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This page updated last on
February 08, 2010
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Energy Efficient Indoor Environmental
Quality Revolves around 75°F (24°C).
Bringing it all together - architecture,
energy and indoor environmental quality.
Copyright © Robert Bean, R.E.T., P.L.
(Eng.), All world rights reserved.
Ok we get it...the original graphic
contained too much info one page so we've broken it down
step by step...the 30 second
message is sustainability revolves around one
temperature...that being 75°F
or 24°C. When you
can design and construct high performance buildings
- everything will be within 25°F
(14°C) of 75°F(24°C)
including body temperatures, fluid temperatures,
discharge air temperatures etc...everything. |
Description: Shown above - on the x-axis (bottom line) are
heating and cooling fluxes (you might know them as heat losses
and heat gains). On the left hand side (y-axis, vertical)
are various
building enclosure performances from high [a] to poor [d] based on
the heating and cooling flux. How did we determine these
categories? Experience...we've been doing this for 30 years and
after doing thousands of designs this in our opinion how
buildings should be categorized (see overview of
housing performance categories in North America).
Description: Now added are the
surface and fluid temperatures. Make note that a poor performing
building designated as [d] has a heating flux equal or greater
to 40 Btu/hr· ft2
(shown on x-axis). At such high heat loss, it is common to use
fluid temperatures greater than 140°F, also shown on the x-axis.
Description: Make note of the close relationship
between human factors such as skin and core body temperature and
operating temperatures typical of high performance buildings.
Description: There is a significant increase in thermal efficacy
(how homogenous the distribution of heat) in good to high
performance buildings. Moderate to poor performing buildings
have poor thermal efficacy.
Description: The objective of sustainability is to stop using
combustion and compression for occupant conditioning, this is
possible with high performance buildings [category a] and
renewable energy such as geothermal and solar thermal. Homes
built to Passivehaus or R2000 standard are represented in this
category. Homes built to typical North American standards are
represented by the other categories [b], [c] and [d]. For
commercial buildings, [a] type buildings would beat ASHRAE 90.1
by 50% and fall inline with Architecture 2030 and LEED's Platinum EA credits.
Description: Note that the further one moves away from a high
performance buildings, not only does the efficacy and equipment
efficiency go down, but also there becomes a greater risk for
occupant and property damage due to the higher temperatures.
Description: When using high temperatures from combustion to
heat our buildings we are destroying the opportunity to make
better use of the fuel (see
exergy efficiency). For example in a high performance
building heated with radiant floor heating
low VOC flooring and
tight radiant tube spacing, we only need 75°F to 90°F
fluid temperatures even though we created 2800°F temperatures in
the furnace or boiler. At 2800°F we could and should be generating power and
heat - if society doesn't grasp this basic principle without a doubt
it will remain the biggest challenge we have
in
achieving sustainability.
Description: When we apply
human factor design principles, based on
skin and core temperatures of the human body, to buildings
we will naturally improve the indoor environment with more
efficient buildings and less greenhouse gas emissions whilst
preserving non renewable energy for future generations.
So now you know why we believe sustainable energy
efficient indoor environmental quality revolves around 75°F
(24°C).
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