• Journal of the Korean Solar Energy Society
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• v.38 no.3
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• pp.29-36
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• 2018

The goal of this study is to retrofit the windows of residential buildings and to activate the green remodeling by verifying energy saving and indoor thermal environment. As a result of analysis of the energy saving effect of 458 units window retrofits, it was possible to reduce the energy requirement by 48.20% ~ 54.97%. According to the improvement on indoor environment, it was possible to operate by reducing heating temperature and supply time. The actual gas consumption of the heating period was reduced by 25% compared with that of the window retarder to save 28,968 thousand won of heating energy cost. Resident's satisfaction surveys were conducted one year after window retrofit. More than 80% of the respondents answered that they satisfied the improvement on window performance, indoor thermal environment and indoor sound environment. As a result, we verified the energy saving effect and the improvement on the indoor environment through window retrofits.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.9
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• pp.455-462
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• 2017

The purpose of this study is to analyze heating and cooling load variation due to envelope retrofits in an old school building. In a previous study, envelope retrofit of an old school building resulted in annual energy consumption reduction. However, cooling energy consumption increased with the envelope retrofit. This is because of high internal heat generation rates in school buildings and internal heat cannot escape through windows or walls when the envelope's thermal performance improves. To clarify this assumption, thermal performance changes due to envelope retrofits were analyzed by simulation. Results revealed indoor temperature and inner window surface temperature increased with high insulation level of windows. Indoor heat loss through windows by conduction, convection and radiation decreased and resulted in an increase of cooling load in an old school building. From results of this study, energy saving impact of envelope retrofits in an old school building may not be significant because of high internal heat gain level in school buildings. In case of replacing windows in school buildings, local climate and internal heat gain level should be considered.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.753-764
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• 2015

Among several types of energy saving smart window technologies, the leader, the dynamic EC (electrochromic) window one needs integrated PV (photovoltaics), to minimize expensive electrical wiring as well as to obviate the need for external energy. Self-powered smart windows were reviewed according to PV types used. DSSCs (dye sensitized solar cells) were found to be compatible with EC cells, to have several categories of next generation smart windows such as PECCs (photoelectrochromic cells), PVCCs (photovoltachromic cells), EC polymer PECCs. In addition silicon solar cells and third generation solar cells were investigated. They are summarized in a table showing their advantages and disadvantages respectively for a fast comparison. The strategy to expedite the commercialization of these next generation smart windows includes developing retrofit smart window coverings for use on flexible polymer substrates adhered to the inside surface of a window and easily replaced after use for upto 10 years.

• Advances in Energy Research
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• v.5 no.4
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• pp.321-339
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• 2017

Energy simulation tools can provide information on the amount of heat transfer through building envelope components, which are considered the main sources of heat loss in buildings. Therefore, it is important to improve the quality of outputs from energy simulation tools and also the process of obtaining them. In this paper, a new Building Energy Performance Assessment Tool (BEPAT) is introduced, which provides users with granular data related to heat transfer through every single wall, window, door, roof, and floor in a building and automatically saves all the related data in text files. This information can be used to identify the envelope components for thermal improvement through energy retrofit or during the design phase. The generated data can also be adopted in the design of energy smart homes, building design tools, and energy retrofit tools as a supplementary dataset. BEPAT is developed by modifying EnergyPlus source code as the energy simulation engine using C++, which only requires Input Data File (IDF) and weather file to perform the energy simulation and automatically provide detailed output. To validate the BEPAT results, a computer model is developed in Revit for use in BEPAT. Validating BEPAT's output with EnergyPlus "advanced output" shows a difference of less than 2% and thus establishing the capability of this tool to facilitate the provision of detailed output on the quantity of heat transfer through walls, fenestrations, roofs, and floors.

• KIEAE Journal
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• v.17 no.2
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• pp.29-34
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• 2017

Purpose: Recently, significant heat loss through the window takes place in buildings. Nevertheless, there exists little literature concerning the exterior horizontal shading devices and the design criteria are not clearly settled yet. Applying the exterior horizontal shading devices is more efficient as compared to the interior shading devices in that solar radiation can be directly blocked before passing through the window or the envelope. The purpose of this study is to reduce the internal load by designing the exterior horizontal shading devices and verify the degree of reduction in energy consumption. Method: This study aims to reduce energy consumption in cooling and heating through proposing proper length and shape of the exterior horizontal shading devices in public buildings. In the process, actual energy data and the Design Builder simulation program are utilized. In addition, economic aspect is considered to figure out the optimal length of the exterior horizontal shading devices that maximizes efficiency. Result: As a result, the proper length and shape of the exterior horizontal shading devices are provided as follows: 1) Energy consumption in cooling and heating is minimized when the exterior horizontal shading devices are designed as 0.5m*2. 2) Electricity bill is the lowest when the exterior horizontal shading devices are designed as 3.3m*2. The gap between maximum and minimum electricity bill is about 7.8~14%.

• KIEAE Journal
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• v.16 no.5
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• pp.39-45
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• 2016

Purpose: The purpose of this study is to analyze the energy saving and cost benefit analysis of the Low-income Energy Efficiency Treatment Program supported by KOREF(Korea Energy Foundation). This program was launched in 2007 and performs building energy retrofit for the low-income and energy poverty houses. Method: Energy simulation and cost benefit analysis were accomplished for the low-income detached houses. The structure of detached house was a lot og block structure, wood frame (single glass) and concrete roof. Baseline model of the low-income detached houses was proposed. Result: Annual heating energy consumptions were decreased by about 3.2% with the window system replacement(Case 1), 9.3% with reinforcement of insulation(Case2), and 12.5% with both(Case 3) compared to those of baseline model. The construction cost will be recouped within 5 years for the Case 1, 3 years for the Case 2, and 3 years for the Case 3. Case 3 was the most cost beneficient construction method in the analyzed cases in this study.

• KIEAE Journal
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• v.14 no.3
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• pp.39-45
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• 2014

Energy poverty has been defined as low-income households who paid energy cost more than 10% of their ordinary income. Therefore, there are various subsidy programs focused on house remodeling for low-income households and one of them is the Home Energy Efficiency Assistance Program which have done by Korea Energy Foundation since 2007. The aim of the program is to improve the thermal performance of dilapidated dwellings and analyzed the detached house for the low-income households to develop the building typology. The database contained approximately 3,061 households which was obtained from the program in 2013 and the results of the study were like this; 1) For the shape of residential houses, the number of rectangular shaped building was higher than non-rectangular shaped ones. 2) For the orientation of buildings, the south layout of the detached housing was dominant to gain heating energy into buildings. 3) For the floor area, the average floor area was $44.2m^2$, although its size varied wide variations, which range from $6.3m^2$ to $107.1m^2$. 4) For the windows and doors, the south-facing window was larger than the other side. Finally it would be possible to determine the characteristics of residential houses for low-income families. A future study could establish typology of low-income housing that it would estimate the performance of each model building before and after the retrofit to improve the energy performance.

• Korean Journal of Construction Engineering and Management
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• v.13 no.6
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• pp.3-12
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• 2012

The slowdown of private building industry resulted in growth of remodeling market as a way to improve energy performance. Remodeling is considered more cost-effective and eco-friendly approach for energy efficient building than new construction. Since 2008, Seoul has promoted Building Retrofit Project (BRP) preponderantly to attract energy-saving renovation by supporting building owners to switch building system into energy-saving system when they remodel their old buildings. According to 2012 press release, 254 Private sectors participated in this green building project and annually reduced 41000ton of greenhouse gas emission, 14000TOE, which also result in 7.5 billion won energy cost savings per year. The paper focuses on the building envelope remodeling as a way to improve energy efficiency. Different components of the building envelope such as wall insulation, window, and shading, were applied to the baseline model and the comparison was analyzed to come up with the ideal solution. This study only assesses the building envelope as to suggest the way to redesign the better energy performing building. Offering solution focusing on the architectural feature is essential because it will provide basic information and standard when remodeling a building for energy efficiency, especially, for the nonresidential buildings used as rental offices.