Traditionally, the smoke front location below the horizontal ceiling of a corridor in fire has been predicted by the numerical analysis. In this paper, an approximate analytical solution is derived. If the progression rate of smoke front is assumed to be constant, the analytical solutions of smoke average temperature and the equation of smoke front location are derived. As the equation of smoke front location is not solved analytically, the integrand of the equation is approximated by 1/At, and on additional condition that the smoke temperature does not exceed the initial inlet temperature the further approximate analytical solution is derived. The final approximate analytical solution shows that the smoke front location is proportional to the time until 1/A, and expand in proportion to the 2/3 power of time thereafter. The approximate analytical solution is compared the experimental results of actual size. The result shows that it is possible to predict the smoke front location in considering heat loss from the ceiling and the walls.

View full abstract

The approximate analytical solution of the location of smoke front below horizontal ceiling at early time in fire is derived by the handling as the axi-symmetric problem. At first the approximate analytical solution of the average temperature of smoke layer is derived in assuming that the progress velocity of smoke front is proportional to 1/2 power of time based on the mass preservation. Then the integral equation to predict the location of smoke front is derived in this smoke average temperature. As this equation is not able to solve analytically, an approximate analytical equation is derived by approximation of integrand and being subject to temperature less exceeding initial inflow temperature. Particularly, in case of the treatment of center sprang out, the location of smoke front is proportional to 1/2 power at early time then to 3/4 power at time. The prediction is compared to the experimental data. It is shown that the location of smoke front is predicted by the approximate analytical solution.

View full abstract

The promotion of the long-term use of high-quality building stock is a very important subject. To accomplish this, it is necessary to understand the long-term changes in the properties of insulation materials. In this research, we verified the durability of glass wool by conducting a survey of the changes in this insulation with long-term use and by performing an acceleration test. As a result, it was found that under high-temperature and high-humidity conditions, the strength of the glass fiber decreases, and the binder deteriorates. However, the thermal conductivity did not increase. We then developed a piercing test to evaluate the aging of glass wool. Finally, we attempted to predict the aging by applying a life prediction model to the accelerated test.

View full abstract

Recently, as increase of eco-awareness, the number of building adopted with natural ventilation is increasing. Naturally ventilated building is expected to effectively reduce the building's cooling load, and also expected to make people feel comfortable and familiar with nature, especially in spring and autumn. Few studies are found about the actual thermal condition of naturally ventilated building in winter. The purpose of this study is to figure out the influence of the ventilation chimney using staircase on the actual thermal environment and occupants' evaluations in winter. The result shows that closing the opening at the top of chimney decreases the air change rate at room. It is also found that the cold draft at the window side and air leakage through the switched-off ventilation fan also influence on the thermal environment, except for that of ventilation chimney.

View full abstract

This paper aims to propose a new method to generate turbulent fluctuations of wind velocity and scalar such as temperature and pollutant based on the Cholesky decomposition of time-averaged turbulent fluxes tensor of momentum and scalar. The artificially generated turbulent fluctuations satisfy not only the prescribed profiles of turbulent fluxes of wind and scalar but also the prescribed spatial and time correlations. Following the method proposed by Xie and Castro (2008), two-dimensional random data are filtered to generate a set of two-dimensional data with the prescribed spatial correlation. Then, these data are combined with those from previous time step by using two weighting factors based on an exponential function. The method was validated by applying it to a LES computation of contaminant dispersion in a half channel flow.

View full abstract

In order to estimate of annual operation results and energy saving effect of a hybrid air-conditioning system in an existing office building, field measurements and thermal and air-flow network analyses were carried out. The following results were obtained : 1) The behavior of the hybrid air-conditioning system was shown based on analyses of measured values within annual operation. 2) The total natural ventilation rate in 2012 was 352.2×10⁵ m³(The average of air change rate was 2-4 times/h). 3) The contribution ratios of each conditions for natural ventilation were shown based on the analyses of BEMS data. 4) The calculation error of natural ventilation rate was about 6.6%, and so the proposed calculation model had sufficient prediction accuracy. 5) In this analysis, the annual energy saving effect of a hybrid air-conditioning system was about 6.1% in 2012. 6) The quantitative effect by improving the operation was clarified by case studies using proposed calculation model.

View full abstract

The main purpose of this study was to correct the raw data on morphological parameters in a high-density urban area; thus, we summarized the spatial distribution of urban morphological parameters and correlation between parameters for an area of 600 km² in Tokyo, Japan. Building height characteristics, such as the mean height and standard deviation of the height were determined for the entire study area. Other parameters describing the urbanmorphology were calculated, including the building plan area fraction, building area density, and frontal area index. These parameters characterized as functions of the building height. The results indicated that the calculated urban morphology statistics significantly differed for buildings with different mean heights. In the correlation analysis, there was a strong correlation between three parameters relevant to the horizontal size of the target area: the building plan area fraction, building area density, and frontal area index. Parameters that are related to the vertical size of the target area, such as the mean height of buildings and building area density, also showed a strong correlation. However, the standard deviation of the building height had a lowcorrelation coefficientwith the other parameters.

View full abstract

Because of the lack of power in Tokyo and Tohoku due to Tohoku-Pacific Ocean Earthquake that occurred on March 11, 2011, ordinance of electric power usage restrictions were triggered for the first time in 37 years. Large consumers of more than 500kW electric power contract were asked to reduce power consumption of 15%. Furthermore, since the power plant was stopped across the country, power-saving and energy-saving measures have been implemented in almost all over Japan. We conducted the investigation on the power saving conditions in the summer of 2011, in order to grasp and analyze the actual condition of power saving which commercial buildings performed. When we compared the energy consumption of the total from April to September of 2011 with 2010, about Office building, Kanto Area showed the biggest reduction of 21.4%, and when we compared the peak load of electricity of 2011 with 2010, the large office building in Tohoku Area showed the biggest reduction of 23.6%.

View full abstract

It would be useful for building designers to consider future climate change by using building thermal simulation to construct an adaptable building to global warming. Future weather data including future changes to climate is needed as an input data to conduct building thermal simulation under the future climate. In this report, a method to produce hourly future weather data is presented. The method combines real present hourly weather data with result from climate models. Hourly future weather data at 833 stations for 2040s and 2090s have been developed and applied to heat load calculation of office buildings.

View full abstract

The data of accidents in the junior high schools and the elementary schools in the ward areas and the urban districts of Tokyo were investigated with considering the meteorological data of relevant areas and the rate of air conditioners being placed in classrooms. The rate of air conditioners being placed in classrooms in the ward areas of Tokyo was four-six times higher than that in the urban districts of Tokyo. The data of accidents of the elementary / junior high schools were obtained from the NAASH (National Agency for the Advancement of Sports and Health), and the period of analysis was set as 3 years from 2005 to 2007. The data of accidents linked with meteorological data were classified for each level of the outside temperature at the time of occurrence of the accident. From this the relation of the outside temperature and the occurrence rate of accidents were determined. While the occurrence rate of accidents in classrooms in the ward areas during summer period was decreased with the years from 2005 to 2007, that in the urban districts was constant with the years. It was found that the difference in the rate of air conditioners being placed in classrooms might have an effect on the occurrence rate of accidents in the classrooms. The effect in the elementary schools could be greater than that in the junior high schools.

View full abstract

Ultraviolet radiation is known to cause erythema action on human skin even under cloudy skies. When it is cloudy and there is no direct sun, people tend to be off guard against UV protection. So people might have more exposure. Shades are useful for UV protection. When shades designed, it is necessary to examine radiance distribution of erythema UV and shield high radiance by shades. Therefore UV exposure can be reduced. In the past, the studies on radiance distribution of sky erythema UV under cloud-free skies have been reported, but there have not been many ones under cloudy skies. This study was based on the measurements of radiance of erythema UV in Ishigaki-si and Miyakozima-si, Okinawa in midsummer. Measurement data were got under cloudy skies and regression equation of radiance distribution of sky erythema UV made by us. Moreover, by using regression equation, ultraviolet daylight factor on the bottom of parasol's pillar and Architectural Sun Protection Factor (ASPF) were calculated. Defense performance for ultraviolet radiation was cleared by this study.

View full abstract