Moving towards greener skylines

In the past few articles, we have discussed the importance of heating and cooling in urban offices and residences, increased use of LED Lights in urban areas, better planning of urban spaces and Net-Zero Buildings. However, the urban environment all over the world has been in existence for decades, with many cities being over 100 years old. In these cities, the urban spaces, including residences and buildings have been around for a long time and green improvements can be undertaken only if we retrofit these buildings.

Retrofitting Buildings: A Necessary Intervention

Since buildings are major energy users, they are also heavy emitters of greenhouse gases. Paul Hawken in his book Drawdown, says that buildings account for 32 per cent of energy use and 19 per cent of greenhouse gas emissions around the world. This energy is used for heating, cooling and lighting and is drawn from the grid. When the buildings were first constructed, the objective was to provide comfortable office spaces and dwelling units, with no concern for the energy intensity of these buildings or even energy efficiency. There was no concept of planning the building to allow the use of natural light or to have an ‘envelope’ that would optimise the heating and the cooling. If the carbon footprint of urban spaces has to be reduced and ultimately phased out, retrofitting of buildings will be an important strategy.

As we saw in the article on Net-Zero Buildings, the most fundamental issue in these buildings is the new design of spaces. For new buildings, there are standards such as LEED (Leader in Energy and Environment Design) developed by the US Green Building Council and Zero Energy and Zero Carbon certifications by International Living Futures Institute in the US and other places. For existing buildings, the US Green Building Code has specified standards and procedures to retrofit buildings. In the UK, the National Building Specification (NBS) has estimated that 30 per cent of all carbon emissions in the country come from buildings, and has set a target of retrofitting 29 million homes by 2050. In India, TERI has outlined procedures for retrofitting buildings and highlighted the energy savings advantages it brings.

In general, retrofitting involves the redesign and restructuring of spaces inside the building. The major components of any retrofitting are:

• Modifying the Building Envelope, which basically separates the inside of the building from the outside environment and includes redesigning and replacing windows, roofs, floors and walls.
• Reducing the electricity needs and improving energy efficiency by using better transformers, motors, net metering and use of renewables such as solar energy.
• Improving lighting systems by maximising the use of natural light and replacing conventional bulbs with LEDs.
• Improving HVAC (Heating, Ventilation and Air Conditioning) systems with increased use of chilled water (CHW) pumps, condenser water (CW) pumps, cooling tower (CT)fans, air handling unit (AHU) fans, fan coil unit (FCUs) etc.

Retrofitting will not only reduce greenhouse gas emissions but also lead to energy savings on a large scale. A report by TERI, India, has estimated that retrofitting will lead to energy savings of about 15-20 per cent. Paul Hawken, in his book Drawdown, has quoted a study by the Rockefeller Foundation and Deutsche Bank, which says that if USD 279 million is spend on retrofitting in the US over 10 years, it would lead to energy savings of 30 per cent of annual spend on electricity, generate 3.3 million job years of employment, and cut US emissions by 10 per cent.

It would be instructive to look at some of the high-profile retrofitting examples in the US: that of the Empire State Building in New York in 2010 and the Willis Tower in Chicago. According to Paul Hawken, during the retrofitting of the Empire State Building, 6514 windows had to be replaced at a cost of USD 15 million. Other changes in this retrofit included improved insulation, upgraded elevators and better lighting. This led to a savings in energy cost of USD 4.4 million annually, which was a saving of 38 per cent. The Willis Tower in Chicago was retrofitted with better water and light management, improved HVAC and better lobbies and Skydeck, and led to energy savings of 70 per cent annually.

Conclusion

Given that urban buildings consume a lot of electricity, which leads to large amounts of greenhouse gas emissions, it is important to undertake a phased retrofit of such buildings. There are many companies and consultancies that are now offering these services. Many buildings have already undergone retrofits and have benefitted in energy savings. This needs to be spread to all cities so that the carbon footprint of these buildings is reduced.

The writer is Additional Chief Secretary, Department of Mass Education Extension and Library Services and Department of Cooperation, Government of West Bengal