Tropical Design Module 5: Climatic Zones for Bldgs

CLIMATIC ZONES FOR BUILDING

Comfort Zone
The range of conditions under which most people feel comfortable. It is a function of a number of variables

Thermal Comfort
Human comfort as determined by the ability of the body to dissipate the heat and moisture it produces by metabolic action.

Relationship between the centre of the comfort zone and the annual mean temperature (Carl Mahoney):
Tcc = Tam/4 + 17.2
where Tcc is the center of the comfort zone in E.T. oC
and Tam is the annual mean temperature
*Always correct to the nearest 0.5 upwards

To get the Tam (annual mean temperature):
Tam = (Highest DBT of the Year + Lowest DBT of the Year) / 2
Psychrometric Chart
A chart relating the wet-bulb and dry-bulb readings from a psychrometer to relative humidity, absolute humidity and dew point

COMFORT ZONE

The comfort zone criteria given above are for sedentary activities:
discomfort due to slight sweating in sedentary activities may be more uncomfortable and disturbing as it interrupts concentration.

The comfort zone is compared with the mean maxima (day) and minima (night) effective temperature for each month to find out if the climate is comfortable or uncomfortable.

Recommendations to achieve comfort can be made for a great number of aspects from space between buildings, building form, down to detail aspects of design.
§ consider window size together with other factors such as glazed area, orientation, shading and building form consider thermal characteristic of roofs and walls, i.e., absorption of the surface and the insulation of the construction.

Tropical Design Module 4: Passive Cooling

Passive Cooling

A cooling system using a building’s design and construction to maintain a comfortable temperature within the building.

Passive design is essentially low-energy design achieved by the building’s particular morphological organization rather than electro-mechanical means.

Passive Cooling Techniques

1. BUILDING CONFIGURATION, SITE LAYOUT and SITE PLANNING
Example : A building can be protected from direct sunlight by placing it on a location within the site that utilizes existing features such as trees, terrain etc.

2. BUILDING ORIENTATION
Example : In tropical countries such as the Philippines, it is best to place service areas in the west and east facing sides of the building because these sides are exposed to direct sunlight.

3. FACADE DESIGN
Use of Double-layered façade
Use Low-emissivity glass (Low-E glass)
Use of Insulation

4. CROSS VENTILATION
The circulation of fresh air through open windows, doors or other openings on opposite sides of a room

STACK EFFECT / CHIMNEY EFFECT
The tendency of air or gas in a shaft or other vertical space to rise when heated, creating a draft that draws in cooler air or gas from below

5. SUNSHADING DEVICES
VERTICAL TYPES
Vertical Sun Shades are generally used on the East-Facing and West- Facing Sides
of a building
EGGCRATE TYPES
Combination of Horizontal and Vertical Shades

WIND ANALYSIS
Wind direction: Desirable and undesirable winds in each of the climatic zones depend largely on local conditions. Any breeze in the lower latitude (tropical and arid climates) is beneficial for most of the year.
Cross ventilation: Cross ventilation is far more important in the tropics than in temperate zones. The theoretical strategy for blocking or inducing wind flow into a building is based on local prevailing wind conditions. Generally, for the tropical zones as much ventilation as possible is desired.

Influences on Built Form
1. Zoning for transitional spaces -the traditional spaces used for lobbies, stairs, utility spaces, circulation, balconies and any other areas where movement take place. These areas do not require total climatic control and natural ventilation is sufficient. For the tropical and arid zones, the transitional spaces are located on the north and south sides of the building where the sun's penetration is not as great. An atrium can also be used a transitional space.

2. Use of atrium
In the tropical zone the atrium should be located so as to provide ventilation within the built form. In the arid zone the atrium should be located at the centre of the building for cooling and shading purposes.

Influences on Built Form
1. Form: Optimum building form for each climatic zone. Research has shown that the preferred length of the sides of the building, where the sides are of length x:y, are: tropical zone - 1:3

Analysis of these ratios shows that an elongated form to minimize east and west exposure is needed at the lower latitudes.

2. Orientation: Orientation as well as directional emphasis changes with latitude in response to solar angle. Building's main orientation for tropical countries would have a directional emphasis on an axis 5deg north of east

3. Vertical cores and structure The arrangement of primary mass can be used as a factor in climatic design as its position can help to shade or retain heat within the building form. For the tropical zone, the cores are located on the east and west sides of the building form, so as to help shade the building from the low angles of the sun during the major part of the day.

Tropical Design Module 3: Climatic Design

Tropical Design

This is concerned with countries where discomfort due to heat and humidity are the dominant problems.

Tropical Design is applicable to Tropical and Sub-tropical climates and Equatorial Climates covering the Southeast Asian Countries.

Importance of Climatic Design

Climate has a major effect on building performance and energy consumption.

The process of identifying, understanding and controlling climatic influences at the building site is perhaps the most critical part of building design.

The key objectives of climatic design include:

ü To reduce energy cost of a building

ü To use "natural energy" instead of mechanical system and power

ü To provide comfortable and healthy environment for people

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.

Tropical Design Module 2: Climate Elements

Basic Concept:

"Weather" is the set of atmospheric conditions prevailing at a given place and time.

"Climate" can be defined as the integration in time of weather conditions, characteristics of a certain geographical location.

At the global level climates are formed by the differential solar heat input and the uniform heat emission over the earth's surface.

The movement of air masses and of moisture-bearing clouds is driven by temperature differentials and strongly influenced by the Coriolis force.

Classification of Climates:

Equatorial
Example: Those countries lying just above or below the equator, Southeast Asian Countries, Central America and the Amazon Basin in South America

Cool Temperate
Example: N.W. Europe, Canada, and parts of North America

Warm Temperate
Example: Mediterranean Countries

Cool Temperate
Example: N.W. Europe, Canada, and parts of North America

Arctic
Example: Iceland, Greenland, Northern Russia, and China

For the purposes of building design a simple system based on the nature of the thermal problem in the particular location is often used.

Further Classification of Tropical, Sub-Tropical & Equatorial Climates:

A. Warm Humid (Tropical Island) overheating is not as great as in hot-dry areas, but it is aggravated by very high humidities, restricting the evaporation potential. The diurnal temperature variation is small.

B. Hot Dry (Arid/Maritime Desert) main problem is overheating, but the air is dry, so the evaporative cooling mechanism of the body is not restricted. There is usually a large diurnal (day - night) temperature variation.

C. Composite (Tropical Uplands)

Warm Humid:
High temp during the day, low diurnal change; Relatively high humidity: Heavy rains especially during monsoon season; Cloudy and glaring sky; Lesser ground vegetation
Hot Dry:
Very high temp during the day; large diurnal range; can be quite low in winter; Low and very low humidity; fairly constant throughout the year; Often low or very low precipitation; Little or no cloud. Cold and non-glaring sky; Sparse and often bare ground vegetation. Very high glare from ground. Rich soil which only requires water
Composite:
Mixture of warm/humid and hot/dry.; 1/3 to 2/3 ratio of monsoon period

The general climate (macroclimate) is influenced by the topography, the vegetation and the nature of the environment on a regional scale (mesoclimate) or at a local level within the site itself (microclimate).

Tropical Climate: Philippines

Temperature – average mean temperature (dbt) 20 – 30 deg C
small diurnal temperature change/range 2-5 deg

Humidity Levels - 50% - 100% Relative Humidity

Wind Conditions – Slow Wind Flow; Average of 2 m/s

Prevailing Wind in the Philippines :
Amihan (NE) – November to April
Habagat (SW) - May to October

Sky Conditions – Overcast Sky most of the time; a lot of reflected heat/ solar gain

Precipitation – high during the year – average of 1000mm/yr

Micro-Climate:
Many factors contribute to micro-climate, for instance, the location of hills, rivers, streams and lakes, the position of buildings and trees, whether the site is on coast or inland, in a town or in the rural areas, whether the location is above sea level, etc.

Some micro-climate phenomena are:
- land/sea breeze
- Courtyards
- Evaporative cooling
- Orientation
- Slope of land height in relation to air movement, rainfall and temperature

Urban Climate:
Almost every city in the world today is hotter - usually between 1 to 4 deg C hotter - than its surrounding area. This difference between urban and rural temperatures is called the "urban-heat-island" effect", and it has been intensifying throughout this century.

Elements of Climate Needed in Design:

A. DBT (Dry-Bulb Temperature) – measurement of the temperature of the air and as far as possible excludes any radiant temperature; measured in the shade.
instrument – silvered thermometer (in 0F or 0C)
- monthly mean of daily maxima (deg C)
- monthly mean of daily minima (deg C)
- standard deviation of distribution

B. Wind – direction, frequency and force of the wind throughout the year.
instrument – vane anemometer for high speeds
kata thermometer for low speeds

C. RH (Relative Humidity) – amount of water in the air.
instrument – hygrometer (in %) or sling psychrometer
measured in 0F or 0C if WBT (wet-bulb temperature)
- early morning relative humidity (in %)
- early afternoon relative humidity (in %)

D. Precipitation – mainly rainfall but could also be dew.
instrument – rain gauge measured in inches or centimeters
- monthly total (in mm)

E. Sky – either cloud cover, measured in 1/8 or 1/10 or % of the sky covered, or it could be measured in hours of sunshine
Cloud cover - 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.

F. Solar Radiation - 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.

Four environmental variables directly affecting thermal comfort are temperature, humidity, solar radiation and air movement, these are the four constituents of climate most important for the purposes of building design. Rainfall data may sometimes be needed, such as for designing drainage systems and assessing the level of precipitation.

Tropical Design Module 1: Introduction

Climate Responsive Architecture is a must in Building Design.

Architects must realize that the building skin is not just specifying materials and creating a façade for aesthetics.

The building envelope serves as a climatic mesh that filters the outside environment to create a proper and hopefully a comfortable indoor environment.

A climate responsive building envelope is only one functional criterion for correct design.

In the Philippines, hot humid conditions require protection from heat and maximum ventilation for interiors, therefore, local designs should firmly consider these issues.

Proper fenestrations and building materials should be selected.

Opening fenestrations such as sun-shading devices should be considered by designers.

Good building orientation must also be looked at by architects to minimize direct solar radiation but maximize potential for natural ventilation.

Planning 3 Module 2: Ekistics

Human settlements are no longer satisfactory for their inhabitants…
�economically speaking
- don’t have the means to satisfy their basic needs
- remain homeless or live in houses of very low quality
�social point of view
- man appears to be lost in the big cities
- feels abandoned by progress in many small towns/villages
�political level
- new types of societies and new types of people have not found their corresponding political institution.
�technical point of view
- most settlements don’t have the facilities indispensable to their proper functioning in spite of the technological achievements
�aesthetically
- the ugliness of human settlements around

creating better conditions for tomorrow can be understood better if we look into the different elements of the human settlements…

Human Settlements & their Elements

Human settlements are settlements inhabited by man. Human settlements should satisfy man.
Human settlements consist of:
a. the CONTENT (man, alone or in societies)
b. the CONTAINER (or the physical settlement, which consists both natural and man-made or artificial elements)

When taken together make up the human settlement whose largest possible dimensions are defined by the geographic limits of the earths surface.

The total surface of the Earth:
�the largest possible container of man
�the whole cosmos of man
�the cosmos of the anthropos
�the anthropocosmos

Such definition of human settlement implies that it is not merely 3-dimensional but 4-dimensional. . .
- man & society change continuously and by so doing, create functions which unlike shells (which can be conceived in 3-dimensional terms) require a fourth dimension ---TIME in order to be carried out
- a 3-dimensional conception of a settlement is very like a film which suddenly stops and arrest all the figures in their movements. A still photograph of a building looks real only if there are no human figures in the pictures; if people have been arrested in the process of walking in front of the building, then the picture is frozen, unreal.


A human settlement needs both categories of elements in order to come into existence…
� man alone or in groups, if not settled anywhere cannot be said to form a settlement or even a part of one.
� once he does settle somewhere even temporary, we have a temporary, elementary settlement in which a pattern of relationship between man and his container comes into existence for a certain period of time (one day, many days, or one season) regardless of whether the container is a natural one ( a cave) or man-made (tent or a building).


Nature alone, without man, cannot be said to form a settlement or even a container, since it has no human content…
� a man-made settlement is only the corpse or the abandoned shell of a settlement, which must be considered dead as in any other corpse.
� some people call dead settlement a “settlement” but this is no more correct calling the shell of a snail a snail.
� term is used in many such cases for reasons of simplicity, but this is not accurate and should be used with care to avoid confusion.

2 basic elements of human settlements (Doxiadis)
THE CONTENT AND THE CONTAINER
This can be further subdivided into 5 categories (in hierarchical order)
(Container)� NATURE – providing the foundation upon which the settlement is created and the frame within it can function
(Content)� MAN – an individual, Homo Sapiens
- biological needs (oxygen, nutrition)
- sensation and perception (5 senses)
- emotional needs (satisfaction, security, sense of belonging)
- moral values
(Content)� SOCIETY – a group of individuals sharing the same culture, values, norms, and traditions
(Container)� SHELLS or the structures within which man lives and carries out his different functions, the built component.
(Container)� NETWORKS or the natural and man-made system which facilitate the functioning of the settlement, or links within the settlement, roads, communications systems, utilities, etc.

Hierarchy of human settlements…
� a hamlet, a neighborhood, a small village
� a community, a town
� a city, an urban area
� a metropolis
� a conurbation – a composite of cities, metropolises, urban areas
� a megalopolis – merging of two or more metropolises with a population of 10M or more; a 20th century phenomenon (Megalopolis - concept coined by Jean Gottmann for urban complexes in the Northeastern United States.)

… a hierarchy of settlements is characterized by a few large cities, some medium-sized cities, and many small settlements.

go to Module 3: http://pupclass.blogspot.com/2008/06/module-3-planning-3-location-theory.html

Planning 3 Introduction (Module 1b)

Cities are a human invention. They are the result of a deliberate effort to expand social life and to make it more satisfying. The invention of agriculture and invention of cities resulted in complex social organizations. Longer life spans, larger populations, expanded knowledge and education, improved health, expanded welfare, and the proliferation of the arts and of recreational activities became major aspects of urban way of life.

Urbanization has saturated many of the world societies. Early cities developed government, commerce, and religion as distinct activities and occupations. Early urban way of life was clearly different from the rural way of life. But urban social organizations continued to grow beyond walls and city limits. Cities are people – ideas of culture and science – more than they are physical buildings or geographical places.

City-generated lifestyles are now spreading so rapidly that we may expect them soon to urbanize the entire archipelago...

HOMOS SAPIENS
…early times, a rare animal living in sporadic but intense competition with other animals and subsisting by hunting and food gathering.
…became successful in adapting his environment to his own needs and in the creation of artificial habitats.
…gained a position of almost complete domination over all other forms of life on earth, greatly expanded his sources of food and energy and his ability to modify the effects of nature on him.
…unique skills and powers evidenced by the great increase in his numbers

Human population is doubling itself within one hundred years.

T.R. Malthus, an English economist theorized that “population increases in a geometric ratio while subsistence increases arithmetically and that unless natural catastrophes, war, or sexual restraint control population increase, worldwide famine or war will follow.”

Exploitation of nature in new and disturbing ways were recognized.
Increasing numbers of mankind and the supplies of food and shelter are the most profound problems

…beyond mere subsistence lie questions of the quality of life – bodily and mental health, happiness, fulfillment, joy.

The ultimate source of all the benefits of life is the EARTH itself and man’s relationship to all its life and resources.

Man’s life is intricately woven into the whole web of life on earth. His astonishing powers have not enabled him to control nature in any categorical sense but merely to administer much more disturbances than before.

No matter how socialized our activities are, how artificial their immediate environment and how much local and immediate control may be exercised, WE ARE PART OF THE PLANET’S ECOLOGY AND WE IGNORE THE FACT AT OUR PERIL

Solutions must come about in two ways…
- there are enormous ethical problems raised by the need to make choices and decisions affecting the relationships between men and all other forms of life and between different human groups.
- there is the problem of understanding the nature of all these relationships in order to create more effective and sympathetic controls over the problem.

This course is concerned with the aspect of understanding the complex systems of man’s activities in the whole context of the planets ecological systems.

go to Module 2: http://pupclass.blogspot.com/2008/05/planning-3-module-2-ekistics.html