The purpose of this paper is to study an energy analysis method considering linear thermal bridge at wall-slab joints in apartment building with radiant floor heating system. In order to analyze linear thermal bridge of wall-slab joints, linear thermal transmittance was used to represent heat loss at thermal bridges. Linear thermal transmittances were calculated from the heat flow through the wall and the equation defined by ISO 10211. The heat flow was simulated by heat transfer program ‘PHYSIBEL TRISCO v13.0w’.
The simulation was conducted for the side walls and the expanded balcony front walls in typical residential buildings. For each case, the impact of insulation methods(internal and external insulation systems) and hot water temperatures on the linear thermal transmittances were investigated. As a reference, linear thermal transmittances of structures without radiant floor heating system were calculated. An evaluation standard is used with linear thermal transmittances obtained by ISO 14683. In addition, the annual heating energy consumption with adjusted linear thermal transmittances were simulated by building energy simulation program ‘DesignBuilder v5.5’.
The results of this study are as follows; at the side walls, the linear thermal transmittances with radiant floor heating system were 15% to 38% higher than the linear thermal transmittances without radiant floor heating system. At the front walls, the linear thermal transmittances with radiant floor heating system were 10% to 17% higher than the linear thermal transmittances without radiant floor heating system.
Regarding annual heating energy consumption, the adjusted linear thermal transmittance was 1.1% to 3.5% higher energy consumption than that is calculated with the default value of ISO 14683.
This research covered linear thermal transmittances under steady states. Further studies need to cover linear thermal transmittances at dynamic states with weather data.