chapter  4
47 Pages

Openings and Shading

ByVishal Garg, Jyotirmay Mathur, Aviruch Bhatia

Openings are required in buildings to bring in daylight and fresh air and provide outdoor views. The energy for artificial electric light can be reduced if there is sufficient daylight in the space. However, daylight increases the heat gain in a space. If the climate is hot/warm, this results in an increase in the air-conditioning energy consumption. Hence, there is a need to optimize the window-to-wall ratio (WWR) to get the minimum energy consumption while getting sufficient daylight.

Choosing glass type is also important for buildings; building glass is specified by certain important properties, such as U-value, solar heat gain coefficient (SHGC) and visible light transmittance (VLT). Generally, the VLT-to-SHGC ratio is taken as an indicator of glass performance in cooling-dominated locations. The higher this ratio is, the better is the glass. Building shades can be used to cut the direct solar radiation in buildings and bring diffused daylight inside the perimeter space. Overhangs and fins are classified as fixed building shades. Operable shades can also be used to cut the direct radiation from windows.

In this chapter, through the four tutorials, you are going to learn how to analyse the impact of different glazing types, fixed shades and operable shades for a given climate. This can be useful in the analysis of different designs and approaches for reducing solar heat gain through windows.