The Godrej Bhavan building in South Mumbai provides replicable practices for cost and energy savings and highlights that energy-saving retrofits are practical and profitable in India’s rapidly transforming building market
Godrej Bhavan at Mumbai, built by Godrej & Boyce in 1972, is a six-story building that houses company’s chief management. After decades of high electricity bills, the company upgraded Godrej Bhavan in 2010 to include comprehensive energy efficiency and sustainability features. The upgraded energy-saving building is now achieving significant financial and indoor environmental quality benefits for its owner and occupants. Based on the electricity bill savings alone, the upgrade costs are expected to be paid back by year 2015.
Recovering Retrofit Investment Costs via Energy Savings
Just two years after the upgrade, Godrej Bhavan is already reaping cost and energy savings and is on track to recover the costs of installing energy-efficiency measures through lower electricity bills. In the first year after the upgrade, Godrej Bhavan’s electricity use dropped to 527,160 kilowatt hours (kWh), for an 11.4% savings in electricity use. In the second year after the upgrade, the building had even greater savings and electricity use dropped to 521,856kWh, for a 12.3% savings in electricity use compared with the baseline.
Three measures – HVAC, lighting, and the building maintenance system account for the bulk of the energy savings. The upgraded HVAC system captures the maximum savings of the measures installed, accounting for an average of 32% in the overall electricity savings for FY 2010-12.
Because of the energy-efficiency measures installed during the building upgrade, Godrej Bhavan is now reaping energy savings and other benefits such as better indoor air quality for the building’s occupants. The HVAC system is the most significant energy-saving measure installed, based on a recent energy audit. The HVAC and building management system was manufactured and installed by Trane, and the lighting system was manufactured and installed by Philips.
Building Management and Electrical System Updates
• Installed Trane Building Energy Management System (BMS) dashboard display with digital energy meters to continuously monitor energy use, check and rectify energy-use discrepancies and increases maintenance staff accountability and productivity.
• The upgraded incoming and outgoing electrical systems for high-voltage electricity to a ring main unit system provide an uninterrupted power supply. The system also offers new information for greater building safety, more reliable operations for incoming and outgoing electricity supply and circuit tripping and faults which were previously unknown.
• Relocated the electrical power system switch gear to a more accessible switcher room to ease operations and maintenance. It upgraded the building’s low-voltage system to facilitate metering of the building’s electricity load to account for energy use and increase flexibility in operations.
• Upgraded the 35-year-old DX system chiller compressor-condenser unit with Coefficient of Performance (COP) of 2.2 to a new Trane system (COP of 5.5), that includes a screw chiller, water-cooled condenser and an electronic expansion valve.
• Replaced the cooling tower motors and fills, installed a conductivity meter, a temperature controller, and a variable primary chiller water pumping system with Kirloskar Brothers Limited pumps and water-flow meters that control the minimum water-flow rate to increase energy efficiency.
• Set up dedicated AHU on each floor.
• Incorporation of Vacon Variable Frequency Drives (VFD) and chiller water-modulating valves helped in temperature and humidity control in the occupied spaces.
• Improved fresh air circulation and indoor air quality by planting large trees around the AHU room to provide shade during high temperatures and installed operable windows to allow access to fresh air.
• Configured the BMS to maintain energy efficiency of the water-cooled chiller system by showing real time and historical data on water quality, condenser approach (or the difference between liquid refrigerant temperature as measured on the liquid line, and leaving condenser water temperature) and the total dissolved solids (TDS) level in the circulating water.
• The company included a Trane Tracer Summit building automation system to ensure that the new air-conditioning system delivered efficiency and reliability. Godrej Bhavan also signed a maintenance contract with Trane to ensure smooth HVAC systems operation.
• Upgrading the refrigerant from HFC R-22 to HFC R-134a, increased efficiency dramatically as also reduced the refrigerant’s ozone-depleting and global-warming potential.
New light fittings included Philips fluorescent tube lamps with high efficiency T-5 fittings (lamp life of 27,000 burning hours and a low mercury content of 1.4 mg per tube) and electronic ballasts with timers to switch office lights off automatically after hours. Natural day light and outside views throughout the building were provided. Double-glazed clear windows and shading devices reduced heat gain through the windows while still providing light (installed in 2012 after the building retrofit).
Green Roof Garden
The building’s original green roof which had a soil depth of nine inches was developed by removing the covering of the “tandoor” roof clay tiles. The Godrej team measured a reduction in the roof temperature by 10°C using thermal imaging. The green roof reduces the heat entering the building and cools the top floor that houses the company’s senior management. Trees were planted around the building to maintain a cool microclimate and reduce the heat island effect.
The Godrej Bhavan project team overcame several challenges during the energy-efficiency upgrade. The solutions used to overcome key obstacles are applicable to other similar projects.
Challenge: Aging Building with Ongoing Operations
The Godrej Bhavan retrofit required implementing new energy-efficiency technologies in an aging office building with ongoing operations. The building’s architectural design, façade, glazing, lighting, and HVAC system were already in use, limiting the opportunity to redesign these components. The aging HVAC system, a directexpansion (DX) system, needed to be replaced. Since two air handling units (AHUs) cooled the entire building, it was difficult to upgrade one floor at a time while keeping other operating floors cooled. For a successful upgrade, the project team needed solutions to these challenges, especially to ensure continued building operations, worker productivity, and building safety, while simultaneously increasing staff awareness on the benefits of the retrofit.
Solution: Upgrade during Non-Working Hours
The retrofit focused on specific equipment and energy management upgrades instead of redesigning the building. The relatively inefficient HVAC DX system was replaced with an energy-efficient water-cooled screw chiller. Because the building structure did not have feasible sites to locate AHUs on every floor, artificial floors were created (using beams in the masonry shaft and horizontal metal plates) to install new AHUs on each level and to provide the desired temperature conditions for each floor while maximizing energy savings. The HVAC retrofit occurred during nonworking hours and weekends to avoid inconveniencing staff during working hours. To ensure continuity of cooling, the old and new HVAC systems were operated simultaneously during the transition.
Challenge: Missing Original Drawings
The building was constructed four decades ago, in 1972. Many of its architectural, electrical, HVAC, and plumbing drawings and records had not been preserved over the years.
Solution: Creating Building Blueprints
Instead of expending resources trying to locate the older drawings and blueprints, the project team prepared new drawings for Godrej Bhavan during the retrofit process. These drawing further assist the company in its ongoing and future building operations and management, including energy savings.
Challenge: Limited Availability of Energy-Efficient Products
Comprehensive information and sourcing of energy efficient technologies and green materials, such as energy-efficient fluorescent (T-5) lamps with low mercury content, were difficult to procure for the Godrej Bhavan upgrade.
Solution: Sourcing from Special Vendors
The retrofit team sourced efficient technologies and materials from special vendors through investigation and research. Sourcing these energy-saving products for the Godrej Bhavan upgrade increased the overall market demand for efficiency technologies, leading to their availability for a larger portion of Indian customers.
Replicable Lessons for Similar Projects
The Godrej Bhavan retrofit demonstrates the low-hanging energy and cost-saving opportunities. By upgrading HVAC, lighting and building management systems, the building maximized energy-saving strategies with ease of maintenance and improved comfort and air quality.
Beyond installing efficient equipment, Godrej Bhavan also upgraded its energy management system and trained staff to analyze continually overall energy performance, transforming building operations and allowing staff to correct discrepancies and increase energy savings.
Godrej Bhavan’s upgrade demonstrates the real energy and cost savings from implementing energy efficiency in existing buildings. The retrofit saves operating costs, lowers electricity use, improves building systems, enhances occupant comfort and increases environmental awareness among building occupants and visitors.