A method of ventilation that uses a ceiling plenum in sitting room of residential houses as the route of airflow has several merits. For example, this method enables us to design higher ceiling in sitting room and to design free floor plan. However, there is obstruction for airflow inside the ceiling plenum in this method. For example, the height of the ceiling plenum is several centimeters. Furthermore, the intersections of furring strips and runners are regularly placed inside the ceiling plenum. Accordingly, for the purpose of adopting this method, it was necessary to investigate the characteristics of airflow inside the ceiling plenum. In this study, a ceiling plenum in sitting room of a detached house constructed of box frame type reinforced concrete was investigated. we mesured the condition of pressure in a full-scale model by experiment and calculated the characteristics of airflow in the same sized model by CFD analysis. The hight inside this model is 55mm, and the plain dimension of this one is approximately 8.2mx4.8m. The results can be summarized as follows: 1) The air resistance coefficient inside a ceiling plenum was caluculated by mesuring a difference of total pressure between air intake and exhaust opening in a full-scale model. As a result of experiment, the air resistance coefficient of experimental model is a little less than 2. 2) The intersections of furring strips and runners lower air velosity inside the ceiling plenum. As a result, furring strips and runners keep the static pressure inside the ceiling plenum uniform. 3) There was a good correlation between speed of air supply in air intake and static pressure. 4) The distribution of static pressure inside the ceiling plenum computed by low-Reynolds-number k-ε model had a good agreement with the experimental values. Moreover, there was no large difference in the results between low-Reynolds-number k-ε model and standard k-ε model.

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The insulation between the different kind metals is done as a prevention measures of the galvanic corrosion that occurs in the equipment piping system. However, it has not been clarified still enough up to now for the insulation length when an external circuit is formed. A carbon steel pipe as the anode and a stainless steel pipe as the cathode were combined. A basic experiment that measured the corrosion potential distribution and the galvanic current distribution in the tap water environment was done. As a result, the following etc. were clarified. 1) The corrosion of the carbon steel pipe with the boundary part of the cathode and the anode is large, and the influence in the boundary part as the cathode of a stainless steel pipe is large. 2) When the diameter of piping grows, the extent is eased when the diameter of piping is small though corrosion concentrates on the edge of the carbon steel pipe. 3) A galvanic current decreases exponentially according to increase in the insulation pipe length.

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This study aims at developing a radiant floor cooling system using existing Ondol (radiant floor heating system) system in Korea. Though the radiant floor cooling system could provide thermal comfort with higher energy efficiency, some problems still exist such as condensation on floor surface while the radiant floor cooling system is in operation. To solve this problem, in this study the radiant floor cooling integrated with controlled ventilation was proposed as an alternative approach. The ventilator brings the fresh outside air to meet the minimum requirement for indoor air quality and it has a capability of dehumidifying the ventilation air by circulating the chilled water through cooling coil in the ventilator. Humidity control is an essential requirement of the control system. A dewpoint sensor will stop chilled water flow to the floor and activate dehumidification by means of a cooling coil in the ventilator. The radiant floor system also has thermal storage effect which is demerit in which response of the system to load changes is slow compared to that of an air-conditioning system. In order to improve this demerit, primarily the outdoor temperature was compensated in determining the supply water temperature and then the indoor temperature was fed back to the controller, so call the outdoor reset with indoor temperature feed-back was applied for the control of a radiant floor cooling. To evaluate the performance of proposed system, both the physical experiment in a laboratory setting and computer simulation have been conducted for the assessment of thermal environmental conditions and energy efficiency

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The purposes of this paper are to determine the influence of floor cooling upon the human body and to propose optimum thermal comfort zone in floor cooling conditions based on the experimental data. Experiments were conducted under the following conditions in a cooled floor room. There were eight combinations of floor surface and air temperature. Air temperature was set to three cases (t_a=25℃, 27℃, 29℃). Floor temperature was set three cases (t_f=t_a, t_a-1℃, t_a-2℃). Relative humidity and air velocity were kept constant level of 60% and less than 0.2m/s. There were six Japanese young female. The following results were obtained. Operative temperature corrected by conduction that describes the combined effects of thermal radiation and thermal conduction was successfully applied to the evaluation of the influence of thermal conditions upon the human body. The thermal neutral vote was associated with operative temperature corrected by conduction of 27.3℃ and with mean skin temperature corrected by conduction of 34.0℃. The maximum point of subjective thermal comfort vote appeared where thermal sensation vote stood at the warmer side of the neutral. The optimum thermal comfort zone for leg-out sitting positioned Japanese in floor cooling conditions was represented with the operative temperature corrected by conduction of 25.3 to 30.5℃

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