Hidden energy

About 25 per cent of India’s total primary energy demand is attributed to manufacture of building materials, and another 15 per cent is to operate them. Buildings account for the largest energy and ecological footprint. Globally, buildings consume one-third of the world’s resources. In India, the construction sector adds 30 per cent of the greenhouse gas emissions, states a 2007 report by the Indian Network for Climate Change Assessment.

Appliances consume energy to operate, but materials used in the construction of buildings consume energy, too. Embodied energy is the total energy used in the construction process—right from extraction of raw materials, manufacture of products to their transportation and incorporation in buildings.

Not so evident as the monthly electricity bill, embodied energy often gets neglected, as reported by Down To Earth. Assessing EE accurately is difficult because energy consumed in the making of a building material is documented only till the factory gate. Cement, steel and bricks, the basic construction materials are major contributors to embodied energy but their use cannot be reduced too much but.materials like ceramic and vitrified tiles, which are highly energy intensive, can be easily replaced with energy-benign materials like stone.

Fly ash brick has less embodied energy compared to stabilised earth block. But if transported across long distances, the advantage is lost. So also with bamboo and mud. The idea is to use locally available materials.

While Indian regulators are pushing for energy-efficient buildings with tools like energy conservation building code (ECBC), the embodied energy is neglected. The West is a step ahead trying to lower embodied carbon of materials. Embodied carbon takes into account the source of energy and then evaluates its impact on environment. So while the same product made in different factories—such as one using coal energy and the other hydro power—may have the same EE, they will have vastly different embodied carbon values.

Low pricing of materials with high embodied energy does not help the cause. Products that can be recycled or reused must be encouraged. More awareness should help. True, there are shades and shades of green and before we can call a building green, we need to cover a lot of ground!