Objective. Briefing on the present situation of the LCA studies in the architectural field.
Result and Discussion. The ecological studies of the architectural field in Japan had started on the era of air pollutions issues in the 1960s. Above studies had progressed into the LCA studies in the 1990s by the trigger of the oil crisis in the 1970s and the ozone depletion issues in the 1980s. Main institutions of the LCA studies in the architectural field in Japan are “Architectural Institute of Japan”, “The Society of Heating, Air Conditioning and Sanitary Engineers of Japan”, “The Institute to Electrical Installation Engineers of Japan”, “Institute for Building Environmental Energy” etc. Major architect offices, major contractors and major housing companies have been proceeded the studies up to now. Environmental assessment methods for building based on the LCA have been proposed. They are BREEAM (UK, 1990), BEPAC (Can, 1993), LEED (USA, 1996), GB Tool (International, 1998), NABERS (Aus, 2001) and CASBEE (Jpn, 2002).
Conclusions. The LCA studies in the architectural field are advancing actively.
Objective. The case study of LCA analysis of a detached wooden house from cradle to grave by Process Analysis Method was performed as the second LCA Project by NEDO (New Energy and Industrial Technology Development Organization). The inventory data of a two-by-four system house and of an aluminum sash were collected in detail. For this two-by-four house, several kinds of aluminum sashes with different size were used as windows or terraces. However we obtained only one inventory data set of the most common sash. It is necessary to estimate the CO2 emission of an unknown different size sashes from the known inventory data of the most common sash. The degree of data coverage is very important because the degree of precision of the analysis depends on it. The effect of data coverage on the precision of inventory analysis was performed for an aluminum sash, heat insulating aluminum sash and detached wooden house. The 1st objective is to estimate the CO2 emission of an unknown different size sashes from the known inventory data of the most common sash. The 2nd objective is to make clear the effect of data coverage on the precision of inventory analysis.
Results and Discussion. For the 1st objective, several estimation methods were studied and the method that uses the power function of the ratio of perimeter was found to be the most precise and a simple method. For the 2nd objective, in the case of both aluminum sashes, about 70 weight % of degree of data coverage was enough to obtain 90% of CO2 emission. On the other hand, in the case of the house, 90% CO2 emission was obtained by 97 weight % of data coverage. In the case of the house, if the data coverage were calculated by accumulating materials weight in descending order of CO2 emission, then 90% of CO2 emission would be attained by 90 weight % data coverage. It is important to collect inventory data with the help of the information about CO2 emission factor of materials.
Conclusions. In the case of aluminum sash, the CO2 emission by production of any sash was found to be able to estimate from the only one known sash by the method that uses the power function of the ratio of perimeter. For collecting inventory data effectively, it is important to collect them in consideration with weight and also CO2 emission factor of materials.
The research on LCA method of buildings started in 1990 as an activity of the Architectural Institute of Japan, and it became LCA guideline of buildings. By using of this guideline, the cost effectiveness evaluation tool to mitigate climate change was developed and applied by the public building department, the Ministry of Land, Infrastructure and Transport as a operation tool for Green government design guideline in 1998. A similar evaluation tool that suits each climate of various regions was developed and applied by local governments and private companies. As well as LCA, the comprehensive assessment system for building environmental efficiency named “CASBEE” was developed supported by the Ministry of Land, Infrastructure and Transport. Since 2004, more than 1300 buildings have been assessed and ranked by national government, local governments and private companies using CASBEE tool, and in 2007, CASBEE was revised to contain simplified LCA method limited to LCCO2 calculation for all kind of buildings such as detached houses and large-scale commercial buildings. This paper describes current situation on these projects of which the author has taken charge.
Objective. Preventing global warming has become a major social issue. So, in life cycle assessment (LCA) of buildings, LCCO2 focusing on CO2 is often used as an assessment index. Additionally, the establishment of sustainable society for resources is another major issue in Japan. The building construction industry has seen problems in the consumption of large amounts of resources during building construction and the generation of massive waste at the time of demolition. To curtail them, it is being called for to use recycled resources upstream of the processes and reduce, reuse, and recycle waste material downstream. So, LCA, which is able to estimate resource sustainability, became necessary in building sector.
Results and Discussion. Firstly a general review of LCA studies in building sector for these issues will be reported. Then LCA study by the Architectural Institute of Japan (AIJ) will be reported in detail.
LCA study for buildings by AIJ has been continued since 1990 and a useful assessment tool, which is called “the AIJ-LCA tool”, has been developed. This tool has been widely used in building sector and made some influence. But this tool is mainly used to assess LCCO2.
On the other hand, this tool was revised to estimate resource consumption and waste generation in 2006. This report will give an outline of resource sustainability assessment function of this tool and show a case study.
Conclusions. New indices, which are life cycle resource (LCR) and life cycle waste (LCW), were introduced to estimate resource consumption and waste generation. By a case study, these indices were shown as useful to estimate resource sustainability.
Background and Objectives. It is difficult that countermeasures against urban heat islands (UHI) are installed really effectively because various environmental impacts by UHI depend on time, season, and location. However, we think that research and development of installation methodology of UHI countermeasures based on life cycle thinking makes their really effective installation possible.
Results and Discussion. One of UHI countermeasure studies based on life cycle thinking is simultaneous evaluation of an air temperature reduction effect and an LCCO2 reduction effect by UHI countermeasures using life cycle inventory analysis (LCI). Although air temperature decrease in summer reduces energy consumption for cooling, the decrease in winter increases energy consumption for heating and installation and operation of UHI countermeasures themselves emit CO2. From the results of the study we can install UHI countermeasures so as not to promote global warming. The other of studies based on life cycle thinking is environmental impact assessment of UHIs based on a framework of life cycle impact analysis (LCIA). From the results of the study we can assess when and where UHI has an impact to a human society.
Perspectives. We wish that life cycle thinking also spreads over UHI countermeasures studies and UHI studies for real environmental impact reductions are being performed widely.
Objective. This paper aims 1) to grasp the mechanism for impacts of ‛location of buildings' on environmental load, 2) to review existing researches, and 3) to examine the environmental load by applying LCA in the scale of urban areas in a case city.
Results and Discussion. There are two types of approaches for estimating the environmental load with buildings. The one is a micro level approach to target each building or town block, and the either is a macro level approach to target the urban area or region. The former approach can estimate the environmental load induced by each building or town block e. g. relating transport activity. The latter sets the boundary for estimating it from the various types of activities which can be changed according to the location of buildings. The literature review shows that the environmental load from transport sector has been studied in transport engineering field, and that from domestic sector has been studied in architectural field separately. However, it is very important to estimate the emission from transport sector in examining location of buildings with the view of environmental load. Our case study applying LCA in an actual city indicates that there might be a correlation between the geographical distribution of CO2 emission and that of population, and that the CO2 emission per capita is larger in dense district than that in suburban area. These results imply that the compact city policy has the potential to reduce the Life Cycle CO2 emission of buildings.
Conclusions. This paper concludes the necessity of the framework for evaluating the impacts of both ‛the locational distribution of buildings in urban areas' and ‛the types of buildings' on the environmental load throughout the change in life- and work-style. LCA approach is effective for the analysis. Further, the collaboration between the researches in the transport sector and domestic sector is needed.
Objective. Detached house LCA Analysis from cradle to grave by Process Analysis Method is scarce. Because huge amount of inventory data related to resources and parts are required and the background data are not enough to link with the foreground data. The purpose of this study, that was performed as a case study of the second LCA Project by NEDO (New Energy and Industrial Technology Development Organization), is to collect inventory data of a detached wooden house in detail with the LCI analysis by Process Analysis Method, and to estimate the global warming impact of the detached house through its life cycle. The influence of the energy saving performance and disposal scenarios are also examined. Results and Discussion. This analysis made the following facts clear. In construction stage, the highest energy performance house emits largest amount of CO2 because of using the most efficient insulator and double glazing fittings. But, in several years after construction, power saving effect of air conditioning recovers negative effect of construction stage. Living stage emits largest amount of GHG (CO2eq.) among construction, maintenance, living and disposal stage. In the disposal scenarios, if materials are recycled as much as possible, the subtraction effect lowers the life cycle global warming impact. Conclusions. The LCI analysis of the detached house through its life cycle by Process Analysis Method was performed and the global warming impact was estimated. The influence of the energy saving performance and disposal scenarios are also examined. The results of this study will make it possible to research on insulation effect of houses in cold region or the effect of life-time on the environmental load and many other subjects. However, to achieve those studies it is essential to enrich the background data.
Objective. It is forecasted that the population of Shiga prefecture should increase until 2030. There is an apprehension that environmental load impact should also increase by population increase. In this study, we estimated future prospect of environmental load related to wastewater treatment systems in Shiga prefecture. The target year is 2003 and 2030. We proposed a new environmental efficiency indicator based on the ratio of water pollutant reduction to greenhouse gas (GHG) emission, and evaluated wastewater treatment systems by utilizing our new environmental efficiency indicator. Our estimation considers sewerage, agricultural community effluent treatment facility, combined household wastewater treatment facility and night soil treatment facility. Results and Discussion. In 2003, 70% of the total GHG related to wastewater treatment systems in Shiga prefecture was emitted from sewerage. On the other hand, 80% to 85% of the total GHG is estimated to come from sewerage in 2030. It is estimated that the introduction of advanced treatment system accompanying water pollutant reduction (COD: 4%, T-P: 15%, T-N: 1%) should cause nearly 30% increase of GHG emission. In focusing environmental efficiency indicator based on the ratio of water pollutant reduction to GHG emission, the efficiency of sewerage is 50% to 80% higher than that of other wastewater treatment systems. Conclusions. In this study, we estimated future prospect of environmental load and environmental efficiency related to wastewater treatment systems based on the lifecycle comparison of 8 scenarios considering future technologies and social trends such as water saving lifestyle. Our estimated results showed that the introduction of advanced treatment system for sewerage have possibilities nearly 30% increase of GHG emission. On the other hand, it was showed that water saving lifestyle should cause a definite reduction of GHG emission. We investigated a scenario in which the introduction of advanced treatment system and water saving lifestyle would spread. In comparing estimated result of this scenario with the present conduction, we could show several advantages of the environmental efficiency proposed in this study.
Objective. The "bottle to bottle recycling" of PET bottle by chemical process, hydrolysis and re-synthesis of PET resin, was put into practical use in April of 2004 in Japan, and this method was regarded as one of the most promising routes of PET bottle recycle. There are, however, several options of PET bottle recycling that should be examined whether they are really useful or not. In this study, LCA analysis was tried to estimate the effectiveness of several alternatives of PET bottle recycling. A new concept of "Social Energy Consumption", defined as sum of energy inputs for production plus feed stock energy minus total energy loss in our society during the use and recycling of PET bottle, was proposed and used as criteria for estimating the effectiveness of the PET bottle recycling: in other words, energy equivalent of resource conservative quantity was used for estimation of recycling, that is a main characteristic of this study. Results and Discussion. Several case studies were carried out to examine the adequacy of assumed values as well as the estimation procedure adopted in this study. As a result, the reliability of the values and method was confirmed. Results of the case studies indicated that the advantage of the chemical recycle for bottle to bottle is not so larger as was expected than that of material recycle for other products, because energy input for chemical recycle is rather large, however the difference in the quality of products is not taken into account. And it was also found that bottle reproduction from flakes obtained directly by crushing used PET bottle has a better potential advantage, meaning that this recycle route will be worthy of serious consideration although this is not practical in present-day Japan by the ministerial regulation from a hygiene point of view. Conclusions. Thus, there should be more emphasis on the necessity of wide-ranging discussions on the recycle of PET bottle based on objective and quantitative LCA investigation from the stand point of, not only CO2 emission, but the social utility of repeated use of petroleum resource.
Objective. In this study, we discussed the evaluation method of mechanical recycling based on life cycle inventory analysis. CO2 reduction effect was considered as an example for the environmental burden of the evaluation and the method was applied to typical cases. Results and Discussion. In case of closed-loop recycling, such as aluminum can recycling, three factors are important for the evaluation: the unit CO2 emission from the processes with and without recycling, and the recycling rate. Meanwhile, in case of open-loop (cascade) recycling, it is essential to make equal functional unit between the two scenarios. In this paper, we introduced performance ratio, which shows how much material is required to fulfill the defined unit function. Since a product from cascade recycling can be different from the corresponding original product in many aspects like as material composition, weight, and heating value, the CO2 emission may change depending on the subsequent processes like as waste treatment processes. Conclusions. In each case of closed-loop recycling and cascade recycling, the CO2 reduction effect per recycling is key gauge. The discussions on evaluation method in this paper will contribute to know the points for an improvement in efficiency of mechanical recycling.