Abstract
Heat loss and gain through opaque envelopes of buildings are major factors that affect the overall cooling and heating loads in buildings. The government has enforced regulations to strengthen the thermal transmittance requirement level as a major means of reducing greenhouse gas emissions in the building sector. In addition, the thermal bridge is considered to be one of the major factors in heating load of buildings. In this study, truss-form wire frame was developed in order to minimize thermal bridge of steel mullion in exterior insulation system. In the case of thermal transmittance test for specimen of 0.145 W/m2 K as design value, the value of the steel pipe was 0.190 W/m2 K and the value of the truss-form wire frame was 0.150 W/m2 K, respectively. This means the other is much smaller than the one in thermal bridge. For four cases, annual energy performance analysis was calculated using Passive House Planning Package (PHPP)—ideal condition without thermal bridge, steel pipe mullion without insulation in the rear side, steel pipe mullion with insulation in the rear side, and truss-form wire-frame mullion filled with glass wool. As results, the annual heating energy demands were 15.68 kWh/m2, 25.42 kWh/m2, 16.78 kWh/m2, and 16.09 kWh/m2, respectively.
Highlights
The present study developed a truss insulation frame (TIF) whose sides were supported by truss-form steel wires, and the interior was filled with insulation materials to minimize the heat loss in the metal vertical members, which were major thermal bridge portions in the dry exterior insulation system
The envelope of buildings should be such that air leakage, water penetration, and structural performances are compliant with the fire resistance and insulation performance regulations that are set in related laws
This study evaluated the site applicability of the dry exterior insulation system by conducting a performance evaluation of the overall envelope using TIF
Summary
Heat loss and gain through opaque envelopes of buildings, such as walls and roofs, are major factors that affect the overall cooling and heating loads in buildings. According to a previous study, the proportions are, respectively, 35% and 32% for heating and cooling of residential buildings, and 46%. The Korean government has proposed regulations to strengthen the thermal transmittance requirement level as a major means of reducing greenhouse gas emissions in the building sector, and it gradually strengthened the design standards in order to realize energy saving in buildings [2]. The design standards of energy saving for buildings were again strengthened in September 2018. For residential houses in the Central I Region of Korea, the maximum required levels of thermal transmittance for external walls and windows are; 015; W/m2 , K. and 0.9 W/m2 K, respectively. For nonresidential houses, the corresponding maximum values are 0.17 W/m2 K and 1.3 W/m2 K [3]
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