Low Energy Thermal Comfort strategy


“Spare a watt. Save a Lot. It takes energy to produce Energy”
Post industrial revolution, energy is one of the quintessential need for human existence. The demand for energy has risen into many folds to meet the requirement of the present population of 130 billion in the world. Its usage spreads across various sectors like industry, commercial & public service, residential, transport, etc., which are among the top consumers of the generated electricity. As per the latest statistics provided by IEA, the total power generated in the world is approximately 25,500 TWh in which the contribution of fossil fuels is approximately 65% of the total generation while the generation through renewable sources is 30%. With raising population and urbanisation, the demand for energy also increases. This causes alarming rise in global warming challenges and carbon emission into the atmosphere. Increasing construction activities and cooling requirements have led to the development of modern low energy efficient strategies to provide thermal comfort in dwelling units.

Some technologies like evaporative cooling, solar air conditioning, radiant cooling, ground-source heat pumps, tri-generation systems, adiabatic cooling systems, etc. have proved to reduce energy consumption substantially. In order to reduce adverse effects globally (ozone depletion, increasing carbon emission and climate change issues) due to usage of refrigerants (CFC, HFC, HCFC), Ozone Depleting Substances (ODS), fossil fuels & non-renewable energy, international communities have joined together (attributed as the successful movement) to emphasise (a) power generation through renewable sources (b) phasing out of ozone depletion substances (c) alternative thermal comfort systems (c) green building and low embodied energy materials for construction. Other factors attributed to power transmission, distribution & storage losses have also been minimised substantially in the recent years enhancing the range of application.

These transformations have potential to meet goals of sustainable development and meet future energy generation and consumption demand. This brings up urban energy transformation. India’s population is approximately 130 crore and is the 3rd largest producer of electricity after China and USA. India mainly relies on thermal power plants for its energy generation. Presently, out of 1,400 TWh generated, approximately 78% of the total power generated is from fossil fuels and the contribution of Renewable Energy Sources (RES) is approximately 16%.

Out of various service sectors, commercial service, public service and residential sector consume the most electricity generated in the country, which is about 35-40% of the total generation. In this sector, the major demand is for providing human thermal comfort (HTC) (40-45%) and visual comfort & lighting (30-35%). It is estimated that by 2050, 60% of the total land will be constructed adding approximately 60 billion square meters of Built Up Area (BUA). This will raise the demand for power by 400%. Until 2022 it is estimated that, the need for energy will raise annually by 7.5% (CAGR). So the need for low energy and passive cooling technique should be prioritised. India has 5 different climatic zones as classified under Indian Meteorological Department (IMD) and these conditions demand different HTC strategies. In India, it is found that, the procurement of AC’s is estimated to be at 8% of the total houses through organized sectors.

The estimation of sales of coolers (direct evaporative cooler (DEC)) from the organised sector which is about 60% of the total market is approximately the same. The trend in consumption also has been surveyed. The DEC run during peak summer period (April-mid June) and during off summer (mid-June – Aug) AC’s run the most. This trend in usage pattern apart from scientific study (climatology and psychrometrics) about different strategy to provide HTC, also provides an insight and potential for alternative low energy cooling strategy. The most efficient air conditioning units in the markets possess 0.28 kW/kW and low energy comfort systems possess atleast 0.23kW/kW. The additional savings in energy can be catered to deficient sectors for improving per capita energy consumption (PEC).

This growth in PEC will lead to growth in economy and the decreasing trend in energy intensity can be maintained. Refrigerants used in the air-conditioning industry are among the contributors for increase in green-house gases (GHG’s) in the atmosphere and certain refrigerants have also been classified under Ozone Depleting Substances (ODS). Commonly used refrigerant based on the Vapour Compression Refrigeration (VCR) cycle are either of Chloroflouro carbon’s (CFC’s), Hydroflouro carbons’s (HFC’s) or Hydroflourochloro carbon’s (HCFC’s). Montreal protocol, is one such agreement that has brought many countries together to protect ozone layer by phasing out the production of substance, that are responsible for depletion of ozone layer. So in the near future, an alternative refrigerant has to be resourced for running our existing air conditioning systems.And in parallel, the global warming potential of the refrigerant has to be reduced. OR low energy comfort strategy integrated with state of the art electronics & communication and computer coding should be brought in to play a pivotal role in mitigating usage of higher and low cost global warming potential substances.

At Integrative Design Solutions Pvt Ltd, we engineers and architects work in synergy to bring about the quintessential changes focussing on the requirements for the future. The Low Energy Thermal Comfort strategy (LETs) is one such area, where we provide HTC solution with minimal/nil interference of refrigerant. The heart lies in heat transfer and the intelligent technology integration we have carried out in our systems. It regulates the operations for all climatic conditions throughout the year to provide HTC. We have made representations at national level competitions with our system and have created milestones setting new targets for betterment of the system. Modern technology, design and simulation tools are utilised to analyse the optimal performance of the product which indeed promises to reduce energy consumption and also provide adequate thermal comfort.


Contributed By: Abhilash K Prabhu


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