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



Introduction: Fundamentals of Indoor Environmental Quality (IEQ)
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IEQ is defined as: a perceived indoor experience about the building indoor environment that includes aspects of design, analysis, and operation of energy efficient, healthy, and comfortable buildings. Fields of specialization include architecture, HVAC design, thermal comfort, indoor air quality (IAQ), lighting, acoustics, and control systems. Note that air quality is not and should not be used as proxy for IEQ, it is only one of six concerns and a flaw in any one or more will be perceived as a flaw by the occupants.

Thermal Comfort

This section on thermal comfort is based on the work of:
David Scheatzle, Ph.D., Arizona State University, Andrew Marsh, Ph.D., Welsh School of Architecture and Square One Research, Ole Fanger, Ph.D. with Bjarne Olesen, Ph.D., both of the Danish Technical University, Fred Rohles Jr., Ph.D., Kansas State University, Gary Settles, Ph.D. of  Penn State University and Dwayne Suter, Ph.D., (Ret.)Texas A&M. We are grateful for their contributions to building science and human comfort.

(Please see our list of additional resources, references and contributors)

It is our hope that these next pages will find their way into every architect, interior and mechanical designers hands and to every consumer, trades person and distributor of HVAC equipment; please understand that Architecture and HVAC is not about conditioning buildings, its about conditioning people.

Note : These pages are best viewed in high resolution 1400 x 1050 format with high speed performance web servers

Section 2:  What is Thermal Comfort?

Thermal comfort is one of six key metrics within indoor environmental quality and is defined by building scientists and healthcare professionals as, "that condition of mind that expresses satisfaction with the thermal environment." (see Indoor Air Quality)

In other words, comfort is not a piece of equipment like a furnace or air conditioner as manufacturers would have you believe, and it is not something we create for the sake of an inanimate building.

If you follow along with this reasoning, then would you agree that for us humans to really understand comfort we should have (paraphrasing Jonas Salk) some rudimentary understanding of how our mind gets information from our architectural settings? If this makes sense to you, then it probably make sense that we should try to understand how our environments influence our bodies. Agree?

I think we can also agree with this excerpt from ANSI/ASHRAE Standard 55, Thermal Environmental Conditions for Human Occupancy which states, "there are large variations, both physiologically and psychologically, from person to person, it is difficult to satisfy everyone in a space. The environmental conditions required for comfort are not the same for everyone."

In fact, we know most folks only voice a negative observation when they experience discomfort as opposed to expressing satisfaction when they are in the absence of discomfort ('..caused by an unwanted cooling (or heating) of the whole or one particular part of the body.'). So the objective in architectural and mechanical design is to create an environment acceptable by a certain percentage of the occupants.

To accomplish this we must study human physiology.

Radiant based HVAC Systems

Architectural Guide to Radiant Based HVAC Systems shows the relationships between building and mechanical components for cold weather environments.

Click here to visit Human Physiology 1

"The absence or presence of heat is one of the primary environmental factors affecting human comfort. We pay enormous attention to the five main sensory organs in our bodies, yet often overlook our true sixth sense, thermal sensitivity."
A. Marsh, Ph D, B. Arch. (Hon)

Suggested Reading:

New Pages
Indoor Air Quality
Design for Aging We must start conditioning people not buildings...




Thermal Comfort Surveys

Learn why indoor air quality is treated separately from indoor comfort quality.

" is about meeting real human needs and not just creating attractive or dramatic surroundings."
Anita Baltimore, FASID
ASID President

Suggested Reading

Cortical, thalamic, and hypothalamic responses to
cooling and warming the skin in awake humans

Egan, Johnson, Farrell et al

Research on the Origins of Thermal Comfort
Orosa, J.A., European Journal of Scientific Research,  Vol.34 No.4 (2009), pp.561-567

Designing for comfort requires integrated knowledge of architecture, interior design, mechanical systems and human physiology...most building and HVAC contractors don't learn this stuff in school or on the jobsite, but are expected unrealistically to meet your physiological needs and wants for indoor environmental quality based predominantly on the skills of assembling building components.

This is the #1 reason why over 50% of occupants are unsatisfied with their thermal environments.


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