Infiltration and heating load analysis of an apartment with respect to window type, window location, and lock operation

Energy consumed by buildings accounts for about 30%-40% of the total energy consumption. In buildings, heat loss through windows accounts for 20%-40% of cooling and heating loads. In this work, airtightness of sliding and lift sliding type windows and its effect on infiltration and heating loads of a building has been studied. Infiltrations according to window types and with/without lock operations are measured following KS F 2292, a Korean standard for measuring window air infiltration. STAR-CCM+ (CD-adapco 2014), a thermal-fluid computational program; CONTAM (NIST 2011), a network based ventilation simulation program; and TRNSYS17 (SEL 2009), a dynamic simulation program, have been used to calculate infiltration rates and heating loads of a building accounting for various factors, including window types, window elevation and horizontal position in a building, and with/without lock operations. When all locks are on, infiltration of lift sliding window is 1.68m³/(m²·h) (0.092fc/fft²-min]), 15% less than that of sliding with 1.98 m³/(m²·h) (0.108ft³/[ft²·min]). When locksare off, infiltration of the lift sliding window is 5.83 m³/(m²·h) (0.319 ft³/[ft²·min]), 121% greater than that of sliding which is 2.64 m³/(m²·h) (0.144ft³/[ft²·min]). Simulation results indicate that average heating load of the lift sliding window with lock on is 17.12 W/m² (5.427 Btu/h·ft²), 1.1% less than that of the sliding window, which is 17.31 W/m² (5.487 Btu/h·ft²). Peak heating load of lift sliding window is 37.46 W/m² (11.875 Btu/h·ft²), 6.7%< less than that of the sliding window, which is 40.17 W/m² (12.734 Btu/h·ft²). When the lock is not engaged, the average heating loads of sliding and lift sliding windows compared to lock engaged increase from 17.31 to 17.36 W/m² (5.487 to 5.503 Btu/h·ft²) and from 17.12 to 17.82 W/m² (5.427 to 5.649Btu/h·ft²), which are 0.3% and 4.1% increases, respectively. The average heating loads of 1st, 8th, and 15th floor becomes 18.16,15.32, and 18.45 W/m² (5.757,4.856, and 5.849 Btu/h·ft²), respectively, which shows the effect of elevation. The heating load is highest at the top floor due to heat loss at the roof. The average heating loads of side house and middle house are 17.93 and 16.69 W/m² (5.684 and 5.291 Btu/h·ft²), respectively, which shows the effect of horizontal position within the same floor. For a side-located house, heating load increase due to infiltration is 3.9%, compared to no infiltration, which is 17.25 W/m² (5.468Btu/h·ft²). For a middle-located house, heating load increase due to infiltration is 5.1%, compared to no infiltration, which is 15.88 W/m² (5.034 Btu/h·ft²). The pressure coefficient is higher at the center of the building, resulting in larger infiltration. This study shows that window type selection, window location, and lock operation are important for reducing infiltration and heating load.