The blue houses of Jodhpur: Traditional wisdom for a cooler future

Jodhpur is in the heart of India’s state of Rajasthan, bordering the Thar desert. Also called Surya Nagri (“Sun City” in Hindi), this city dared to brave a harsh environment, adapting to extreme temperatures and water stress, to flourish as the capital of the erstwhile Kingdom of Marwar in 1459.  

Jodhpur is also known as the “Blue City” for its captivating blue-painted houses. But, beyond their visual appeal, these houses hold a hidden secret; a revelation that could pave the way for a cooler, more sustainable urban future.

In an age where climate change is an impending threat, young professionals from GRRID Corps & the Confederation of Risk Reduction Professionals (CRRP India), working in disaster risk reduction and climate action, embarked on an investigation that would challenge long-held beliefs about the cooling effects of the Blue City. 

The impact of climate change in semi-arid regions

Regions across the globe are grappling with the harsh realities of climate change. 2023 is a stark example with some of the hottest months ever recorded. Research has shown that, come what may, the societal impacts of climate change will be substantial.  

Ecosystems in semi-arid regions – like Rajasthan – appear to be experiencing various processes of degradation, aggravating the impacts of climate change in the region. Local warming in semi-arid regions is likely to be greater than the average global warming in the coming decades. This means that the already-hot semi-arid regions will be exposed to additional pressures of heat stress, in the form of longer heatwaves and a greater number of extremely hot days.  

The existing vulnerabilities of semi-arid communities due to high levels of poverty, inequality, and rapidly changing socioeconomic, governance, and developmental contexts, shall be exacerbated further by heat stress. This shall adversely affect people’s livelihood, health, and well-being. Since human health is highly sensitive to the thermal environment, extreme heat events can increase morbidity and mortality as well as reduce work productivity. To address these issues, future development must take into account these climate-induced stresses. 

The situation in Jodhpur is no different. The effects and impacts of these changes are felt in the daily lives of the people; while they are used to the loo (hot winds prevalent in summer in the northern and north-western part of India), many find the rising humidity unbearable. This is exacerbated by  contemporary building materials and built-up areas, which aggravates the urban heat islands effect. 

The traditional architectural resilience of Jodhpur

Interestingly, Jodhpur's traditional architecture, characterized by its distinctive blue-painted houses, may offer an ingenious response to the city's blistering heat.  

The communities here say and believe that the indoor temperatures in these traditional houses are lower than the scorching exterior. Commonly told among tourists and tour guides is a narrative that the indigo-blue colour itself is responsible for moderating ambient indoor temperatures.  

Our research sought to definitively quantify this notion.  

Could the blue colour be a definitive cooling factor?  

If not, but still the indoor temperatures can be shown to be demonstrably cooler,  are other factors at play? And could these be mainstreamed or integrated into contemporary designs and developmental plans? 

The quest for truth begins 

A group of young professionals from GRRID Corps (a startup committed to disaster risk reduction & management and climate action based in India) and the Confederation of Risk Reduction Professionals (CRRP India  – the national platform for youth and young professionals working in disaster risk management in India), recognizing the potential of Jodhpur's traditional wisdom, embarked on a journey to unravel the truth.  

A prototype to unveil the truth 

The team developed a prototype to test the temperature differences between the interior and exterior of a traditional Jodhpur house.  

Contained within a tiffin box (an Indian lunchbox), the prototype was loaded with a temperature-humidity sensor, an atomic clock and a Wi-Fi module. With two such tiffin- boxes, the team visited two traditional houses, placing one prototype outside and the other one in the innermost room. 

The results were clear: The indoor temperatures were indeed significantly lower than the outside temperatures, even without the blue colour.  

The indoor temperature of a traditional house was also lower than the indoor temperature of a more contemporary house. Additionally, the humidity was also found to be lesser in the inner rooms than the outside. 

This revelation sent our team down a new avenue of architectural investigation. 

Uncovering architectural elements 

The research team's findings highlighted the crucial role of architectural elements in maintaining cooler indoor temperatures. While the blue colour did not contribute to the cooling effect, other architectural features such as courtyard houses, carved stone façades, jharokhas (overhanging enclosed balconies), jaalis (perforated screens), meandering streets, open chowks (squares), and community spaces played a pivotal role.  

The irregular pattern of streets in the old city was revealed to be a masterful design that diverts wind patterns, providing natural ventilation. Courtyards, a common feature in these houses, also act as ventilation sources. Thick sandstone walls, sturdy roof tiles, and carefully crafted façades were found to be instrumental in maintaining a cool indoor environment. 

It was also discovered that the traditional blue colour, historically introduced by the Brahmin community, makes no discernible contribution to the houses' ability to stay cool during the harsh summers.  

The importance of this discovery: Debunking myth and establishing facts 

The implication of this discovery that the blue colour plays no significant role in indoor cooling, and that the traditional way of constructing houses is more suited to the changing climate in Jodhpur, is profound.  

The young professionals’ investigation has uncovered some architectural secrets of Jodhpur’s old city, through innovation at a hyper-local level. As global temperatures continue to rise, the urban heat island effect is making city centres unbearable during hotter and longer heatwaves. Newer buildings, constructed with contemporary materials and techniques, often trap heat and exacerbate these heat islands.  

However, the integration of traditional architectural elements identified in the old city of Jodhpur can significantly contribute to alleviating this problem. 

In addressing the urban heat island effect, city planners and architects can look to the past for innovative solutions. Courtyard houses, shaded façades, and open community spaces are not obsolete relics of the past but practical solutions to the challenges of extreme heat. They offer a path forward for the construction of more sustainable, cooler urban environments. 

A blueprint for sustainable urban development 

This research has opened up a promising avenue for sustainable urban development. By understanding and implementing architectural elements inspired by tradition, cities can address the challenges of climate change and create cooler, more comfortable living spaces for their inhabitants. 

The place-based wisdom of Jodhpur provides a blueprint for a sustainable urban future. These insights could pave the way for a cooler, more resilient tomorrow.  

It's time for cities around the world to learn from the architectural wisdom of Jodhpur and embark on a journey of transformation that takes us back to the future.

Repaul Kanji is a computer scientist at heart and a disaster risk management professional by training. He holds a Master's in disaster mitigation and management and a Ph.D. from the Indian Institute of Technology Roorkee. After having worked with and for the government at the state, national and regional levels, he has recently started working on his own socio-entrepreneurial venture - GRRID Corpis, which is a transdisciplinary startup working at the crossroads of disaster risk management, climate action and sustainable development. He is associated as a 'Young Scientist' with the Integrated Research on Disaster Risk (IRDR), which is a trans-disciplinary research platform of the International Science Council and the United Nations Office for Disaster Risk Reduction (UNDRR).