weather strategies

working with the wind

Conv = f(Windspeed) x (T_skin – T_air)

in summer:   There is very little potential for convective cooling due to the small differential between skin temperature and air temperature. Wind can be used to augment evaporative cooling.

in winter: There is great potential for cooling due to the large differential between skin temperature and air temperature.

working with the sun

in summer:  The solar radiation received is determined by the angle between the sun and the earth.  In summer, with the sun high in the sky,  radiation reaches its most intense level.

in winter: low sun angle = less radiation    Radiation is not affected by air temperature, therefore it can act to increase energy.

conclusions

1. In winter, the wind is the primary consideration. (One is unlikely to be comfortable in a convective cooling situation.) Direct or reflected solar radiation is useful for heating surfaces.

2. In summer, blocking solar radiation is the primary consideration.  Wind strategies are typically less effective, though light winds can be intensified using the Venturi effect.

3. In spring and fall convection and radiation are relatively equal.  First block the wind. Then, because of the variability of equinox weather, determine an approach where solar radiation can be controlled to suit the particular weather of the moment.

general rule

Make a place comfortable for the most people for the majority of time.

useful facts

resting clothed humans are comfortable     20⁰ – 25⁰C = 68⁰ – 77⁰F

evaporative cooling through lungs and skin 25⁰C = 77⁰F

true perspiration occurs (water on skin)     28⁰C = 82.4⁰F

convection becomes a heat source                 35⁰C = 95⁰F

deep body temperature for humans             37⁰C = 98.6⁰F

deep body temperature for mammals          35⁰ – 40⁰C = 95⁰ – 104⁰F

deep body temperature for birds                  40⁰ – 43⁰C = 104⁰ – 109⁰F

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