Thermal control in public buildings with low energy consumption

Evaporative cooling effectively controls ingress heat in a public building, even by circulating water through them or keeping walls wet. Shading also is a way of cooling the structures.

Thermally efficient structures ingress implies heat entering from the outside as a result of construction, which allows less heat to enter because of how the architect designs or designs. Vikram Murthy talks about thermal structure buildings in India and abroad, detailing instances and methods of cooling for different buildings.

Energy consumption in India 

There are numerous examples in India. As a country, we have at least five different climate zones: hot and dry, warm and humid along the coast, and composite and cool weather. Also, we are the third largest producer of electricity. Despite our large population, our per capita electricity use is low, but we produce enormous amounts of electricity – a large portion of which is used for cooling. We generate around 1600 terawatt hours of electricity in a year. (A terawatt is one quadrillion of a watt, one followed by 12 zeros. This power is increasing by 10- 15 percent per year.) There is an urgent need to act. Four years ago, we needed less than 35 terawatt hours. By 2038, 16 years from now, we will need four or five times that amount.

Public or commercial buildings make up only 30 percent of the air conditioning installed. The other 70 percent is residential, whereas commercial and public buildings work is ten percent. On multiplying hours by cooling energy, it was found that public buildings consume more energy. Commercial buildings consume much more energy than residential buildings, as per the ‘India Cooling Action Plan’ source.

Radiant cooling is another popular method. The cooling is done for the roof, the floor or the walls with pipes buried in the ceiling or the floor that circulate cool water. Hence, as radiation removes body heat, there is no need for a fan or anything. It’s a great way to cool down, as the cooling is limited to where the person is. And this is increasingly being used in public and private buildings. Infosys, for example, is not a public space, but radiant cooling is being used extensively in Mysore and Hyderabad offices to reduce loads by 35 percent.

Displacement ventilation 

The Mumbai International Terminal was designed by Skidmore, Owings & Merrill, a well-known Chicago architectural firm. The beauty of this building is that it easily admits natural light and has very open spaces. Outside, it has excellent natural shading due to its design. Its ventilation systems are designed to throw air at a low level. The entire space needs to be cooled. The cooling is done only up to eight or ten feet above the ground because that is where the people are. Most airports in India are cooled from a lower level rather than cooling air from the top. As a result, this is an excellent way to save energy in public spaces.

Underfloor air conditioning, similar to displacement cooling, is yet another option. This also gives us better control over cooling spaces. Chilled beams are a more modern way of cooling that quietly removes all the sensible heat and is ideal for large spaces.

And if there is a higher humidity load, it can be removed with a separate duct system. There are various ways the adsorption chiller is made by Bry-Air, which uses desiccant and vapour pressure differences to cool water down to seven degrees. It does not require electrical energy. It requires warm water at 360c, which can be obtained using waste heat or solar thermal. In America, machines weighing up to 300-400 tons are produced, even bigger ones. This speaks of a future method of cooling public buildings. It may have higher capital costs but has no operating cost if powered by solar.

Managing heat ingress One of the most challenging tasks in managing heat ingress or a building’s behaviour is peak drying. As a result, these studies are critical in controlling public buildings. The palaces in the past allowed many citizens to visit the palace on certain days. This palace is cooled by evaporative cooling; there is a large reservoir at a great height, and the water comes in and flows out of the small jets as a fountain, cooling the entire structure.

While it is 43 degrees in Rajasthan, Bharatpur is as cool as 22.5 degrees, which is the wet bulb temperature and is naturally cool. The Taj Mahal, frequently visited by the general public throughout the year, is a public place. It is cold because of the Yamuna River. In the winter, it acts as a thermal ingress to cool the entire base of the Taj Mahal, which is very large and extends deep into the ground. Apart from that, the Taj is also cool because of ventilation and its architectural design to admit high velocity air.

Thermal Efficient Structures abroad By definition, public buildings or utilities are occupied by anyone and everyone. These are typically larger areas. They can also be used for long or short periods. They should be easily accessible and comfortable. For instance, a church in the Netherlands has been beautifully converted into a public library. A church is naturally comfortable because its walls are thick, and it admits or allows less heat into the building. The air conditioning load is then significantly reduced.

Another example is a museum in China, constructed with very thick walls and tiny window slits to allow light into the appropriate areas. As a result, it is naturally comfortable inside. And those who come inside want to stay longer to see the museum’s exhibits. This structure is also more comfortable because it requires less cooling.Yet another example is a large structure with modern art-inspired shade, similar to a large tent. As a result, it significantly reduces solar radiation from the sun and adds an architectural feature to the building. As a result, it has been cooled by an architectural process. Because of this, we get excellent protection from solar radiation for many parts of the day, from noon to 3 p.m.

Another structure is in Brooklyn, New York. This appears to be a converted roof into a garden. But it’s a cool roof because the garden protects from heat. It also adds some natural beauty. And it gives the public a grand appearance when they visit and watch this building. So shading is an important consideration. 

Evaporative cooling structures 

There is a library in Seattle, Washington, located on the coast of the United States. It has a relatively mild climate; it does not get very hot or cold. At times, a building becomes very hot due to its abundance of glass, but to prevent heat, orientation and the angles of the glass should be focused. An architect designed the angle of the shade. The glasses are reflective surfaces that make them look very shiny. They reflect the sun away, and a lovely pool surrounds them. As a result, evaporation occurs with natural cooling, and it admits light, but only in a minimal way. Evaporative cooling is an excellent way to control ingressive heat in a public building. 

Finally, our collective lament is not the stiflingly hot day in May or people constructing glass and steel towers. Only a few people are protected in air-conditioned offices and homes. Those who can afford to are comfortable. However, the problem is not just that. The big problem is that the Wet Bulb’ is rising worldwide. When the wet bulb is low, body heat can be removed more quickly. If the wet bulb temperature rises above 30, we will die, and this is happening because the ground is no longer having moisture. Social cost is high, and we must wake up; hence, taking care of public utilities is necessary