Anil Ahuja, President
Much like the human body, buildings and cities have intricate systems that keep them running. Several principal elements of building systems are comparable to body system’s blood composition is similar to air quality in building systems, blood pressure is similar to pumping pressure in buildings, and body temperature control is similar to building temperature control.
Blood composition, blood pressure, and body temperature control are all regulated by adjusting other items in the body such as cardiac output, the resistance of the vessels during microcirculation, and the relative apportionment of blood to the various organs. Similarly, buildings are regulated by adjusting control output, the friction of pipes, and the relative apportionment of power.
Human Respiratory vs. Building Air Systems
Respiration in humans involves two related processes. The direct exchange of gases between environment and organism is called breathing or ventilation, and this exchange in the body involves oxygen transfer from the respiratory system to the blood, which carries oxygen to every cell of the body in exchange for carbon dioxide. The carbon dioxide is then carried back to the respiratory system, where it is exchanged for more oxygen. In the respiratory systems of buildings, oxygen is transferred from the atmosphere to the air circulatory system which supplies oxygen to all internal spaces and exchanges it for carbon dioxide. The carbon dioxide is then carried back to the air handler where it is exchanged for more fresh air.
As you can see, the human air filtering and conditioning system has unique similarities with building air systems. Air first enters the respiratory tree through the nostrils, where projecting hairs filter out dust and debris. The air then enters the nasal cavity, where mucus film traps debris. Beneath the nasal epithelium is a rich network of blood vessels that help to warm the air as it eddies about in the nasal cavity. The sinuses form a complex labyrinth of passages that further assist in filtering, warming, and moisturizing the incoming air.
Warmed, humidified, and scoured of dust and small particles, the air passes from the nasal cavity to the throat then to the voice box through a slit-like opening, the glottis. The glottis acts like a damper, remaining open at all times except when we swallow, just like a damper in an air handling unit remains open at all times except when air is bypassed.
Human beings take 410 million breaths a year, equivalent to a fan running constantly at 15 revolutions per minute. Any number of things may go wrong when air moves from the nose to the lungs, but if nothing goes wrong, the respiratory systems functions reliably. To increase the reliability of building environmental systems, one only needs to study methods of reliable human respiratory systems.
Human Circulatory vs. Building Hydraulic Systems
The human heart is indispensable to the body’s very existence. The heart pumps blood, oxygen, and food to every cell of the body, and by return circuit of the bloodstream, cellular wastes and carbon dioxide are removed. The human heart has an energy demand that varies with its workload, similar to the energy demand of a buildings hydraulic system. For example, the heart of an individual with a higher BMI (body mass index) requires more energy to operate than that of a person with a normal BMI. It is estimated that for every pound of fat in the human body, blood vessels are required to pump three extra miles. Similarly large building systems require more pumping, and more energy.
Both the mechanical integrity of the body’s circulatory system and proper exchange across capillary walls require that the pressure of the circulating fluid be kept within reasonable limits. Average blood pressure is determined by two factors: how hard the heart is pumping and the overall resistance of the microcirculatory vessels. A change of circumstance may lead to an increase in the resistance of some, a decrease in others, and still leave others unchanged. In a buildings pumping system, a good flow control system works over a range of flows, temperatures, pressures, and loads. To optimize a buildings hydraulic system, its crucial to place the sensor where control needs to be most effective and where alterations in the controlled variable are least tolerable.
Body Temperature vs. Building Temperature Controls
Our bodies strive to maintain a nearly constant core temperature for our vital organs at all costs. This protected zone takes thermal precedent over the less vital zone of our extremities. Similarly, buildings are frequently thermally zoned, and users (paralleling human blood flow) can retreat from or advance to the less-protected zones as conditions demand.
The presence of temperature sensors in the skin is obvious to us all. When we are cold, our bodies increase heat production by shivering and non-directed increases in metabolic rate. The opposite occurs when we are hot: blood flow toward the skin surface increases and sweat glands greatly increase their secretion of water and salt to the skins surface in an attempt to cool the body.
Human Body System vs. Building System Automations
The body receives messages from both its own organs and the external world. We perceive light, sound, odors, pressure, temperature, chemicals, and the like. We think, we move, we have unconscious thoughts and conscious ones. The normal functioning of the body depends both on the receipt of stimuli and the production of integrated responses. For the body to perform its activities in coordinated fashion, there must be a connecting link between stimulus and response, between receptor organ and effector organ and that link must be a system capable of channeling information from one to the other.
Two systems in our bodies act as coordinating links between stimulus and response: the endocrine system and the nervous system. The endocrine system regulates the activities of cells through hormones. The hormonal system slowly communicates on a long-term basis, similar to time delay control action in building logic control. The nervous system, on the other hand, rapidly communicates between the various tissues and organs of the body. The nervous system employs electrochemical messages, known as nerve impulses, that run along specialized nerve pathways receiving and transmitting information to and from various organs. Nerve cells, or neurons, are fundamental units of the nervous system, specialized to conduct electrochemical messages at high speed. Building systems communication protocols are based on neuron chips on the same guidelines popularly known as LON (Local Operating Network). Neurons, when bundled together in a cable-like fashion, form as nerves regulating the direction in which information flows just like in buildings.
In short, the body’s organs are integrated to produce organ systems. Unlike most building systems that are not smart or optimized, body systems are highly organized. To maintain this order, energy must be fed into the body’s system. All living cells depend on the release and use of energy for the maintenance and operation of the living state, just like building systems. Smart buildings transform all forms of energies that surround it, like wind, solar, geothermal and feed from smart grid. By being aware of and integrating these best practices from the human body systems, smart cities can achieve the most efficient building systems.
Anil Ahuja is a seasoned engineering professional and author of the recently released book Integration of Nature and Technology for Smart Cities, which explores trends and paradigms in the smart building and smart city sectors, and offers a new approach to green, innovative building and city design.
Having experienced what it was like to live in a refugee camp in India and grow up with limited resources such as power, water and food, Ahuja has dedicated his life’s work to sustainability and leading a movement to design cities and systems that are sustainable to protect the earth and the people who live on it.
Ahuja has more than 30 years of experience in sustainable building systems design, including the past 14 years as president of CCJM, a multi-disciplinary engineering firm providing infrastructure solutions to Smart Cities and Smart Building designs. He is a frequent speaker and contributor on the topics of holistic smart city development, re-engineering existing urban systems and sustainable infrastructure.