Many of us focus on plantation drives and opting for environment-friendly products to reduce carbon emissions. But in the process, we tend to overlook, or are unaware altogether, that the very walls surrounding us in our homes are also massive contributors to climate change. Gravel, sand, and cement extracted from the earth and mixed together with water have created a recipe for disaster.

The problem becomes evident if we understand the process of making cement.

Raw material such as limestone and clay comes from quarries. The materials are crushed and mixed with iron ore or ash and fed to cylindrical kilns at around 1,450 degrees Celsius. The process is called calcination, which splits the mixture into calcium oxide and CO2, giving out a new product called clinker. The new marbled-sized and grey product is cooled and mixed with gypsum and limestone and sent as a ready-mix to concrete companies.

Half of the CO2 emissions from cement happen during the process. If cement were considered a country, it would become the third-largest CO2 emitter in the world, surpassing a massive country like India.

But a Roorkee and Visakhapatnam based social enterprise, GreenJams, might just have an alternative. The venture is creating carbon-negative building material from agriculture biomass and hemp blocks.