Why does India have glass buildings despite a hot climate?

Glass façades have increasingly become a defining feature of India’s urban skylines, from Gurugram and Mumbai to Bengaluru and Hyderabad. Their spread has also triggered a wider debate among architects, planners and energy researchers over how well glass-heavy buildings suit India’s predominantly warm climate and rising cooling demand.Modern glass-and-steel commercial architecture became globally popular alongside advances in steel-frame construction, curtain-wall technology and corporate office design, particularly in Europe and North America. In India, however, where cooling requirements dominate energy consumption for much of the year, questions are often raised about the long-term efficiency of highly glazed buildings.Several studies, including research by The Energy and Resources Institute (TERI) and IIT-Delhi, have examined the relationship between glazing and energy consumption in Indian climatic conditions. These studies suggest that larger glazed areas can increase cooling loads in many commercial buildings, particularly where façade orientation, shading and ventilation are not optimised.Critics of extensive glass façades argue that such designs can increase glare and heat gain in dense urban areas, while supporters point to their commercial, aesthetic and functional advantages.For developers and corporations, glass façades are often associated with modern office design, global architectural trends and premium commercial branding. Large glazed surfaces can improve daylight penetration into interior spaces, reduce dependence on artificial lighting during daytime hours and allow flexible floor layouts through curtain-wall construction systems.Green building certifications have also influenced design choices in commercial real estate. Rating systems such as LEED (Leadership in Energy and Environmental Design), IGBC (Indian Green Building Council) and GRIHA (Green Rating for Integrated Habitat Assessment) award credits for factors including daylight access, views, ventilation and overall energy performance. Developers often pursue these certifications because they can improve marketability and rental value.The main regulatory framework governing commercial building energy efficiency in India is the Energy Conservation Building Code (ECBC) 2017, administered by the Bureau of Energy Efficiency (BEE) under the Ministry of Power.ECBC applies to commercial buildings with a connected electrical load of 100 kilowatts or more, or a contract demand of at least 120 kilovolt-amperes. It covers sectors including offices, hotels, hospitals, educational institutions, shopping complexes and assembly buildings.The code includes provisions related to daylighting and energy performance. It encourages buildings to achieve prescribed levels of Useful Daylight Illuminance (UDI), a measure of usable natural light within indoor spaces during daylight hours.Architects and building designers often rely on larger windows and glazed surfaces to meet such daylighting targets, although passive design approaches such as shading devices, courtyards, skylights and orientation strategies may also be used.ECBC also places limits on the Window-to-Wall Ratio (WWR) — the proportion of exterior wall area covered by transparent surfaces such as glass. Under the prescriptive path of ECBC 2017, WWR is capped at 60%.At the same time, several studies and climate-responsive architecture experts have suggested that lower WWR ranges — often between 20% and 40% depending on climate zone and building type — may perform more efficiently in many Indian conditions.ECBC additionally provides a Whole Building Performance Method, under which designers may exceed prescriptive façade limits if the building’s projected overall energy consumption remains within prescribed benchmarks. In such cases, energy savings may be balanced through more efficient cooling systems, insulation, lighting or renewable energy integration.State governments also have the authority under the Energy Conservation Act, 2001 to adapt ECBC provisions based on local climatic requirements. Some states have adopted stricter norms. Andhra Pradesh, for example, prescribes a maximum Window-to-Wall Ratio of 40% under its state-level code.As India’s commercial real estate sector continues to expand, the debate around glass-heavy architecture increasingly reflects a broader balancing act between aesthetics, market expectations, energy efficiency and climate responsiveness.Rather than a simple question of whether glass buildings are “good” or “bad”, the discussion among architects and policymakers is increasingly focused on how buildings can adapt global design trends to local climatic realities more effectively.