BUILDING SCIENCE (ENVIRONTMENT)

INTRODUCTION
Regional climate condition, macro environment & micro environment all affect the risk at moisture damage, & must be taken into account in design.

CLIMATE
· Weather is defined as the general atmospheric condition at a given place and a given time with respect to temperature, humidity precipition, wind, radiation & other meteorological evens. Weather is a dynamic process, changing from moment to moment, from day to night and from season to season.
· Climate ( from Greek; klima) is defined by the Oxford Dictionary as “region with certain conditions of temperature, dryness, wind, lights, etc.
· Climate also can be defined the characteristic weather condition of an area average over an extended period of time.
· A somewhat more scientitic definition is “an integration in time of the physical states of the atmospheric environment, characteristic of a certain geographical location.
· Tropical climates are those where heat is dominant problem, where, for the greater part of the year buildings serve to keep the occupants cool, rather than warm, where the annual mean temperature is not less than 20°C

Before tropical climates can be examined is detail, we must survey the factors shaping the climates an a global scale.


A) GLOBAL CLIMATIC FACTORS
1) Quality Of Solar Radiation
· The Earth receives almost all its energy from the sun in the form of radiation, thus the sun is the dominating influence on climates
· The spectrum of solar radiation extends from 290 to 2300nm (nanometer 10-9m)
· According to human means of perception we can distinguish.

a) Ultra-violet radiation
· The spectral energy distribution varies with altitude, due to the filtering effect of the atmosphere.
· Some of the shorter wave lengths are absorbed by the atmosphere and reradiated at much longer wave lengths eg. Long infra-red, up to 10 000nm.
· As luminous efficiency of energy-radiation depends on its spectral composition, there is no constant relationship between radiation intensity & its lighting effect. However, the value of 100 Lumens / watt can be used for solar radiation. This would give an illumination of 100 lux per every W/m2 intensity or 100 000 lux per kW/m2.