Module 1-Climate & Weather PDF

MODULE 1: CLIMATE & WEATHER Duration: March 2022 Session: Week 2 Number of Hours: 2.4 hours Objective: To learn the basic of weather and climate and learn how to use climate characteristics in the design. DEFINITION OF TERMS CLIMATE origin: from the Ancient Greek word ”klima”, meaning inclinat...

MODULE 1: CLIMATE & WEATHER Duration: March 2022 Session: Week 2 Number of Hours: 2.4 hours Objective: To learn the basic of weather and climate and learn how to use climate characteristics in the design. DEFINITION OF TERMS CLIMATE origin: from the Ancient Greek word ”klima”, meaning inclination Climate is the characteristic condition of the atmosphere near the earth's surface at a certain place on earth. It is the long-term weather of that area (at least 30 years). This includes the region's general pattern of weather conditions, seasons and weather extremes like hurricanes, droughts, or rainy periods. Two of the most important factors determining an area's climate are air temperature and precipitation. encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time. Climate can be contrasted to weather, which is the present condition of these same elements over periods up to two weeks. "Climate is what you expect, weather is what you get." affected by the location’s latitude, terrain, altitude, ice or snow cover, vegetative cover as well as nearby water bodies and their currents. Climates can be classified according to the average and typical ranges of different variables, most commonly temperature and rainfall. Alterations in the quantity of atmospheric greenhouse gases determines the amount of solar energy retained by the planet, leading to global warming or global cooling. The variables which determine climate are numerous and the interactions complex, but there is general agreement that the broad outlines are understood, at least insofar as the determinants of historical climate change are concerned. Macroclimate – climate of the entire region or country Microclimate – climate of the immediate environments which are affected by site features such as hills, rivers, streams, lakes, position of buildings, trees etc.  Monsoon – a seasonal prevailing wind which lasts for several months, ushering in a region's rainy season. SEASONS As the Earth rotates on its tilted axis (23°30') around the sun, different parts of the Earth receive higher and lower levels of radiant energy. The sun emits rays that hit the earth's surface at different angles. These rays transmit the highest level of energy when they strike the earth at a right angle (90 °). Temperatures in these areas tend to be higher. Other locations, where the sun's rays hit at lesser angles, tend to be cooler. This creates the seasons. TROPICAL CLIMATE A tropical climate is a kind of climate typical in the tropics Prevailing conditions: a. Temperature average mean temperature (dbt): 20 – 30 deg C small diurnal temperature change/range: 2-5 deg b. Humidity Levels 50% - 100% RH (Relative Humidity) c. Wind Conditions Average wind speed: 2 m/s d. Prevailing Wind (Philippines) Amihan (NE) – November to April Habagat (SW) - May to October e. Sky Conditions predominantly overcast; with considerable reflected heat/ solar gain f. Precipitation average rainfall 1,000mm/year TROPICS origin: from the Ancient Greek word ”tropos” meaning "turn", because the apparent position of the Sun oscillates between the two tropics with a period that defines the average length of a year. The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the Tropic of Cancer in the northern hemisphere, at approximately 23°30' N latitude, and the Tropic of Capricorn in the southern hemisphere at 23°30' S latitude. This region is also referred to as the tropical zone and the torrid zone.  − Tropic of Cancer – This parallel marks the farthest point north at which the sun can be seen directly overhead at noon; north of the parallel the sun appears less − Tropic of Capricorn – This parallel marks the farthest point south at which the sun can be seen directly overhead at noon; south of the parallel the sun appears less The sun is directly overhead at lat. 23°30' N on June 21 or 22, the summer solstice, and at lat. 23°30' S on Dec. 21 or 22, the winter solstice. Since the entire tropical zone receives the rays of the sun more directly than areas in higher latitudes, the average annual temperature of the tropics is higher and the seasonal change of temperature is less than in other zones. The seasons in the tropics are not marked by temperature but by the combination of trade winds taking water from the oceans and creating seasonal rains called monsoons over the eastern coasts. TROPICAL DESIGN an art and science of designing a building that uses tropical climate as basis upon which design evolves. Applicable to tropical, sub-tropical and equatorial climates where discomfort due to heat and humidity are dominant problems. CLIMATE MODELS Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface and ice. They are used for a variety of purposes from study of the dynamics of the weather and climate system to projections of future climate. Factors Affecting Climate Physical conditions that determine the climate in a given area, e.g. latitude, altitude, ocean streams, etc. DISTANCE FROM THE SEA (CONTINENTALITY) Areas near the coasts generally have lower temperature but higher humidity level. They have greater cloud cover as due to the formation of clouds as warm inland air meets cooler sea air. Landlocked areas experience a wider range of temperatures reaching the maximum in summer because the moisture from the sea evaporates before reaching this distance. DIRECTION OF PREVAILING WINDS TOPOGRAPHY (ALTITUDE) Areas with higher altitude have lower temperature than areas near the sea level. Mountains also receive more rainfall than low-lying areas. The air is also thinner in higher altitudes which make it less able to absorb and retain heat. PROXIMITY TO THE EQUATOR (LATITUDE) The equator receives greater solar exposure than any other part of the earth because it is positioned directly to the heat of the sun, and the heat is received by a smaller area. The temperature decreases in the areas approaching the north and south poles as the sun heats up a bigger area and the heat is more spread out. HUMAN INFLUENCE Human activities have been affecting the climate for millions of years. However, before the Industrial Revolution (starting at the end of the 19th century), the effect human had on climate was quite small. Trees were cut down to provide wood for fires. Trees take in carbon dioxide and produce oxygen. A reduction in trees will therefore have increased the amount of carbon dioxide in the atmosphere. With the invention of the motor engine and the increase in burning of fossil fuels, the amount of carbon dioxide released into the atmosphere also increased. The depletion of forests also meant that the extra carbon dioxide produced cannot be changed into oxygen, and only contributed in warming up the earth. Climatic Elements Required in Design TEMPERATURE usually considered is Dry Bulb Temperature (DBT), it is a measurement of air temperature taken within a shaded area (you may also use an umbrella to avoid radiant heat) using a silvered thermometer; expressed in °F or °C RELATIVE HUMIDITY is the amount of water in the air usually measured by hygrometer (in %) or sling psychrometer or Wet Bulb Temperature (WBT) expressed in °F or °C. PRECIPITATION  amount, frequency and intensity of rainfall (may also include hail, snow, dew) in the locality; usually measured by rain gauge, can be expressed in mm or inches per unit time (day, month, year). WINDS direction, frequency and movement of air throughout the year. SKY measured in hours of sunshine or cloud cover expressed in ratio and percentage. The measurement of cloud cover is based on visual observation and expressed as a fraction of the sky hemisphere (tenths, or 'octas' = eights) covered by clouds SUNSHINE DURATION the period of clear sunshine (when a sharp shadow is cast), measured by a sunshine recorder which burns a trace on a paper strip, expressed as hours per day or month. SOLAR RADIATION amount of visible light, ultraviolet light and radiant heat; measured by a pyranometer, on an unobstructed horizontal surface and recorded either as the continuously varying irradiance (W/m2), or through an electronic integrator as irradiance over the hour or day. Common climatic elements for building design Temperature: - monthly mean of daily maxima (deg C) - monthly mean of daily minima (deg C) - standard deviation of distribution Humidity: - early morning relative humidity (in %) - early afternoon relative humidity (in %) Solar radiation: - monthly mean daily total (in MJ/m2 or Wh/m2) Wind: - prevailing wind speed (m/s) and direction Rainfall: - monthly total (in mm) Factors Affecting Climatic Design The local micro-climate and site factors will affect the actual environmental conditions of the building. The important site-related factors should be considered when making the climate analysis: Topography - elevation, slopes, hills and valleys, ground surface conditions. Vegetation - height, mass, silhouette, texture, location, growth patterns. Built forms - nearby buildings, surface conditions. Major thermal design factors to be studied include: solar heat gain, conduction heat flow and ventilation heat flow. The design variables in architectural expression that are important will include: Shape - surface-to-volume ratio; orientation; building height. Building fabric - materials and construction; thermal insulation; surface qualities; shading and sun control. Fenestration - the size, position and orientation of windows; window glass materials; external and internal shading devices. Ventilation - air-tightness; outdoor fresh air; cross ventilation and natural ventilation.