Energy Consumption Characteristics of High-rise Apartment Buildings according to the Building-shape and Mixed-use Development

Energy Consumption Characteristics of High-rise Apartment Buildings according to the Building-shape and Mixed-use Development Sung Heui Cho1*, In Young Choi1 1 Dept. of Housing & Interior Design, Pusan National University, Busan 609-735, Korea Abstract The purpose of this study was to identify the energy consumption characteristics according to building-shape and mixed-use development in high-rise apartment buildings. For the purpose of the study, it tried to identify the energy consumption characteristics of high-rise apartment buildings by applying the energy consumption unit of electricity and city gas as an objective index and reviewing and analyzing the electricity and city gas consumption according to actual living of the residents. The results of the study are as follows: (1) When looking into the electrical energy consumption characteristics according to whether to be mixed-use, mixed use apartment building was found to use more energy than general apartment building. Especially the power consumption of mixed-use building was remarkably higher in summer. When surveying the residents, the residents perceived that the apartment unit was not pleasant to stay in from the perspective of thermal sensation in summer. On the other hand, there was no significant difference in electric energy. It can be interpreted that it is because the residents of mixed-use apartment reduce the time to spend in the house rather than use air conditioners to cool down the temperature of the house. (2) In the electric energy consumption characteristics according to the building shape, plate type building consumed less energy than the tower type buildings. If we classify the electricity consumption as one for unit and one for common area, tower type showed 1.48 times more consumption than the plate type in common area. It showed the influence of building shape on the estimation of electrical energy consumption unit. (3) When looking into the city gas consumption characteristics according to whether to be mixed-use or not, there was no big difference between mixed use apartments and general apartments. On the other hand in the city gas consumption characteristics according to the building shape, the plate type building showed 10% higher consumption of gas than the tower type buildings. In the survey on the residents, it was found that the gas consumption in winter and the living comfort in summer had been affected by the building shape. (4) When looking into the energy consumption characteristics by converting the electricity and city gas consumption unit value to CO2 emission, it was found that the mixed-use building had higher emission than the general apartment buildings. 1. Introduction The recent interest in energy makes us think about the importance of energy management beyond energy savings by technologies. Therefore the importance of energy management in residence buildings which are responsible for 24% of domestic energy consumption and constitute 68% of the buildings became a hot issue. Apartment buildings are the representative residential buildings in Korea. High-rise apartment buildings higher than 30 stories became not unusual since apartment buildings with 25~30 stories were built in so called New Towns. tower type buildings as well as conventional plate-type buildings, mixed-use high rise residential buildings have been developed and supplied. However, quantitative studies regarding the energy consumption characteristics according to the diverse development of such high-rise buildings have not sufficiently been made. Most of the researches have approached setting the energy efficiency as the basic unit and have not been able to reflect the energy characteristics of the actual residents. Accordingly, this research tries to identify the energy characteristics of high-rise buildings from the comprehensive perspective by analyzing the energy consumption according to the shapes and the purpose of use of the buildings through quantitative data and reviewing the energy consumption characteristics of the residents through empirical surveys. It is meaningful in that it would help to show a practical direction of the energy savings in high-rise apartment buildings. 2. Study Contents and Methodology The purpose of this study was to identify the energy consumption characteristics in high-rise apartment buildings. For the purpose of the study case studies and residents’ survey were performed. First of all, subject’ apartment complexes were selected through preliminary studies and their circumstances were identified for the case studies. For the analysis of energy consumption, electricity and gas which became major energy sources from mid of 1990’s were selected as energy sources and their consumption was compared and analyzed by apartment. Monthly and Yearly Consumption Data in 2008~2009 were used for the study with the help of KEPCO (Korea Electric Power Corporation) Pusan Office and Pusan City Gas. To identify the energy consumption characteristics, residents survey was performed on the residents of the subject’ apartment complexes in the form of structural questionnaires. The questionnaires consist of questions asking the perception of the comfort of indoor environments, electricity and gas consumption status. As the mixed-use apartments in Korea are usually developed with mid to large size units, the subjects of the study were selected from the apartment buildings larger than 132 ㎡. The survey has been performed from September 13, 2010 to September 30. 160 copies of questionnaires were distributed and 142 copies were collected. Excluding the copies with missing or insincere answers, 128 copies (30 copies from Complex A, 34 copies from Complex B, 32 copies from Complex C, and 32 copies from Complex D) were used for the final analysis. The collected data were analyzed using SPSS WIN 14.0. 3. Review of Previous Studies Apartment buildings are the most representative residential type in city areas in Korea and 25 to 30 story high rise apartment buildings are not unusual any more. Since the late 1990s, high-end high-rise mixed-use residential apartments have been developed in full scale. Now over 30 story buildings are common and super high-rise buildings with more than 50 stories are being developed in some areas. In this study, high-rise buildings are conceptualized as the buildings with over 30 stories reflecting such development characteristics. It is trend that apartment buildings in Korea are being built as a complex with business or commercial facilities as some mixed-use apartment buildings. To avoid monotonous development, various kinds of shapes are being planned and such planning is encouraged by the government (apartment house design guideline- Official Announcement of the Ministry of Land, Transport and Maritime Affairs, September 8, 2009). Thanks to these efforts tower-type shape buildings are built in addition to the conventional plate type buildings. Accordingly, the development characteristics of high-rise apartment buildings can be classified as mixed-use and general apartments from the functional aspect and tower type and plate type from the floor plan configuration aspect. Studies regarding the energy consumption in the high-rise apartment buildings are mostly biased to total amount of energy consumed, Energy savings of window systems and building envelope system or the measurement of facility efficiency. In particular, from the perspective of energy consumption characteristics, S.C. Cho (2009) pointed that tower type buildings or high-rise mixed-use residential buildings with high proportion of curtain wall application over-consumed energy comparing to general multi-family apartment units. However, in this study the investigation index was the energy consumption by household. As the space per household in the mixed-use residential buildings is much larger than that in the general apartment housing units, the result of that study had limitation to explain the energy consumption status. On the other hand, in the study analyzing the consumption per actual area not houseld [6], there was no significant difference in the consumption of electricity and City Gas (LNG) between mixed-use residential buildings and general apartment buildings. Additionally, W.K. Choi et al. (2007) reported that actually there was no significant difference in energy consumption between the general apartment model and high-rise mixed-use residential building model when energy consumption in the same cubic meter in each model type was investigated. However it is also pointed that cooling and heating energy cost in the high-rise mixed-use residential building is high and according to some newspaper article, the electricity bill of the households in the high-rise mixed-use apartment building was 10 times higher and consumes 4 to 5 times more energy than the general households [8]. Additionally there are other issues such as too much sunlight in summer and consequential overload because of curtain wall structure, the problems in ventilation and the use of common electricity because of high speed elevator and ventilation facilities [1, 7, 10]. It shows that the energy consumption status in the super high-rise apartment buildings cannot be fully understood with the simple approach of the analysis of energy consumption unit as a ratio of energy consumption per area. Accordingly, to identify the actual energy consumption characteristics, the perception of the residents on the indoor environments and the type of their use of energy should be identified together. 4. Energy Consumption Analysis 4.1 Characteristics of Subjects’ Apartment Complexes Subject’ Apartment Complexes were selected to identify the energy consumption characteristics according to the purpose of use and shape which are the development characteristics of high-rise apartment buildings. First of all, the subjects were selected from the complexes planned after 2001 when the insulation standards were added to ‘Energy Savings Building Design Standards’ legislated by the Ministry of Construction and Transportation (currently the Ministry of Land, Transport and Maritime Affairs) from the perspective of insulation performance of the buildings. As high-rise apartment buildings are located along the coast in Busan [3], Wu-dong, Jaesong-dong in Haewundae-gu and Minrak-dong in Suyoung-gu were selected as the target area as they have similar outdoor environments such as geography, weather and city environments. Eight complexes were abstracted from the database of “Status of Multi-family Housing Units with more than 20 households in Busan (2009)” of Busan Metropolis. Finally 4 complexes were selected by considering the time of completion of those mixed-use residential buildings and general apartment buildings. Complex A is a complex of mixed-use apartment buildings with commercial facilities in the ground floor of a building out of 4 buildings. It has tower shape and glass envelope encompassing the building with curtain wall structure. Complex B was completed at the same time with Complex A. It has a reinforced concrete wall structure and tower shape. It has similar floor plan to Complex A with expandable balconies which some bedrooms do not have. Complex C has ‘I’ or ‘L’ shape floor layout plans (plate-type). It has reinforced concrete wall structure and has floor plan with the balconies in the living-room and bedrooms which are difficult to be expanded. Complex D is very similar to Complex C except that it is designed as tower type. Table 1. Characteristics of Subjects’ Apartment Complexes Complex A B C D Whether to be Mixed-use Mixed-use Building Apartment Building Residential Apartment Building Residential Apartment Building Location (Busan) Construction Completion Date Number of Stories Number of Households Number of Apartment Buildings Building Shape Guwu-dong, Haewundae-gu 2005.06.28 38 390 4 Tower Type Jaesong-dong, Haewundae-gu, 2005.10.26 30-51 2,752 14 Tower Type Minrak-dong, Suyoung-gu 2003.08.18 31 1,082 10 Plate Type (I or L shape) Minrak-dong, Suyoung-gu 2003.11.29 35 591 6 Tower Type Apartment Unit Plan Expandable Balcony Balcony Structure Expandable No (×) Curtain Wall Structure Partially Expandable Some have balconies (ᇞ) Concrete Wall-type Structure Non-expandable Some have balconies (ᇞ) Concrete Wall- type Structure Non-expandable Some have balconies (ᇞ) Concrete Wall-type Structure Heating Type Individual Heating (City Gas) Individual Heating (City Gas) Individual Heating (City Gas) Individual Heating (City Gas) In multi-family housing units in Korea, balconies are provided with compliment as service areas. Therefore, we need to consider whether the balcony has been expanded when calculating the residential area by household. Additionally, on December 2, 2005 balcony expansion became legal by the enforcement of balcony related construction law by the Ministry of Construction and Transportation and apartment buildings constructed afterwards have been developed with expandable balconies in case of floor plan with wall type structure. However, as expandable balconies were selectively applied to the apartments completed before 2005, Complex A was developed with the floor plan considering the expansion from the planning stage while Complex B was planned to apply the expandable balconies selectively. Although Complex C and Complex D were developed without expandable balconies, approximately 50% of households expanded their living room by including balconies in their individual area by the residents themselves because of their own needs. Therefore, in order to identify the energy consumption characteristics, we need to consider not only the supplied areas but also the service areas to calculate the actual living space. Accordingly, it was assumed in this study that 50% of balconies had been expanded. ... - tailieumienphi.vn