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We spend a lot of time talking about indoor environmental quality in the modern building construction world. Most of the creatures on earth don’t live in buildings; they can only change their daily routines to deal with extreme weather. What are animals doing to regulate temperature and how could humans adapt these techniques for IEQ?
World Science Festival has a column on the topic of animals keeping cool. They point out a few effective, and sometimes odd, things that animals do. Koalas prefer to shed their heat by conduction. Specifically, tree hugging. Scientists noticed the koalas would get really clingy when the temperatures increased.
“The researchers eventually calculated that on a 95-degree day, hugging a tree in the shade could help a 25-pound koala lose up to 68 percent of its extra body heat — a good strategy to remember next time you’re sweating in a park this summer,” WSF notes.
Energy transfer via conduction is key for koalas. The trees are slowly pulling water from the ground, transpiring it up to the leaves and dissipating the heat through their leaves. The koalas are along for the Btu-transfer ride. They splay out on the trunks and cool down.
Humans can sweat and dissipate some energy via evaporation. Many animals don’t have that capability and have to apply their own sweat, essentially. Pigs are one of many examples of animals looking for mud to roll in to cool themselves when the water evaporates, since they don’t produce their own sweat.
Kangaroos have a different approach. They will lick their forearms, maybe because finding a pit of mud in the Australian summers is a tall task. The evaporating saliva cools them down because they have a lot of blood vessels in their wrists.
Surface area is key for heat dissipation. Elephants have big heat sinks on the sides of their heads. Like a big capillary mat, elephant ears have lots of blood vessels and surface area. They can shed some heat by increasing the air speed across their ears when they flap around, enhancing convection. The large ears also provide more space to radiate and evaporate when covered in mud or water.
Some creatures are excellent energy-efficient home builders. Termites build their mounds in a way that encourages natural ventilation. The tall, cone-shaped mounds they build encourage the stack effect, where cool air is pulled into the bottom of the structure as the more buoyant, warm air exits the top.
How do other species handle the extreme colds? Polar bears invest in insulation. They survive in the cold because their fur is so fluffy and thick, it provides an excellent R-value. Scientific American explains that, if you take a picture of a polar bear with a thermal camera, they may not show up, except for their nose and eyes. Their fur insulates them so well that the outermost fur can be the same temperature as the ambient air. This is a big difference compared to humans, who can be spotted easily with a thermal camera, even when wearing heavy jackets.
Other polar creatures go the insulation route, as well. Blubber is a layer of fat that is a good thermal insulator and can be consumed by the body when food is hard to come by. It is more dual purpose than the fiberglass stuff humans use. Many polar creatures also have an oily, water-repellent layer of fur or feathers that don’t mat when wet.
If you are tired of fighting the cold, you can opt to just go with it. Alaskan wood frogs sometimes partially freeze when it gets really cold. According to jeb.biologists.org, “Alaskan frogs survived freezing at temperatures as low as 3.2 degrees.” This is much colder than similar frogs in warmer places. The Alaskan wood frogs “endured a two-month bout of freezing at 25 degrees. The profound freeze tolerance is presumably due to their high levels of organic osmolytes and bound water, which limits ice formation.”
Essentially, these frogs have a higher amount of a natural glycol in their bodies, which keeps them from freezing their blood vessels and dying. They can survive freezing about two-thirds of their body water. There isn’t much humans can do with that information. Fireball Whisky won’t keep you from freezing.
Learning from animals
Humans bodies aren’t very good at surviving in extreme temperatures. If we didn’t have the intelligence to build shelters or protect ourselves from our surroundings some other way, we wouldn’t be able to survive one full day much outside the temperature window of 39-85 degrees, according to LiveScience.com.
Biomimicry is the general topic of learning from the animal kingdom. There are two different categories of IEQ lessons for us here. First, there are physical things that can make our buildings more animal-like. We can use more insulation like a polar bear, maximize heat-transfer surface area like an elephant ear and design around the stack effect like termites.
Early humans lived in caves because spray foam insulation wasn’t an option. We now have lots of insulation options, yet most buildings I have been in look as if they value-engineered the insulation right out of the concept. Don’t look for HVAC machines to fix a problem that is caused by poor insulation. Even the best heating or cooling systems available won’t operate at peak efficiency in an all-glass building. That is like a naked polar bear.
The second category of animal lessons learned relates to how we adapt to our surroundings instead of mechanically controlling every IEQ factor. For example, we can adjust our clothing and expectations of what we are supposed to do to make ourselves comfortable. A fox looks much smaller in the summer because it sheds its winter coat to stay cool. A fancy investment banker may wear a suit every workday of the year.
One thing I have noticed about Americans: Wherever we go, regardless of what we are wearing and what is happening outside, we expect to be comfortable. In most other places in the world, people expect to be hot in the summer and cold in the winter, even in their homes. In the United States, the expectation is not only to temper the outside world in our indoor climate but to create winter in the summer and summer in the winter.
The trick for the built environment design and construction community is to create the ideal radiation, convection, conduction and evaporation atmosphere inside buildings, without the occupants noticing it is happening. Since comfort is hard to quantify, you can use tools such as the Center for the Built Environment’s ASHRAE 55 calculator to play with the variables affecting human comfort.
You can start with the default settings and only change the clothing level from typical summer indoor clothing to typical winter indoor clothing and see that you now fall outside of ASHRAE 55 compliance. You can do the same with metabolic rate, humidity, mean radiant temperature, air speed and air velocity. You will find comfort is hard to define and achieve because it is a series of moving targets.
Max Rohr is a graduate of the University of Utah and manager of REHAU Academy in Leesburg, Virginia. He has worked in installation, sales and marketing in the hydronics and solar industries since 1998 and writes this column in his personal capacity. The views expressed are his own and do not necessarily reflect those of the company he works for. He can be reached at email@example.com. and on Twitter @maxjrohr.