In current times, the terms green building, green design, and energy conservation have become synonymous with building design. For the sake of the environment, one has to design buildings that tackle the issue of an increase in carbon footprint and are energy efficient. The green buildings are somewhat contributing to the reduction of carbon footprint. But, what about the other 90% of buildings which are not green? How are they contributing? Prior to generating new green buildings, isn’t it better to make the existing buildings green?
Opportunities to reduce energy use in an existing building differ distinctly from those in the design of new buildings. In the existing buildings, the major determinants in the physical aspects of the building, such as building configuration, orientation, materials, construction, mechanical systems, and location, are already in place. Most of these are, therefore, difficult to modify. But the design assumptions of the occupancy, space utilization, and environmental standards, are subject to change over a period of time. What is the solution to this problem?
The answer lies in retrofitting. To retrofit is to modify an existing building for energy efficiency. Retrofit measures are actions taken to upgrade a building, enabling it to respond positively to climate change. Reducing the property’s carbon footprint is one of the key objectives of a retrofit. Other important considerations include increasing the comfort of the building for its occupants and reducing the incidence of fuel poverty. Thus, to be competitive in the world, the owner/user has to resort to a less energy-hungry way of existence, i.e., he must retrofit!
The big question emerges, what measures can be taken to make an existing building more efficient in terms of energy consumption? Are green retrofit technologies a worthwhile investment? Let us answer these questions with a few Indian & international examples of retrofitting in architectural buildings.
1. Paharpur Business Centre, Delhi
Paharpur business center is a 25- year old building in Delhi, a living example of achieving the lowest carbon footprint in the city with retrofitting. It has received numerous certifications for its exceptional indoor air quality and energy efficiency, viz. LEED Platinum rating, NABERS certification, etc. The focus of the building is on the health, wellness, and happiness of its employees.
The six-story building, spread across 50,000 square ft, has over 1,200 plants. The plants in this indoor jungle are strategically placed, depending on the floor capacity and time of usage. On the terrace is a greenhouse that helps circulate fresh air after removing toxic particles from the ambient air and pumps it into the air-conditioning system. Furthermore, LED lights have replaced CFL bulbs. Candles, that were once used to keep food warm inside large aluminum containers, have given way to tiny induction heaters. Solar panels set up on the rooftops. The building is focused on every aspect of an employee’s life- air, water, nourishment, light, and fitness.
2. Godrej Bhavan, Mumbai
An iconic office building located in Mumbai, Godrej Bhavan demonstrates the profitability and practicality of green energy-saving retrofits. Built-in 1962, the six-story building was upgraded in 2010 to incorporate comprehensive energy-efficiency and sustainability features, such as efficient HVAC, lighting, and building management systems. It is the perfect example of how a high performing office space can maximize energy-saving strategies with ease of maintenance, improved comfort, and air quality. The building recovered the cost of initial investment within five years of installation, with substantial savings projected in the next fifteen years.
The building’s architectural design, façade, glazing, lighting, HVAC system were already in usage. In order to ensure continued building operations, worker productivity, building safety, and increased awareness of the benefits of retrofits, the company came up with a unique solution to tackle the multiple issues. Undertaking retrofitting during non-office hours, replacement of outdated HVAC system, creation of artificial floors to locate AHUs, and sourcing energy-efficient technologies and green materials from special vendors, were some measures adopted to retrofit the building efficiently. Moreover, the fresh air circulation and indoor air quality improved by planting large trees, and operable windows installed allowed access to fresh air. DGUs and shading devices installed to reduce heat gain while still providing light. A green roof garden developed to reduce the heat gain from the roof.
Replicable lessons from Godrej Bhavan’s upgrade show the real energy and cost savings from implementing energy efficiency in existing buildings. The retrofit helps lower electricity usage, improves building systems, enhances occupant comfort, saves operating costs, and increases environmental awareness among building occupants.
3. Mahindra Towers, Mumbai
Mahindra Towers headquarters is located in Mumbai and was constructed in 1985. With a built-up area of 200,000 sq.ft., the retrofit focused on improving efficiency in lighting and cooling systems. The Mahindra Towers had an impressive payback period of less than a year. The implementation of energy-saving mechanisms undertaken in conjunction with an energy servicing company demonstrated the benefits of working with such an organization.
The energy-saving company did an energy audit for the Mahindra Towers, and based on their recommendations, existing low- efficiency lighting replaced with high efficiency, high frequency, low-harmonic electronic ballasts; the air-conditioning system optimized with reduced wasted energy and capacity; the metering altered and optimized along with a reduction in power losses. These energy conservation measures not only saved energy, but also improved equipment reliability, increased the quality and property value of the building, enhanced occupant comfort, and amplified the company’s environmental commitment.
4. One Prudential Plaza, Chicago
The One Prudential Plaza, constructed in 1955, is one of the landmarks of the city of Chicago. The building’s original curtain wall system was made of vertical strips of limestone and rigid aluminum windows with center-pivot units for easier maintenance. However, the seals on the windows failed and the windows caulked shut to reduce air and water infiltration.
In order to match modern standards, improve aesthetics, and increase the comfort of the building tenants, the façade underwent a retrofit, whereby 1200 bays of existing single-pane windows were replaced with energy-efficient ones. Contributing to a safer, more comfortable, more energy-efficient, and more attractive workplace, high-performance windows with thermal barriers, aluminum framing, and experienced engineering and fabrication, were chosen. These windows helped dramatically lower the building’s heating and cooling costs while increasing occupants’ comfort and minimizing window surface condensation issues.
5. Harvard House Zero
Intending to intelligently address the challenge of retrofitting existing buildings, Harvard University retrofitted the CGBC’s Headquarters in a pre-1940s timber-framed building, creating an ultra-efficient and energy-intensive prototype with a comfortable indoor environment.
Up-gradation of the existing envelope with additional insulation, enlarged windows, skylights along with retention of the building’s original character, was part of the retrofit process. Sophisticated room sensors to open-close the windows and maintain air quality, solar vents to direct air to the basement, and naturally pumped heated or cooled water through the floor slabs, further helped maintain thermal comfort and indoor air quality.
Moreover, sculpted window shrouds protected interior spaces from direct sunlight or heat. Locally available, low-emission materials, such as clay plaster, birch wood, and ultra-high-slag concrete, helped create a balanced, comfortable indoor environment. Rooftop photovoltaic panels accomplished the electrical energy requirements. This array of environmentally-conscious retrofits helped achieve the goal of long-term energy autonomy.