Dayanand Sagar Acadamy of Technology&Management. Udayapura, Bangalore 560 082

CLIMATOLOGY study for building design.

By Prof Mukund Dean School of Architecture

Bhaskaracharya calculated the time taken by the earth to orbit the sun hundreds of years before the astronomers; The Smart. Time taken by earth to orbit the sun:

(5th century) 365.25 days

Understanding Earth from SpaceTo pinpoint your position on a map of the world you need to work out your co-ordinates, known as latitude and longitude. Latitude is your position north or south of the Equator. Lines, or parallels, are drawn around the Earth at intervals. The North Pole is assigned the latitude 90º north and the South Pole latitude 90º south Lines of longitude, or meridians, are drawn a little differently. The line of longitude corresponding to 0º, which passes through Greenwich in London, is called the Prime (or Greenwich) Meridian. Longitude lines run along the Earth’s surface in a north–south direction, and unlike latitude lines, they divide the globe into segments like those of an orange, rather than regular strips

CLIMATOLOGY- CONTENTS OF SYLLABUS

Objective: To develop the knowledge required for understanding the influence of climate on architecture. Outline: Introduction – Elements of climate, measurement and representations of climatic data. Classifications of tropical climates, Major climatic zones of India.Thermal comfort: Effect of climatic elements on thermal comfort environment. Body’s heat exchange with surrounding environment. Thermal comfort indices viz., Effective temperature, bio-climatic chart etc., Kata-thermometer and globe thermometer. Thermal performance of building elements: effect of thermo-physical properties of building materials and elements on indoor thermal environment. Thermal properties. Conductivity, resistivity, diffusivity, thermal capacity and time lag and ‘U’ value. Construction techniques for improving thermal performance of walls and roofs. Natural ventilation: Functions of natural ventilation, Design considerations, effects of openings and external features on internal air flow.  Site Climate: Effect of landscape elements on site/micro climate. Day Lighting: Advantages and limitations, Day light factor, components of Day light factor, design considerations. Shading devices – Sun-path diagram, use of solar charts in climatic design. Types of shading devices. Procedure of designing shading devices.  Design considerations for buildings in tropical climates with special reference to hot-dry, warm-humid and composite climates References: 1)  “Manual of Tropical Housing & Buildings (Part-II)” by Koenigsberger2)  “Housing, Climate and Comfort” by Martin Evans 3)  “Buildings in the tropics” by Maxwell Fry4) Climate Responsive Architecture “by Arvind Kishan, Baker & Szokolay”.

Definitions Weather; It’s the momentary state of environment at a certain location Climate: The weather in some location averaged over some long period of time Atmosphere: A particular environment or surrounding influence / The mass of air surrounding the Earth Space ; Any location outside the Earth's atmosphere Zenith: The point above the observer head, the imaginary sphere against which celestial bodies appear. Altitude; Angular distance above the horizon (especially of a celestial object) Latitude: An imaginary line around the Earth parallel to the equator Longitude; The angular distance between a point on any meridian and the prime meridian at Greenwich Earth; The 3rd planet from the sun; the planet we live on in global form & it moves around the sun in elliptical orbit“ Azimuth; the angle between the vertical plane containing it and the plane of the meridian Meridian; An imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator Equinox: when the sun crosses the plane of the earth's equator during 2 times of the year Equator; An imaginary line around the Earth forming the great circle that is equidistant from the north and south poles, A circle dividing a sphere into

two equal and symmetrical parts Ocean; A large body of water constituting a principal part of the hydrosphere Topography ; Precise detailed study of the surface features of a region Solar radiation; Radiation from sun Cyclone; A violent rotating windstorm with a low pressure center; circling counterclockwise in the northern hemisphere and clockwise in the southern Wind; Air moving from an area of high pressure to an area of low pressure Breeze; A slight & pleasing wind (usually refreshing) it’s a low pressure wind condition. Storm; A violent weather condition with winds 64-72 knots and precipitation and thunder and lightning Precipitation; The water in any form falling to earth at a specific place (rain, snow, hail, sleet or mist) Solastice; Either of the two times of the year when the sun path is at its greatest distance from the equator Albedo; The ratio of reflected to incident light Bathymetry; Measuring the depths of the oceans Relative humidity ; The ratio of the amount of water in the air at a give temperature to the maximum amount it could hold at that temperature; expressed

as a percentage R Value; A measure of thermal resistance used in building and construction, with larger values corresponding to better insulation and less heat loss; it is

the inverse of the U value (U-value is the inverse of R-value. U=1/R R-value is the standard way of describing how effective an insulation is ) it is easier to explain to consumers that R-19 insulation is better than R-11 rather than telling them U=0.05 insulation is better than U=0.09 The R-value of a structure made of layers of different materials can be estimated by adding the R-values of the layers.  The R-value of a layer can be estimated by multiplying its thickness in inches by the R-value per inch.

U Value :A measure of how well a building element transfers heat, with smaller values corresponding to better insulation and hence less heat loss; it is the rate of energy loss per unit area per degree difference in temperature, and is equal to the inverse of the R value "a solid brick wall has a U value of about 2, similar to double glazing; well-insulated modern buildings should have walls with a U value less than 0.3“

Gale : A strong wind moving 45-90 knots; force 7 to 10 on Beaufort scale Knot mile ; A unit of length used in navigation; exactly 1,852 meters; historically based on the distance spanned by one minute of arc in latitude

Introduction of climateThe root of all weather is the Sun, which heats the Earth. The heating is uneven, because of night and day, because different surfaces (such as rocks and trees) absorband reflect sunlight in different amounts, and because sunlight hits the equator more directly than the poles. Uneven heat creates pressure differences, and Wind flows between areas of high and low pressure High and Low Pressure Because the Earth is warmer at the equator than at the poles, major differences in pressure occur. Air moves north and south to try to equalize the pressure difference created by the temperature difference. The Earth rotates under this air, which deflects its direction

Every one knows that its warmer in summer & colder in winter, why is that? The main factor is temperature due to the position of the earth in its elliptical orbit around the sun, the 23 .5 degree tilt of the earth’s axis of rotation which gives rise to seasons in various places and the path of the sun in the sky over the course of the day etc,. The rotation of the earth on its axis gives rise to Day and night periods and because of the tilt the length of day & night times keeps varying at different places on earth. If there was no tilt of earth then we would have had equal day & equal night periods throughout the year. The path of the sun on earth changes after every 6 months for the Northern & Southern hemispheres. The polar climates have unbearable cold conditions for normal human existence and they have conditions of continuous day or darkness for almost 6 months.

The sun daily rotates towards the east & Solar radiation has a lower intensity in polar regions because it travels a longer distance through the atmosphere, and is spread across a larger surface area. The sun shines 24 hours in the summer, and barely ever shines at all in the winter

EARLIER BUILDING CONSTRUCTION PRACTICESNot too long ago, building practices were almost entirely a cultural process, based on tradition. Building styles were developed over time to suit the local climate and building techniques made use of available, often local, building materials. Since World War II many countries have established and set standards of construction for safety.Weather - related events such as extreme cold, extreme heat, extreme wind, heavy snow conditions effect the efficiency, running costs of buildings and their failures. So there is good reason for using climate services to define building standards and performance. In different areas of the world, thermal comfort needs may vary based on climate. In China there are hot humid summers and cold winters causing a need for efficient thermal comfort. Energy conservation in relation to thermal comfort has become a large issue in China in the last several decades due to rapid economic and population growth. Researchers are now looking into ways to heat and cool buildings in China for lower costs and also with less harm to the environment. In tropical areas of Brazil, urbanization is causing a phenomenon called urban heat islands (UHI). These are urban areas, which have risen over the thermal comfort limits due to a large influx of people and only drop within the comfortable range during the rainy season. Urban Heat Islands can occur over any urban city or built up area with the correct conditions. Urban Heat Islands are caused by urban areas with few trees and vegetation to block solar radiation or carry out evapo-transpiration,

Sun may be described as the engine of climate as he supplies large amount of energy to Earth

Bangalore’s position on our globe is at 14 degree NORTH latitude

The positions of these circles of latitude (other than the Equator) are dictated by the tilt of the Earth's axis of rotation relative to the plane of its orbit. The Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on the Earth that marks the most northerly position at which the Sun may appear directly overhead at its zenith. This event occurs once per year, at the time of the June solstice, Its Southern Hemisphere counterpart, marking the most southerly position at which the Sun may appear directly overhead, is the Tropic of Capricorn.during December

Weather issues

Clouds are often created when two different types of air masses run into each other -- a warm air mass and a cold air mass. Typically, the warm air gets pushed up over the cold air..

High-speed winds race around the globe between four and six miles above the earth, mostly from west to east. These rivers of air are often collectively referred to as the jet stream, and they form at the boundaries of warm and cold air, Rain converts wind force to heat, by friction and Abrupt electric discharge from cloud to cloud or from cloud to earth accompanied by the emission of lightning & thunder.

Spectacular, powerful, and sometimes deadly, lightning is one of the most common weather phenomena. Satellites detect more than 3 million lightning flashes each day around the world, or an average of more than 30 flashes per second. Lightning kills more people than tornadoes, hurricanes, or any other kind of bad weather except floods. But because lightning usually kills people one at a time, it tends to be underrated as a hazard. The best protection against lightning is to stay indoors during a thunderstorm. But stay away from the telephone; about 1% of people killed by lightning were talking on the phone at the time. If you cannot reach a building, a car offers excellent protection.

Hurricane, cyclone, typhoon, these are all describing the same thing, a powerful wind and rain storm that can tear apart houses and flood entire cities. Even though the name is different, they have the same make up, need the same conditions for formation, and cause the same damaging side effects.

What Causes a Hurricane? Relatively simple in composition, what we are going to refer to as a hurricane is made up of a low-pressure center called ‘the eye’ and a

spiral arrangement of thunderstorms extending from its center. To make this particular combination occur, there are several natural factors that need to be present in the environment.

First, wind conditions are only suitable from roughly latitude 5° and 20° North and South of the Equator, where the Coriolis Effect, the force which causes rotary motion in winds, is strong enough to cause rotation. Typically, the conditions are not right from 0° to 5° North and South.

Second, you need the right wind conditions, meaning the temperature in the atmosphere must at greatest difference from the sea surface temperature.

Third, the water needs to be warm, at least 79.7 degrees Faren height at a depth of 160 feet. Finally there needs to be a disturbance in the atmosphere. When these factors are presents, a storm is capable of forming.

Hundreds of millions of people in urban areas across the world will be affected by climate change. The vulnerability of human settlements will increase through rising sea levels, inland floods, frequent and stronger tropical cyclones, periods of increased heat and the spread of diseases. Climate change may worsen the access to basic urban services and the quality of life in cities. Most affected are the urban poor – the slum dwellers in developing countries. UN-HABITAT's Sustainable Cities Programme help cities get the most out of their vital role in social and economic development by promoting better environmental policies and programmes, aimed at reducing pollution, and improving urban environment managementWeather - related events such as extreme cold, extreme heat, extreme wind, heavy snow conditions effect the efficiency, running costs of buildings and their failures. So there is good reason for using climate services to define building standards and performance. .

The Elements of Climate Climatology is the study of the long-term state of the atmosphere, or climate. The long-term state of the atmosphere is a function of a variety of

interacting elements. They are: Solar radiation Air masses Pressure systems (and cyclone belts) Ocean Currents  Topography

Solar radiation Solar radiation is probably the most important element of climate. Solar radiation first and foremost heats the Earth's surface which in turn determines

the temperature of the air above. The receipt of solar radiation drives evaporation, so long as there is water available. Heating of the air determines its stability, which affects cloud development and precipitation. Unequal heating of the Earth's surface creates pressure gradients that result in wind. So you see, just about all the characteristics of climate can be traced back to the receipt of solar radiation.

Air masses Air masses as an element of climate subsumes the characteristics of temperature, humidity, and stability. Location relative to source regions of air

masses in part determines the variation of the day-to-day weather and long-term climate of a place. For instance, the stormy climate of the mid latitudes is a product of lying in the boundary zone of greatly contrasting air masses called the polar front.

Pressure systems Pressure systems have a direct impact on the precipitation characteristics of different climate regions. In general, places dominated by low pressure tend

to be moist, while those dominated by high pressure are dry. The seasonality of precipitation is affected by the seasonal movement of global and regional pressure systems. Climates located at 10o to 15o of latitude experience a significant wet period when dominated by the Intertropical Convergence Zone and a dry period when the Subtropical High moves into this region. Likewise, the climate of Asia is impacted by the annual fluctuation of wind direction due to the monsoon. Pressure dominance also affects the receipt of solar radiation. Places dominated by high pressure tend to lack cloud cover and hence receive significant amounts of sunshine, especially in the low latitudes. 

Ocean Currents Ocean currents greatly affect the temperature and precipitation of a climate. Those climates bordering cold currents tend to be drier as the cold ocean

water helps stabilize the air and inhibit cloud formation and precipitation. Air traveling over cold ocean currents lose energy to the water and thus moderate the temperature of nearby coastal locations. Air masses traveling over warm ocean currents promote instability and precipitation. Additionally, the warm ocean water keeps air temperatures somewhat warmer than locations just inland from the coast during the winter.

Topography Topography affects climate in a variety of ways. The orientation of mountains to the prevailing wind affects precipitation. Windward slopes, those facing

into the wind, experience more precipitation due to orographic uplift of the air. Leeward sides of mountains are in the rain shadow and thus receive less precipitation. Air temperatures are affected by slope and orientation as slopes facing into the Sun will be warmer than those facing away. Temperature also decreases as one moves toward higher elevations. Mountains have nearly the same affect as latitude does on climate. On tall mountains a zonation of climate occurs as you move towards higher elevation.

Climatic changes

Links to Climate Data SourcesGIS-based map interface provides access to US and global climate/weather data. This is a listing of variable types of data sets available that are pertinent to paleo climatological modeling or data analysis. They are broken up into categories that are hopefully not too arbitrary to facilitate find what you need. Weather rainfall and temperature data with long-term monthly averages for over 20000 weather stations Time series dataThis category includes such things as data from ocean cores, sea level history data, and various other data varying over time rather than space

Classification of climates

climate classification system. The system is based on the concept that native vegetation is the best expression of climate. Thus, climate zone boundaries have been selected with vegetation distribution in mind. It combines average annual and monthly temperatures and precipitation, and the seasonality of precipitation.

1 .1 GROUP A: Tropical/megathermal climates 1.2 GROUP B: Dry (arid and semiarid) climates · 1.3 GROUP C: Mild Temperate/mesothermal

climates 1.4 GROUP D: Continental/microthermal climate · 1.5 GROUP E: Polar climates

Tropical climates are characterized by constant high temperature (at sea level and low elevations) — all twelve months of the year have average temperatures of 18 °C (64 °F) or higher. They are subdivided as follows:Tropical rainforest climate All twelve months have average precipitation of at least 60 mm (2.4 in). These climates usually occur within 5–10° latitude of the equator. In some eastern-coast areas, they may extend to as much as 25° away from the equator. This climate is dominated by the Doldrums Low Pressure System all year round, and therefore has no natural seasons. Some of the places that have this climate are indeed uniformly and monotonously wet throughout the year (e.g., the

northwest Pacific coast of South and Central America, from Ecuador to Costa Rica, see for instance, Andagoya, Colombia), but in many cases the period of higher sun and longer days is distinctly wettest (as at Palembang, Indonesia) or the time of lower sun and shorter days may have more rain (as at Sitiawan, Malaysia).

A few places with this climate are found at the outer edge of the tropics, almost exclusively in the Southern Hemisphere; one example is Santos, Brazil.

Tropical monsoon climate (Am):This type of climate, most common in South America, results from the monsoon winds which change direction according to the seasons. This climate has a driest month (which nearly always occurs at or soon after the "winter" solstice for that side of the equator) with rainfall less than 60 mm, but more than (100 − [total annual precipitation {mm}/25]). Examples: Cairns, Queensland, Australia Miami, Florida, United StatesThere is also another scenario under which some places fit into this category; this is referred to as the trade-wind littoral climate because easterly winds bring enough precipitation during the "winter" months to prevent the climate from becoming a tropical wet-and-dry climate. Nassau, Bahamas is included among these locations.

Tropical wet and dry or savanna climate :These climates have a pronounced dry season, with the driest month having precipitation less than 60 mm and also less than (100 − [total annual precipitation {mm}/25]).  Examples: Darwin, Northern Territory, Australia Caracas, Venezuela

Mumbai, India Bangkok, Thailand

GROUP B: Dry (arid and semiarid) climates These climates are characterized by the fact that actual precipitation is less than a threshold value set equal to the potential

evapo transpiration. The threshold value (in millimeters) is determined as follows: If the annual precipitation is less than 50% of this threshold, the classification is BW (desert climate); if it is in the range of 50%-

100% of the threshold, the classification is BS (steppe climate). Desert areas situated along the west coasts of continents at tropical or near-tropical locations are characterized by cooler

temperatures than encountered elsewhere at comparable latitudes (due to the nearby presence of cold ocean currents) and frequent fog and low clouds, despite the fact that these places rank among the driest on earth in terms of actual precipitation received. This climate examples can be found at Lima, Peru, and Walvis Bay, Namibia.

Introduction Regions having similar characteristic features of climate are grouped under one climatic zone.

According to a recent code of Bureau of Indian Standards, the country may be divided into five major climatic zones:

1 Hot & Dry (mean monthly temperature >30 and relative humidity <55%); 2 Warm & Humid (mean monthly temperature >25-30 and relative humidity >55-75%); 3 Temperate (mean monthly temperature 25-30 and relative humidity <75%);4 Cold (mean monthly temperature <25 and relative humidity – all values);5 Composite (This applies, when six months or more do not fall within any of the other categories)

India Climate can be divided into mainly four zones namely, Alpine, Sub tropical, Tropical and Arid. Situated roughly between 8º N and 37º NBrief Description Buildings in different climatic zones require different passive features to make structures energy-efficient. Some features that can be adopted in particular zones are listed below.

Hot and dry The hot and dry zone lies in the western and the central part of India; Jaisalmer, Jodhpur and

Sholapur are some of the towns that experience this type of climate. In such a climate, it is imperative to control solar radiation and movement of hot winds. The design

criteria should therefore aim at resisting heat gain by providing shading, reducing exposed area, controlling and scheduling ventilation, and increasing thermal capacity. The presence of “water bodies” is desirable as they can help increase the humidity, thereby leading to lower air temperatures. The ground and surrounding objects emit a lot of heat in the afternoons and evenings. As far as possible, this heat should be avoided by appropriate design features.

Some of the design features for buildings in this climate are: Appropriate orientation and shape of building Insulation of building envelope Massive structure Air locks, lobbies, balconies, and verandahs Weather stripping and scheduling air changes External surfaces protected by overhangs, fins, and trees Pale colours and glazed china mosaic tiles Windows and exhausts Courtyards, wind towers, and arrangement of openings Trees, ponds, and evaporative cooling

Climatic Zones of India

Warm and humid The warm and humid zone covers the coastal parts of the country, such as Mumbai, Chennai and Kolkata. The main design criteria in the warm and humid region are to reduce heat gain by providing shading, and promote heat loss by maximizing cross ventilation. Dissipation of humidity is also essential to reduce discomfort.

Moderate ; Pune and Bangalore are examples of cities that fall under this climatic zone. The design criteria in the moderate zone are to reduce heat gain by providing shading, and to promote heat loss by ventilation.

Some of the design features for buildings in this climate are: Appropriate orientation and shape of building Roof insulation and east and west wall insulation Walls

facing east and west, glass surface protected by overhangs, fins, and trees Pale colours and glazed china mosaic tiles Windows and exhausts Courtyards and arrangement of openings

Cold ; Generally, the northern part of India experiences this type of climate. the design criteria are to resist heat loss by insulation and controlling infiltration. Simultaneously, heat gain needs to be promoted by admitting and trapping solar radiation within the living space.

Some of the design features for buildings in this climate are: Appropriate orientation and shape of building Use of trees as wind barriers Roof insulation, wall

insulation, and double glazing Thicker walls Air locks and lobbies Weather stripping Darker colours Sun spaces, greenhouses and trombe walls (One of the simplest and most elegant solutions to retain solar heat is the Trombe wall, where solar heat is collected and stored in a wall of high thermal mass, tempering the heat gain during the day and releasing it at night. )

The Trombe wall is named after a French engineer Félix Trombe in the 1970s particularly well-suited to sunny climates that have high diurnal (day-night) temperature swings.

Composite The composite zone covers the central part of India, such as New Delhi, Kanpur and Allahabad. The design

criteria are more or less the same as for hot and dry climate except that maximizing cross ventilation is desirable in the monsoon period.

Some of the design features for buildings in this climate are: Appropriate orientation and shape of building Use of trees as wind barriers Roof insulation and wall

insulation Thicker walls Air locks and balconies Weather stripping Walls, glass surfaces protected by overhangs, fins, and trees Pale colours and glazed china mosaic tiles Exhausts Courtyards, wind towers, and arrangement of openings Trees and ponds for evaporative cooling Dehumidifiers and desiccant cooling

Thermal comforts & Effects of climateThermal comfort is affected by heat conduction, convection, radiation, and evaporative heat loss. Thermal comfort is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. It has been long recognized that the sensation of feeling hot or cold is not just dependent on air temperature alone.Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC (heating, ventilation, and air conditioning) design engineersSex differences While thermal comfort preferences between genders seems to be small, there are some differences. Studies have found men report discomfort due to rises in temperature much earlier than women. Men also estimate higher levels of their sensation of discomfort than women

Effects of thermal discomfort Thermal discomfort has been known to lead to sick building syndrome symptoms. The combination of

high temperature and high relative humidity serves to reduce thermal comfort and indoor air quality. The occurrence of symptoms increased much more with raised indoor temperatures in the winter than in the summer due to the larger difference created between indoor and outdoor temperatures

Since there are large variations from person to person in terms of physiological and psychological satisfaction, it is hard to find an optimal temperature for everyone in a given space. Laboratory and field data have been collected to define conditions that will be found comfortable for a specified percentage of occupants. There are six primary factors that directly affect thermal comfort that can be grouped in two categories: personal factors - because they are characteristics of the occupants - and environmental factors - which are conditions of the thermal environment. The former are metabolic rate and clothing level, the latter are air temperature, radiant temperature, air speed and humidity.

Even if all these factors may vary with time, standards usually refer to a steady state to study thermal comfort, just allowing limited temperature variations

Air temperature Main article: Dry-bulb temperature The air temperature is the average temperature of the air surrounding the occupant, with respect to

location and time. According to ASHRAE 55 standard, the spatial average takes into account the ankle, waist and head levels, which vary for seated or standing occupants Air temperature is measured with a dry-bulb thermometer and for this reason it is also known as dry-bulb temperature.

Radiant temperature Main article: Mean radiant temperatureThe radiant temperature is related to the amount of radiant heat transferred from a surface, and it depends on the emissivity of the material - i.e. the ability to absorb or emit heat. The mean radiant temperature, defined as the uniform temperature of an imaginary enclosure in which the radiant heat transfer from the human body is equal to the radiant heat transfer in the actual non-uniform enclosure, is a key variable for thermal comfort calculations for the human body.

Air speed Air speed is defined as the rate of air movement at a point, without regard to direction. According to ASHRAE 55 standard, it is the average speed of the air to which the body is exposed, with respect to location and time. The temporal average is the same as the air temperature, while the spatial average is based on the assumption that the body is exposed to a uniform air speed, according to the SET thermo-physiological model. However, some spaces might provide strongly non uniform air velocity fields and consequent skin heat losses that cannot be considered uniform. Therefore, the designer shall decide the proper averaging, especially including air speeds incident on unclothed body parts, that have greater cooling effect and potential for local discomfort.

Relative humidity While the human body has sensors within the skin that are fairly efficient at feeling heat and cold, relative humidity (RH) is harder to detect. The influence of humidity on the perception of an indoor environment can play a part in the perceived temperature and their thermal comfort. As a matter of fact, relative humidity affects the evaporation from the skin, which is the prevailing way of heat loss at high temperatures, normally from 26°C (80°F). At lower RH more sweat is allowed to evaporate from the body, while at higher values it is harder for this process to happen, because the air's moisture content is already elevated. Therefore, very humid environments (RH > 70-80%) are usually uncomfortable because the air is close to the saturation level, thus strongly reducing the possibility of heat loss through evaporation. On the other hand, very dry environments (RH < 20-30%) are also uncomfortable because of their effect on the mucous membranes. The recommended level of indoor humidity is in the range of 30-60%, but new methods allow lower and higher humidities, depending on the other factors involved in thermal comfort

Bio-Climatic Chart & Pschometric charts

A bio-climatic chart is a graphical means of depicting the human comfort region. It shows the association between air speed, thermal energy, dry-bulb temperature and relative humidity. It applies for a person in a specific activity and wearing a particular amount of clothes.

Psychometric chart; A psychrometric chart is a graph of the thermodynamic parameters of moist air at a constant pressure, often equated to an elevation relative to sea level. Dry-bulb temperature (DBT) is that of an air sample, as determined by an ordinary thermometer. Wet-bulb temperature (WBT) is that of an air sample after it has passed through a constant-pressure, Dew point temperature (DPT) is the temperature at

which a moist air sample at the same pressure would reach water vapor “saturation.”

Wind Measuring Instruments

Weather vanes are one of the oldest of all weather instruments, working by swinging around in the wind to show which direction it is blowing from. An Anemometer is commonly used to measure wind speed. Wind speed, or wind velocity, is a fundamental atmospheric rate. The main instrument used to measure the speed of the wind is an anemometer. The little cups on this device catch the wind and spin round at different speeds according to the strength of the wind. Wind Socks Another device used to measure the wind is a wind sock. The wind doesn't always blow at the same speed however, so it is also necessary to look at strong winds

Pictures ; Weather cock, Weather vane , wind socks & Anemometer cups

Beaufort Scale

The Beaufort Scale  : It is also possible to measure the speed of the wind by looking at its effects on the local environment. His scale was later adapted for use on land, and the same system is still used by many weather stations today.

In the Beaufort Scale, wind strengths are divided into 12 forces:  Light air Smoke drifts 1-3 mph Force 2 Light breeze Wind felt on face. Leaves rustle. Weather is usually clear 4-7 mph Force 3 Gentle breeze Leaves and twigs move. Light flags flap 8-12 mph Force 4 Moderate breeze Small branches move 13-18 mph Force 5 Fresh breeze Bushes and small trees sway. Crests are common on sea and known as

"white horses" 19-24 mph Force 6 Strong breeze Wind whistles in electricity and telephone wires. Hard to use umbrellas

25-31 mph Force 7 Near gale Whole trees sway and it becomes hard to walk in the wind. Sky may be dark

and stormy 32-38 mph Force 8 Gale Now very difficult to walk and tree twigs start to break 39-46 mph Force 9 Strong gale Tiles and chimneys blown from roofs and branches may snap. Sky may be

covered in thick cloud 47-54 mph Force 10 Storm Trees are uprooted and severe damage is caused to buildings 55-63 Force 11 Violent storm Widespread damage is caused to buildings 64-72 mph Force 12 Hurricane Severe devastation is caused 73+

Wind rose diagram A wind rose is a graphic tool used by

meteorologists to give a succinct view of how wind speed and direction are typically distributed at a particular location over a particular period..

Presented in a circular format, the modern wind rose shows the frequency of winds blowing from particular directions over a thirty-year period. The length of each "spoke" around the circle is related to the frequency that the wind blows from a particular direction per unit time. Each concentric circle represents a different frequency, emanating from zero at the center to increasing frequencies at the outer circles. A wind rose plot may contain additional information, in that each spoke is broken down into color-coded bands that show wind speed ranges. Wind roses typically use 16 cardinal directions, such as north (N), NNE, NE, etc., although they may be subdivided into as many as 32 directions.[3] In terms of angle measurement in degrees, North corresponds to 0°/360°, East to 90°, South to 180° and West to 270°.

Compiling a wind rose is one of the preliminary steps taken in constructing airport runways, as aircraft typically perform their best take-offs and landings pointing into the wind.

Kata Thermameter; A kata thermometer measures the cooling power of the environment; it is used to estimate the personal comfort of workers (see also "heat stress monitor" and "personal temperature monitor"). A spirit-in-glass thermometer is usually used: its bulb is heated to above body temperature, removed from the heat source and allowed to cool. The time taken for the thermometer reading to drop from above to below normal body temperature (e.g., from 38 °C to 35 °C) is used to calculate the cooling power of the atmosphereGlobal Thermometer; A globe thermometer is used to measure radiant heat. It basically consists of a thermometer with its bulb or sensor located at the centre of a Matt black copper bulb. Mean radiant temperature can be calculated from this result if air temp and velocity are known

Natural Ventilation Natural ventilation; The benefits-environmental, economic and health-of ventilating buildings naturally, rather than mechanically, are becoming

increasingly recognized. Approaches can be high-or low-tech but need to be a part of an integrated design approach. A range of technical barriers like building codes, fire regulations and acoustics also needs to be taken into account.

Natural ventilation of buildings is the flow generated by temperature differences and by the wind. The governing feature of this flow is the exchange between an interior space and the external ambient Natural ventilation, unlike fan-forced ventilation, uses the natural forces of wind and buoyancy to deliver fresh air into buildings

Almost all historic buildings were ventilated naturally, although many of these have been compromised by the addition of partition walls and mechanical systems. With an increased awareness of the cost and environmental impacts of energy use, natural ventilation has become an increasingly attractive method for reducing energy use and cost and for providing acceptable indoor environmental quality and maintaining a healthy, comfortable, and productive indoor climate rather than the more prevailing approach of using mechanical ventilation. In favorable climates and buildings types, natural ventilation can be used as an alternative to air-conditioning plants, saving 10%-30% of total energy consumption.

Natural ventilation systems rely on pressure differences to move fresh air through buildings. Pressure differences can be caused by wind or the buoyancy effect created by temperature differences or differences in humidity. In either case, the amount of ventilation will depend critically on the size and placement of openings in the building.

Wind causes a positive pressure on the windward side and a negative pressure on the leeward side of buildings. To equalize pressure, fresh air will enter any windward opening and be exhausted from any leeward opening. In summer, wind is used to supply as much fresh air as possible while in winter, ventilation is normally reduced to levels sufficient to remove excess moisture and pollutants

As a designer it is important to understand the challenge of simultaneously designing for natural ventilation and mechanical cooling—it can be difficult to design structures that are intended to rely on both natural ventilation and artificial cooling

In Natural Ventilation the airflow is due to wind and buoyancy through cracks in the building envelope or purposely installed openings.Single-Sided Ventilation: Limited to zones close to the openingsCross-Ventilation:; Two or more openings on opposite walls -covers a larger zone than the Single sided openingsStack Ventilation:; Buoyancy-driven gives larger flowsWind cacthers; Wind and buoyancy driven -effective in warm and temperate climatesSolar-Induced Ventilation:; using the sun to heat building elements to increase buoyancy more effective in warm climates

Almost all historic buildings were ventilated naturally, although many of these have been compromised by the addition of partition walls and mechanical systems. With an increased awareness of the cost and environmental impacts of energy use, natural ventilation has become an increasingly attractive method for reducing energy use and cost and for providing acceptable indoor environmental quality and maintaining a healthy, comfortable, and productive indoor climate rather than the more prevailing approach of using mechanical ventilation. In favorable climates and buildings types, natural ventilation can be used as an alternative to air-conditioning plants, saving 10%-30% of total energy consumption.Natural ventilation systems rely on pressure differences to move fresh air through buildings. Pressure differences can be caused by wind or the buoyancy effect created by temperature differences or differences in humidity. In either case, the amount of ventilation will depend critically on the size and placement of openings in the building

Airflow in Natural Ventilation; Factors Influencing the airflow through openings–Wind speed–Wind pressure–Buoyancy (stack) pressure–Characteristics of openings –Effective area of multiple openingsIndoor Environmental considerations–Thermal comfort–Indoor air quality

Sun Path Diagrams

Sun path refers to the apparent significant seasonal-and-hourly positional changes of the sun (and length of daylight) as the Earth rotates, and orbits around the sun. The relative position of the sun is a major factor in the heat gain of buildings and in the performance of solar energy systems.[1] Accurate location-specific knowledge of sun path and climatic conditions is essential for economic decisions about solar collector area, orientation, landscaping, summer shading, and the cost-effective use of solar trackers.Sun path diagrams are a convenient way of representing annual changes in the path of the Sun through the sky within a single 2D diagram. Their most immediate use is that the solar azimuth and altitude can be read off directly for any time of the day and day of the year. They also provide a unique summary of solar position that the designer can refer to when considering shading requirements and design options.

The sun’s movement through the day and through the year is one of the most crucial environmental factors to understand when designing high performance buildings. If you design your building with careful consideration of the sun’s path, you can take advantage of strategies such as natural day lighting, passive heating, PV(photovoltic)energy generation and even natural ventilation. However, if you are not careful, these same opportunities can work against you, producing glare or overheating.

Sun path and solar position

The first thing to understand is the sun’s path at your location. At any given point on the sun’s path, its height in the sky is called its altitude and its horizontal angle relative to true north called its azimuth. Seasonal Variations and Important Dates.

The sun’s path varies throughout the year. In the summer the sun is high in the sky, and rises and sets north of east-west in the northern hemisphere (in the southern hemisphere, it’s south of east-west). It also rises much earlier and sets much later in summer than in winter. To study the extreme of hot summer sun, you often want to study the sun’s path on the summer solstice, the day when the sun is at its highest noon altitude. In the winter the sun is low in the sky, and rises and sets south of east-west in the northern hemisphere (in the southern hemisphere, it’s north of east-west).

To study the extreme of the winter sun path, you often want to study the sun’s path on the winter solstice, the day when the sun is at its lowest noon altitude. To study more average positions, you can look at the sun’s path on the spring and autumn equinoxes, when the sun rises and sets due east-west. The altitude of the noon sun at the equinox is determined by the latitude of the site. This is why the rule-of-thumb for the optimum angle of solar panels is the latitude of the site. At this angle, the sun's rays are most perpendicular to the panel for most of the year.

There are four important dates to remember when considering sun position

Po Sun Path Diagram for Rotterdam, the Netherlands

Sun path Sterio-Animation

sun path stereo-animation.zip

hourly-sun-path-anim.zip

FACTORS THAT CAUSES THE CHANGE IN SUN PATHS   Depending on the day of the year and the latitude of the observer, it affects where the

sun exactly rises or sets, or how long the sun is above the horizon. As seen from the 2 diagrams above the sun does not necessarily rise due East or set due west. The location of the sun in the sky is described as having two components: its daily movement around the horizon and its height above the horizon (altitude).Its altitude varies

with the seasons and location of the observer. At 40 degrees latitude, Figure 2.2a, during the equinox the sun rises due east, while during solstices the sun

rises due south east or north east. At 65 degrees latitude, Figure 2.2b, the sun rises further southof east during the winter solstice and further north of east during the summer solstice.

  The sun’s daily path across the sky on or about the 21st day of each month is indicated

by means of seven curved lines. The path is highest in June and the lowest in December. The sun travels across the earth’s sky along 7 main paths. Each of the other five paths is for two months in the year. For instance, the path on the March 21 is the same as on September 23.

  We observe the sun in the northern hemisphere with regards to its paths.The tilt of the

earth causes the seasons which constitutes the difference in the sun paths. The sun paths are different due to factors such as the: 1)Location (local latitude) 2)Rising and setting position (based on the time of the year) 3) Duration of the day and night

The Shading Effect The sun will always cast a shadow on any object. Only the length, shape and size of the

shadow will change with respect to the sun’s position in the sky throughout the year. When designing buildings, it is important to notice the amount of shade cast on the building, or otherwise how its shadow will affect its surroundings. As mentioned earlier above, at different latitudes, the sun will travel along different paths across the sky at different times of the year The suns peculiar behavior is a very important factor when designing and constructing buildings. For locations which are at latitudes away from the equator, during the summer months the sun will cast relatively short shadows while during the winter months the sun will cast long shadows of objects. In the equatorial regions, the suns path remains relatively unchanged hence the length of the shadows does not vary much throughout the year.

Sun path s @ 20 deg N Latitude and @ 40 deg N Latitude is shown above sketchSun chart

Sun path charts can be plotted either in Cartesian (rectanglar) or Polar coordinates.Cartesian coordinates where the solar elevation is plotted on X axis and the azimuth is plotted on the Y axis.Polar coordinates are based on a circle where the solar elevation is read on the various concentric circles, from 0° to 90° degrees, the azimuth is the angle going around the circle from 0° to 360° degrees, the horizon is represented by the outermost circle, at the periphery.

WINDW SHADE DESIGNS

Enabling shadows (SketchUp)The Shadows feature is designed to give you a general idea of how the sun and shadows relate to your model during the course of a day and throughout the year. The calculations are based on the location (latitude and longitude, directional orientation of the model, and an associated time zone) There are many different reasons to want to control the amount of sunlight that is admitted into a building. In warm, sunny climates excess solar gain may result in high cooling energy consumption; in cold and temperate climates winter sun entering south-facing windows can positively contribute to passive solar heating; and in nearly all climates controlling and diffusing natural illumination will improve daylighting. Sun control and shading devices can also improve user visual comfort by controlling glare and reducing contrast ratios

The use of sun control and shading devices is an important aspect of many energy-efficient building design strategies. In particular, buildings that employ passive solar heating or day-lighting often depend on well-designed sun control and shading devices

Thermal performance of building roof & Wall elements  The study concerns the evaluation and comparison of the thermal performance of building roof & Wall elements subject to

periodic changes in ambient temperature, solar radiation and nonlinear radiation exchange. A numerical model, based on the finite-volume method and using the implicit formulation, is developed and applied for six variants of a typical roof structure used in the construction of buildings in Saudi Arabia. The climatic conditions of the city of Riyadh are employed for representative days for July and January. The study gives the detailed temperature and heat flux variations with time and the relative importance of the various heat-transfer components as well as the daily averaged roof heat-transfer load, dynamic R-values and the radiative heat-transfer coefficient. The results show that the inclusion of a 5-cm thick molded polystyrene layer reduces the roof heat-transfer load to one-third of its value in an identical roof section without insulation. Using a polyurethane layer instead, reduces the load to less than one-quarter. A slightly better thermal performance is achieved by locating the insulation layer closer to the inside surface of the roof structure but this exposes the water proofing membrane layer to larger temperature fluctuations.

Efficient and economical technology that can be used to store large amounts of heat or cold in a definite volume is the subject of research for a long time. Thermal storage plays an important role in building energy conservation, which is greatly assisted by the incorporation of latent heat storage (LHS) in building products. LHS in a phase change material (PCM) is very attractive because of its high storage density with small temperature swing. It has been demonstrated that for the development of a latent heat storage system (LHTS) in a building fabric, the choice of the PCM plays an important role in addition to heat transfer mechanism in the PCM. Thermal energy storage in the walls, ceiling and floor of buildings may be enhanced by encapsulating or embedding suitable PCMs within these surfaces. They can either capture solar energy directly or thermal energy through natural convection. Increasing the thermal storage capacity of a building can increase human comfort by decreasing the frequency of internal air temperature swings so that the indoor air temperature is closer to the desired temperature for a longer period of time.

Environmental quality has become increasingly affected by the built environment—as ultimately, buildings are responsible for the bulk of energy consumption and resultant atmospheric emissions in many countries. In recognizing this trend, research into building energy-efficiency has focused mainly on the energy required for a building's ongoing use, while the energy “embodied” in its production is often overlooked. Such an approach has led in recent years to strategies which improve a building's thermal performance, but which rely on high embodied-energy (EE) materials and products. Although assessment methods and databases have developed in recent years, the actual EE intensity for a given material may be highly dependent on local technologies and transportation distances. The objective of this study is to identify building materials which may optimize a building's energy requirements over its entire life cycle, by analyzing both embodied and operational energy consumption in a climatically responsive building in the Negev desert region of southern Israel—comparing its actual material composition with a number of possible alternatives. It was found that the embodied energy of the building accounts for some 60% of the overall life-cycle energy consumption, which could be reduced significantly by using “alternative” wall infill materials. The cumulative energy saved over a 50-year life cycle by this material substitution is on the order of 20%. While the studied wall systems (mass, insulation and finish materials) represent a significant portion of the initial EE of the building, the concrete structure (columns, beams, floor and ceiling slabs) on average constitutes about 50% of the building's pre-use phase energy.

Daylighting

For thousands of years, men have made structures to protect themselves from the perils and discomforts of the environment. A shelter shields from the weather, animals, and other men. It is a place for work and rest.

Modern building technologies such as air conditioning and electic lighting have allowed us to take the concept of sheltering from the elements to the extremes. During the 1960s and 70s, many buildings were designed to have no connection with the outside at all. After millennia of struggle, man had finally won over nature. Or so he thought.

It turned out that living and working in sealed boxes is not at all what people need or want. Airconditioned and artificially lit buildings are not only unpleasant to live and work in, they also make us sick. Over the past few decades, the trend has been to allow natural light and ventilation into the building, utilising it for saving energy and for enhancing the indoor environment

Daylighting is the art and science of allowing natural light into buildings. It involves the co-ordination of different disciplines: architecture, engineering, building science, planning amongst many others.

Daylight factor A daylight factor is the ratio of internal light level to external light level and is defined as follows:

DF = (Ei / Eo) x 100% where, Ei = illuminance due to daylight at a point on the indoors working plane, Eo = simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of overcast sky.

In order to calculate Ei, one must establish the amount of light received from the outside to the inside of a building. There are three paths along which light can reach a point inside a room through a glazed window, rooflight, or aperture, as follows:

Direct light from a patch of sky visible at the point considered, known as the sky component (SC), Light reflected from an exterior surface and then reaching the point considered, known as the externally reflected

component (ERC), Light entering through the window but reaching the point only after reflection from an internal surface, known as the

internally reflected component (IRC). The sum of the three components gives the illuminance level (lux) at the point considered:

Lux = SC + ERC + IRC A study of daylight factors within a single storey building resulting from different perimeter glazing and rooflight designs

and glass types. Undertaken using the IES Raidance software Module. Daylight factors are used in architecture and building design in order to assess the internal natural lighting levels as

perceived on the working plane or surface in question, in order to determine if they will be sufficient for the occupants of the space to carry out their normal duties. The design day used for daylight factor calculations is based upon the Standard CIE overcast Sky for 21 September at 12:00pm, and where the Ground Ambient light level is 11921 Lux. CIE being the Commission Internationale de l´Eclairage, or International Commission on Illumination.

Calculating daylight factors requires complex repetition of calculations and thus is general undertaken by a proprietary computer software product such as Radiance. This is a suite of tools for performing lighting simulation which includes a renderer as well as many other tools for measuring the simulated light levels. It uses ray tracing to perform all lighting calculations.

In order to assess the effect of a poor or good daylight factor, one might choose to compare the results for a given calculation against published design guidance. In the UK this is likely to be CIBSE Lighting Guide 10 (LG10-1999) which broadly bands average daylight factors into the following categories:

Under 2 – Not adequately lit – artificial lighting will be required. Between 2 and 5 – Adequately lit but artificial lighting may be in use for part of the time. Over 5 – Well lit – artificial lighting generally not required except at dawn and dusk – but glare and solar gain may cause

problems.

Miscellaneous informations Climatic data sheet for any place on earth, must include the followingA 1. Name of the station, 2. its Longitude , 3. its Latitude & 4. its height above mean sea levelB 1. Maximum Dry Bulb Temperature (DBT) of August & February, 2. Minimum DBT of August & February, 3. Average RH of Aug & Feb, 4. Prevelant wind direction during summer months and 5. Total Yearly Rainfall

The Spectrum of Solar Radiation extends from 290 to 2300 nanometer (Nanometer = Ten to the power of minus nine meters 10_9 m)

When people began to travel long distances over deserts or seas, they needed a way to fix their position. Accordingly, a global grid was

developed, incorporating lines of latitude and longitudeIn ancient times, people positioned themselves using landmarks and rudimentary maps. This worked well locally, but different

methods wereneeded for travelling further afield across featureless terrain such as sea or desert. Travellers now required a frame of reference, or

co-ordinates,to fix their position Global positioning systemsAt long last, both latitude and longitude could now be determined accurately, and for the first time you could say exactly where on

Earth youwere.? Today, it's all done electronically through GPS, a world-wide radio navigation system made up of a constellation of 24 satellites

and theirGround stations. These 'artificial stars' are used as reference points to calculate a terrestrial position to within an accuracy of a few

metres. In fact, with advanced forms of GPS you can make measurements to within a centimetre!

In meteorology, an air mass is a volume of air defined by its temperature and water vapor content. Air masses cover many hundreds or thousands of square miles, and adopt the characteristics of the surface below them. They are classified according to latitude and their continental or maritime source regions. Colder air masses are termed polar or arctic, while warmer air masses are deemed tropical. Continental and superior air masses are dry while maritime and monsoon air masses are moist. Weather fronts separate air masses with different density (temperature and/or moisture) characteristics. Air masses can be modified in a variety of ways. Surface flux from underlying vegetation, such as forest, acts to moisten the overlying air mass.[12] Heat from underlying warmer waters can significantly modify an air mass over distances as short as 35 kilometres (22 mi) to 40 kilometres (25 mi).[13] For example, southwest of extratropical cyclones, curved cyclonic flow bringing cold air across the relatively warm water bodies can lead to narrow lake-effect snow bands. The temperature decrease with height and cloud depth are directly affected by both the water temperature and the large-scale environment. The stronger the temperature decrease with height, the deeper the clouds get, and the greater the precipitation rate becomes.[15]

Question Bank each question is

only for 10 marks

Explain ,What kind of climatic data are to be projected for a place? What are the climatic zones identified in India? Explain any one in detail How does the heat exchange mechanism in the body work in surrounding

environments? What is Thermal comfort ? What factors influence it. Explain it using Bio-climatic

chart. How would you measure the velocity of moving wind? What are the features which affect the micro (site) climate of a place ? The building envelop determines the indoor climate, Explain clearly with sketches. How do you measure the condition of natural light in a working environment Explain your architecture of walls & roof in a hot dry climate with sketches. Explain with sketches the need for vertical & horizontal shading devices. What is climate conscious design? Give proposals for a beach house in Indian

west coast ? Explain the Importance of sun path diagram & its use in climatic design Explain Natural lighting & ventilation issues for building design with sketches What do you understand by Passive techniques for solving the indoor thermal

environment ? Explain the following climates briefly. 1.Tropical climate 2. Savanna climate 3. Polar climate 4.Desert climate 5.Rain

forest climate. Write brief short notes on 1. Urban heat zones 2.Daylight factor 3. Relative Humidity 4. kata thermometer

5. Storm.

The END : Thank you

END - Thank you