Journal of Environmental Engineering (Transactions of AIJ)
Online ISSN : 1881-817X
Print ISSN : 1348-0685
ISSN-L : 1348-0685
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Showing 1-7 articles out of 7 articles from the selected issue
  • Yuhei NISHIO, Takafumi NOGUCHI, Yasuhiro ODA, Hisayuki MUTO
    2020 Volume 85 Issue 776 Pages 705-715
    Published: 2020
    Released: October 30, 2020

     Heat transfer at void slab has been unknown in detail. In order to clear the mechanism of that, the fire performance of void slab is evaluated by calculating in this paper. The existing fireproof test report on the void slab indicates that void affect heat transfer for some reasons. In the previous study, the authors made the heat transfer calculating model about void slab with consideration of latent heat of water and melting of EPS, and it revealed that calculating heat transfer at void slab by finite difference method matched results of the experiment to some extent. However, it is needed that verifying the effect of EPS combustion in void and various parameters of void slab on both heat transfer and mechanical properties of void slab under fireproofing performance in order to evaluate fireproofing performance of void slab reasonably.

     At the chapter2, the authors verified the analysis model with considering EPS combustion for the void slab on which the fire test was performed. As the result, the effect of EPS combustion can be analytically confirmed by this analysis model, although EPS combustion affect fire proofing performance a few in the case with the targeted void slab. It is considered that fireproof performance, in other words, maximum back surface temperature and deflection at the center of void slab, can be evaluated on the safe side by this model.

     At the chapter3, the authors conduct parametric study in order to confirm how each parameter of void slab affect the fireproofing performance. As a result, on almost parameter study analyses, the effect of EPS burning on the maximum backside temperature and the amount of deflection in the center were small. In addition, it is indicated that the maximum backside temperature can be predicted as the safe side in case of considering EPS burning. Even in the case of thicker void slab, EPS combustion has little effect on the central deflection of the void slab, and the backside temperature can be predicted as the safe side by the analysis in the case of considering EPS burning.

     As a result, it is suggested that the proposed analysis model in this study can analytically complement the fireproofing performance test result of void slab, and that it can presume the fireproofing performance of the void slab of different thickness as long as the slab has the same void configuration as the test slab.

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  • Kazunori HARADA, Keiji KAWAI
    2020 Volume 85 Issue 776 Pages 717-723
    Published: 2020
    Released: October 30, 2020

     Many children, from 0 to 5 years old, spend most of their active hours in child day-care centers. Rooms in these centers are often very noisy due to voices of children and sounds of their various activities, enhanced by the excessive reverberation attributable to the little use of sound-absorbing materials in the room. Some researches have examined the speech intelligibility of elementary school pupils and the results show the score of the lower age group was the more affected by noise and long reverberation. It is expected that pre-school children could be even more affected than low-grade elementary pupils, but no study is found about this. Thus, in this study, experiments were carried out twice in actual classrooms of two child day-care centers with the participation of 3- to 5-year-old children to find the effect of acoustic condition on the word intelligibility of pre-school children.

     The procedure of experiments was like a game so that children can participate in with joy and without losing concentration. After the first experiment (1st Exp.) at a child day-care center, the second experiment (2nd Exp.) was conducted at another center, in which the procedure was revised coping with the problems found in the 1st Exp. Teachers, college students, and elementary school pupils (1st to 3rd grades, 6 to 9 years old) participated in the 1st Exp. and teachers participated in the 2nd Exp. as control groups. Six words that have three morae in Japanese and are familiar to children were chosen for the intelligibility test. Each of the vocalization of the words was mixed with pink noise at one of the three S/N ratios of -5, 0, and 5 dB, and convolved with the room impulse responses of three reverberation times of 0.4, 1.0, and 2.5 s. Children were asked to judge whether the word was food or not and to answer it by raising their hands holding a plate with either yes or no sign on it.

     The correct answers were judged from recorded videos and Correct Answer Score (CAS, %) of each subject was calculated as the ratio of correct answers to the total number of the test words. As a result, it was shown that the mean CAS of the 3- to 5-year-old groups were lower and the standard deviations of CAS of 3- to 5-year-old groups were greater than the teacher group in both of the experiments. On the other hand, these results did not indicate that the score difference between 3- to 5-year-old group and elementary pupil group, and that the cross effects of the age groups and acoustic conditions to the score. Nevertheless, the result that the CAS of 3-year-old group was the lowest as a whole and 34 %, in contrast to 80 % by the teacher group, in the worst condition suggested that pre-school children need a better acoustic environment than adult.

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  • Suitable illuminance and CCT on steady adaptation state
    Yuki OE, Youko INOUE, Mizuki TANGO
    2020 Volume 85 Issue 776 Pages 725-732
    Published: 2020
    Released: October 30, 2020

     This study aims to suggest a lighting environment corresponding to the life activity and age of users. In this paper, we took up six everyday life activities (checking steps, reading newspapers, eating, get-together, relaxing, and sleeping) and analyzed whether lighting conditions were common or different between age groups and life activities. The experiment involved eight females each from the young and elderly age groups. We suggested the tables which show a suitable range of illuminance and CCT on each or plural life activities for each or both age groups. We can obtain information for a design of lighting environment depending on the age group and life activities of the user by referring to each table. The main findings are as follows:

     1) For the young, a suitable lighting condition of four life activities (checking steps, reading newspapers, eating, and get-together) is determined by a combination of illuminance and correlated color temperature (CCT). The suitable range of “relaxing” is low CCT and it doesn’t depend on illuminance. On the other hand, for the elderly, the influence of CCT is small and the suitable range for each life activity almost solely depends on illuminance. For both age groups, a level of illuminance lower than this experimental range is suitable for sleeping, regardless of CCT.

     2) The suitable range for each life activity differs between the young and the elderly; however, there is a common suitable range between the age groups on six life activities. The higher the degree of visual performance required for life activity is, the higher the illuminance of the common range. The higher the degree of relaxation, the lower the CCT of the common range.

     3) In comparison with JIS general rules of recommended lighting levels, the standards of “reading newspapers”, “eating”, and “get-together” almost match the results of this study. It is necessary for the young to consider CCT because they are influenced not only by illuminance, but also by CCT. In addition, for the elderly, it is necessary to grasp an upper limit level of illuminance because a suitable ratio of each life activity may lower when an illuminance is too high depending on the life activity.

     4) In comparison with the Kruithof curve, we found that the common ranges for the suitable ratio to be more than 75% were the uncomfortable range and the range between the comfortable and uncomfortable range, depending on the life activity and age group. It is necessary to pay close attention to this result when we use the Kruithof curve.

     More reliable tables can be suggested by increasing the number of subjects and their characteristics in future. We suggest that future studies look into developing a prediction method of suitable illuminance and CCT for various life activities by determining the degree of visual performance and relaxation achieved from each life activity.

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  • A rough estimate of the amount of renewable energy from air-source heat based on the EU guideline
    Satoshi YAMAKAWA, Masashi KAWANO, Kimiya MURAKAMI
    2020 Volume 85 Issue 776 Pages 733-743
    Published: 2020
    Released: October 30, 2020

     In 2009, the natural heat such as air-source heat was defined as renewable energy. However, there exists no quantitative method for evaluating the amount of renewable energy supplied by heat pumps from heat collected from the air, and the actual performance of heat pumps are therefore unknown. In the present study, we investigated a method to estimate the renewable-energy-based heat from air supplied by a heat pump in Japan. This method is based on the quantitative evaluation method by the EU. And we estimated it roughly.

     With the aim of introducing aerothermal, hydrothermal, and geothermal energies as renewable resources, the EU defines the Guideline for the calculation method of the amount of renewable energy supplied by a heat pump. It represents renewable aerothermal, hydrothermal and geothermal energies captured by the heat pump, which is the amount of heat supplied by the heat pump minus the input energy of the heat pump.

     Although the EU defines the statistics of the heat pump output and default SPF values, this is not the case in Japan. Therefore, in the present study, these values were estimated using statistical data from the government and various organizations. The analytical targets considered in the civil sector (such as offices, hotels, commercial buildings, and hospitals) were air-source heat pumps for central air-conditioning, electric heat pumps for individual air-conditioning, and heat pump water heaters. The analytical targets considered in the civil sector (residential buildings) were room air-conditioners and heat pump water heaters. In the industrial sector, the targets considered were air-source heat pumps for factory heating. The target considered in the agricultural sector was heating for greenhouses (housing 10 varieties of vegetables, 16 varieties of fruits, and five varieties of ornamental plants).

     We investigated the method used to estimate the amount of renewable energy supplied by air-source heat pumps based on the quantitative evaluation method of the EU. Upon making estimates based on data from 2013, we obtained the following findings:

     1) Although the EU has statistics and default values prepared for quantitative evaluation, Japan does not have such information. Thus, we proposed a macro-level estimation method that uses the statistical data from the government and various organizations. Specifically, we calculated the SPF and Qusable values for each department, each building application, and each heat use application according to the approximate procedure shown in the flow charts (Fig. 2-8). Then we arranged each value as shown in Table 18-(a), (b). And by using these SPF and Qusable, we estimated the amount of renewable energy supplied by the heat pump.

     2) The renewable energy supplied by air-source heat pumps was 75.5 PJ/year for non-residential buildings in the civil sector, 328.1 PJ/year for residential buildings in the civil sector, 35.7 PJ/year in the industrial sector, and 0.09 PJ/year in the agricultural sector, resulting in a total of 439.4 PJ/year. The renewable energy supplied by the air-source heat pumps was equivalent to approximately 36.1% of the renewable energy with an existing track record, such as solar power (1,216 PJ/year).

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  • Junya YAMASAKI, Toshiharu IKAGA, Norihiro ITSUBO
    2020 Volume 85 Issue 776 Pages 745-755
    Published: 2020
    Released: October 30, 2020

     In the environmental accounting of local governments in Japan, it is considered important to introduce the concept of eco-efficiency into the assessment of each industry and administrative division. Therefore, in this study, eco-efficiency assessment by industry was conducted uniformly for all Japanese municipalities based on two indicators: economic value and environmental load. For these, the respective indicators were gross regional product (GRP) and amount of environmental damage, as defined in a previous study. That study quantified annual environmental loads in Japanese municipalities within the framework of the endpoint-type life cycle impact assessment method “LIME2 (Life-Cycle Impact Assessment Method Based on Endpoint Modeling 2)”. In this method, assessment results are calculated in monetary units called the “Eco-index Yen” (unit: Japanese yen) and environmental loads of several impact categories are integrated, such as “global warming” and “land use, ” based on environmental conditions and knowledge unique to Japan. Another indicator, eco-efficiency, was defined as a division of monetary units (GRP divided by amount of environmental damage), as calculated for wide regions and individual municipalities in Japan in order to discuss their situation from the perspective of economics and the environment.

     Based on reliable, verifiable, and comparable statistical information, each index value was calculated for all industries throughout Japan in 2015: GRP was 2.28 million yen/capita, environmental damage was 32.6 thousand yen/capita, and eco-efficiency was 69.8. The assessment results of all municipalities were placed on a map to visualize the regionality of eco-efficiency, which revealed industry trends nationwide. For example, the eco-efficiency of “manufacturing” showed a trend that reflected the major local products in each area. The eco-efficiency value tended to be higher in areas that had active automobile and electronic component industries because these products produced relatively large benefits compared with their environmental loads. Next, the study focused on 21 large municipalities, including government-designated cities, located in representative urban areas in Japan. The results showed that the eco-efficiency of many industries in most of the 21 municipalities exceeded the national average. This suggests that the eco-efficiency of each industry tends to be higher in more densely populated cities in Japan. This hypothesis is potentially important for discussing “centralization of city functions” from the perspective of industry structure. Verification of this hypothesis will be investigated in the future.

     Taken together, these results indicate that it has become possible to quantify the real situation of each industry throughout Japan for both individual municipalities and regions. No studies to date have quantified the eco-efficiency of each industry in all Japanese municipalities monetarily and uniformly—this study is the first to provide an example from each industry throughout Japan in the field of environmental science.

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  • Kazunosuke IKENO, Tomohiro FUKUDA, Nobuyoshi YABUKI
    2020 Volume 85 Issue 776 Pages 757-765
    Published: 2020
    Released: October 30, 2020

     The importance of the administrative authorities communicates information about disaster prevention is increased. When a natural disaster occurs in Japan, administrative authorities communicate this information using disaster administrative radio system. Ministry of Internal Affairs and Communications recommends distribution individual house receivers to all family, however, many municipalities use not individual house receivers but outdoor loudspeakers due to financial matters and limited cost-effectiveness.

     There is a problem that some regions don’t receive the information from outdoor loudspeakers. Municipalities need to reconsider the placement of outdoor loudspeakers, but it is difficult to confirm audibility intuitively and there are few cases that experts and non-experts such as government and citizens share and consider acoustic analytic results.

     High-precision outdoor acoustic analysis method is proposed. Virtual Reality (VR) and Mixed Reality (MR) System for visualizing simulation of environmental circumstances are developed. However, these simulation need many computer resources and take a long time. Therefore this study aims to develop an interactive visualization system for simulations of sound circumstance from outdoor loudspeakers using MR.

     By using an optical see-through Head Mounted Display (HMD) and tablet terminal, users can view the acoustic analytic results of the simulation. Sound simulation is carried out on PC. Furthermore, when users change the simulation condition such as sound source positions, users can view the results of the simulation immediately.

     It is necessary to create three-dimensional model of the object region and input our system preliminarily. This system uses the Ray-Tracing Method which is a type of geometric acoustic simulation method because this method can reduce calculation load. And, using the approximate of Maekawa Chart, this system can handle transmission of diffracted sound which cannot be handled in geometric acoustic simulation method. This system converts simulation results into sound pressure level (SPL) and shows heatmap and bar histogram by using MR.

     Our proposed system can reduce calculation load by using Sound Ray-Tracing Method. Our system is appropriate for an interactive system. However, when users view the acoustic analytic results of simulation by using HoloLens which is one of the optical see-through Head Mounted Display, this system needs time for rendering objects such as sound receiver and heatmap because of too many objects. The cause of this problem is the data transmission speed between PC and HoloLens. By reducing drawn objects and improving transmission speed, this problem is solved.

     We set coordinates of the sound source at the same place as the current position of one of the outdoor loudspeakers and simulated by using our system. We tested the effectiveness of our system by comparing the simulation results to more detailed simulation results and actual measurement value.

     The conclusions of the present study are shown below.

     ● Develop the groundwork of interactive visualization system for sound environment simulation using MR.

     ● Reduce calculation load by using Ray-Tracing Method which is a type of geometric acoustic simulation method.

     ● Confirm audibility intuitively by heatmap and bar histogram by using MR.

     The future prospect is to enable simulation in consideration of plural sound sources, wind and temperature.

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  • Focusing on people's values, energy-cognition and energy consumption among two-generation families in Tokyo Metropolitan Region
    Ayami OTSUKA, Tatsuya MASUDA, Daisuke NARUMI
    2020 Volume 85 Issue 776 Pages 767-777
    Published: 2020
    Released: October 30, 2020

     The dissemination of energy-saving lifestyles is a policy agenda under Japanese strategic energy plans. Increased importance has also been placed on household sector in terms of tackling global warming. With an aim to understand lifestyles promoting energy-saving, the effects of people’s values and energy cognition on energy-saving behavior and energy consumption were analyzed in this study. Specifically, this study follows the authors’ previous work whereby the conceptual framework states that socially oriented values are related to factors that form energy-attitude and therefore a higher level of behavioral intention and actual behaviors taken, whereas personally oriented values form behavioral intention without a corresponding development of energy-attitude and are thus more energy consuming.

     An internet-based questionnaire was conducted in February 2019, targeting two-generation families residing in Tokyo Metropolitan region. A two-phased approach - a screening process before the main survey- to ensure the aimed target would be recruited. The screening conditions included Place of residence, family member constructs (i.e. two generations family), opinion on future energy choice for Japan as according to the national debate in 2012 after the Great East Japan Earthquake and Fukushima Nuclear accident, and finally availability of electricity / gas bills in 2018. The main survey asked 20 items on people’s values, 30 items on energy cognition, behavioral intention and the level of action on 19 specific energy-saving behaviors, energy consumption data for 2018 (separately for electricity and gas), other questions related to energy/Earthquake, etc., and demographic facts. Factor scores and sub-scale points were used for comparison by value clusters, where IBM SPSS 25 was used for statistical analyses.

     The results show that effects of social, namely self-transcendent, values was evident for formation of behavioral intention, but this was not the case when dependent variables were changed to action, then to energy consumption. Instead, more personally oriented values, namely openness to change, was influencing on people to take actions, whereby no “value” variables were noted to be influencing energy consumption. This in all suggest that the influence of people’s values were limited, as compared to other factors known to be influencing energy-saving behavior and especially energy consumption. Having social values per se does not lead to taking action, whereas “openness to change” values, a construct of personal values with tendency to be open to new ideas and to behave according to one’s own thoughts, are likely to influence people to take actions, providing implications for environmental education and policy.

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