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Adam Kroll ‐ New York Law School Curtain Wall Breadth Page 161 of 236 Curtain Wall Solar Gain Analysis The clear glass façade is a prominent architectural feature of NYLS’s New Community Facility. The glass curtain wall envelops the building almost entirely along its northwest sides, along West Broadway and Leonard Street. The other sides of the building are pressed against adjacent structures, so the glass façade exists wherever people may look at the building from the exterior. With such a large area of glass, solar heat gain could become an issue. Since the façade is north‐facing, direct sunlight is not typically a problem, but the large surface area of glass throughout the building makes the glazing system worth considering. Undesirable solar gain is highest in the summer, due to the high solar angle. In the winter, the solar gain is actually desirable to offset heating loads. The ideal solar glazing will be selected based on several criteria. Fitting with the existing design, a clear glazing will be selected. Introducing tints and colors to the glass would clash with the clean architectural style of the building and the theme of transparency. Particularly in the Student Dining Area, tinting the glass would break the connection to the exterior Roof Terrace. A high visible transmittance (T vis ) is desirable, to allow in diffuse northern daylight. The glazing should also have a low heat gain coefficient (SHGC), which measures the transmittance of solar radiation in all wavelengths of the solar spectrum. A balance between visible transmittance and SHGC needs to be met. The light to solar gain (LSG) ratio describes the overall efficiency of the glazing in terms of maximizing visible transmittance while minimizing SHGC. This study analyzes three types of glazing systems using Carrier’s Hourly Analysis Program (HAP). Glazing data, shown in the table below, comes from PPG. All data is for 1” insulated glass units with ½” airspace and two panes of ¼” glass. PPG Glazing Data Description T vis T total ρ vis u winter u summer SHGC LSG Clear glass, uncoated 0.79 0.61 0.15 0.47 0.50 0.70 1.13 Solarban 60 Clear, low‐E coating 0.70 0.33 0.11 0.29 0.27 0.38 1.85 Solarban 70XL Starphire Clear, low‐E coating 0.64 0.25 0.12 0.28 0.26 0.28 2.37 This analysis will only look at the Level 5 Student Dining area. This space has a large amount of glass area and is representative of the building as a whole. The space is approximately 5500 ft 2 , with floor‐ to‐ceiling glass walls facing north to northeast. For the HAP analysis, the windows were defined as the entire north wall, which is 11’ by 186’ for a total glass area of 2046 ft 2 . This is a rough approximation, since window frames and some variations due to the stairwell are not taken into account. However, since this analysis is comparative, these variations will not affect the conclusion of the study. The findings of the HAP analysis, which calculates mechanical loads according to annual climate patterns, appears below.
