Insulation Science Project

"R-value" is an insulation term that refers to how resistant a material is to heat flow.

What is the R value of your sweater, do you know? How about your jeans, your hoodie, and finally, your leather jacket? (if you have one.) You may want to know this information because winter is coming.

R value is usually used in reference to the material you put on your house, underneath the siding. It won’t hurt to find out what is the best insulating material to wear however. You will be walking, and there is the wind-chill factor with which you should be concerned. Not that you’ll have to worry about it as much as the man did who first named it. He was Paul Sipple. He first used the term in 1939 in his Ph.D. Dissertation when writing about his experiments in the Antarctic. In the ensuing years, Sipple and Charles F. Passel experimented more with the concept. They found that water freezes in a cup, depending on how warm the water is at the beginning, the outside temperature, and the speed of the wind. Anyone who walks outside on a blustery day would say that skin does too!

This is actually what prompted the new Wind Chill Temperature Index, that is, the effect of wind chill on a human face. The wind chill temperature index also incorporates modern heat transfer theory, which is heat loss from the body to its surroundings during cold and windy days.

The important thing to notice here is that the thinking person really can affect history, or make it, by thinking about her/his surroundings. The new wind chill temperature index was only adopted in 2001. Here are the algebraic formulas for calculating it:

New method:

WC = 35.74 + 0.6215 TF + ( 0.4275 TF - 35.75) V 0.16

Old method:

Twc = 0.0817 ( 3.17 V 1/2 + 5.81 - 0.25 V )( TF - 91.4) + 91.4

Where WC is the wind chill index, T(wc) is the wind chill factor, V is in the wind speed in statute miles per hour, and TF is the temperature in degrees Fahrenheit.

Note: There will occasionally be times when this formula will be off. One of them is when the wind speed is below four mph. If the wind velocity is near zero and you aren’t moving either, there’s a cushion of warm air around you, insulating you. In both of these cases the wind chill will make the air feel warmer than the actual temperature.

When speaking of insulation, it is important to keep it dry. Even the animals coat their outsides with oil to that effect. Clothing in humans is a bit more complicated. From a scientist’s point of view, clothing is chosen to maintain the temperature of the human body.

When the body’s heat rises, clothing must allow sweat to evaporate so the body can cool itself. Billowing fabric during movement creates air currents that increase evaporation and cooling. Layering fabric insulates slightly and keeps skin temperatures cooler rather than otherwise.

To fight cold, it’s important to keep the skin absolutely dry. But at the same time, several layers are a good idea as well in order to insulate and retain the body’s heat. From practical experience most people who have ever lived in a temperate zone know that footwear is a world of its own in the universe of insulation.

Experiment:

Design your spacesuit based on the atmosphere in the winter of earth, during

1 A windstorm

2 A sleety night

3 A balmy night

Step 1. What fabric?

Step2. What shapes?

Step3. What about footwear?

Step 4. The economics of production (to be continued).