WINTER RULE: ADD LAYERS FOR FLARES Bibhisha Uprety MEEN 340- Fall /30/2010

 Winter is here and so is the snow. So, how do you stay warm?  ASHRAE defines Human Thermal comfort as the “state of mind that expresses satisfaction with the surrounding environment.”  The primary function of clothing is to assist the body in maintaining a core temperature of 37˚C, regardless of environmental conditions.

Objective: To compare how layered clothing affects the body temperature of a person and their thermal comfort. Experimental Setup: Time : 10 minutes for each case Case 1: Single thick layer (t-shirt and a big Jacket) Case 2: Multiple layers (2 layers of thin shirt, a thin sweater and a medium-sized Jacket)

Results :  Initial body temperature (out in cold): 32°C  Temperature Measured (Body part): Neck  Device used to measure temperature: Thermocouple The results are tabulated and the graph illustrates the change in body temperature in every 2 minutes.

S.N.Time (min) Single Layer - Temperature (°C) Multiple Layer- Temperature (°C)

Mode of Heat Transfer: Convection Air between multiple layers eliminated heat transfer through Radiation. Conclusions:  Air is a good insulator. Wearing multiple layers of thin clothing creates a larger air barrier above the skin, which is optimal for preventing heat loss.  Prevention of air exchange between the environment and the warm air barrier created by clothing is a primary determinant of the clothing’s insulating effectiveness.  Multiple thin layers provide better insulation and greater comfort control than a single thick layer.

Recommendations:  You can reduce convective heat loss by wearing a windproof out shell. This will stop the air from flowing into your insulative layers of clothing and robbing the body heat that is stored there.  In cold weather, clothing serves to prevent heat loss through convection and conduction. It provides a barrier of air between the clothing and skin, as well as a physical barrier to the surrounding environment.  Multiple layering helps you attain Thermal comfort quickly and helps stay warm!