Combustible ceilings are typically known to enhance fire growth in a room fire. For wooden linings, impregnating fire-retardant chemicals is popular and simple solution, but there is still a concern that fire safety cannot be assured due to unevenness of the chemical amount inside wood. This unevenness is caused by efflorescence during manufacturing process and their service lives, with fire-retardant chemicals being excess near the surface and less inside the wood. This study evaluated those effect on its heat release and flame spread through cone calorimeter test (ISO5660) and model box test (ISO/TS 17431:2006).
In this study, three patterns of chemical distribution were considered. Group-S represents the wood after efflorescence; more chemicals near the front, and group-B is opposite. U is the group of uniformly treated wood. All fire-retardant-treated specimens were processed in a chemical pool under a pressure of 0.95MPa and then dried. The eventual thickness of the specimens was 18mm thick. The base wood was Japanese cedar (Cryptomeria Japonica D. Don) and the main component of fire-retardant was polyphosphate carbamate, both commonly used in Japan.
To figure out potential effects of unevenness, cone calorimeter tests were carried out. Each group consists of four or eight specimens with 11 to 186kg/m3 of chemical content. The specimens were heated to ignite under 50kW/m2 intensity, and heat release rate and mass loss rate were observed for 20 min.
To evaluate the changes in flame spread characteristics during their service lives, model box tests were carried out for group-S and U. Both groups had two specimens with chemical content of approximately 70 and 120kg/m3, which respectively corresponds to the recommended amount to achieve fire-retardant material and quasi-noncombustible material in Japanese building standard laws. A small room (W0.84×D1.68×H0.84m) with one opening (W0.3×H0.67m) was finished with each specimen, and burnt for 10min by a diffusion burner set at one corner. The burner was 17cm square, and heat release rate of the source was 40kW constant. During the experiment, heat release rate and the air temperatures were measured.
Based on the cone calorimeter tests on group-U, it was clarified that the amount of chemicals for suppressing flame combustion lies between 23 to 42kg/m3, and above this amount, both peak and total heat release rarely decrease. Compared to group-U, the combustion of group-B was generally enhanced, and flame combustion partially occurred with areas less than 34kg/m3. As a result, the integrated heat release up to 20 min also increased compared to that uniformly treated. On the other hand, in group-S, flame combustion as the surface carbonizes is suppressed, so the total heat release up to 20 min were equal or less than group-U. From these experiments, it was expected that efflorescence hardly influences on flame spread as long as the least area exceeds 34kg/m3 for this chemicals. Flame spread in model box tests agreed with this tendency, while the burnt area and eventual heat release rate significantly decreased as the average chemical content increased. It may be that heat resistance that fire-retardant obtains suppressed flame spread. Through these experiments, we concluded that unevenness in fire-retardant-treated product potentially enhance its combustion, but efflorescence hardly enhance flame spread as seen in interior usage.
Floor impact sound insulation performance is evaluated by sound pressure level of receiving room when the floor of the upper surface was impacted by the standard impact source. Therefore, it is necessary to make the sound receiving room for a closed space.
We propose an estimation method of heavy floor impact sound insulation rank of concrete floor slab using measurable driving-point impedance only at the slab upper surface.
First, we compared driving-point impedance in impact time or driving-point impedance in response time with heavy floor impact sound level. As a result, driving-point impedance in response time was better corresponded to heavy floor impact sound level.
Next, in order to improve the correspondence, multiple regression analysis was performed to estimate factors affecting the floor impact sound level. We investigated a method of correcting by using parameters using this factor in predictive calculation by impedance method 2009.
As a result, it was confirmed that by correcting driving-point impedance in response time with sound receiving room area and number of edge fixing, it is possible to grasp heavy floor impact sound insulation of concrete floor slab.
By using this result, it becomes possible to satisfy the required performance at completion more reliably.
One of the main aims of daylighting in conventional office buildings is still to reduce electric power consumption of artificial lightings, however, as the efficiency of LEDs has been much improved, the impact of daylighting upon energy savings is getting smaller. Buildings without openings may cause serious problems in visual quality of indoor spaces, therefore it is now more necessary than ever to grasp the psychological values of windows quantitatively.
The final purpose of this study is to position the psychological "view effects" as one of the performance items of windows that can be quantitatively evaluated. In this paper, a quantitative evaluation structure of views is derived by analysis of covariance structure based on data obtained from subject evaluation experiments about views from windows in actual commercial buildings.
Firstly, users' own criteria for evaluation in views from windows were collected by interviews based on the evaluation grid method (EGM). The EGM was conducted to derive evaluation criteria in views from windows using 31 photographs of the window with different conditions for room use, the floor, floor area, characteristics of viewing landscape, window shape, and window equipment. As a result, items of upper concepts indicating general psychological effects and items of medium concept indicating merits and impressions obtained from environmental factors were derived.
Secondary, subjective evaluation experiments about views from windows were conducted for 12 commercial buildings and 26 windows using 19 evaluation items which added "preference" to 18 items derived through the EGM. The height of viewpoint was 1.2 meters above floor level, and its distance from the windows was 2.43 meters. Views from windows with blinds were evaluated under three conditions: slat angle 0°/ 45°/without blind, and views through rolling screens or lace curtains were evaluated under two conditions: fully opened/fully closed.
Thirdly, the relationship between psychological value judgement of views from windows and the environmental evaluation conditions of the window was examined through factor analysis and covariance structure analysis based on the results of subjective evaluation experiments. Two factors (“good view”, “openness”) were detected from psychological items by exploratory factor analysis, and four factors (“landscape evaluation”, “range of view”, “clarity”, “sky view”) were detected from environmental items. These factors were sorted out by confirmatory factor analysis using SEM, and the factors of environmental items were divided into four factors, “landscape evaluation”, “wide views”, “far views” and "clarity". Next, by analyzing the causal relationship between factors by path analysis in SEM, quantitative evaluation structure of views is determined.
As a result, “good view” is determined by three factors: “clarity”, “wide view”, “landscape evaluation”. “Clarity” and “wide views” influenced “good view” via “openness”, and the indirect effects were 0.42 and 0.16, respectively. Since the direct effect of “landscape evaluation” to “good view" was 0.30, “clarity” among the three factors has the strongest influence on the evaluation of "good view". The results show that when designing a window with good viewing effects in an actual commercial building, “clarity” depends on the degree of visibility of the external landscape, so even after the completion of the building there is a possibility of enhancing the viewing effects with the operation of the window equipment.
This paper addresses the use of CLT siding usage and its effect on the thermal environment to better understand the possibilities for wooden structures for public buildings, in particular school facilities. Results and findings of this research are as follows:
1. Measurements of the thermal environment during cold and hot seasons of buildings:
One building utilizing CLT on the external, southern-exposed wall for thermal enhancement was used for measurements, and another building with the CLT was used for measurements and comparison to understand the inside thermal environment. For the basic experiment during the winter season, it was found that the building with CLT used on the external walls experienced a gradual change in room temperature as opposed to the sudden changes in temperature noted outside. During the summer season, it was noted for the same building that though the room temperature was initially recorded as high, with the use of air conditioning, the room temperature was able to drop to a comfortable level. After the air conditioning system was turned off, the change in the room temperature was gradual. In regards to the other building, the natural temperature of the room as well as the globe temperature were basically the same, and in comparison with the outside temperature, little change in temperature over the course of a day was noted. Furthermore, the humidity in the room throughout the day fluctuated little if any. These findings, when charted, were found to be quite similar to those of the building with external CLT usage.
Also, the actual measurements and findings from the experiments were found to be similar to those determined by simulations and calculations resulting from the use of the LESCOM-mint computer simulation program.
2. Comparison of RC and CLT buildings in seven different climatic regions
We considered medium to large sized wooden structures, in particular public school buildings, for our simulations. As the majority of public schools are RC buildings, we used the RC building model and compared it with a CLT model and considered the heating and cooling load for seven different climatic regions in Japan. We found that the cooling load for both the RC and CLT models were similar throughout all seven regions; however, when considering the heating load for the two types of buildings, we found that the CLT model had a lighter heating load than the RC model. From this comparison, we determined that CLT building model was superior for heating and maintaining the warm environment in the cold season.
3. Differentiation in CLT thickness in seven different climatic regions
We calculated the differences in heating and cooling loads for a typical classroom in the seven different regions. In each area except Naha, the change in cooling load due to the difference in CLT thickness is small.
On the other hand, the heating load is reduced by 16 to 20% for CLT 60 mm with respect to CLT 10mm, and is further reduced for 4 to 6% for CLT60 mm for CLT 90 mm. Even if the thickness is increased by 30 mm after CLT 90 mm, the reduction rate is small.
When comparing these findings with the RC simulations, it was further noted that if the CLT was 60 mm or more, the heating / cooling load was slight, and even if the CLT’s thickness was increased, a significant change in the load was not noted. CLT was found to be highly more efficient than RC in absorbing heat, thus helping to reduce the heating load while maintaining a comfortable room environment for work or study.
This study focuses on the renovation of apartment houses using the external insulation method which the number of cases is expected to increase in the future, and we conducted a systematic heat load simulation changing the window orientation, the window size (window-to-wall ratio), the window proportion, the type of glass, the thickness of the insulation, to clarify the annual heat load / the heat balance characteristics of each area and the factors that influence it. In addition, we prepared a basic data on the influence of the solar heat gain quantity and the annual heat load due to a difference of the location of window frame in "a thick wall" with thick insulation. Ultimately, the study deduced the following points.
1) In Tokyo, it is necessary to consider a reduction of both the cooling load and the heating load depending on the type of glass used. In the case which the type of glass is a double low-e glass insulating type, the annual heat load can be reduced by decreasing the window-to-wall ratio with the main window direction set to the south.
2) In Sapporo, it is important to consider mainly a reduction of the heating load. However, if the window-to-wall ratio is made too large, the cooling load will increase and the annual heat load will also increase due to the increase in the solar heat gain quantity in summer, so it is necessary to consider the appropriate window size.
3) In Kagoshima, it is important to consider mainly a reduction of the cooling load, and when the window-to-wall ratio is reduced, the annual heat load can be reduced. In addition, as for the glass type, a double low-e heat reflecting type with a low solar heat gain coefficient resulted in the smallest the annual heat load.
4) When a heat load simulation is conducted considering a solar radiation shading effect by "a thick wall", even when the thickness of insulation is 50mm, the solar heat gain quantity is reduced by 25% which affects the cooling load and the heating load because of a difference of the location of window frame. Especially in Sapporo where the coldness in winter is severe and it is assumed that the external insulation method using thicker insulation (200mm in this study) is expected to be adopted, both the heating load and the annual heat load increase due to the solar radiation shading effect of the wall thickness.
From this study, it is suggested that it’s necessary to simulate shading devices in all openings and reproduce the influence of the solar radiation shading by the wall thickness. In the future, since the annual heat load is greatly affected by the insulation level of external wall or the internal heat generation quantity, we will add further verification, and we plan to develop a method to correctly predict the load reduction effect by the external insulation method.
An air conditioning system that actively utilizes the heat capacity of the building frame (building thermal mass storage system) has a history of almost 100 years. Until now, in Japan, models and research results have been primarily obtained by blowing cold and hot wind against a concrete structure using fans. In recent years, technologies capable of efficiently producing medium-temperature cold water have progressed, and the technology of humidity control has been enhanced by separating the sensible and latent heat components. Therefore, building thermal storage systems in which piping is embedded in the building structure and cold water is directly introduced into the embedded pipes are increasingly being adopted. Compared to the commonly used convection air conditioning system, the building thermal mass storage system is expected to improve the radiant thermal environment in the building and efficiency of the system by reducing the air transfer fan power. However, to the best of our knowledge, there are few studies that report comparisons on these points. Therefore, in this study, we first developed a model using the measured values of the building thermal mass storage system installed in an office building in Tokyo. The maximum error values for temperature and heat flow were 0.2 °C and 1.8 W/(m2·K), respectively, and the average error values were respectively 0.6 °C and 4.3 W/(m2·K). Next, by comparing the calculated result of this model with the results from the convection air conditioning system model, the differences in the thermal environment of the room and energy consumption were verified. In the case where the dry-bulb temperature was maintained at a constant value, the Predicted Mean Vote (PMV) of the convection air- conditioning system was higher by an average of about 0.3 compared with that of the building thermal mass storage system. In addition, when the PMV was maintained constant, it was confirmed that the difference between the mean radiant temperature and dry-bulb temperature was large in the convection system. Based on the heat load obtained using simulations, energy consumption was compared between the convection system and building thermal mass storage system. The system coefficient of performance (COP) ratio was calculated by changing the heat source COP and heat transfer efficiency. If the water transfer factor (WTF) at the time of thermal storage is not extremely low, the energy consumption of the building thermal mass storage system is lower than that of the convection system.
In recent years, the temperature rise of the city caused by global warming and urban heat island phenomenon is regarded as a problem in Japan, and the necessity of urban development considering that mitigation is pointed out. The main factors of the urban heat island phenomenon are an increase in anthropogenic heat release and an increase in urban land use, and mitigating temperature rise by changing urban land cover to natural land cover (for example, green land).
Meanwhile, Japan is beginning to enter declining population era, and various problems caused by downgrading of urban district accompanying this are going to be concerned in the future. The need for "compact city" has been pointed out as a countermeasure, and examination of future land use arrangement is required. In the previous researches, authors will first prepare future land use deployment scenarios for the specific cities, predict and evaluate future city climate under those scenarios, and make effective land use arrangement from the viewpoint of mitigation of the city high temperature are considering. However, since the climate characteristics differ among cities, the appropriate land use scenario in each city may be different.
Based on such background, it is thought that urban development should be considered in consideration of mitigation of high-temperature urbanization. And it is also thought that cities in Chugoku region has several climate characteristics (Tottori, Matsue, Okayama, Hiroshima, Yamaguchi). Authors first created the direction of urban area consolidation under the declining population as scenarios for each land use. Then numerical simulation by meso weather model WRF for each scenario is carried out.
Authors set four scenarios: master plan scenario, sea breeze effect oriented scenario, distributed green scenario, suburban green scenario. Through the relative comparison of the results under each scenario, the objective is to grasp the suitable land use scenario for mitigating the urban warming for each city.
According to the results of numerical simulation, it is inferred sea breeze effect scenario are effective in cities with less wind pattern of urban areas, and distributed green scenarios are more effective in cities with lower relative humidity. In addition, the master plan scenario and the suburban green scenarios are found to be less effective being compared with the other two scenarios. The scenario in which the average temperature in the urban area is the lowest is sea breeze effect scenario in Tottori, Matsue, Yamaguchi and the one in which distributed green scenario in Okayama, Hiroshima.
As a conclusion, the land use scenario which has larger influences on the mitigation urban warming is different in each city. It is thought that it is necessary to make the strategic land use plan considering the local climate characteristics of each city in the future.
During the Hokkaido Eastern Iburi earthquake that struck in September 2018, Hokkaido realized the vulnerability of its centralized energy systems through failures such as large-scale blackouts throughout the prefecture. It was reported that owing to the blackouts, the dairy industry, which is the key industry of Hokkaido, was forced to discard about 20,000 tons of raw milk, with the total damage amount reaching approximately 2 billion yen. To prevent such damage, Hokkaido must build a stable energy infrastructure by introducing autonomous distributed energy.
To this end, this study aims to build a “recycling-type community model” that would achieve the following: regional independence through renewable energy, reduction of CO2 emissions, complete recycling of waste, and the establishment of autonomous dairy management. The role of dairy management would be to analyze and evaluate on the “recycling-type community model” on the basis of the following three perspectives: “material recycling, ” which refers to local production and consumption, “environmental nature, ” which indicates the effect of CO2 emission reduction, and “economy, ” which indicates the effect of investments influencing stability.
Three effects can be extracted from the results of the studied model: self-sustainment (local production and consumption) of the annual energy usage can be facilitated by building a “recycling-type community model, ” utilizing the model will positively contribute to the reduction of CO2 emissions (2,110.2 t of CO2 per year) and the use of waste (livestock manure 34,500 t), and the model can recover its construction cost in 11 years, thereby enabling independent management of biogas plant (BGP) facilities and livestock.