Wood Pergola Energy & Heat Transfer
A 14x31 over-sized timber framed pergola.
Stepping into the shade under a massive solid wood timber framed pergola is a very pleasing experience. The timbers are heavy duty, standing majestically still, and yet I become aware of being re-energized by the timber itself.
The earth’s primary source of energy is derived directly or indirectly from the sun. The sunlight warms the earth at an optimal temperature that can sustain life. Sunshine gives us energy and is wonderful, yet too much sun can get uncomfortable and also drain us of energy.
Wood is a natural and extremely effective insulator. It retains heat during the daytime and releases heat at night and is four hundred times warmer than steel.
Heat is only a shortened way to say heat energy. Energy and matter are the building blocks from which our entire universe is formed. Matter can be seen all around us as we can physically witness in a moving train, automobile, hurricane or the tide. Energy on the other hand is invisible and so we are not quite as aware of it but energy can make things around us move or change from one form into another.
At the University of Houston College of Engineering, engineers from around the world attended a series of meetings at the National Heat Transfer Conference. Here they gather to discuss the motion of energy and how it transfers itself from place to place, the machines that move our present civilization and the people who were inspired to create them.
Here are three examples of the transferring of heat given by John Lienhard a M.D. Anderson Professor Emeritus of Mechanical Engineering who attended the National Heat Transfer Conference:
1: Hot water freezes faster than cold water.
When you put an ice cube tray into a frosted over freezer the frost will insulate it. The hot tray will melt the frost and cause the water to have more thermal connection with the cooling coils. The hot water then evaporates into the colder, drier air and there becomes less water to freeze and the evaporation then speeds up the cooling process.
Conclusion: This can be true.
2: Wearing white clothing in the summer is better because black clothing absorbs more heat.
First, they presented skin color and why is it that nature place lighter-skinned people in the colder far North and darker-skinned people on the equator where the energy of the sun is greater.
Football players first began putting black streaks onto their cheeks so that the sun being attracted to dark would help to keep it from their eyes.
Darker skin does absorb more energy from the visible light than lighter skin, but darker skin is more protected from ultraviolet light. Most of the heat from the sun is invisible and comes from infrared radiation; which causes light and dark skin to be within the same color range. Darker skin does not absorb any more heat than lighter skin does.
Conclusion: The color of the clothes you wear makes no difference in regards to giving you more warmth.
3: Metal is colder than wood at the same room temperature.
When your body is warmer than a room it will shed heat and the nerves on your body will be warmer than wood or metal. The ends of you fingers are warmer than wood or metal. Metal conducts heat more rapidly than wood and your finger will feel much colder. On the other hand, if the wood or the metal were much hotter than your hand, the metal will feel much hotter than the wood will.
Conclusion: Metal conducts heat away so it feels colder.
Timbervolt lighting on a timber frame pergola.
Additionally a very large diamond is colder than metal. Yet, most diamonds are small and draw the heat out of a finger so quickly that is will become the same temperature as the finger which is why people sometimes say that diamonds are warm.
Harnessing energy for the good of mankind is a fascinating science and I believe we have only touched the surface of what is yet to be. For example, sonic levitation can be manipulated with sound waves to move matter particles. And what I find to be even more fascinating than sonic levitation is optical manipulation; the use of light for delicate experiments using optical tweezers, levitation and traps. The difference between sonic levitation and optical manipulation is that sonic levitation is matter moving matter, whereas optical manipulation is light moving matter.
Yet, with all the advancements and discoveries in science man wherein we may seem to be closer to truth that our predecessors recent discoveries have proved that in some cases it is only being rediscovered as in following narrative:
A notable professor of mathematics, Louis Bertrand (1731-1812) asked a Mr. Pictet as to whether or not he believed that cold could be reflected. With much confidence, Pictet answered that cold was simply the absence of heat and did not exist, therefore it was a negative and could not be reflected. Louis then asked Mr. Pictet if he would be willing to try an experiment to prove it and he would assist him.
Mr. Pictet placed a flask filled with some snow in the reflection of one mirror with a thermometer having been placed previously on a second mirror. The thermometer immediately dropped several degrees. It was as if the snow had immediately emitted rays of cold that were reflected onto the thermometer. Pictet then poured nitrous acid onto the snow to make it colder. The cooling effect was immediately enhanced and the thermometer dropped again.
“How could this be?” he wondered, “Can a dark object enhance more darkness by making the light dimmer?”
Initially Pictet was amazed at the outcome of his experiment. However, as this did not fit with what Pictet had been taught to believe about cold, Pictet later convinced himself that he was only seeing the heat as it was radiated away from the thermometer as it sunk into the ice. The thermometer having lost its heat would just naturally go down.
Giving a mirrored explanation using Pictet’s reasoning you could just as easy say, “Heat does not exist. It is merely the absence of cold.” Two hundred years later, Louis Bertrand wasn't so off base. Cold can indeed be reflected under the right circumstances.
I don't need to attend a heat transferring conference to appreciate the driving force of heat transfer or the amazing dynamics of a solid wood timber framed pergola that maintains more comforting temperatures. There may be misconceptions at times about how and when heat is transferred, but my body tells me that nature offers us the best. Timber is a wonderful, sustainable product of nature, offering the best protection and most human friendly temperatures in outdoor shade.
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