Toshio Ojima

Energy impacts of recycling disassembly material in residential buildings

In order to stop the global warmth due to the CO2 concentration, the energy use should be decreased. The investment of building construction industry in Japan is about 20% of GDP. This fraction is much higher than in most developed countries. That results the Japanese building construction industry including residential use consumes about one third of all energy and resources of the entire industrial sectors. In order to save energy as well as resource, the recycle of the building materials should be urgent to be carried out. In this paper, we focus on the potential energy savings with a simple calculated method when the building materials or products are manufactured from recycled materials. We examined three kinds of residential buildings with different construction techniques and estimated the decreased amount of energy consumption and resources resulting from use of recycled materials. The results have shown for most building materials, the energy consumption needed to remake housing materials from recycled materials is lower than that to make new housing materials. The energy consumption of building materials in all case-study housing can be saved by at least 10%. At the same time, the resource, measured by mass of building materials (kg) can be decreased by over 50%.

CFD analysis of mesoscale climate in the Greater Tokyo area

Abstract The results of CFD analyses of mesoscale climate in the Tokyo area are presented. Here, the model for geophysical flow problems developed by Mellor and Yamada is used for turbulence closure. In the first half of the paper, the accuracy of CFD analyses is examined by comparing their results with the measured data. The topography and present land-use situation in Japan are incorporated into the predictions by using the numerical data-base provided by the National Land Agency of Japan. For comparison, a computation which does not consider the effects of the distribution of land-use conditions at the present is also carried out. In the latter part, urban climates during the 1930s and the 1990s are analysed by the CFD method developed here. By comparing the results of these analyses, the effects of urbanization on heat island circulations over the Tokyo area are investigated.

Changing Tokyo Metropolitan area and its heat island model

Tokyo region consists of Tokyo Metropolis and Kanagawa, Saitama and Chiba prefectures. Its population has been growing from 17.8 million in 1960 to 31 million in 1985 and is predicted to reach 35 million in 2000. The temperature in Tokyo has gone up by 2 degrees on average, and its humidity has fallen by 15% during the last hundred years, and the phenomena of ‘heat island’ and ‘dust dome’ have arisen. As a consequence of the heat island phenomenon, from the industrial areas of Tokyo Bay, SOx, NOx, COx and dust particles flow into the residential areas of the city center, rise up from areas of Ikebukuro and Shinjuku, float 100 – 300 meters up in the air, and fall down as photochemical smog over the central areas and round about within a 20-km radius. These are the most overpopulated residential areas, and the green areas and the dwellers suffer from it. The first cause of the heat island phenomenon is the changes of the natural surface of the earth. Lakes, ponds and the green areas have been ruined and whole central areas have been covered with asphalt and concrete to be roads and buildings. Canals, rivers and bays have been filled up with earth. The second cause is the increase of energy consumption brought by high activities of production and consumption in Tokyo. Working out the effect of these heat impacts upon the air, the changes of the natural surface of the earth increase the temperature of the first 25 meters of upper air by 1 °C, and the artificial heat discharged from thermal power plants and the like, increase it by 0.5 °C. To prevent heat island phenomena, we have to split up a heat island into pieces by putting ‘the deep underground space’ to practical use. By cutting up the succession of city areas by making greenbelts and canals, we can make ‘cool islands’ among segregated heat islands. To prevent the dust-dome phenomenon, we have to decentralize industries set along Tokyo Bay. By building urban residential and industrial complexes, we can prevent polluted air from flowing into central city areas. Taking measures to meeet the prevention of the phenomena of heat island and dust dome means making fire interception belts in case of predicted disasters over wide Tokyo areas. For safety as well as for health, it is important and expected that Tokyo will be reconstructed.

Earth surface heat balance changes caused by urbanization

Abstract The relationships, in regional environmental planning, between land use and earth surface heat balance in urbanized areas have been investigated. In the first part of this study, the calculation procedure and field observations of earth surface heat balance (natural heat) are described. The summer earth surface temperature was observed at Tokyo. Calculated values showed good agreement with observed values, though observed surface temperatures varied widely with differing land use. The results of an Osaka Prefecture (1856 km 2 ) case study are also presented. The amount of natural heat (the earth surface heat balance) and the artificial heat released are estimated according to land usage. The regional mean earth surface temperature in Osaka City (a developed region) during August is higher by ca. 3 °C than it is in Sennan district (an undeveloped region). The artificial heat released was 174.2 × 10 12 kcal/year in Osaka Prefecture (1970 – 1974). The heat flow at the earths surface varies remarkably with urban development.

A Basic Study on Utilization of the Cooling Effect of Sea Breeze in Waterfront Areas along Tokyo Bay

abstract ″Priority Urban Redevelopment Areas″ in Tokyo, Japan, are currently undergoing large-scale urban renewal. However, the heat island phenomenon has become a serious problem in large cities in Japan. We surveyed the temperature and wind conditions in two adjacent areas: a new skyscraper district on the coast (A district) and a typical inland urban district (B district). Our observations indicated local temperature increases and unstable wind with weak velocity in B district. It is possible that differences in the wind environment influence the local temperature. We analyzed the relationship between undulations in ground level and the wind environment by wind tunnel experiments. The results confirmed that there was a weak wind area in B district located behind A district from the direction of the coastline. Our findings indicate that it is important to consider the heat island phenomenon in urban planning in order to make best use of the cooling effect of the breeze from the sea at waterfront areas.

Investigation on the Situation of Combined Heating and Power System in Japan

Abstract In Japan, during the last 20 years, combined heating and power (CHP) system has been developed rapidly. In order to grasp the present condition of introduction and the existing problems of CHP system, the questionnaire survey on CHP system had been carried out at Tokyo. According to the results of investigation, it can be summarized as follows: 1) CHP system had been used widely in various sectors. The generating electricity capacity ranged several ten to several thousands kilowatt. 2) The percentage of CHP total capacity to the electricity demand peak was low and the average value for all users investigated was only 25%. 3) Gas turbine and gas engine achieved 60%-80% overall energy utilization efficiency with 20%-34.5% generating electricity efficiency and 19.5%-50% exhaust heat utilization efficiency. 4) Education buildings had the maximum average generating electricity efficiency with 30.6%, followed by hospital buildings with 29.6%, amusement facilities with 29.5%, office buildings with 28% and compound buildings with 25%. Hospitals attained the maximum average exhaust heat utilization efficiency with 46.1%, followed by offices with 41.3% and compound buildings 39.8%. 5) Various users had different motivation of selecting CHP system. Both office and compound buildings selected economy as the most important reason introducing CHP system; while hospital and education users concerned more saving energy. Hospital and office users were satisfied with the CHP system introduced; while compound building users were not satisfied very much with the CHP system

MITIGATION OF URBAN HEAT ISLANDS : METEOROLOGY, ENERGY, AND AIR QUALITY IMPACTS

This paper presents results from energy, meteorological andphotochemical (air quality) modeling for the Los Angeles Basin, one ofthe largest and smoggiest urban regions in the U.S. and the world. Oursimulations suggest that by mitigating urban heat islands, savings of 5to 10 percent peak utility load may be possible. In addition, heat islandmitigation can reduce smog formation by 10-20 percent. in summer, whichis as effective as controlling emissions from all mobile sources in theregion. For a typical late-August episode, our simulations suggest thatimplementing cool cities in the Los Angeles Basin would have a net effectof reducing ozone concentrations. Peak concentrations at 3 pm decrease byup to 7 percent (from 220 down to 205 ppb) while the total ozone mass inthe mixed layer decreases by up to 640 metric tons (a decrease of 4.7percent). Largest reductions in concentrations at 3 pm are on the orderof 50 ppb whereas the largest increases are on the order of 20 ppb. Withrespect to the National Ambient Air Quality Standard, domain widepopulation weighted exceedance exposure to ozone decreases by up to 20percent during peak afternoon hours and by up to 10 percent during thedaytime.

Urban environmental design of land use in Tokyo metropolitan area

Abstract Tokyo metropolitan area is one of the biggest cities in the world, where about 30 million people live and work within the area of dia. 50 km. But the residential environment is not comfortable because of its hugeness. In this area, plans for new land use are indispensable. In this study, land use and thermal environment, especially land surface temperatures and distribution, in Tokyo metropolitan area were analyzed by using remote-sensing data, LAND-SAT-5 TM data, and mesh data about land use made by the Geographical Survey Institute.

Investigation on the Standard for Energy and Environmental Design of Residential House in China

Abstract In this research, the authors have carried out the research to investigate the characteristics of building energy standards of the residential building in China. Efforts have also been made to promote a better understanding of the energy policy and relevant standard for architects and building designers to achieve optimal energy efficient building design in China. The results can mainly summarized as follows:(1) As for the thermal environment design, the climate of China has been classified five zones.(2) The sunlight, lighting, ventilation environment of residential building have been specified in the new standards.(3) Prescribed the building design elements, such as layout, orientation, shape, color, plan and the type of window. In particular, the thermal insulation measures for heating system has been added in hot summer and cold winter region, which was not described in old standard.(4) It is admitted that there is still a difference compared with the standard of many foreign countries, and the improvement in the further heat insulation performance and positive execution of the standard continue to be expected.

Field Survey of the Emergency Power Supply Related to Business Continuity

Abstract With the development of economic globalization, as well as the current industrial structure in which the interruption of business activities would have a worldwide impact, preparations to maintain the operation level of important business tasks in the event of a disaster have become increasingly important in both the public and private sectors. This study focused on the electrical power system in buildings and a field survey was performed on emergency power supply facilities to secure an emergency power supply in the major business districts of Japan. The objective of the study was to extract beneficial information regarding the emergency power supply capacity related to business continuity in buildings located in the central business district, to contribute to the future establishment of BCPs. The results of the analysis indicated that the percentage of the capacity of the emergency power supply in contract demand tends to be larger when running time equivalent to full-load operation is longer on the whole. The survey indicated that in the majority of the buildings, the maximum operating time on the emergency power supply is 24 h or less. Therefore, business continuity will be impossible if the power supply is interrupted for more than 24 h.