The purpose of this study is to identify effective methods of improving the condensation resistance and thermal insulation performance of triple-glazed windows. These improvements should satisfy the required temperature difference ratio (TDR) of the Design Standard for Preventing Condensation in Apartment Buildings and the required thermal transmittance (U-factor) of the Construction Standards for Energy-Efficient Green Homes. In apartment buildings, various altatives were selected for tilt-and-t triple-glazed windows that directly face the exterior. The TDR was calculated using a three-dimensional heat transfer simulation performed with TRISCO (Physibel, Belgium), and the U-factor was calculated after the Window/Therm simulation. Under the same glazing composition, compared with Case 1 with an aluminum spacer, Case 2 with a TPS; thermal insulation spacer showed a 19.5% lower TDR on average, and Case 3 with a TPS and a 5-mm extended glazing overlap height of the frame exhibited a 23.4% lower TDR on average, thereby verifying that the condensation resistance performance was improved. The application of thermal insulation spacers is essential along with the extended glazing overlap height of the frame for satisfying the required TDR criteria of region III and above. Among the 16 altatives that met the region II criteria of the design standard, two altatives met the required mid region U-factor criteria of the construction standards, and 12 altatives met the required south region U-factor criteria. As a result, the most effective altatives for satisfying the required TDR and U-factor of Korean design standards were outlined.