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


"As warm-blooded mammals, humans produce energy by metabolising food, with most of this energy taking the form of heat. This metabolic heat is produced by the body all the time, mainly as a result of muscular activity, although almost all bodily functions produce some heat. In general the more active we are, the more heat we produce."
Dr Andrew Marsh

"There is no normal temperature but a range over which temperature fluctuates and changes."
Dr. Tim Lowenstein


Human Physiology 3 - The body's thermoregulatory system
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The human body wanders through its environment constantly sensing everything including light, humidity, temperature and pressures.

Our external sensors are grouped this way:

Mechanoreception–pressure or touch (tactile sensitivity)

Thermoreception-temperature (thermal sensitivity)

Nociception-noxious (damaging or potentially damaging) stimuli (noxious sensitivity)


As noted by Maged N. Kamel, M.D.1, "Receptors for warmth and cold are specialized free nerve endings (see item 2 below in Figure 1); a rise in skin temperature above body temperature causes a sensation of warmth, while a fall in skin temperature below body temperature is experienced as cold sensation; pain is felt if skin temperature increases above 45 C or decreases below 10 C; the mucous membrane of the mouth is less sensitive than the skin, thus tea can be drunk at a temperature which is painful to fingers"

Skin sensors measure radiant heat loss

Figure 1, Skin Sensors with free nerve endings serving as thermal receptors.2

The Body's Release of Heat

Figure 2. Animation of vasodilatation (increase in blood flow) and sweating (skin wettedness)4

The heat released within the body warms the blood which circulates to all body tissues, keeping them at the homeostatic temperature. The body temperature is a result of the balance between heat production and heat loss.. The hypothalamus is the body's thermostat. Located in the brain, the hypothalamus continuously regulates the body's temperature, using the nervous system's pathways, to a constant setpoint of around 37.7C (98.6F).4

Increase Heat Loss

The body must be protected from excessively high temperatures. Heat loss from the skin surface occurs mostly from radiation or evaporation (Figure 3). As the body's temperature increases above what is desirable, the warm blood comes to the skin via dilated blood vessels and the capillary beds in the skin become flushed with the warm blood. The result is heat radiating from the skin surface.4

Click here to visit Human Physiology 4

1. Copyright (c) Maged N. Kamel, M.D., Anatomy of the Skin

2. 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

3. Copyright (c) 2005, The Sourcebook of Medical Illustration, P. Cull, ed., The Parthenon Publishing Group, 1989, used for educational purposes under the terms listed by the University of Minnesota.

4. Copyright (c) 2005, Arizona State University, All Rights Reserved, Republished by with restricted permission from ASU.

Additional Resource: logo




University of California eScholarship Repository
The skin’s role in human thermoregulation and comfort E. ARENS and H. ZHANG, University of California, Berkeley, USA

The Body's Release of Heat have been lent to us by David Scheatzle, Ph.D
and the team at the College of Architecture and Environmental Design

Copyright (c) Arizona Board of Regents 2002, All Rights Reserved


A must read excerpt from

The School for Blind Children Insights

Children’s Garden To Delight The Senses will envelop the senses, stretch the body, tickle the imagination and provide a place in the sun for relaxation and respite.

Hear the sounds of a waterfall and enjoy the fragrances of earth, flowers and bushes. Touch the flowers set out in raised planters...

Wind your way up a little
hill and through a maze, feeling the path below, touching the walls, learning to trust your sense of direction. Step into the shade. Feel the breeze in the tall grasses. Sit down for a snack and raise your face to the sun.

...selecting plants, grasses, and bushes based on their sensory qualities...children will be attracted to the
rustling of leaves and pods, the scent of jasmine, herbs and berries, and the textures of ornamental grasses, lamb’s ears, burning bush and oriental arborvitae.

RB's comments:

..another WOW moment in my life came after reading this stuff...its beautiful and it's summed up by art teacher Carol Kreiser theme of...

“Inside Your Head.”

Students decorated the
outsides of the boxes
to represent themselves.

A WOW idea...

The North American HVAC Industry needs to hire people who are visually challenged to create spaces not just for the blind but those of us who take for granted our abilities

...just because we can see doesn't mean we should forget how to feel, hear and smell.

A must read interview
Beyond Appearances - Architecture and the Senses



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