Sustainable buildings have always been the way ahead for the Godrej Group. Having created several benchmarks in this area, Godrej & Boyce recently achieved the ‘Net-Zero Energy Rating’ from the Indian Green Building Council (IGBC) for its Plant-13 Annexe Building, which is part of its Vikhroli campus in Mumbai. This multiuse, office-cum-convention centre has won many accolades like the ‘IGBC-EB Platinum Rating’ and the ‘BEE 5-Star’. “Last year, when we partnered with the World Green Building Congress (WGBC) to further the cause of ‘Net Zero’ in the Asia-Pacific Region, we were determined to demonstrate that in our own campus, and here we are!” says George Menezes, COO, Godrej Electrical and Electronics. “I have no doubt that this will be the harbinger for many more ‘net-zero’ buildings to follow in the country.” He shares more on the green features and the net-zero mark: What’s green?Over the years, Plant-13 Annexe has demonstrated the highest standards of performance. The building has been supported by several green features including recessed glazing and shading device; natural daylight harvesting in the occupied area (Centre Core lighting concept); operable windows for fresh air; roof garden; high SRI paint on paved terrace areas; natural surrounding with trees, which help maintain the microclimate; screw chiller with secondary variable pumping system; VFD for the canteen’s kitchen ventilation system; building management system (BMS); system-level monitoring and analytics of energy end use; non-potable water use for landscaping, flushing and C Tower make up; retrofitted T-8 fluorescent tube lights with T-5 (HE) low-mercury tube lights; retrofitted PL-36 square light fittings with LED lamps in the staff dining area; and segregation of waste at source.Several additional features and upgrades have been added to achieve net zero. These include improving upon the building’s systems (HVAC, lighting) performance; monitoring energy performance at the system level to understand energy end-use efficiencies; addressing cost streams associated with building operations; improving occupant comfort resulting in productive employee workspaces; enlightening building occupants and visitors regarding the benign impact on the environment; providing public recognition for leadership in sustainability; and becoming a case study for other corporates to emulate in future.Achieving the net-zero goalA sustainable thought process has been applied right from the conceptual design stage to the construction stage, systems integration and operations. This has been keeping in line with India’s Intended Nationally Determined Contribution (INDC), wherein the country is committed to reduce its emissions by 33 per cent with respect to the 2005 level by 2030.  Existing buildings far outnumber new buildings. The thought process behind IGBC-EB (Indian Green Building Council-Existing Building), IGBC NZEB and BEE 5 Star certifications for ‘existing building’ was to demonstrate the fact that with an incremental investment and some smart efforts, it is possible to improve upon the operational performance (energy, water, waste management) of the building’s systems. For existing buildings, operational efficiency and maintenance issues receive a great deal of attention in the IGBC rating system where the primary challenge is not optimal design but optimal utilisation of assets (systems). Addressing improvement in operational efficiency and maintenance issues in the existing building has a greater outreaching impact. The management’s school of thought for the PL-13 Annex building: ‘Be Lean Before Green’: Improve upon the building’s systems performanceImprovement in occupant comfortDemonstrate the merits of institutionalisation of sustainable practice in the building industry.A self-sustainable modelBy virtue of the building’s design, most areas are natural daylit. The centralised air-conditioning system has been designed considering the diversified occupation of the building. Also, 2# 125 TR + 2# 250 TR water-cooled chillers (redundancy of one chiller in both capacities) have been installed.System-level monitoring and analytics of HVAC, lighting, ventilation energy consumption and solar PV generation on a daily basis has resulted in identification of potential energy-saving opportunities and control of operations; Rs 0.15 million has been invested towards institutionalising a system-level metering system, which has yielded significant benefits by way of monitoring and control of wasteful energy in the building.The overall energy consumption reduction in the past two years is 276 mwh (7 per cent of total energy consumption).Energy cost reduction for the past two years has been Rs 4.8 million (8 per cent of the total energy cost).Total energy generated from renewable sources (rooftop solar PV) is 8 per cent.Energy performance and renewable energy sourcesThe NZEB rating system gives significant weightage and thrust to enhancing energy-efficiency of systems in the building. Of all the points scored by this building, the major points have been scored in the area of energy-efficiency and the least in renewable. Total points attempted: 77Total points awarded: 77Energy-efficiency improvement: 75Renewable energy: 2  ECBC baseline The Energy Conservation Building Code (ECBC) defines the roadmap to build up the ‘base case’ of the building’s energy performance wherein ‘base-level energy conservation measures (ECM)’ are instituted. We have compared the actual energy consumption computed from the Electricity Board (TATA Power) invoice with the base case to determine the Energy Performance Index (EPI), which is denoted as ‘kwh per sq m per annum’. As seen in the table below, there is 46 per cent improvement with respect to the base case with EPI ratio: 0.54.   Base case Actual (As per Tata invoice) Energy consumption 3,364,834 kwh 1,825,276 kwh EPI 137.66 kwh per sq m per annum 74.67 kwh per sq m per annum Energy-efficiency improvement wrt ECBC-2007: 46 per cent To offset the energy consumed in the building, the following solar generation is required, and has been met in this project, as shown in the table below. The aim of the project proponent should be to lower energy consumption in the building by implementing ECMs and then offset the consumption with solar power. Total energy Consumption (kwh per annum) Solar PV on-site (120 kwp) total energy generation (kwh per annum) Solar PV off-site (1.2 mwp) total energy generation (kwh per annum) 1,825,276 148,487 1,676,789 Per cent contribution towards total energy 8 per cent 92 per cent Takeaway from the certification journeySeveral challenges were faced in planning the building as a green one and achieving the net-zero vision. This included diverse building operations (dining, food manufacturing, office, food court, conference rooms) and executing the plan keeping these in mind and varying occupancy and retrofits (carrying out modification in occupied spaces).However, the certification system helped identify the gaps in operations and maintenance (O&M) performance. It helped to institutionalise best practices, which provides an outline for enhancement of the building’s performance. This included optimisation in energy, water end use, natural resources; waste management; improving the indoor environment; and continual focus on operating efficiencies.Costs and returns Activity Investment (Rs) Savings  (Rs) RoI Energy metering at system level  150,000 NA NA Retrofitting of PL-lamps with LED 340,000 470,000 9 months VFD at canteen’s kitchen blowers 280,000 330,000 10 months Project details• Location: Mumbai• Built: 2008• IGBC-EB Platinum: 2015• BEE 5 Star Rating: 2016• Architect: Rumy Shroff & Associates Architects. Tel: 022-2203 7745. E-mail: rumyshroff@gmail.com• MEP: Eskayem Consultants. Tel: 022-2528 2645; E-mail: eskayem@vsnl.com Website: www.eskayem.com• Green consultant: Godrej Green Building Consultancy Services. Tel: 022-6796 2130. Website: www.godrejgreenbuilding.com• Solar PV (120 kwp) (On site): 2016• Solar PV (1.2 mwp) (Off site): 2015• IGBC-NZEB: 2019• IGBC-EB Platinum (Recertification): 2019• Built-up area: 24,443 sq m• Air-conditioned area: 16,050 sq mBuilding usage – Floor-wise:• Basement floor: Utilities and parking• Ground floor: Kitchen and canteen• First floor: Cafeteria and office• Second floor: Office• Third floor: Conference rooms• Fourth floor: Auditorium and banquet