Given the global push towards sustainability, buildings play a major role in the efforts towards decarbonisation. They account for 30 percent of global energy consumption and 21 percent of the global Green House Gas (GHG) emissions. Existing buildings make up a significant amount of the building stock available. According to the International Energy Agency (IEA), by 2040, existing buildings will comprise two-thirds of the global building stock. 

Demolition and reconstruction of existing building stock will have a significant negative impact towards the sector’s decarbonisation efforts. For instance, demolition alone can cause enough harm to the environment — air and water pollution, construction and demolition waste disposal in landfills, and the large amounts of energy required (and in-turn, emissions released) for the work.

Reconstruction of buildings can ensure that the end product is more energy efficient, but it will involve a large amount of energy and emissions. Therefore, reuse, renovation and retrofitting —  addition of new technologies or features to older systems of existing buildings — become essential to improve their existing energy consumption patterns and reduce overall emissions by 75 percent from the sector. 

Retrofitting for energy efficiency

Within a building, several applications need energy to operate. These include heating, ventilation and air conditioning (HVAC) systems, lighting, and other appliances such as refrigerators and televisions. Retrofitting buildings for energy efficiency will mean replacing outdated, inefficient appliances with modern, high-efficiency models. However, it may also entail more significant modifications to the building envelope, including the exterior walls, roof and windows. As buildings require regular maintenance — in some cases, significant renovations — these retrofitting efforts can be aligned with them.

Existing building retrofits are of three types —  low-cost, easy and quick to implement with minimal risks; mid-cost, with relatively higher implementation time and risk; and high-cost, with longer implementation time and more permanent solutions.

Low-cost retrofits include simple tasks such as using curtains or louvered blinds to block excess sunlight and heat during afternoons and keeping these curtains open during the other times to allow for natural light. This can help in reducing air conditioning and artificial lighting loads. Using reflective coatings and tinted film on glass also allows for minimal heat through the windows and optimum natural light. 

Another low-cost measure is to replace any incandescent and CFL bulbs with energy-efficient LED lights (with appropriate wattage for required brightness) which will reduce the overall energy consumption for artificial lighting. Also, setting the air conditioner (AC) temperatures between 24°C to 26°C for cooling and using ceiling fans with ACs provides improved thermal comfort and decreases energy consumption. 

Applying light-coloured or reflective paints for the exterior faces of roofs and walls can reduce the heat entering the building. Providing lighter colours for indoor spaces will allow for better light distribution. Such measures can help save energy in the range of 5 – 15 percent. High-cost retrofits are usually driven by the desire for significant space modification rather than energy savings. However, energy efficient measures can be easily integrated with the renovation works. These can include significant building modifications such as reducing over-sized windows — especially those with limited ventilation or obstructed views — providing proper shading for them, replacing existing window glass with high performance glass such as double-glazing or low-emissivity (Low-E) glass, adding insulation materials to walls and roofs, and installing green roofs with native vegetation. 

These can reduce the heat ingress into the building, and in-turn reduce the building cooling consumption.  Another significant addition is to install solar photovoltaic or wind energy systems to power the building lighting and appliances with clean energy. Several government incentives can be utilised for installing these systems in a cost-effective manner.  Implementing these high-cost retrofits can result in an energy savings of 40 percent and above, along with a potential of generating energy on-site and moving towards a net-zero target. 

Towards a sustainable future

Although a wide range of retrofit technologies is readily available, the large-scale adoption of energy efficient retrofitting measures faces several challenges such as high upfront costs and uncertainty on their return of investment. Besides, the tenant-landlord dilemma slows adoption, as building owners may not directly benefit from energy savings. While energy efficiency policies exist, weak enforcement and limited knowledge and financial support further hinder progress. Results of a recent pan-India survey involving 56,640 participants, released as part of the report, ‘Energy-Efficient Retrofit Manuals: Transforming Existing Buildings’ revealed interesting insights into the factors influencing people’s decision to choose retrofitting. 

Less than a quarter (21.7 percent) of the respondents prioritised energy bill savings, 12.3 percent relied on government rebates and incentives, and only 11 percent were motivated by environmental benefits. A majority of the participants reported being influenced by a combination of these factors. 

Energy efficient residential building: before and after

Most residential dwellings can be retrofitted with energy efficient appliances.

Several business models can help address these barriers. These include Public-Private Partnerships (PPP) which enable collaboration between governments and private firms for large-scale retrofitting projects; green building rating-based incentives that link financial benefits to existing building ratings and certifications; government grants, subsidies, tax rebates, and low-interest loans which can make retrofitting more affordable; and community-level retrofit models which lower costs by allowing multiple buildings to upgrade together.

Training and knowledge dissemination on the benefits of retrofitting and practical implementation methods can also enhance adoption and effectiveness. A mix of financial mechanisms, policy support and market-driven strategies, along with collaboration among governments, financial institutions and industry is essential to unlocking retrofitting’s full potential for a sustainable future. 

To encourage the adoption of retrofitting existing buildings for energy efficiency, BEE, The Energy and Resources Institute (TERI) and Pledge4Earth, a research and advisory organisation, have developed the ‘Energy-Efficient Retrofit Manuals: Transforming Existing Buildings’. The document serves as a guide to understand suitable retrofitting options for buildings in terms of cost and potential savings. It contains exhaustive energy conservation measures and a robust framework for integrating modern energy-efficient technologies while addressing structural and operational challenges. 

The guidelines also include industry best practices and technological innovations, and provide practical and actionable guidance for enhancing building energy performance across diverse climatic zones. As part of the project, training and knowledge dissemination programs have also been conducted for various urban local bodies, residents’ welfare associations, commercial building owners, operators, engineers and industry professionals. Such programs help raise awareness about energy-efficient building practices, and support India’s goal of reducing emission intensity by 45 percent by 2030, and achieving net-zero emission target by 2070.

Rapid urbanization, increased floor area and higher air-conditioning demand drive electricity consumption and GHG emissions. Retrofitting of existing buildings offers an opportunity to reduce energy demand and enhance the sustainability of the building sector. 

This article was jointly commissioned by TERI (The Energy And Resources Institute),  GRIHA (Green Rating for Integrated Habitat  Assessment) Council, and 360info.

Prajna Aigal is an Associate Fellow in the Sustainable Buildings Division at TERI. Swetha A B is a Research Associate in the Sustainable Buildings Division at TERI. Sanjay Seth is a Senior Director at TERI and the Vice President and CEO of the GRIHA Council.

Originally published under Creative Commons by 360info™.

(Cover Photo: The office of Malaysia’s Energy Commission, also known as the Diamond Building, is a showcase of technologies that reduce building energy consumption and potable water usage, promote the use of sustainable building material and provide enhanced indoor environmental quality. Photo by CEphoto, Uwe Aranas/Wikimedia Commons, Credits CC-BY-SA-3.0)

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