IMPROVING SUSTAINABILITY OF BUILDING BLOCKS BY EXTENDED USE OF DECENTRALIZED COMBINED HEAT AND POWER SYSTEMS

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1 IMPROVING SUSTAINABILITY OF BUILDING BLOCKS BY EXTENDED USE OF DECENTRALIZED COMBINED HEAT AND POWER SYSTEMS Ken Aozasa 1, Shuzo Murakami Dr. Eng. 2, Satoru Sadohara Dr. Eng. 3 Toru Ichikawa Dr. Eng 4, Ryota Kuzuki 4 and Iwao Hasegawa 5 1 Environment System Planning Group, Japan Environment Systems, Tokyo, Japan 2 Department of System Design Engineering, Keio University, Yokohama, Japan 3 Graduate School of Environment and Information Sciences, Yokohama National University, Yokohama, Japan 4 Energy Strategic Planning Dept., Tokyo Gas Co., Ltd., Tokyo, Japan 5 Mechanical and Electrical Planning Group, Nikken Sekkei, Tokyo, Japan ABSTRACT To achieve the Kyoto Protocol target, additional measures for reducing GHGs from the building sector is a strong requirement in Japan. While this situation, building occupants are eager to secure a sufficient energy supply in terms of developing business and living continuity plan (BLCP). To deal with both of these issues, we are proposing the concept "Sustainable Town", the key items of which are; 1) electric and thermal load leveling by block-scale load aggregation, 2) installation of decentralized combined heat and power (CHP) supply system, 3) installation of private electric wire and thermal pipelines in the block. By effective management of these items within a building block, total energy saving (primary energy efficiency) and risk reduction against disease can be increased; this can not be achieved within a single building. Many densely-constructed blocks, such as in central business districts have a great potential to reduce GHGs along with contributing BLCP in the district. Case studies being conducted to some existing blocks in Tokyo are also introduced. KEYWORDS Decentralized energy system, Combined heat and power, Primary energy efficiency, Risk reduction, Business and living continuity plan INTRODUCTION Along with the further maturation of its society, all Japanese cities share the tasks of creating communities that are both pleasant and highly resistant to disaster while harmonizing their operation with the environment to achieve the Kyoto Protocol target. They also must rebuild existing urbanized districts and heighten their vitality in preparation for further population aging and decrease. While this situation, the construction of energy-conserving buildings and promotion of utilizing natural energy, these tasks demand an increase in energy utilization efficiency in cities with high energy demand densities so that additional reduction of greenhouse gases (GHGs) can be achieved. Urban renaissance projects and large-scale improvement provide excellent opportunities for the building of sustainable cities. Cities can use these occasions to promote not only action on the level of single buildings but also area-wide approaches covering entire building blocks. By so doing, they could expect to achieve both an increase in the efficiency of energy utilization and a decrease in the risk of disaster that would not be possible from measures taken separately in each building. This research focuses on improvement of sustainability of building blocks as viewed from the energy aspect. Specifically, its subject is the building of energy systems that cover entire areas consisting of Corresponding Author: Tel: , Fax: address: aozasa@jes-corp.co.jp

2 one or more blocks and offer both high primary energy efficiency and a certain level of availability even in emergencies such as disaster. BASIC CONCEPT Major policies serving as bases As basis for this research, major national policies are outlined as below. - In June 2004, the Environmental Working Committee of the Social Infrastructure Development Council released a policy statement on improvement of social assets. The statement emphasizes policies that consider the whole life cycle, and takes up measures for conserving energy and other means of mitigating environmental load, prolonging the service life of buildings and housings, as well as alleviating the heat island effect. - In April 2005, the cabinet determined the Kyoto Protocol Target Achievement Plan. This plan mentions urban design oriented toward lower CO2 emissions and promotion of area-wide introduction of new energy and interchange of heat and power. - The New National Energy Strategy unveiled by the government in June 2006 calls for the achievement of the world's most advanced energy supply and demand structure (featuring an improvement of at least 30 percent in consumption efficiency) and a fuller assortment of measures for diversifying risks and emergencies (response to accidents, natural disasters, and acts of terrorism in Japan). - The tentative draft of National land Sustainability Plan, which is planned to be determined this year, is anticipated to incorporate aims such as a conversion from dispersed to intensive urban structures and refer to the need for approaches of the self-help, mutual aid, and public assistance types for higher levels of safety and security. Proposed area-wide energy systems In line with these policies, this research takes up the following two tasks to be tackled on a priority basis, with attention to supply of energy, in both normal times and emergencies, led by decentralized combined heat and power systems (). 1) Area-wide energy utilization (on the building block level) and load leveling to mitigate urban GHG emissions, for considerations of both environmental friendliness and energy conservation. 2) Expanded installation of power generation facilities for use in both normal times and emergencies, and multiple backup of the same, toward the goal of contribution to business and living continuity plan (BLCP) within the building blocks, in light of benefits for reducing risk against disease. With Urban district With Neighboring Neighboring Buildings (Large central energy supply networks) Decentralized combined heat and power () system With City gas pipelines With Figure.1 Image of building blocks consisting of decentralized heat and power

3 The systems proposed here are of the on-site, on-demand type, and convert energy such as natural gas, biomass, solar light, and wind into heat and power for consumption while harmonization of their operation with large central energy supply networks. An Image of building block consisting of decentralized heat and power system are shown in Figure.1. Natural gas cogeneration systems are capable of prompt response to load fluctuation through operation along with the city gas pipeline network in central urban districts with a high demand density for heat and power. Recent years have seen the appearance of gas engines with a receiving end efficiency equivalent to that of large power plants (about 40%LHV). These engines enable use of the waste heat from the gas engines on the site, and heat and power interchange through thermal interchange pipelines and private wires installed in some building blocks. They therefore can play a role in complementing relatively unstable sources such as wind power and photovoltaic (PV) systems, and so help to encourage the installation of renewable energy systems. METHOD OF ENERGY SYSTEMS ASSESSMENT An assessment has been made of the efficacy of the systems in the two aspects noted above for several actual building blocks in central urban districts. The details are mentioned below. Energy supply in normal times - assessment of environmental and energy-conserving features In normal times, the load aggregation within the block can reduce the peak load, and the continuation of load demand on a certain scale for a long time can level the load per space. The entire block can be covered by the conversion and interchange of heat and power freed by the load leveling through integrated management of facilities and equipments in it. As compared to ownership of thermal energy facilities with separated operation by each building, this area-wide setup can achieve higher efficiency through the reduction of facility capacity as a whole which results in avoidance of low-efficiency operation at long-time partial load. Figure.2 shows the images of energy supply in normal time. A building A building Buildings block Heat A District heating and cooling plant Electricity form and Electricity form and Heat interchange Heat City gas Separated equipments (Large central energy supply network) (Large central energy supply network) City gas pipelines Power generator Haeter / Chiler A District heating and cooling plant Decentralized combined heat and power () system Figure.2 Image of energy supply in normal time With the installation of the systems featuring high generation efficiency in blocks with such load characteristics, the systems could be operated with a good balance into the long time. The expanded opportunities for use of waste heat would raise potential for energy conservation that could not be

4 achieved with separate operation by each building, and also contribute to cut the peak demand for grid power. Figure.3 shows the image of load, energy consumption characteristics, and harmonization with grid power in cases of building separate systems and block systems) Individual building level Entire block level *Expression on a graph arraying hourly load in order, beginning with those having the largest loads Load characteristics Energy consumption characteristics Heat and power load per space Anticipated rate of reduction in the facility capacity Improvement of partial load Load aggregation 8,760 hours 8,760 hours Fig.3-1) Load characteristics of individual buildings Fig.3-2) Load characteristics of the entire block Energy consumption and Heat and power load per space Systems on a certain scale Annual energy consumption Occurrence of large energy loss due to operation at partial load (ex. loss at less than half efficiency) for long periods Area-wide energy load utilization Fig.3-3) Energy consumption characteristics of separated operation by each building Use of the waste heat from The limited time of operation of at rated load causes insufficient use of waste heat 8,760 hours Operating time Fig.3-5) Energy consumption characteristics in use of individual thermal energy sources and Heat and power load per space Load leveling results in reduction of energy loss due to improvement of load 8,760 hours 8,760 hours Fig.3-4) Energy consumption characteristics of area-wide energy utilization Installation of Further reduction in the annual energy consumption by use of the waste heat from Area-wide energy utilization Systems on a certain scale Prospects for expansion of effects for reducing energy loss due to improvement of partial load and for the spread of systems through area- wide energy utilization for the whole load (heat and power) in an entire block load Operating time (expansion) Reduction of Annual energy consumption can be operated at a favorable load for a long time 8,760 hours Fig.3-6) Energy consumption characteristics of area-wide energy use plus Harmonization with grid Power consumption Grid Power Time Fig.3-7) Hourly power consumption trend in individual buildings (grid power only) Effective use of (Load leveling and contribution to grid power peak saving) systems (grid power peak shaving) Peak power reduction Grid 分散型電源 Power Time Fig.3-8) Hourly power consumption trend in entire block (decentralized energy system plus grid power) Figure.3 Image of load aggregation, energy consumption characteristics, and harmonization of with grid power in the cases of individual building and entire block level

5 Energy supply in emergencies assessment in the aspect of energy for contribution to BLCP The installation of the systems cored by gas engine and waste heat driven boilers / absorption chillers would also make a positive contribution to BLCP by assuring a certain supply of heat and power based on the city gas supply network (medium-pressure) in case the power grid is down. Building 1 Building 2 Building 3 Emergency use generator (the duration of the availability limited depending on the amount of fuel) Heat and power from (Certain amount of continuous supply available in emergencies) Electricity form Heat City gas for both normal time and in emergencies (Large central energy supply network) (Large central energy supply network) City gas pipelines Power generator Haeter / Chiler Decentralized combined heat and power () system Figure.4 Image of energy supply in emergencies If buildings are installed only with emergency-use generators, the duration of the availability of building functions is limited by the amount of fuel stored for emergencies (ex. Oil or LPG). With the combination of the city gas network and the systems (a type for both normal times and emergencies), in contrast, certain amount of heat and power can be continuously supplied, and tenants/occupants therefore may expect the continuation of a certain level of life and business functions, and the prompt resumption of building functions as grid power service is restored. Figure.4 shows images of energy supply in emergencies through the systems. The research will draw a comparison between the amount of energy (heat and power) that could be supplied in emergencies such as power grid down for some reason by systems of varying cases premised on the aforementioned environmental and energy-conserving features in normal times. By comparing the availability of supply by with the demand for power needed for functional activities in emergencies, the level of functional activities that could be continued on the demand side are evaluated. CASE STUDIES IN ACTUAL BLOCKS Case studies are aimed at ascertaining the characteristics that would make the area-wide the system model more effective and ascertaining the tasks to be addressed for actual application. Case studies have been made of types of building block and patterns of energy supply, and the findings served as the basis for block classification into some typical categories appearing in central urban districts. For the case studies, a selection was made of some building blocks by category. systems Figure.5 shows some case studies. In Cases 1, 2 and 3, the studies applied a model consolidating the energy supply in a district energy plants or in one of the buildings installed with gas engines of appropriate capacity (350-9,000-kilowatt class). In each case, the facilities would be used in both normal times and emergencies, and act to conserve energy in the former and assure the continuation of energy utilization in the latter.

6 Area-wide use of heat and power In Cases 1 and 2, the waste heat from the systems are put to effective use for production and interchange of thermal energy for heating and cooling. Case 1 is installed with PV systems and a heat pump system using thermal energy from river water to make maximum use of natural energy. The studies posit expansion of the existing DHC plants and connect the adjacent DHC plants in Case 2 for flexible response to block load fluctuation. On the occasion of building and facility renovation, Cases 3 is installed with heat interchange pipelines and private wires to connect adjacent buildings for interchange of heat and power. The case studies are currently under way and expected to reveal reductions of between 10 and 25 percent in energy consumption and CO2 emissions as compared to the present status. In addition, the systems will provide percent of the peak-time power, and help to improve the block BLCP by assuring the supply of heat and power to block evacuation shelters in emergencies as well as sources of at least the minimum power required for important use such as for elevators and lighting in apartment buildings. Case1: New area-wide development Proposal of a leading-edge model taking account of making the most use of natural energy and currently energy Case2: Interconnection of existing DHC systems Proposal of a model based on further expansion of area-wide use of through connection of adjacent systems by means of pipes for thermal interchange and a private wire Case3: Connection of existing buildings Proposal of a model based on more extensive area-wide use of energy through installation of pipes for thermal interchange and a private wire linking adjacent buildings on the occasion of renovation of housing facilities etc. Figure.5 Case studies of area-wide energy utilization POLICY PROPOSALS FOR DIFFUSION In parallel with the case studies, the research is trying out policy proposals for the diffusion of the systems on the block level. Table1 and Table2 present examples of such proposals. It classifies the proposals into five categories and lists issues and other items for study with a view to diffusion. A study will be made of these policy proposals, classifying them from the perspective of the energy demand side and energy supply side.

7 Table1. Examples of policy proposals for the diffusion of the system on the block (part1) Preparation of schemes (consensus-building, incentives, etc.) Regulatory tightening and relaxation Provisions for support (project approval/administrative guidance) [Promotion of introduction] 1. Positioning of integrated promotion of energy conservation on the district and block levels in the context of schemes for community-building and joint reconstruction 2. Incentives to assist the formation of a consensus among energy users in each block, alignment of interested parties and sharing information of equipments [Optimization of the operation] 3. Construction of a scheme for integrated operation of the block energy systems and for life-cycle management 4. Construction of a scheme for performance of the PDCA cycle (as an on-going approach to energy conservation and BLCP) 5. Provision of incentives to businesses, managers, tenants, and residents for optimal operation [Promotion of technology development] 6. Provision of incentives for development of additional technology for high-efficiency cogeneration, utilization of waste heat, and optimization of operation 7. Promotion of technology development related to connection of existing DHC systems with mutually different specifications and interplant linkage 8. Establishment of technology for assessment and checking of the applicability of the systems [Regulatory tightening] 9. Limitation of block-level energy consumption and CO2 emission levels (per unit of total floor area, per unit of productivity, etc.) and assurance of a certain level of disaster prevention capability on the block level [Regulatory relaxation] 10. Provision of incentives such as relaxation of cubage rate limits for measures of substantial energy conservation, reduction of CO2 emissions, etc. on the block level 11. Provision of incentives such as relaxation of cubage rate limits for installation of disaster prevention power sources 12. Definition of requirements for installation of thermal energy interchange pipes along public roads (treatment of such pipes like mandatory exclusive-use property, permission for installation along roads, etc.) 13. Measures of support for power interchange on the block level (relaxation of regulations in consideration of the need for intra-block cooperation to prevent disaster, on the grounds of territorial unity, which is a requirement for joint power reception) [Provisions for support for energy-conserving measures] 14. Support for projects for installation of the systems on the block level - Example: Addition of environmentally sustainable block-level energy management models to the list of subjects of model projects for the environmental action plan program under the Ministry of Land, Infrastructure and Transport 15. Active use of the existing urban infrastructure (under passages, subways, etc.) in installation of pipes for thermal energy interchange etc. 16. Provisions for support for installation of the systems in DHC facilities 17. Reinforcement of guidance for area-wide energy networks in connection with redevelopment projects [Provisions for support of BLCP preparation] 18. Provision of incentives for installation of energy systems for use in both normal times and emergencies from the BLCP perspective 19. Provisions for promotion and support of block-level energy assessments from the BLCP perspective - Example: Support for the quantification of the concept of level of energy self-sufficiency and for community development projects marked by excellence in respect of energy self-sufficiency 20. Provisions for support of preparation of BLCPs based on installation of the systems

8 Table2. Examples of policy proposals for the diffusion of the system on the block (part2) Provisions for financial assistance (tax incentives, grants, subsidies) Guidelines [Financial assistance for planning and assessment] 21. Assistance for assessments of energy conservation and load factor improvement due to installation of thermal energy interchange pipes etc. 22. Assistance for the cost of maintenance of DHC facilities in correspondence with the attainment of a minimum energy conservation level on the block level [Assistance for commercial facilities] 23. Alleviation of the burden and risks associated with business investment, and the burden of leading investment, in thermal energy interchange pipes etc. 24. Assistance for installation of devices for energy monitoring on the block level 25. Establishment of guidelines for community improvement applying the systems 26. Establishment of guidelines for promotion of inter-business coordination in connection with energy management 27. Establishment of guidelines for measurement and settlement related to thermal and electrical energy interchange CONCLUSIONS This paper presented an outline of the research which is currently under way to improve sustainability in building blocks in the energy aspect. More specifically, an investigative research has been executed on the following tasks to be addressed on a priority basis with a view to achieving a supply of energy, in both normal times and emergencies, centered on the systems. 1) Promotion of energy conservation that cannot be achieved on the level of individual buildings, through area-wide energy utilization and power load leveling on the block level. 2) Promotion of the spread of installation of the systems in many building blocks for use in both normal times and emergencies, and multiple backup of the same, for contribution to BLCPs The study for future research include fuller case studies, quantification of the levels of environmental friendliness and energy conservation in normal times and contribution to BLCP in emergencies based on the block characteristics, and investigation of application together with business models. ACKNOWLEDGEMENTS This paper represents a part of the activities of the Sustainable Town Study Committee (chaired by Shuzo Murakami), whose secretariat is the Institute for Building Environment and Energy Conservation (IBEC). The authors would like to acknowledge their indebtedness to all concerned for their assistance with its preparation. REFERENCES 1. T. Fukushima et al. (2006) Study on sustainable town using distributed energy supply system in block area, Part1 Basic concept of sustainable town, Summaries of technical paper of annual meeting Architectural Institute of Japan 2. R. Kuzuki et al. (2007) Improving Sustainability of Building Blocks by Extended Use of Decentralized Combined Heat and Power Systems, Part1 Frameworks of Issues for Implementation, Summaries of technical paper of annual meeting Architectural Institute of Japan 3. I. Hasegawa et al. (2007) Improving Sustainability of Building Blocks by Extended Use of Decentralized Combined Heat and Power Systems, Part2 Assessment Models for Adoption, Summaries of technical paper of annual meeting Architectural Institute of Japan 4. K. Aozasa et al. (2007) Improving Sustainability of Building Blocks by Extended Use of Decentralized Combined Heat and Power Systems, Part3 Case Study 1: Model Cases Illustrating Actual Energy Management in Building Blocks, Summaries of technical paper of annual meeting Architectural Institute of Japan