Tropical design hand out 2, Summaries of Design history

Download Tropical design hand out 2 and more Summaries Design history in PDF only on Docsity! TROPICAL DESIGN PREPARED BY: AR. MHELFORD JUN T. PIGAO, UAP, RMP Definition of Terms: ALTITUDE‐ measured in the vertical plane, between the sun’s direction and the horizon plane. Also referred to as elevation. ‐ The height above the horizon AZIMUTH‐ the direction of the sun measured in the horizontal plane from north in clockwise direction. Also referred to as “bearing”. ZENITH ANGLE‐ measured between the sun’s direction and the vertical and it is the supplementary angle of the altitude. ZEN= 90 deg‐ ALT HOUR ANGLE‐ expresses the time of the day with respect to the solar noon; it is the angular distance, measured within the plane of the sun’s apparent path between the sun’s position and its position at noon; i.e. solar meridian (the plane of the local longitude that contains the zenith and the sun’s noon position).As the hourly rotation of the earth is 360 deg/24h= 15deg/hr, HRA is 15 deg for each hour from the solar noon. HRA= 15 * (h‐12) Where h= the hour considered (24‐hr clock) so HRA is negative for the afternoon and positive for the afternoon hours. HEAT‐ form of energy generated by the random motion of molecules. The flow of heat is always from a point of higher temperature to the points of which the temperature is lower. There are three processes by which heat is transmitted: they are conduction, convection, and radiation. CONDUCTION‐ the process in which heat energy is transferred from one vibrating molecule to the one immediately adjacent to it without any relative displacement of the molecules. CONVECTION‐ transfer of heat between a surface and a moving fluid or the transfer of heat by movement of themolecules from one point in a fluid to another. It can either be natural or forced. Natural Convection occurs when fluid comes in contact with a heat source. When air is blown against the surface of a hot fluid, it cools fast. The air molecules that have been warmed at the surface of the liquid are blown away and replaced by the cooler air molecules which are capable of absorbing more heat. This process is called forced convection. RADIATION‐ the transfer of heat through a space by the electro‐magnetic waves and is measured as temperature at the surface of the material. There are two aspects of radiation; emissivity and absorptivity. Emissivity is the ability of the material to give off thermal radiation. All materials emit heat, yet vary in degree. Apsorbtivity is the capacity of the material to absorb radiant energy and convert it to other forms of energy. TROPICAL DESIGN PREPARED BY: AR. MHELFORD JUN T. PIGAO, UAP, RMP EVAPORATION‐ the change of phase from liquid to gaseous state: the sensible heat (dry –bulb temperature) in the air is lowered by the latent heat absorbed from air when moisture is evaporated. THERMAL STORAGE‐ the heat charge and discharge both diurnally and seasonally, a function of its specific heat, weight and conductivity. SOLAR TIME‐ is measured from Solar noon. i.e noon is taken to be when the sun appears to cross the local meridian. Clocks are set to the average length of the day, gives the mean time. The mean time at Greenwhich is referred to as GMT, but recently also as UT (universal time). The performance of horizontal shading devices is measured by the vertical shadow angle (VSA). It is measured as the sun’s position projected parallel with the building face onto a vertical plane normal to that building face, and it can be found from the expression. VSA‐ is also the angle between two planes meeting along a horizontal line on the building face which contains the point considered, one being the horizontal plane and the other a titled plane which contains the sun. SOLAR GEOMETRY 1. Rays of the sun vary with time and place (latitude) 2. Celestial Sphere: earth is static; sun moves from east to west 3. The sun moves across the sky at a rate of 15.04° per hour 4. The earth’s polar axis is inclined at 23°47’ from the vertical 5. June 21 is considered the longest day = summer solstice 6. December 21 is the shortest day = winter solstice 7. March 21 and September 21 = equinoxes SUN PATH 1. Solar Altitude Angle = the angle with height above the horizon. Ranges from 0° when on horizon to 90° when directly above (noon) 2. Solar Azimuth Angle = the sun’s position as projected on a horizontal plane. 3. The two solar angles change with Latitude (location on Earth)