Seung-Yeong Song

Cost Efficiency Analysis of Design Variables for Energy-efficient Apartment Complexes

Abstract Energy-efficient buildings are essential to reduce greenhouse gas emissions. However, improved energy efficiency may also bring about a rise in construction costs. If design variables can be prioritized according to their cost efficiencies, energy-efficient buildings can be designed more cost-efficiently. The aim of this study is to analyze the cost efficiencies of design variables related to energy efficiency of the apartment complex. After making 78 alternatives for 29 target items, each alternatives increased amount of construction cost and decreased amount of energy cost against the baseline model were then estimated using actual price data and the assessment methods of the Building Energy Efficiency Rating System that has been implemented in Korea, respectively. The life cycle cost, net present value, internal rate of return, and payback period of each alternative were shown as cost efficiency indexes. The order of priority of each alternative was presented and very cost-efficient alternatives were suggested.

Energy Efficiency Analysis of Internally and Externally Insulated Apartment Buildings

Abstract Apartment buildings are the most common type of residential buildings in Korea, where hot water heating pipes are installed in the floor structures. An internal insulation system (IIS) has been applied to the outside walls of most Korean apartment buildings, so there are many cases in which the layer of insulation is disconnected by structural components at the wall-slab joints. These joints become thermal bridges where heat transfer increases. An external insulation and finish system (EIFS) is a possible solution to this problem. In this study, the surface temperature distributions of actual apartment buildings with an IIS and an EIFS were investigated with an infrared thermal imaging camera. Annual heat losses and gains through the wall-slab joints with an IIS and an EIFS were calculated by three-dimensional transient heat transfer simulations in which hot water heating was excluded and included, respectively, in order to evaluate not only the heating and cooling loads, but also the heating efficiency when the building is actually heated. The results show that the amount of heat transfer through the wall-slab joints with an IIS is considerable, even though additional insulation is installed under the slab, and the EIFS significantly reduces the heating and cooling loads and improves the heating efficiency.

Empirical Validation of Heat Transfer Performance Simulation of Graphite/PCM Concrete Materials for Thermally Activated Building System

To increase the heat capacity in lightweight construction materials, a phase change material (PCM) can be introduced to building elements. A thermally activated building system (TABS) with graphite/PCM concrete hollow core slab is suggested as an energy-efficient technology to shift and reduce the peak thermal load in buildings. An evaluation of heat storage and dissipation characteristics of TABS in graphite/PCM concrete has been conducted using dynamic simulations, but empirical validation is necessary to acceptably predict the thermal behavior of graphite/PCM concrete. This study aimed to validate the thermal behavior of graphite/PCM concrete through a three-dimensional transient heat transfer simulation. The simulation results were compared to experimental results from previous studies of concrete and graphite/PCM concrete. The overall thermal behavior for both materials was found to be similar to experiment results. Limitations in the simulation modeling, which included determination of the indoor heat transfer coefficient, assumption of constant thermal conductivity with temperature, and assumption of specimen homogeneity, led to slight differences between the measured and simulated results.

Study on the Characteristics of Thermal Output and Thermal Storage in a Thermally Activated Building System with Phase Change Material

Abstract TABS (Thermally Activated Building System) has recently applied by huge commercial buildings, airports, and convention centers in Europe. TABS provides night-time thermal storage by heating or cooling. The embedded water-basedheating and cooling system uses the high thermal inertia of concrete in the building construction, in which a heating orcooling pipe is embedded. The aim of this study is to analyze the thermal storage and thermal output of TABS applied with PCM (Phase Change Material). To achieve this, prototypes of TABS and the thermal properties of various PCMs wereinvestigated. By using the simulation program Physibel Voltra 6.0 W, the thermal storage and thermal output were evaluatedaccording to a heating and cooling operation schedule. Key words Thermally activated building system(TABS, 구체축열시스템), PCM, Phase change material(상변화물질), Thermal output(방열량), Thermal storage(축열)†Corresponding author, E-mail: limit0@ewha.ac.kr 1. 서 론 콘크리트 구조체를 이용하는 구체축열 공조시스템은 배관을 콘크리트 내에 매설하여 건물 구조체를 축열

Heating Performance and Occupants′ Comfort Sensation of Low temperature Radiant Floor Heating System in Apartment Buildings of Korea

Abstrct To develop an energy-efficient low-temperature radiant floor heating system in an apartment housing unit from an improved the overall heating system efficiency perspective, it is essential to consider the occupants′ thermal comfort and evaluate the thermal environment and thermal output of the radiant panel. This study evaluated the heating performance of a low temperature radiant floor heating system by monitoring the water flow rates, supply and return water temperatures, indoor room temperatures and floor surface temperatures through field measurements, and surveyed the occupants′ thermal comfort through questionnaires. Based on the results of field measurements and the occupants′ questionnaires, the heating performance and thermal comfort sensation of a low-temperature radiant floor heating system were analyzed. The design considerations of a low temperature radiant floor heating system are suggested.

Influence of Thermal Bridges on the Insulation Performance of Curtain Wall Panel Systems

Abstrct Thermal insulation plays a key role in saving energy consumed by buildings. To obtain a high level of insulation performance, repeated thermal bridges should be minimized. These bridges may cause a substantial heat loss through the building envelope. Recently, the application of curtain walls has been rapidly increasing. However, thermal bridges frequently occur in the non-vision panel system in which the insulation materials are installed because of the numerous metal members passing through the insulation layer. The aim of this study was to analyze the influence of thermal bridges on the insulation performance of curtain wall panels in terms of the energy performance and internal surface condensation risk. A three-dimensional steady state heat transfer simulation was performed for four types of panel systems: insulation-joined metal sheet, insulation-separated metal sheet, bracket-fixed metal panel and screw-fixed metal panel. The heat loss, effective U-value, lowest internal surface temperature and lowest temperature factor of each panel system with and without thermal bridges were calculated and compared.

Characteristic of Thermal Output of Thermally Activated Building System During the Heating Operation According to FDM Analysis

T his study is focused on the evaluation of thermal output of TABS (Thermally Activated Building System). The aim of this study is to evaluate TABS in terms of the temperature difference between heating medium supply temperature () and return temperature (), thermal output and the surface temperature distribution according to the design flow rate and the design flow temperature. Through the transient heat transfer simulation using temperature calculation using Crank-Nicolson FDM using Physibel Voltra 6.0 W, the temperature difference between  and , thermal output and the surface temperature distribution of specific TABS was calculated and evaluated. The results show that specific thermal output and temperature difference at 60°C of supply water temperature were about 162 W/m 2 , 13.6°C respectively

Influence of Drainage Holes on Condensation Risk and Air-tightness of Windows An Experimental Case Study of Triple Glazing PVC Windows

Triple glazing windows incorporate drainage holes on glazing beads or gaskets to provide a path for condensed water from the inside to the outside. These holes are considered to be effective for draining condensed water but may decrease the air-tightness and increase the condensation risk due to the drop in surface temperature resulting from the intake of cold outside air. In this study, the related specifications and documents on the application of drainage holes and previous studies were reviewed. For the triple glazing windows with and without drainage holes, the condensation resistance and air-tightness were evaluated and compared. Condensation resistance and air-tightness were tested in accordance with KS F 2295 and KS F 2292, respectively. The results showed that the use of drainage holes did not have a significant negative impact on the condensation resistance and air-tightness.

Field Measurements and Evaluation of Insulation Performance of Opaque Outer Walls for Green Remodelling of Old Commercial Buildings

In order to achieve the national goal of greenhouse gas emission reduction in building sector, it is essential that insulation performance of existing buildings should be improved. Because old buildings built before 2001 accounts for 73.2% of total buildings in Korea, when the building insulation regulation was highly tightened. The aim of this study was to evaluate the actual insulation performance of opaque outer walls of old commercial buildings by field measurements. A variety of standards and relevant research which deal with the field measurement of thermal transmittance were surveyed. Outer wall U-values of old commercial buildings were measured and compared with the required value prescribed in the insulation regulation enforced when evaluated buildings were designed. As results, actual insulation performance was found to be approximately two-thirds of required level prescribed in the insulation regulation.