Bio-climatic Design
The design of a habitat which reflects the consideration and analysis of environmental variables like dry bulb temperature, relative humidity, air movement and radiation as they effect human perception and response, can be called Bio-climatic Design.

Bio-climatic Analysis can be carried out with the help of either the Bio-climatic chart or the psychrometric chart. This tutorial will work with the psychrometric chart for bio-climatic analysis. The psychrometric chart was developed for engineering calculations for the design of HVAC systems. The psychrometric chart helps to determine the comfort zone, in terms of the four environmental variables for a person engaged in a specified activity and wearing a specified amount of clothing. We are going to adapt its use in an architectural context.

Psychrometry (from the Greek: psukhros = cold) is the study of moist air (which is mostly oxygen, nitrogen and water vapor) and of the changes in its condition. We are going to use the psychrometric chart to determine comfort conditions.

Human response to heat
Heat, or rather the thermal state of the environment, is perceived by the skin surface of a living body. The temperature sensors on the skin are most sensitive around 34°C (93.2 °F), where quite small changes or differences in the temperature can be perceived. The sensitivity decreases towards the limits of tolerable temperatures.

The heat produced by a resting adult is about 85.83 Kcal/h (340 Btu/h). Because most of this heat is transferred to the environment through the skin it is often convenient to characterize metabolic activity in terms of heat production per unit area of skin. For the resting adult, this is about 50 kcal/(h.m²) (18.4 Btu/h.ft²) (average person has a skin surface area of about 1.82 m² (19.6 ft²) and is called 1 met). Higher metabolic rates are often described in terms of the resting rate.