Structure Cooling by Oorja Energy Eng'g
ACs cool air in the building & do not cool the biggest source of indoor heat - building structure. Cool the structure, it will cool the rest
With a rapidly growing economy, India is going to add 5 times the current stock of buildings in next 15 years. There is going to be exponential rise in the air conditioning requirement to cooling these buildings from the current low penetration level of 6%. So, if we are to cool our buildings in an energy efficient way and not massively increase the need for power generation plants, we cannot ape the old energy guzzling ways of cooling buildings and need to find new ways that provide significant jump in efficiency to cool our buildings.
Oorja's structure cooling provides just that. Oorja's structure cooling solution offers an energy efficient way to cool building spaces without air conditioning. In tropical countries, the building thermal mass accumulates a lot of heat during the day and is not able to purge the heat in the night as the night temperatures are also high. Due to this accumulated heat, the operative temperatures in unconditioned buildings remain above 40 deg C even after sunset, during peak summer in most cities in India. Building almost behaves like a large oven whose inner heated surfaces re-radiate heat to indoors creating a need for cooling. In winters, the same surface is at a lower temperature, thus requiring no air conditioning. Oorja has done different simulation and thermographic studies to validate the same.
Structure cooling removes this heat continuously and does not allow the heat to build up in the structural mass. A network of pipes is embedded in the structure during its construction and water is circulated to remove heat trapped and accumulated in the building structure. Water is then cooled using a 2-stage cooling tower.
Structure cooling can provide comfortable indoors with just a fan and natural ventilation can also be enjoyed instead of closing all doors and windows.
Oorja's solution uses less than 0.05 KW per ton of cooling compared to 1.2 KW per ton used by air conditioner! This provides massive savings for cooling our indoors.
Is this proposal for a practice or a project?
What actions do you propose?
During the construction of the building itself, we lay the network of pipes depending on the sensible heat that needs to be addressed using this system. These pipes are specially grade pipes and have to be laid very precisely in accordance with the heat loads. Also, the network of pipes is carefully planned to have multiple smaller pipes each individually attached to a manifold. This maximizes the cooling factor and also gives much more control and flexibility. The system is thoroughly tested after being laid. Only after all the tests are successfully completed, concrete is poured to cover the pipes.
The water circulated in the system, is run through a 2-stage cooling tower. The water is cooled in 2 stages. In dry conditions, 2-stage cooling tower can bring the temperature of water under the wet bulb temperature of the water. Single stage cooling towers can deliver water temperature above wet bulb temperature. This water is then circulated through the system to cool the structure.
Oorja wants work with industry bodies, green building consultants and the government to popularize Structure Cooling in tropical countries. Structure cooling allows heat at different grades to be treated with different temperatures. By identifying the high temperature of the trapped heat and using higher temperature water (20-25 deg C) to flush this heat, structure cooling avoids the usage of low temperature water (7 deg C) that is currently used by the HVAC systems. 7 deg C water is produced using refrigeration equipment. By cooling tower, Structure Cooling eliminates the need for refrigeration equipment and harmful refrigerants. The water used by the cooling tower can be treated waste water from the buildings.
We would like to bring this technology under the National Cooling Action Plan initiated by Govt. of India and also work with other governments to bring a change in the way our buildings are cooled.
For buildings requiring lower space temperatures, air conditioning system can be installed along with Structure Cooling. Implementing Structure Cooling can significantly reduce the size of the air conditioning system by 30-70% depending on the building type and location.
Who will take these actions?
Oorja is already working with various influencers in the building sector to promote structure cooling and have a few projects that are under execution. The key actors we are working with are:
1. Architects - to create awareness about this technology as this needs to be considered from the design stage itself.
2. HVAC designers & Green Building professionals - We are working with the industry body of the HVAC professionals and different building rating agencies in India. Would like to work with similar bodies in other countries.
3. Government - Need to work with Govt. of India to include this in their National Cooling Action Plan that aims to reduce the energy required for cooling the buildings. We would like to get involved in similar actions by other governments.
4. Real Estate Developers - We are in discussions with a few real estate developers to include this technology in their buildings so that the practice of installing individual AC units can be stopped. This offers capital cost benefit to the developer and operational cost benefits to the residents.
Where will these actions be taken?
We will be taking up these projects in India. Ideally building spaces over 50000 sq ft are the best fit for the economics.
In addition, specify the country or countries where these actions will be taken.
What impact will these actions have on greenhouse gas emissions and/or adapting to climate change?
This technology will have a huge environmental, social and health impact.
Environment Impact: Coal based power generation plants use tremendous amount of ground water and are one of the biggest reasons of lowering of ground water levels at many places. Also, these power plants are based on fossils which also cause tremendous amount of environmental pollution. As more and more buildings are going to come in the future, we can not depend on having more and more power plants. Almost for every gram of coal burnt, 4grams of CO2 is released.
Coal plants are responsible for more than 40 percent of mercury emissions, millions of tons of SO2 (sulphur dioxide), Nitrous oxide, millions of tons of coal ash, lead, and many other harmful substances.
The released hot water used in the power plants can also adversely effect the flora and fauna of the area near the water source typcially a river or lake.
Oorja Solution: Our solution will be able to reduce the GHG emissions by at least 40 million tons
Health Impact: Coal based power plants have many adverse effects on the health of people around, apart from the flora and fauna. Also, ACs causes many air borne diseases when its centralized.
Oorja Solution: Our solution offer a much natural ventilation and flow of air which doesn't aid in air borne diseases. Also as there are not emissions coming out, there are no health risks.
Social Impact: As more are more buildings are coming and the demand for cooling is growing exponentially, there is also a trend of coal based power plants closing and no newer plants coming up. If this trend continues, it will have a impact on the social economic behaviour of the people effected.
What are other key benefits?
Buildings account for 35% of the energy produced and almost 40% of the CO2 emissions. And out of all the energy that is used in a building, 65% is used for Heating and Cooling purposes. This is a massive amount of energy that is utilized for one purpose. As this need keeps on growing, we need more power plants need to be added to satiate the demand for cooling. In India, majority of the power is generated by coal power plants and this will create significant environmental hazard.
Our solution can be easily integrated for either providing cooling or heating to the building. At a global scale, this will have millions of tons of CO2 emissions reduced and will use a more energy efficient natural means for heating/cooling purposes.
What are the proposal’s projected costs?
For a total of 50000 sq ft, each sq ft cost comes to about $4-$5 depending on the sensible load of the area. With saving of over 70-80% on operational cost, the initial expense can easily be recovered within an year or two.
In the next 10 yrs, our impact just from our efforts will be close to 40million tons of CO2 emissions. With just our organization in the next 15yrs, we plan to be responsible in reducing the GHG emissions of any new buildings over 50000 sq ft in India by atleast 5% of the total emissions across the country.
About the author(s)
PRADEEP RAPOLE, Head – Sales & Marketing. 17yrs of working with multinationals like Microsoft, Amazon
MADHUSUDHAN RAO, Managing Director. Mech Engg, MBA, 18 years as entrepreneur, 3rd Venture