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Estimating the Energy Consumption of urban buildings in India

A team of scientists at IISc have calculated the energy consumption of urban buildings across India thus paving the way for efficient energy usage by one of the highest energy consumers’ worldwide-buildings.

Buildings consume around half of all the energy produced worldwide. A modern urban household consumes energy for several electrical appliances including television, refrigerator, heating, cooling and lighting equipment, aside from the energy consumed during the construction of a modern structure. Understanding the power consumption of a building during construction and after, enables us to build structures that consume energy much more efficiently and conservatively.

The team comprising of Prof. KI Praseeda, Prof. BV Venkatarama Reddy and Prof. Monto Mani from IISc has calculated the total energy consumed during the entire life span or Life Cycle Energy (LCE) of urban buildings. They chose 16 residential buildings situated in warm, cold, moderate and composite climatic zones, in urban and peri-urban areas across India.

The LCE of a building is a sum of four terms. The Embodied Energy (EE), which is the energy consumed during the construction of the building, including the energy consumed during manufacture of the materials, transportation and construction. The Operational Energy (OE), which is the amount of energy utilized during operation and maintenance of the building. The Recurring embodied energy, which involves the energy used during any maintenance work. And finally, the energy consumed during the demolition of the building. The recurring embodied energy and demolition energy, of the building was ignored in the current study as it contributes less than 1% to the Life Cycle Energy of the building.

The Embodied Energy of the materials is a major contributor to the EE of the building. The Embodied Energy was calculated by referring to shop drawings, bills of quantities and specifications. The research has shown that using modern building materials like Reinforced concrete blocks and burnt clay brick masonry increased the Embodied Energy of structures. Using materials like cement, steel and glass within a structure especially contributed to increasing this factor. The study also did not find much variation in the Embodied Energy of the building and the different climatic zones which is attributed mainly to the stereotypical construction methods adopted across the urban parts of the country

Operational energy, on the other hand, is affected by the design of the structure. Not allowing for natural ventilation during the design and construction of the building increases the dependency of the household on electrical and mechanical heating and cooling equipment like ceiling fans and air conditioners, thus increasing the operational energy of the building. The operational energy was determined in some cases by referring to the energy bills of a household. The study found that buildings in composite climatic zones had the highest operational energies followed by the ones in cold climatic zones. This is mainly because of the extensive use of room temperature conditioners in these zones, which could be avoided to an extent by better space conditioning.

The study has thrown light on the different practises one could adapt while building, in order to reduce energy consumption and thus reduce the carbon footprint of such a building. Research has shown that the usage of alternative building materials like stabilized soil blocks and rammed earth can considerably reduce the Embodied Energy of buildings. Also, by designing better space- conditioned structures, one can better utilise natural air ventilation and light, reducing the dependency on heating, cooling and lighting equipment.

Thus, by making suitable modifications in the way we construct, we could make giant leaps towards energy conservation. The study can be used as a manual while designing new structures such that buildings, that would otherwise devour high amounts of energy, would be efficient and conservative with energy consumption.

About the authors:

K.I Praseeda is a research student at the Department of Civil Engineering at IISc.

Contact: kipraseeda@civil.iisc.ernet.in

Prof. B.V Venkatarama Reddy is an associate professor at the Department of Civil Engineering at IISc.

Contact: venkat@civil.iisc.ernet.in

Prof. Monto Mani is an Associate Professor at the Centre for Sustainability Technologies at IISc.

Contact: monto@astra.iisc.ernet.in