elements of climate.1ppt

8/13/2019 Elements of Climate.1ppt

1/19

CLIMATE RESPONSIVE

ARCHITECTURE


2/19

THE ELEMENTS OF CLIMATE

Temperature: data

Humidity: data

Precipitation Climatic information

Temperature:measurement

Driving rain Sky conditions

Solar radiation:measurement

Solar radiation: data

Wind: measurement

Wind : data Special characteristics

Vegetation

Graphic representation


3/19

CLIMATIC INFORMATION

The designer is interested in thoseaspects of climate which affecthuman comfort and the use ofbuildings.

They include averages, changesand extremes of temperature, the

temperature differences betweenday and night, humidity, skyconditions, incoming and outgoingradiation, rainfall and itsdistribution, air movements andspecial features such as tradewinds, thunderstorms, duststorms and hurricanes.

Climatic records as gathered atairports and meterological stationsare not primarily intended for theuse of designers.


4/19

TEMPERATURE MEASUREMENT The temperature of the air is

measured in degree celsiusmost often with mercurythermometer.

Readings taken at specifiedtimes of the day, or if amaximum minimumthermometeris used one

reading daily can give themomentary temperatureaswell as the maximum andminimum temperaturesreached in the past 24 hours.

The dry bulb or true

air temperatureis a

value taken in the

shade, the inside a

louvered wooden box,

known as the

Stevenson screen ata height of 1.20 to 1.80

thermometer being

mounted m above the

ground

Thermographcan be used,which is based on abimetallic thermometerandgives a continuous graphicrecording of temperature

variations.


5/19

TEMPERATURE DATA

Monthly mean temperaturescan be given for each of the 12months.

The averageis taken betweeneach days maximum andminimumand then the averageof the 30 daysaverage isfound.

To give an diurnal variationsthis can be supplemented bymonthly mean maxima andminima.

These will establish themonthly mean range of

temperatures. It will be useful to indicate the

highest and lowesttemperaturesever recorded foreach month, i.e., the monthlyextreme maxima and minima

to establish the monthly meanrange of temperatures. Locations of climate stations with meantemperature data.


6/19

HUMIDITY MEASUREMENT

The humidity of aircan bedescribed as absolute humidityi.e., the amount of moistureactually present in unit mass orunit volume of air, in terms ofgramme per kilogramme.

The relative humidityishowever a much more usefulform of expression, as it givesa direct indicationofevaporation potential.

The amount of moisture the air

can hold depends o n itstemperature.

Relative humidityis the ratio ofthe actual amount of moisturepresent to the amount ofmoisture the air could hold at

the given temperature. RH=AH/SHX100 %


7/19

Humidityis usually measuredwith the wet and dry bulbhygrometer.

This consists of two ordinarymercury thermometers

mounted side by side. The first one measures the air

temperature. The bulb of thesecond one is covered with agauze or wick and is kept wet.

Moisture evaporatinggives a

cooling effect, thus the readingof wet bulb temperature will beless than the dry bulbtemperature.

As in dry air the evaporation isfaster, the cooling is more

pronouncedand the differencebetween the two readingsisgreater in case of 100%RH thetwo readingswill be identical,as there is no evaporation.

Having made the two readingsthe corresponding RH can befound from the psychometricchart.

wet and dry bulb hygrometer

Psychometric chart.


8/19

HUMIDITY DATA

To give an indication of prevailing humidity conditions, it is sufficient

to establish the monthly mean the maximum and monthly mean

minimum relative humidity values for each of the 12 months.

This is only possible where continuous hygrographrecordings are

available. Where these are notavailablereadings are made just before

sunrise,e.g at 6.00 hours (maximum value) and at 15.00

hours(minimum value)


9/19

VAPOUR PRESSURE

Another indication or

expression of atmospherichumIdity is the vapourpressure . i.e the partialpressure of water vaporpresent in the air.

The atmospheric pressureisthe sum of the partial pressureof dry air and partial vapourpressure.

P=Pa+Pv

The air is saturated when thevapour pressure(pv) is equal tothe pressure of the saturatedvapour of the sametemperature(pvs).

Relative humiditycan also beexpressed as the ratio ofactual vapour pressure to thesaturation point vapour

pressure. RH=AH/SHX100=Pv/Pvsx100%


10/19

PRECIPITATION

Precipitation is the collective

term used for rain, snow, hail,dew and frost that is for allforms of water deposited fromthe atmosphere.

It is measured by raingauges,i.e. calibrated receptacles, andexpressed in millimeter per atime unit.

Rain gauge

Th i i f ll f
http://en.wikipedia.org/wiki/Image:250mm_Rain_Gauge.jpg


11/19

The maximum rainfall for any24 hour periodis a usefulguide for the predication offlooding and for the design ofsurface drainage( roofs, pavedareas, gutters and downpipes)

the maximum hourly rainfallintensity should be known.

Values indicating the totalprecipitation for each month of the

year would show the pattern of dry

and wet seasons.

Ever recorded maxima and

minima would give an indication of

the reliability of rains.

Roof drainage

Ground drainage


12/19

DRIVING RAIN

The building designer maywant to know whether intense

rains are associated with

strong winds, in other words

what is the likelihood of driving

rain.

The driving rain index

characterisesagiven location

and express the degree of

exposure.

It is the product of annual

rainfall and annual average

wind velocity.

Actual rain penetrationwill

depend instantaneous rain on

the intensity and the

simultaneous wind velocity.


13/19

SKY CONDITIONS Sky conditions are usually

described in terms of presence

or absence of clouds. On average, two observations

are made per day, when theproportion of sky covered bycloudis expressed as apercentage.Few records exist of

night time sky conditions. It would be useful for the

designer to know the time of dayand frequency of observations.

A single average figuregiving

the sky conditionsfor a typicalday of a given month mayconceal significant differences,e.g. between morning andafternoon conditions, which mayaffect the design of roofs,

overhangs and shading devices.


14/19

SOLAR RADIATION MEASUREMENT

A simple sunshine recorderwillregister the duration ofsunshine, which can beexpressed in number of hoursper day, as an average for

each month. A variety of more

sophisticated instruments(solarimeter, heliometer,actinometer and pyranometer)are used for the quantitative

recording of solar radiation, butreliable and comparable datais few and far between.

Pyranometer

solarimeter


15/19

SOLAR RADIATION DATA

Average daily amounts of solarradiation for each month of theyear would give a fair indication ofclimatic conditions, includingseasonal variations.

This could be supplemented by

the highest and lowest dailytotalsfor each month, to setthe limits of variationswhichcan be expected.for thepurpose of detailed design,hourly totals or rather hourlyaverage intensities must be

known for typical day of eachmonth-or atleast for a typicallyhigh and a typically lowradiation day of the year.


16/19

WIND MEASUREMENT

Wind velocityis measured by acup-type or propeller anemometer,or by a pilot tybe and its directionis measured by a wind vane.

An anemographcan producecontinuous recordingsof wind

velocityand directional changes.

Measurements in urban areas aretaken at a height of between 10 to20m to avoid obstructions.

Velocities near the groundare agood deallower than the free wind

speed.a wind forcescaledeveloped by beaufort in 1806,based on visual observation, isstill in use in spite of its completelyunscientific nature.

Anemometer

Anemograph


17/19

WIND DATA

The designer must try todetermine whether there is aprevailing direction of winds,whether predictable daily orseasonal shifts occurand

whether there is arecognizable pattern of daily orseasonal velocities.

It is also important to note thecalm periodsin each month.allobservatories record the

occurrence of storms,hurricanes, typhoons, ortornadoes.


18/19

SPECIAL CHARACTERISTICS

Most regions experienceconditions which areparticularly unfavourable suchas hail and thunder storms,line or arched squalls,earthquakes,tornadoes,hurricanes and duststorms.

Although such events must berare it is important to extractfrom meteorological data theirfrequency, likely duration andnature.

The designer must classifyrare events into those whichaffect human comfort andthose which may endanger thesafety of buildings and thelives of inhabitants.
http://images.google.co.in/imgres?imgurl=http://earthscience.files.wordpress.com/2007/05/tornado.jpg&imgrefurl=http://earthscience.wordpress.com/&h=600&w=800&sz=35&hl=en&start=6&tbnid=_-dLqYjhR3N63M:&tbnh=107&tbnw=143&prev=/images%3Fq%3Dtornadoes%26gbv%3D2%26hl%3Den%26sa%3DGhttp://images.google.co.in/imgres?imgurl=http://www.ngdc.noaa.gov/hazard/icons/quiz/earthquakes.jpg&imgrefurl=http://www.ngdc.noaa.gov/hazard/quiz/jsp/quiz/kq.jsp%3Fhtype%3DEarthquakes&h=287&w=408&sz=24&hl=en&start=31&tbnid=mV8VjFg0ywse7M:&tbnh=88&tbnw=125&prev=/images%3Fq%3Dearthquakes%26start%3D18%26gbv%3D2%26ndsp%3D18%26hl%3Den%26sa%3DNhttp://images.google.co.in/imgres?imgurl=http://farm1.static.flickr.com/74/168182657_1fd2d10b3b.jpg%3Fv%3D1154064145&imgrefurl=http://flickr.com/photos/47897425%40N00/168182657/&h=500&w=400&sz=120&hl=en&start=12&tbnid=cZn_eBrigdkUyM:&tbnh=130&tbnw=104&prev=/images%3Fq%3Dhail%2Band%2Bthunder%2Bstorms%26gbv%3D2%26hl%3Den%26sa%3DG


19/19

VEGETATION

The picture of climate is

incomplete without some noteson the character andabundance of plant life.

Although generally regardedas a function of climate,vegetation can in its turn

influence the local or siteclimate.

it is an important in the designof out door spaces providingsun shading and protectionfrom glare.

This section of the climaticsurvey may range from a fewnotes about local species ofplant life to a lengthycompendium of the majornative plants and trees- theirshape and colour, also their

preferred orientation andsituation
http://images.google.co.in/imgres?imgurl=http://www.botany.unibe.ch/vegeco/images/danum_hi.jpg&imgrefurl=http://www.botany.unibe.ch/vegeco/index.php&h=300&w=400&sz=41&hl=en&start=9&um=1&tbnid=ag53cC_xw7fwOM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dvegetation%26gbv%3D2%26um%3D1%26hl%3Den%26sa%3DG

elements of climate.1ppt

Documents