Architectural solutions for summer

Published May 1, 2023
A moot of experts has discussed the issues of Karachi and called for preparing a master plan for the metropolis with special focus on infrastructure and public transport. — Photo by Ali Raza Khatri/File
A moot of experts has discussed the issues of Karachi and called for preparing a master plan for the metropolis with special focus on infrastructure and public transport. — Photo by Ali Raza Khatri/File

Pakistan and India are currently experiencing an unprecedented heatwave, with cities such as Jacobabad and Sibi in Pakistan recording temperatures as high as 47°C at the end of April 2022.

The heatwave is believed to be a result of the climate crisis. The effects of climate change are making heat waves last longer, devastatingly impacting food and water cycles and public health.

The Intergovernmental Panel on Climate Change (IPCC) Special Report on Climate Extremes concluded that temperature extremes are shifting globally. Heat waves are projected to become more frequent and severe in India and Pakistan.

Around 1.5 billion people in these two countries are affected by this heatwave, with the poorest communities being the most vulnerable. The high temperatures caused by the heatwave can lead to dehydration, heat exhaustion, and heat stroke and worsen chronic cardiovascular and respiratory diseases.

The urban heat island effect, due to the increase in land use, building density and pollution, makes cities more vulnerable to heat waves

Overstretched hospitals may face additional pressure from people suffering from heat-related illnesses, especially in Pakistan, where electricity load shedding is already causing hardship.

The heatwave is expected to hit the poorest and eldest communities the hardest, especially in Pakistan, where electricity load shedding is already causing hardship. Urban centres in Pakistan are experiencing load shedding for up to six to 10 hours, while rural regions face power outages lasting approximately 18 hours a day.

Irregular water supplies exacerbate the problem for urban populations. Although fans can help circulate cooler air, they are only effective up to temperatures of approximately 37°C. Air conditioning is prohibitively expensive, even for middle-income families in both countries. The heatwave could result in a significant loss of life.

Government officials are advising citizens, particularly children and the elderly, to take precautions against the extreme heatwave, such as avoiding unnecessary trips during the day.

Outdoor and indoor workers, such as police officers, street vendors, miners, and industrial workers, are also at high risk of heat stress during extreme heat days. This year’s heatwave is particularly severe and early, with March being the hottest on record, with an average temperature of 33.1°C.

Urban areas are more vulnerable to the impacts of the heatwave due to the Urban Heat Island (UHI) effect. UHIs occur due to a combination of factors, including land use, building density, geography, pollution, and high temperatures.

The replacement of green areas with dark, heat-absorbing surfaces, such as asphalt and concrete, is a chief cause of UHIs, and factors such as pollution, climate change, and city sprawl intensify their effects.

Higher urban temperatures lead to increased energy use during the summer, higher air pollution and greenhouse gas emissions, negative impacts on human health and comfort, and warmer stormwater runoff that affects water quality.

To address this issue, urban planning interventions can be implemented, such as increasing the reflectance of hard surfaces by painting rooftops white, adding greenery and water features, reducing anthropogenic heat emissions, and improving airflow through the city.

In June 2015, a severe heatwave in Karachi resulted in over 1,200 deaths and 50,000 cases of heat illness, catching all levels of government and first responders off-guard. In response, the Commissioner’s Office in Karachi collaborated with the Climate and Development Knowledge Network (CDKN) to develop a heatwave management plan.

The plan outlines the actions of implementation partners to ensure that weather conditions and heat health information is timely and specific, organisations can respond to their roles, and strategies and actions become more effective over time.

During the early Mughal era in the Indian sub-continent, various traditional and indigenous methods were used to cope with high temperatures. The early European colonists adapted these methods to suit modern conditions.

For instance, they constructed high ceilings and spacious but lowered verandas to provide more shade. Thick layered thatch roofing was used to keep temperatures inside the house lower during nights, and wet tattie — two to four-inch-thick screens made up of long roots of the Khas — were used for home cooling.

In Mughal buildings, courtyards were often added with vegetation and water bodies to enhance humidity, cool the air by evaporation, keep the dust down, and provide shade for comfortable living during hot, dry seasons.

English bungalows were built within compounds of shady trees, with rooms having thick walls, high ceilings, and surrounded by covered verandas. Even today, people in villages spend their daytime on lower floors while they spend their nights on the terraces.

To combat Karachi’s extreme heat, the government must take significant steps to increase the city’s green cover. Solutions for the urban heat island effect will need to be formulated at different scales, with various quantitative measures developed to model the local climate at the street, neighbourhood, and city levels.

With a population of around 20 million, Karachi ideally requires 20m plants, following the one-person, one-plant principle. However, there are currently only 3m trees in the city, which is far too few to make an impact. Ideally, cities should have 12 meters of open space available per person.

One approach to increasing the city’s green cover is to transform large parks into urban forests, although this task is too big for the government to complete alone.

Charitable organisations have already made significant contributions to food, shelter, and health in Pakistan, and their services were effectively utilised during the Covid-19 pandemic.

Although the government has encouraged universities to lead tree plantation campaigns, the impact is only visible when these institutions develop the capacity to nurture and care for the trees.

World Wildlife Fund-Pakistan is making commendable efforts to conserve the country’s endangered forests, precious freshwater, and wildlife. Nonetheless, the task at hand is too vast to be accomplished by a single organisation.

The country needs appropriate measures to identify and quantify the effectiveness of different policies, including those related to planning, energy, buildings, and health, over the long term.

Architecture that facilitates natural sunlight and ventilation is conducive to the health of the occupants.

Urban forests, green belts, greenhouses, and vegetation can improve the quality of outdoor spaces and enhance cooling through evapotranspiration. Fountains are an effective way to enhance air quality by spraying water droplets into the air, which speeds up evaporation.

Published in Dawn, The Business and Finance Weekly, May 1st, 2023

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