Roof cooling solutions to beat the heat

Unprecedented Autumn heat gripping Assam for the past couple of days has sounded the caution that an increase in the number of extreme weather events, like unusually hot days, may have become a permanent feature. Learning to cope with drastic changes in weather patterns requires both long-term and short-term adaptation strategies. Frequent load shedding has made people’s lives miserable in the entire state. Rising temperatures have led to more electricity demand for increasing use of fans, air conditioners, air coolers, and refrigerators to beat the heat. The demand for electricity exceeding availability compels the power distribution companies to resort to load shedding. Purchasing air conditioners for cooling down room temperature is a costly solution and not affordable for the majority households. Increasing the overall thermal comfort of buildings, as recommended by the National Institute of Disaster Management (NIDM), is a more viable option, provided the building design cost is kept at a minimum. Low-cost traditional housing technology for space cooling can be adopted with suitable modifications for concrete buildings. Housing patterns have undergone change, with RCC buildings replacing the Assam-type houses not just in Guwahati and various towns but also in villages, keeping with the need for an increase in demand for accommodation due to population increase. According to NIDM, the roof contributes to 70% of the heat gain of a building when temperature rises, and, therefore, roof cooling solutions can make the rooms cooler. NIDM recommendations include the installation of a secondary roof made of bamboo, thatch, or palm leaves or spraying water on the roof to bring down the roof temperature. The design of the secondary roof needs to have the flexibility of allowing adequate sunshine on the roof during winter so that thermal comfort is not reduced when temperature falls below normal during the winter season. Appropriate architectural models will have to be evolved through extensive research so that house owners find those easier to adopt both from the perspectives of additional expenditures and flexibility in structural design and keeping in mind about different requirements in summer as well as in winter.  Solar units on individual and public buildings are another requirement to increase use of renewable energy to cut down on fossil-fuel-based electricity generation. Phasing down coal use in electricity generation is critical to achieving the decarbonisation goals in the energy sector for climate change mitigation. Solar panels can also block direct sunlight, make the roof cooler during the summer, and insulate the roof during the winter at night. Expediting installation of rooftop solar units under the ‘PM Surya Ghar Muft Bijli Yojana’ can provide double benefits of insulating roofs during increasing heat or falling temperatures during winter in addition to the generation of eco-friendly and low-cost electricity. About 2 lakh house owners have applied for the installation of heavily subsidised solar units on their rooftops under the scheme, but the pace of installation has not picked up. Focusing on the roof cooling benefit of solar panels can be expected to influence public discourse on the scheme and take more interest in faster installation. The central government and the Assam government together pay subsidy to the tune of Rs 1.3 lakh against the installation of a rooftop solar unit costing Rs 1.5 lakh. This implies that the applicant needs to bear a cost of only Rs 20,000 from his own pocket for the installation of a 3-kilowatt capacity unit. Installation of solar units can significantly reduce the electricity bill, and money saved can be utilised in other solutions for raising the thermal comfort of buildings. Once the experts come up with the suggested models and solutions, those can be included in guidelines issued by the Assam State Disaster Management Authorities. Wider dissemination of affordable roof cooling solutions or any other alternative building construction design that increases thermal comfort of building for house owners and occupants will help people explore the possibilities for adoption. Heat generated in cities and other urban areas is generally much higher than in rural areas, as buildings and roads absorb heat and emit heat into the environment. Vehicles, air conditioning units in offices, hotels, hospitals, educational institutions, and industrial units emit heat, which makes the cities and towns warmer than villages. Building design and utilities must be reimagined for the next 100 years, keeping in mind climate change impact, giving rise to global temperatures, longer summer days. Other solutions, like improving the public transport system to reduce carbon emissions, and reducing the use of air conditioners in private cars, can contribute to reducing heat generation in Guwahati City and other urban areas and help people to cope better with rising temperatures in the environment. The most crucial long-term and sustainable solution is to plant trees and increase the green cover. Planting of trees in every residential campus, apartment block, government and private offices, and market places needs to be made compulsory and legally binding, as an awareness drive alone cannot make people realise the importance of it. Nature-based climate change mitigation solutions are sustainable and low-cost.