness varied from 0.93 to 1.0 for mixing ventilation and from 1.06 to 1.14 for displacement ventilation with or without floor or ceiling heating. The results are relevant to the design and control of mixing and displacement ventilation with or without floor or ceiling heating in a multi-occupant room.

Decreasing energy use and influence to environment by radiant panel heating using different energy sources

In Serbia, radiant heating is increasingly used. Also, in Serbia, the largest portion of produced electricity is from the fossil fuels which results in a high value of primary energy consumption coefficient (R). This situation raises the question of the justification of the use of ground sources heat pump (GHSP) over natural gas boiler and GSHP with PV array. Also, the impact of the embodied energy and embodied carbon was included in this paper. The operation of this house is simulated by software EnergyPlus. The results indicated that the newly-developed floor-ceiling radiant heating system has the best performances and classical ceiling heating has the worst performances. However in future with decrease of R, it is shown that the panel heating powered by GSHP may have lower total energy consumption than that of such a system powered by natural gas. For the wall panel heating, this would happen for the highest value of R, while in the case of the ceiling heating, it would appear for the lowest value of R.

A study of the performances of low-temperature heating systems

In Europe, high energy consumption in the building environment has raised the need for developing low-temperature heating systems both in new buildings and in retrofitting buildings. This paper addressed many different topics related to energy saving in central heating systems with reduced supply temperature and radiant panel heating including floor heating, ceiling heating and wall heating. The paper investigated the performance of these different types of low-temperature heating system using numerical modelling, simulation tools and also site measurements. Thus, energy performance of radiator and radiant floor heating systems connected to a ground-coupled heat pump (GCHP) is compared, as obtained with experimental measurements in an office room. Furthermore, the thermal comfort of these systems is compared and a mathematical model for numerical modelling of thermal emission from radiant floors is developed and experimentally validated. Additionally, a comparative analysis of the energy, environmental and economic performances of floor, wall, ceiling and floor-ceiling heating using numerical simulation is performed. Finally, the energy efficiency of a heat pump in conjunction with a radiator or radiant floor heating system is calculated for different supply, return, and air design temperatures. This study showed that floor-ceiling heating works better than other low-temperature heating systems regarding providing better thermal comfort, lower energy consumption, lower CO2 emission and lower operating cost.

Effective Ventilation and Heating Systems in Office Buildings

The paper is oriented on the effective ventilation, heating and cooling systems in office buildings by utilization of renewable energy sources. All these systems must be in mutual harmony and ensure thermal comfort. Ventilation system must use the power of wind, the heated air from the double skin facade, heat recovery system, preheating or cooling in the ground channel. In the summer, there must be used the night natural cooling of building. For the heating is the most suitable to use radiant floor heating (30%) in combination with radiant ceiling heating (70%). The next progressive way is the combination of new concrete core conditioning and floor convector heaters.

Emptying non-adiabatic filling boxes: the effects of heat transfers on the fluid dynamics of natural ventilation

AbstractA model for steady flow in a ventilated space containing a heat source is developed, taking account of the main heat transfers at the upper and lower boundaries. The space has an opening at low level, allowing cool ambient air to enter the space, and an opening near the ceiling, allowing warm air to leave the space. The flow is driven by the temperature contrast between the air inside and outside the space (natural ventilation). Conductive heat transfer through the ceiling and radiant heat transfer from the ceiling to the floor are incorporated into the model, to investigate how these heat transports affect the flow and temperature distribution within the space. In the steady state, a layer of warm air occupies the upper part of the space, with the lower part of the space filled with cooler air (although this is warmer than the ambient air when the radiant transfer from ceiling to floor is included). Suitable scales are derived for the heat transfers, so that their relative importance can be characterized. Explicit relationships are found between the height of the interface, the opening area and the relative size of the heat transfers. Increasing heat conduction leads to a lowering of the interface height, while the inclusion of the radiant transfer tends to increase the interface height. Both of these effects are relatively small, but the effect on the temperatures of the layers is significant. Conductive heat transfer through the upper boundary leads to a significant lowering of the temperature in the space as a proportion of the injected heat flux is taken out of the space by conduction rather than advection. Radiative transfer from the ceiling to floor results in the lower layer becoming warmer than the ambient air. The results of the model are compared with full-scale laboratory results and a more complex unsteady model, and are shown to give results that are much more accurate than models which ignore the heat transfers.

Comfort and energy analysis of heating up

Abstract The research work was done in the Building Physics Laboratory of the Department of Building Services and Building Engineering, University of Debrecen. The test room could be heated by radiator, wall, floor and ceiling heating. The main goal of this research was to see how the internal temperature varies during the heating up period, how much is the increment during the 3 hours measurement and how much the energy consumption is. This paper presents the results of the research work. The obtained results have proven that in our case the ceiling and radiator heating gave the higher increment of operative temperature and the lower energy consumption.