|
There is tension and
synergy between homeostasis and alliesthesia...the body
tries to default to balance when systems are disturbed
and when systems are disturb the body goes out of
balance. It is an interesting dance where scientific
arguments are made that exercising our sensory system
makes for healthier human systems much like athletic
training makes better athletes. In both cases there are
forms of stress and how that stress is perceived
psychologically should not be trivialized. For example
(ignoring nutrition and rest), the slaves forced to
build the pyramids and the Olympian both experience
physical, physiological and psychological exhaustion and
yet one is working towards death and the other is
training for life. One has had choices removed the other
is given free choice. Would love to hear your thoughts
on how this fits into the world or architecture and
indoor environmental ergonomics.
Adopting alliesthesia
principles often leads to expanding the general PMV/PPD
index and that could have a negative effect on the local
factor PPD. For example drifting the operative
temperature up or down for alliesthesia triggers a known
homeostatic response in T3/T4 hormone production, and
vasodilation /vasoconstriction. But drifting beyond the
current limits could also lead to increased radiant
asymmetry, temperature stratification, drafts and cold
floors. These metrics could have greater weighting in
perceived discomfort.
Since these local
discomforts are generally not directly measured and
controlled by the HVAC system their increasing intensity
during drift could potentially be perceived as
“sustained” which could lead to undesirable
physiological and psychological stress. Thus it would be
nice to know the genetic relationships between
alliesthesia and homeostasis; and at what stress level
does the undesirable production of cortisol, epinephrine
and norepinephrine kick in…hope that also finds a way
into someone’s study.
|
Health & Well-Being through Architecture,
Building Science & HVAC Design
Playing with Fire: Homeostasis and Alliesthesia
Considerations in Architecture, Building Science and HVAC Design
Copyright © 2015 Robert Bean, R.E.T.,
P.L.(Eng.) originally published for HeatSpring
Most people employed in the world of architecture,
building
science and
HVAC understand the need for spaces which are
thermally acceptable to the majority of occupants. But, as
repeatedly demonstrated from my informal research, it appears
the industry does not actually understand
the principles of thermal comfort.
Statistics obtained by polling industry audiences over the past
15 years across North America show 97% were unaware that
Standards exists for thermal comfort and of the 3% which are
aware only 1.5% own them and only 50% of them can actually
converse with understanding, the principles described within. As
such it remains a mystery to me that those who make a living
selling thermal comfort equipment or promoting thermal comfort
systems or designing thermally comfortable spaces do not know
what thermal comfort is. Consider we would never want mechanics
to work on our automobiles if they didn’t know about the
mechanics of cars. Nor would we want heart surgeons to operate
on our hearts if they didn’t know about hearts. It is strange
that society lets the construction industry practice “thermal
comfort” when the industry generally doesn’t know the principles
behind it. Clearly it’s a big topic, but let’s
continue by
introducing two human comfort factor terms of, “homeostasis” and
“alliesthesia” which practitioners ought to know when
considering occupants and the design of buildings.
By definition, homeostasis is the tendency of the body to seek
and maintain a condition of balance or equilibrium within its
internal environment, even when faced with external changes.
Figure 1. Homeostasis is the tendency of the body
to seek and maintain a condition of balance or equilibrium (A.)
within its internal environment. When disrupted (B.) the body's
systems will attempt to return to normal (A.).
Physiologically this, seeking to maintain equilibrium with the
environment, includes
vasodilatation and
vasoconstriction. “Vaso” is a blood vessel, “dilation” is to
open or have less restriction and "constriction" is to close or have
more restriction. This is how the body controls the flow of
blood and thus the distribution of body heat. For example,
to
shed thermal energy the body increases the flow of blood to the
skin which increases the skin surface temperature. An increase
in the skin surface temperature increases the potential for
radiant and
convective transfer to the surrounding environment.
If the architecture, building enclosure and HVAC system are of
poor function such that the surrounding surfaces and air
temperatures are near or higher than skin temperature then it
becomes more difficult for the body to
shed heat. When the body cannot cool itself, it triggers stress
responses which are psychologically and physiologically based.
To mitigate thermal stress responses in the human body, we have
universally defaulted to using electrical and thermal energy
derived from industrial processes (combustion) to condition our
non-industrial spaces. From this one simple example you get a
peek at the inside of “Integrated
Design” which sits at the crossroads of building science,
health science, hybrid HVAC systems, interior systems, and the
study of energy and energy efficiency.
 Alliesthesia
can be defined as the change to a sensory experience that can be
perceived as positive or negative. It applies to all senses
which help define the broader definition of indoor environmental
quality. Proponents of adaptive thermal comfort and naturally
ventilated spaces use alliesthesia to draw attention to the
benefits from exercising ones thermal regulatory systems.
Unfortunately, some who prescribe exclusively to this philosophy
of design, choose to ignore subjective thermal boundaries that
when breached can also cause psychological and physiological
stress responses in some individuals. Stress responses can also
be invoked with the “lack of control” or “inability to adapt”.
You may ask how this is possible in a space designed for
adaptation. Well, it’s a mistake to think that buildings
designed for adaptive comfort and natural ventilation equates
universally to equal distribution of authority over opening
windows or operation of space heaters or use of personal fans.
These spaces are not immune from failure if individuals lack the
authority to operate the building features, cannot thermally
adapt due to business or personal cultural practices or have
physical, physiological and psychological challenges. For these
individuals in these scenarios the conflict and resulting stress
is nothing more than extensions of the proverbial “thermostats
wars” in traditionally designed spaces.
So what are the consequences of stress due to thermal
conditions? Mortality and morbidity statistics from the world of
healthcare demonstrate the
dangers of overheated or under heated spaces especially amongst
the elderly population or those populations that have
limited control over their environments such as infants and the
infirm. These populations cannot always adapt physically,
physiologically and psychologically as such become victims of
bad buildings especially in the presence of climate changes of
consequence. Consider someone with arthritis or Parkinson’s
trying to open windows or put on or remove clothing? It’s easy
to promote “green” building strategies until one considers the
growing population of people who unintentionally can’t execute
on the principles.
But what about the general population? At what point and to what
intensity in the “normal” human body does infrequent, sporadic
or sustained thermal stress become harmful? Since the body
responds to stress in several ways including the release of
hormones cortisol, epinephrine and norepinephrine it would serve
us well to not trivialize that which we might not fully
understand. Consider the works of Dr. Christopher Wild at the
International Agency for Research on Cancer, World Health
Organization who coined the term “exposome” and industry
colleague Dr. Gary Miller from the, “The Human Exposome
Project”. Those involved in this study, believe that “the role
of our environment is underappreciated and are studying how the
environment influences our health, both in negative and positive
ways.” As noted by researchers, “We believe that pursuit of a
Human Exposome Project, similar to the Human Genome Project or
the BRAIN Initiative, will help reveal the importance of the
environment in our lives.”
Though we have an understanding of the relationship between
buildings and bodies it really is immature knowledge given
recent studies in the
epigenome and
microbiome. It is for this
reason I am pleased to talk about programs such as the WELL
Building Standard®. This Standard is “the world’s first building
standard focused exclusively on human health and wellness.” As
noted from its website, “It marries best practices in design and
construction with evidence-based medical and scientific research
– harnessing the built environment as a vehicle to support human
health and wellbeing.” This resonates with me and assures
students that our “boot
camp” for recent grads of building and mechanical
engineering and HVAC technology programs is a vital step in
connecting the various aspects found within integrated design. |
