Application of Low Cost Active and Passive Energy Saving Technologies in an Ultra-low Energy Consumption Building

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1 Available online at ScienceDirect Energy Procedia 88 (2016 ) CUE2015-Applied Energy Symposium and Summit 2015: Low carbon cities and urban energy systems Application of Low Cost Active and Passive Energy Saving Technologies in an Ultra-low Energy Consumption Building Hongting Ma a,b, *, Weiye Zhou a,b, Xinyu Lu a,b, Zequn Ding a,b, Yang Cao a,b a Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin , China b MOE Key Laboratory of Efficient Utilization of Low and Medium Grade Energy, Tianjin University,Tianjin , China Abstract Some low cost but practical passive and active energy saving technologies have been successfully used in an office building energy saving technological transformation in Tianjin. The energy consumption and operating cost have been compared and analyzed before and after the transformation. The results show that the building energy consumption has decreased from 52.6 kwh/(m 2 a) to 36 kwh/(m 2 a), having reached the level of international ultralow energy consumption building. The operating cost has been reduced from 96 RMB/(m 2 a) to 30RMB/(m 2 a), and the energy consumption and maintenance account for the most of life time cycle cost The The Authors. Authors. Published Published by Elsevier by Elsevier Ltd. This Ltd. is an open access article under the CC BY-NC-ND license ( Selection and/or peer-review under responsibility of CUE Peer-review under responsibility of the organizing committee of CUE 2015 Keywords: Ultra-low energy consumption building; Passive energy saving technology; Active energy saving technology; Life time cycle cost 1. Introduction With the development of economy and improvement of comfort requirements, building energy consumption has increased year by year, which promotes the development of building energy-saving technology, such as application of solar energy and other renewable energy in building. The application of the solar thermoelectric cooling technologies, and combination of heat pump and free cold source used in zero energy consumption buildings were analyzed[1-2], and indicated that the technologies have a good application prospects. Passive energy saving technology is indispensable to achieve the zero energy consumption, for example, the trombe wall, lightweight concrete wall, natural ventilation, roof greening and architectural design [3]. While the phase change wall contains 5% phase change materials was used in a building, the electricity saving can achieve 23%[4]. The refrigeration and ventilation energy consumption can be reduced through controlling the way of ventilation and rational utilization of natural wind [5-7]. The passive energy saving technologies, such as natural ventilation and improve the heat The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( Peer-review under responsibility of the organizing committee of CUE 2015 doi: /j.egypro

2 808 Hongting Ma et al. / Energy Procedia 88 ( 2016 ) storage capacity of maintenance structure are introduced [8], and it is known that different effect of energy saving can be obtained in different climate zones [9]. The active energy saving technology has also been widely used to reduce the building energy consumption. A greater energy saving potential was received with separately free air cold source and energy storage technology, and the most economic and effective way of energy saving is using natural cold source cooling was also proved [10]. In this study, a three-star green office in Tianjin has been presented, amounts of energy saving technologies are used, which passive technology is preferential, active technology is complementary. The energy consumption and operation cost have reduced year by year with the control strategy improved continuous in operation process, and realized the low energy consumption and operation cost at last. 2. Application of some effective active and passive energy saving technologies 2.1. Passive energy saving technology In order to decrease the building energy consumption, some passive energy saving technologies are used in a low energy consumption building and show a good effect, as listed below: (1) Increasing of shared atrium in the south side Conventional glass atrium has disadvantages of heat loss in winter, overheating in summer in Tianjin climate conditions. As a result, the practical and cheap 40 mm thick polycarbonate curtain wall, having a good insulation effect and a heat transfer coefficient of 1.1 W/(m 2 K), was used in the expanded atrium and side-opened space to obtain the diffuse natural light and prevent the introduction of heat. (2) Adjustable external shading technology The external shading technology is very useful to reduce the summer air conditioning energy consumption in Tianjin. An electric sunshade was fixed on the outside of metal steel grille, keeping a distance between the windows. In summer, the electric sunshade prevents sunlight from entering the interior, and risen fully, allowing the sunlight to enter the interior in winter. The result shows that the external shading technology can reduce the air conditioning energy consumption by 12%. (3) Utilization of natural light In order to utilize the natural light, the measures increasing the south window wall ratio to 0.4, setting reflector on the south window and others are used to reduce the energy consumption. (4) Roof greening and shading technology Roof greening and shading can significantly improve the temperature of the roof. In the hot summer, when the environment is about 30, the roof temperature may exceed 40 without roof greening and shading on the roof, while it can be reduced to only 20 or so as there is roof greening and shading on the roof. In winter, the roof greening plays a role of insulation, which can prevent heat loss, reduce heat consumption. In addition, the green plants on the roof can absorb the dust particles and carbon dioxide in the air, emitted oxygen, improved the urban air quality, etc Active energy saving technology (1) Free cooling technology Many kinds of air conditioning terminal have been used in the low energy consumption building, such as modular floor radiant cooling and heating terminal, frequency conversion fan coil, water ring VRV, etc. In late spring and early summer, free cooling can be provided to the room by using the ground floor

3 Hongting Ma et al. / Energy Procedia 88 ( 2016 ) radiation way from the cold water side. In the winter and spring, free air conditioning cold source can be provided for the network room by using the cold water on the ground source side. (2) Modular ground source heat pump system In order to improve the efficiency of heat pump units in partial heat and cold load, five sets of heat pump units with 10 compressors have been selected. Thus, it is convenient to meet the demand cold and heat load by adjusting the number of compressor operation and lead the efficiency of heat pump units to a higher level. (3) Air conditioning under temperature and humidity controlling independently In order to improve the efficiency of heat pump units (COP), the outlet temperature of heat pump units B is set at 20 to meet the need of air conditioning from July 8th to September 2nd each year, which is much higher than the normal outlet temperature 7. According to the theoretical analysis and experimental results, the COP of heat pump units will be increased 3-4% as the outlet temperature is increase 1. At the same time, the outlet temperature of heat pump units A is set at 7 to meet the need of the desiccant from June 3rd to July 7th and from September 3rd to September 22nd each year. (4) Optimization of operation strategy and behavior energy saving In the low energy consumption building, many energy saving strategies are implemented to reduce the building energy consumption. Such as making full use of natural ventilation to reduce the operating time of heat pump unit, shortening the running time of air units and reducing the fresh air and exhaust air, full use of the non-powered floor radiant and equipment, etc. In addition, many other energy saving measures are also used in the low energy consumption building. Including air conditioning design energy saving, equipment energy saving, behavior energy saving and energy saving by operation adjustment, etc. 3. Energy consumption and economic analysis 3.1. Structure of building energy consumption The low energy consumption building has a perfect energy metering system, the annual energy consumption from has been completely recorded and stored, including socket energy consumption, lighting energy consumption and air conditioning energy consumption. (a)

4 810 Hongting Ma et al. / Energy Procedia 88 ( 2016 ) (b) Fig.1. Building energy consumption from to In Fig.1, it can be seen that the monthly socket energy consumption and lighting energy consumption has a narrower fluctuation margin, but the air conditioning energy consumption changes greatly. The air conditioning energy consumption from July 2014 to June 2015 is significantly lower than that a year ago, especially in winter. The distribution of building energy consumption is shown in Fig.2. It is known that the air conditioning energy consumption accounted for the largest. From 2014 to 2015, the refrigeration energy consumption per unit building area varies from 8.49kWh/m 2 to 7.22kWh/m 2, and the heating energy consumption changes from 21.04kWh/m 2 to 19.26kWh/m Variation of the energy consumption Fig.2. Distribution of building energy consumption from July 2013 to June 2014 With continuous improvement of operation strategy, the total building energy consumption per unit building area decreases from 52.6kWh/(m 2 a), 42.35kWh/(m 2 a) to 36 kwh/(m 2 a) from , felling by 19.48% and 15.01%, respectively. In this paper, comparison of energy consumption for different office buildings has been conducted (in Tab.1)

5 Hongting Ma et al. / Energy Procedia 88 ( 2016 ) Table 1 Comparison of energy consumption for different office buildings Building type Energy consumption kwh/(m 2 a) Operation expenses RMB/(m 2 a) Operating cost of air conditioning RMB/(m 2 a) Traditional building Energy saving building The ultra-low energy consumption building Comparing with the traditional building and energy saving building, the ultra-low energy consumption building has saved 70.0% and 48.57%, even having reached the international advanced level. The operating cost has reduced by 68.75% and 46.43%, the operating cost of air conditioning has fallen by 69.83% and 48.26% Economic analysis By using the passive and active energy-saving technology, the building has a high performance with low cost, the green building incremental costs is about 350 RMB/m 2, and has a 4-year payback period. By comparing the power consumption and operating costs before and after the transformation, in 2013 and 2014, 72800kWh and 82400kWh have been saved, and and of operating costs have been reduced. The heating cost is 11.1RMB/(m 2 a) and RMB/(m 2 a) in winter, the air conditioning cost is 6.60 RMB/(m 2 a) and 4.45 RMB/(m 2 a) in summer. In the present study, life time cycle cost has also been analyzed, and the result is shown in Fig.3. Fig.3. Analysis of life time cycle cost of the ultra-low energy consumption building From Fig.3, it can be seen that energy consumption and maintenance account for the building life cycle cost about 65%, therefore, the key of building energy efficiency is to reduce the cost of building operation and maintenance. However, building energy consumption throughout the building lifecycle, the corresponding energy saving technologies should be taken in each stage of the building lifecycle. In the architectural design stage, the passive energy saving technology should be used. At the operating stage,

6 812 Hongting Ma et al. / Energy Procedia 88 ( 2016 ) the high efficiency of the air-conditioning heating system and reasonable operation strategy can be adopted, so as to achieve the lowest total life cycle energy consumption. 4. Conclusions 1) With the active and passive building energy saving technologies and reasonable operation strategy, the total building energy consumption can decrease more than 15%, the operating cost can reduce about 50%. 2) The building has an optimistic economic, the energy consumption and operating cost can be saved by 13%, and has a 4-year payback period. 3) Building energy efficiency in each stage should be considered as a circulatory system, and corresponding energy saving strategy is adopted, so the resources can be rational used, energy consumption reduced, and the real energy saving and sustainable development of the construction industry is realized. Acknowledgements This research was funded by the National Natural Science Foundation of China( ) 12th Five Year National Science and Technology Support Key Project of China under grant numbers 2015BAJ01B00 and 2013BAJ09B01, Tianjin Municipal Science and technology project under grant number 14ZCDGSF00035, the Environmental protection public welfare project under grant number , Guangdong provincial science and technology project under grant number 2013B , and Sino-Singapore green building-related research and development program (Ecocity district energy station system optimization and its dispatch system based on weather forecast. References [1] Liu Zhongbing, Zhang Ling, Gong Guangcai, et al., Review of solar thermoelectric cooling technologies for use in zero energy buildings. Energy and Buildings, 102(2015) [2] A. Mohamed, M. Hamdy, A. Hasan, et al., The performance of small scale multi-generation technologies in achieving costoptimal and zero-energy office building solutions. Applied Energy, 152(2015) [3] Sadineni S B, Madala S, Boehm R F. Passive building energy savings: A review of building envelope components. Renewable & Sustainable Energy Reviews, 15(2011) [4] Zhou Quan, Guo Hong-bin, Zhou. Sheng-nan et al. A study on active and passive energy-saving evaluation method of phase change energy storage wallboard. Journal of Functional Materials, 45(2014) [5] Liping Wang, Greenberg. S, Window operation and impacts on building energy consumption. Energy and Buildings, 92(2015) [6] T. Schulze, U. Eicker, Controlled natural ventilation for energy efficient buildings. Energy and Buildings, 56(2013) [7] Yu Tao, Heiselberg Per, Lei Bo, et al., A novel system solution for cooling and ventilation in office buildings: A review of applied technologies and a case study. Energy and Buildings, 90(2015) [8] M Zhao,G Gao,Y Cheng, Applicability Analysis of Passive Energy-saving Strategy in Chongqing, 2011 International Conference on Electronics, Communications and Control, (2011) [9] B. Raji, M.J. Tenpierik, van den Dobbelsteen, et al., The impact of greening systems on building energy performance: A literature review. Renewable & Sustainable Energy Reviews, 45(2015) [10] Eduard Oró, Depoorter V, Pflugradt N, et al. Overview of direct air free cooling and thermal energy storage potential energy savings in data centres. Applied Thermal Engineering, 85(2015)

7 Hongting Ma et al. / Energy Procedia 88 ( 2016 ) (Hongting Ma) Biography Building Environment and Equipment Engineering, School of environmental science and Engineering, Tianjin University mht116@tju.edu.cn Tel: Research directions: 1) Heat and mass transfer enhancement mechanism and technology research; 2) Solid waste resource recovery technology research; 3) Industrial waste heat recovery and cascade utilization technology research; 4) Building energy consumption analysis and building energy saving technology research.