Online educational resource on achieving indoor environmental quality with radiant based HVAC systems
Not for profit educational resource on indoor environmental quality.
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Fundamentals of indoor environmental quality / thermal comfort and air quality solutions using radiant based HVAC

Human Physiology 1
Human Physiology 2
Human Physiology 3
Human Physiology 4
Human Physiology 5


"...the Academy of Neuroscience for Architecture came to be when Jonas Salk had stimulated Norman Koonce and Syl Damianos [then president and chairman of the American Architectural Foundation, respectively] to get someone to explore the brain’s role in how architecture affects human experience. What Salk said was...
Architects should have a better understanding of human experience with architectural settings.”
Academy of Neuroscience
for Architecture

"We can detect temperature changes of 0.01 C in the hypothalamus where body temperature is controlled"
Professor David Hanes
Sonoma State University

The vast majority of building and mechanical contractors believe that the HVAC systems is about making sure the building is warm and comfortable...but it isn' is about making sure that the tiny area in the hypothalamus is satisfied.

We need to stop focusing on the big building and start focusing on the tiny hypothalamus.

Wikipedia Definitions





Metabolic Rate

"Complex systems, such as a human body, must have homeostasis to maintain stability and to survive. These systems do not only have to endure to survive; they must adapt themselves and evolve to modifications of the environment."

"We don't have words for high-quality space. We don't have words for anything other than quantities. Realtors have a real challenge on their hands because if they're trying to say, 'This is a cool house,' they have to use words like spacious, and if you can say high ceilings, it sounds better. Or cathedral ceiling-that sounds pretty cool. But when you say cozy, it's a euphemism for too small. And there is nothing in-between. So what I am trying to do is develop some words that help people to understand that there is more to a house than just size."
Sarah Susanka, Architect 

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Human Physiology 5, Your Brain - Your Thermostat, Part II
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Review: How does it all work? ( do you 'work' in sensing comfort).

The sensors in your skin are part of the nervous system. Information about temperature, pressure, and humidity picked up at the sensors and sent to your brain through the nerve fibers up into the spinal cord passing through the thalamus to your cerebral cortex.

Thermal Comfort Sensors

This is an illustration1of all the skin "comfort" sensors in your body which ultimately have to be satisfied by the environment created by the architectural/mechanical systems. It doesn't matter if you are standing on a cold floor (conductive heat loss) or next to a cold window or wall (radiative heat loss) your sensors pick up the loss of energy and your brain says..."hey...I'm cool, cold ..maybe darn right miserable!"

It is the very essence of why we say we are not in the business of conditioning buildings, rather we are in the business of conditioning people.

The thalamus acts as a gatekeeper for messages passing through the spinal cord into the cerebral hemispheres.

Your Brain - Your Thermostat

This is an illustration1 of the spinal cord carrying thermal information (left side) as it enters the thalamus (right side). Note the similarities between this and the wiring of an HVAC system...the body is a great metaphor for designing radiant based HVAC systems. Click graphic for a larger image.

The pea-sized hypothalamus regulates your body's temperature and is responsible for crucial urges — such as eating, sleeping and sexual behavior. It says..."if I'm hot - I need to sweat, if I'm cold - I need to shiver."

Your Internal Thermostat

This is an illustration1 of the hypothalamus and the parts which regulate body temperature. Click graphic for a larger image.


Extreme Heat

"If, due to an increased environmental temperature or metabolic rate, the body begins to heat up, a process called vasodilation is initiated in the hypothalamus. This involves the dilation of blood vessels near to the surface of the skin to increase its temperature. This leads to increased radiant and convective heat loss.

If the body temperature is still increasing, the sweat glands are activated to produce moisture on the skin surface. When this moisture evaporates, latent heat of vaporisation is drawn from both the surrounding environment and the skin. As sweat flows directly onto the surface of the skin, conduction from circulating blood immediately beneath forms one of the most significant components. Sweat can be produced at up to four litres per hour for short periods and is supplemented by the evaporation of moisture from within the lungs and respiratory tracts.

If heat build up continues, hyperthermia sets in and heat stroke may develop. This occurs when deep-body temperature reaches about 40 deg C and can cause fatigue, headache, nausea, shortness of breath and, in some cases, mental disturbances such as apathy, poor judgment and irritability. After heat stroke is developed, sweating stops, rapidly increasing body temperature until serious brain damage results in coma and imminent death.

Extreme Cold

In cold conditions the body’s first response to heat loss is vasoconstriction. This involves the contraction of blood vessels near to the surface of the skin, increasing its insulative value and reducing heat loss. If heat loss continues, blood supply to extremities such as fingers and toes may be cut off completely before deep-body temperature is affected. If these extremities subsequently freeze, this is known as frostbite and often results in their loss.

Vasoconstriction is often accompanied by the erection of hair follicles (also known as goose pimples or pilo-erection) which, if enough matted hair were present, would greatly increase its insulation potential. With even greater heat loss, shivering is initiated. This is simply involuntary spasms within certain muscle groups designed to increase metabolic heat production.

When deep-body temperature falls below 95 deg F (35 deg C), hypothermia sets in. Metabolic controls cease to function and body cooling is increased. In some extreme cases, where body cooling occurred very quickly, individuals have survived long periods of almost suspended animation. If body cooling occurs at slower rates, death results at a temperature of between 77 deg F (25 deg C) and 86 deg F (30 deg C)."

Copyright (c) Dr Andrew Marsh, Square One Research PTY LTD  and the Welsh School of Architecture

Click here to visit the Conclusion of Human Physiology

1. Copyright (c) 2005, GIUNTI PUBLISHING GROUP, Via Dante, 4, 20121, MILANO , All Rights Reserved, Republished by with restricted permission from GIUNTI PUBLISHING GROUP, Atlas of Anatomy


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