Thursday, February 9, 2012

So the groundhog got me thinking... do animals adapt to freezing Chicago winters?

Humans seal ourselves off in conditioned homes and cars, burning a lot of fossil fuel energy to do so.  But animals don't have that option.  So how do they do it?  I decided to revisit my grade school classes and relearn what I've forgotten.  And maybe there is something we can learn for design.

Photo credit: National Geographic Society 
Groundhog Day got me think, of course, about groundhogs.  As I learned in grade school, they do in fact hibernate from approximately October to March, but toward the end of hibernation (oh, say February 2nd or so?), they enter various stages of arousal to test the temperature and scope out new territory before entering into a semi-hibernated state like torpor.  The purpose of hibernation, of course, is to conserve calories when food is scarce, so the animal's metabolic rate slows and the body cools, respiration and heart rate are depressed.  Groundhogs enter into obligate hibernation, where they are aroused by internal mechanisms and usually unable to be aroused due to external stimluli. Other animals enter into facultative hibernation, or semi-hibernation, where they are able to be aroused but the purpose is the same: conserve energy when it is scarce.

As is common in nature, this is caused by a chemical reaction.  The mechanism that causes this state, dubbed the hibernation inducement trigger (HIT), as a chemical process is not yet fully understood.  In mice, studies show the mechanism to be a type of adrenalin that stimulated fat cells to induce dormancy.  It is triggered as a response to (usually) lower ambient temperature and time of year, among other individual body characteristics of the animal such as fat levels and hair type.  The animals pack on enough fat before hibernation to survive the winter, both in terms of insulation and calorically, and they enter into a deep sleep state that suppresses their metabolic rate to conserve energy that would have otherwise been spent to keep them warm.  Groundhogs designate separate "winter burrows" for this purpose, dug just below the frost line (42" below grade in Chicago), where temperatures remain constant and above freezing.

Photo credit: Brooklyn.Eva.Bailey 

So what can we as humans learn from the groundhog?  

I'm pretty sure I wouldn't want to sleep 6 months out of the year, but the idea of entering into a state of dormancy to conserve energy is something we practice but can can do more.

  • We now have programmable thermostats that can drastically decrease the temperature of rooms when unoccupied, such as the first floor or basement of your home when you are asleep upstairs.  You just need to remember to set them.
  • Building operations phasing.  Sections of a building, or even entire buildings, can be rendered dormant when not in use, leaving only crucial functions such as dehumidification or heating to maintain above freezing temperatures, intact.  This can be used in existing buildings.  
  • In a business resilience context, protocols could be set in place that automatically shut down operations or product lines in locations where resources are temporarily scarce with protocols for their reinstatement when resources come back online. 
  • The hibernation inducement trigger as a chemical response has design applications that include extended life for organ transplants, less stress to the body during surgery, and suspended animation for interstellar space travel.  The sky's the limit!  

What about building underground?  Burrowing down multiple stories and building undergound cities is something out of science fiction for a reason - it is cost prohibitive, interferes with water tables, and is not feasible for areas with high density populations.  But perhaps we can take these lessons and apply them to our existing context.

  • The steady state temperature below the frost line is used in geothermal heat pump systems to cycle water through a building and more passively heat and cool structures.   Wouldn't it be cool if our basement concrete floor slabs incorporated geothermal technology by cycling water through the slab, which is already below the frost line, through the building to partially heat and cool the building? 
  • During the energy crisis of the 1970s, underground housing started to become popular.  In it's way, it's genius.  The earth above acts as insulation and a wind break, thereby saving energy in a completely passive way.  The issue with underground housing is density - it just isn't feasible in more populated areas.  But the concepts of hyper insulation and curved structures to deflect wind can be emulated in building form and performance design and are directly applicable to cold climates.
  • In areas where building partially underground is feasible, the earth removed from the excavation can be reused at the sides of the building as a berm, directing cold winter air up and over the building passively.
Up next...learning from insects to survive the winter...specifically, honeybees.  So much to learn!  I welcome your comments, thoughts, and ideas.


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