BMC plans ₹116-crore net-zero building

BMC plans a ₹116-cr net-zero building in Mumbai to achieve Centre's goal. It will consume net-zero energy, water, and waste, aiming to reduce carbon footprint.

Mumbai: To achieve the Centre’s ambitious target of net zero by 2070, the Brihanmumbai Municipal Corporation (BMC) plans to build a ₹116-crore net-zero building, which will replace its H East ward office in Santacruz.

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Net-zero buildings are structures that produce as much energy as they consume, with an aim to reduce their carbon footprint. The BMC’s plan is to construct a building that will consume net-zero energy, water and waste.

“The BMC is attempting a net-zero building for the first time on a pilot basis. It is net-zero not just on one criterion but three: energy, water and waste. Our cost given is our estimate, which may be on the higher side,” said an official from the civic body’s building construction department.

“The tender we’ve called for is for a turnkey contractor, which means the contractor will oversee everything, from project management, technical oversight, day-to-day supervision, completion certificates, and more,” the official added.

Some preliminary ideas for the building include running on solar energy, energy-efficient brushless direct current (BLDC) fans, cavity walls providing insulation, and sustainable construction techniques. There will also be a tree plantation.

“The maximum energy use in the ward office is for cooling, lights and electronic appliances. For that, we are considering solar energy and insulated walls to reduce the need for cooling. For water efficiency, there will be rainwater harvesting and a sewage treatment plant (STP) on site. Waste will be composted and recycled; however, if the contractor comes up with different techniques, that will be accepted. If it fits with the concept well, we will run with it,” said the official.

To be considered net-zero, the building will have to be certified by Leadership in Energy and Environmental Design (LEED), a worldwide green building rating system, and/or the Indian Green Building Council (IGBC), which is part of the Confederation of Indian Industry (CII). Yearly audits by EDGE, an international green building certification system, will also be mandatory.

Current plans for the building span two basements, a ground floor and six upper floors. However, this may be increased to seven if the Airports Authority of India’s regulations allow for it. The building will cover 1,223 square metres on the ground, increasing to 1,475 sqm on the topmost floor. The timeline for the construction is two years.

Although the tender was first released in March, it has since been extended six times. The last extension was on July 11, and the deadline for tenders is August 14.

“Because this is the first time we’re doing this, we have been discussing with various vendors and the IGBC to iron out the specifications of the tender, what net-zero means, and our plans. That has led to modifications in the tender, which is why we have extended the bid duration,” said the official.

The Lok Sabha elections earlier this year, which led to a staff crunch, also delayed the process. Further conditions need modification, which is awaiting the municipal commissioner’s approval, said the official. If approvals do not come in time, the tender may have to be extended again.

Ashish Rakheja, chairman of the IGBC’s technical committee, put the plans in context: “India is actually a leader in net-zero buildings, with many corporates taking the lead. Among the categories, net-zero energy has become easier to achieve due to the greater acceptance of solar energy, which has reduced the cost. Night-time energy poses an issue, but wind energy can be used in some cases, or green energy can be bought. Any additional energy taken from the city will have to be given back.”

Similarly, net-zero waste is also easy to achieve as it requires discipline. The waste has to be sent to authorised vendors so that none of it ends up in the landfill. “Net-zero water is harder, as it rains only in a condensed timeframe in Mumbai, so where will all that water be stored? But more and more buildings are attempting it,” said Rakheja.

Energy-efficient construction techniques play a big role in sustainable buildings, as they reduce the energy requirement of buildings – a bulk of which goes towards air conditioners, added Rakheja. Insulated walls and roofs that keep the heat out and day-lit spaces, along with the use of fans, can reduce energy requirement by half.