Buildings account for a significant portion of a nation’s total energy consumption. To meet the global demand for greater energy efficiency, many countries are drastically strengthening insulation regulations for buildings. Thus, dramatically thicker wall insulation may be required, which can adversely affect the value of a building by reducing its effective floor area. Hence, high-performance insulation materials, such as vacuum insulation panels (VIPs), are of interest in building design. In this study, external insulation systems using VIPs were examined to determine their effectiveness in high-performance insulation systems for high-rise apartment buildings. A variety of mechanically and adhesively fixed external insulation systems with various insulation layer compositions have been proposed as alternatives to conventional internal insulation systems. The performance of conventional insulation systems and the proposed alternatives were compared through three-dimensional heat transfer simulations. The construction costs and the ease of installation of the various systems were also compared. The overall performance of each alternative in terms of the insulation performance, construction costs, and ease of installation was thus evaluated to determine the most effective alternative.

To reduce condensation and ensure occupant comfort, the Korean Design Standard for Preventing Condensation in Apartment Buildings was enacted in 2014. However, glazing edges remain vulnerable to condensation. Because this design standard is recent, few window products satisfy the condensation resistance requirement for glazing edges, especially in the coldest region, and there have been limited investigations on improvement measures. This study evaluates and verifies various treatments for improving the glazing edge thermal resistance of double-glazed four-track horizontal sliding windows to reduce condensation risk and satisfy the design standard. Three-dimensional heat transfer simulations are performed for each alternative to obtain the surface temperature and temperature difference ratio (TDR) for the bottom edge of the glazing. The U-factors of the alternatives satisfying the required TDR for the coldest region are simulated, and the effects of increased local thermal resistance in the glazing edge on the U-factor of the window are analyzed. Mock-up tests are performed on the most economical and best-performing alternatives satisfying the coldest region TDR, and the TDRs and U-factors from the simulations and mock-up tests are compared to verify the performance of the most economical alternative. Insulating spacers, frame extensions, and low-emissivity coatings are effective in various cases.

Disputes and repairs due to window condensation problems frequently occur after the completion of apartments. However, most repairs are performed individually and confidentially by construction participants, who are forced to minimize economic losses. Thus, actual cases of inspection and repair for condensation defects have rarely been addressed in public even though condensation on windows remains the primary cause of defect disputes. This study aims to contribute to the resolution of similar disputes by presenting an actual case of a new apartment complex in which defect disputes arose from window condensation; the condensation resistance performance was inspected, and repair measures were proposed. On-site measurements and mock-up tests were performed. The results demonstrated that the $U$ -factor satisfied its required specifications but that the temperature difference ratio did not satisfy the requirements. Repair measures were proposed and evaluated; the combination of adding sealant, double glazing near the existing glazing, and an insulation cover on the frame was found to be effective. These repair measures were applied to the apartment complex and the number of condensation complaints decreased significantly.