The insulation of a building envelope influences the hygrothermal performance as well as the thermal performance of the building. While most of Korean wood frame houses have an interior insulation system, the exterior insulation system with high thermal performance has recently been applied. While i...
The insulation of a building envelope influences the hygrothermal performance as well as the thermal performance of the building. While most of Korean wood frame houses have an interior insulation system, the exterior insulation system with high thermal performance has recently been applied. While it can be effective in energy savings for better insulation performance, without consideration of the moisture, condensation and mould growth can occur. Therefore, in this study, hygrothermal behaviour, water content, and mould growth were analyzed using hygrothermal simulation of an exterior wall of a wood frame house with which the interior insulation and exterior insulation systems were applied. The wall layer included Wall A (Interior insulation) and Wall B (Exterior insulation). The U-values were identified as 0.173 and $0.157W/m^2K$, respectively. The total water content and OSB absolute water content of Wall A were confirmed to be higher than those of Wall B, but the absolute water content did not exceed the reference value of 20%. The moisture content of the two walls was determined to be stable in the selected areas. However, mould growth risk analysis confirmed that both Wall A and Wall B were at risk of mould growth. It was confirmed that as the indoor setting temperature decreased, the mould index and growth rate in the same area increased. Therefore, the mould growth risk was affected more by indoor and outdoor climate conditions than by the position of the insulation. Consequently, the thermal performance of Wall B was superior to that of Wall A but the hygrothermal performances were confirmed to be similar.
The insulation of a building envelope influences the hygrothermal performance as well as the thermal performance of the building. While most of Korean wood frame houses have an interior insulation system, the exterior insulation system with high thermal performance has recently been applied. While it can be effective in energy savings for better insulation performance, without consideration of the moisture, condensation and mould growth can occur. Therefore, in this study, hygrothermal behaviour, water content, and mould growth were analyzed using hygrothermal simulation of an exterior wall of a wood frame house with which the interior insulation and exterior insulation systems were applied. The wall layer included Wall A (Interior insulation) and Wall B (Exterior insulation). The U-values were identified as 0.173 and $0.157W/m^2K$, respectively. The total water content and OSB absolute water content of Wall A were confirmed to be higher than those of Wall B, but the absolute water content did not exceed the reference value of 20%. The moisture content of the two walls was determined to be stable in the selected areas. However, mould growth risk analysis confirmed that both Wall A and Wall B were at risk of mould growth. It was confirmed that as the indoor setting temperature decreased, the mould index and growth rate in the same area increased. Therefore, the mould growth risk was affected more by indoor and outdoor climate conditions than by the position of the insulation. Consequently, the thermal performance of Wall B was superior to that of Wall A but the hygrothermal performances were confirmed to be similar.
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가설 설정
The risk of mould growth increases at an indoor setting temperature below 21℃, except in Area d. In addition, it was confirmed that the standard temperature of mould growth risk increased in Area a and Area c. Because the outdoor relative humidity is higher toward Area c, the water content of the wall increased. Consequently, the mould growth rate increased despite having the same temperature and substrate as that of Area a because the humidity of the indoor wall surface increased.
제안 방법
The areas were determined as being in a dynamic steady state because the total water content of Wall A and Wall B did not increased in the four comparison areas for 3 years and there was no change after two years. After confirming the dynamic steady state for the study areas, we evaluated the absolute water content. The absolute water content analysis result showed that the wood based material OSB in Area c had the highest total water content, Wall A, was higher than Wall B but it did not exceed 20% of the standard.
In this study, the mould index and mould growth of Wall A and Wall B were evaluated using the WUFI Bio program for the mould growth risk of the interior surface according to the regional climate and indoor setting temperature. The mould index indicated 0 to 6, calculated according to the temperature, humidity, time, and substrate, as shown in Table 3 (Ojanen and Airaksinen, 2015).
The surface radiation properties used the WUFI database depending on the exterior surface material of the selected wall layer. Simulation was set to three years for evaluating to long-term hygrothermal performance.
The hygrothermal behavior of the composed wall layer is confirmed using the WUFI simulation, and the water content can be quantitatively analyzed. The results of simulation, showing the change of total water content for three years in the four areas is shown in Fig.
A high water content for wood based materials can cause corrosion and mould growth, and can reduce the insulation efficiency because the moisture is transferred in closed insulation. The total water content of both wall layers moves to a dynamic steady state for the measurement periods, so we analyzed to the absolute water content of OSB (Oriented Strand Board) as the wood based materials. Fig.
The exterior walls of wood frame houses are composed of an interior insulation system and an exterior insulation system; the hygrothermal performance evaluated of these walls was evaluated in four selected areas according to the indoor setting temperature. The water content was evaluated and mould growth risk was analyzed, using the WUFI simulation program. The U-value of Wall A (Interior insulation) and Wall B (Exterior insulation) was 0.
, 2005; Mudarri and Fisk, 2007). Therefore, in this paper, a simulation was used to analyze the hygrothermal performance of the wall according to the position of internal and external insulation in wood frame houses. Also, the simulations of the inside and outside climatic conditions were carried out differently with consideration for the different climatic conditions that occur depending on the national geography.
대상 데이터
WUFI simulation models are heat and mass transfer models used for evaluating the extensive heat and moisture distribution of building materials and climatic conditions. The program was composed of a one-dimensional cross-section of buildings. It calculates hygrothermal behavior with consideration of moisture, rainfall, solar radiation, longwave radiation, capillarity, and condensation, and evaluates the hygrothermal performance of a component according to the setting conditions (Budaiwi and Abdou, 2013).
이론/모형
This study used the WUFI Pro 5.3 and WUFI Bio simulation programs developed by Fraunhofer IBP (Institute in Building Physics) for hygrothermal performance analysis of walls by variable conditions. WUFI simulation models are heat and mass transfer models used for evaluating the extensive heat and moisture distribution of building materials and climatic conditions.
성능/효과
3(b) shows the mould growth that occurs during the measurement for three years. It was confirmed that as the indoor setting temperature is reduced, the mould index and mould growth increased. If the indoor setting temperature is set to below 25℃, the mould index was 2 and over.
After confirming the dynamic steady state for the study areas, we evaluated the absolute water content. The absolute water content analysis result showed that the wood based material OSB in Area c had the highest total water content, Wall A, was higher than Wall B but it did not exceed 20% of the standard. The problems mentioned above, however, will not occur since the water content of both walls in that indoor setting temperature did not exceed the standard value at 18℃.
In the same area, as the indoor setting temperature is increased, the mould index and growth rate decrease. The results of analysis by region confirmed that the risk of mould growth for the indoor setting temperature range increased at the lower latitude. In Area c, the risk occurred within the range of indoor setting temperatures of 18 - 26℃, and the risk was higher compared to that in another areas.
참고문헌 (12)
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