Citation
The influences of the natural climatics system in designing residential buildings in hot-humid climates

Material Information

Title:
The influences of the natural climatics system in designing residential buildings in hot-humid climates
Creator:
Virapat, Yananuch
Place of Publication:
Denver, Colo.
Publisher:
University of Colorado Denver
Publication Date:
Language:
English
Physical Description:
1 v. (unpaged) : ill., charts, plans ; 28 cm.

Thesis/Dissertation Information

Degree:
Master's ( Master of Architecture)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
School of Architecture and Planning, CU Denver
Degree Disciplines:
Architecture
Committee Chair:
Kindig, Robert W.
Committee Members:
Boonyatikarn, Soontorn
Gallegos, Phillip

Record Information

Source Institution:
University of Colorado Denver Collections
Holding Location:
Auraria Library
Rights Management:
Copyright Yananuch Virapat. Permission granted to University of Colorado Denver to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Resource Identifier:
24236094 ( OCLC )

Full Text
A+P LD 1190 A72 1990m V57
jU18700 7620401
Virapat, Yananuch.
The influences of the
natural climatics system in
THE INFLUENCES OF
THE NATURAL CLIMATIC SYSTEMS
IN DESIGNING RESIDENTIAL BUILDINGS
IN HOT HUMID CLIMATES
by
YANANUCH VIRAPAT
THESIS SUBMITTED
IN PARTIAL FULFILMENT OF REQUIREMENTS FOR THE
DEGREE OF MASTER OF ARCHITECTURE
POST PROFESSIONAL PROGRAM
SCHOOL OF ARCHITECTURE AND PLANNING
UNIVERSITY OF COLORADO AT DENVER
SPRING 1990


THESIS TITLE The Influences of the Natural Climatic Systems in Designing
Residential Buildings in Hot-Humid Climates.
BY Lt. Yananuch Virapat ,wrtn.
ADVISOR Prof.Robert W. Kindig
Prof. Soontom Boonyatikam
ACADEMIC YEAR Fall, 1989 and Spring ,1990
Accepted by School of Architecture and Planning, University of Colorado at
Denver in partial fulfillment of the requirements for Thesis Research and
Programming.
Committee Members
..................... f- Member
(Prof.Soontom Boonyatikam)
........................ Member
(Prof.Phillip Gallegos)
Student
(Yananuch Virapat)


Climate Data
Local weather data
(Thailand)
- Temperature
- Relative Humidity
- Sunshine
-Wind
- Precipitation
<>
A detailed analysis the
complete yearly cycle
O
Evaluate the climatic
situation of a given
location
SCOPE OF STUDY
The Influences of the Natural Climatic Systems
in Designing Residential Buildings in Hot-Humid Climates
by
Yananuch Virapat
Biological Evaluation Technological Solutions Architectural Applications
Evaluate the climatic
impact in physiological
terms
( Bioclimatic chart)
O
Climate comfort problems
Apply the technological
solutions to climate -
comfort problems
- External factor
- Landform
- Vegetation
- Water body
- H.T. capacity
- Building envelope interfere
- Form / Envelope
- Material use
- Shading device /
Solar control
- Orientation
- Building placement
- Interior factor
-Interior heat gain
O
Experimentation and
case study analysis

Design goals

Combine the solutions with the architectural unity
o
Architectural design

Fall semester 1989
Spring semester 1990


CONTENTS
Introduction
Climate Data
Hot-humid climates
Climatic evaluation by region
Micro climate and site integration
Climate conditions (Thailand)
Biological Evaluation
The bioclimatic approach
The bioclimatic chart
Technological Solutions
Shading device / Solar control
Form / Envelope / Material use
Wind
Internal Factor
Case Studies
Design Goals
Bibliography


INTRODUCTION
All living beings have to cope successfully with climate in order to survive on
this earth. By interposing another level of environmental between human beings and
the environment beyond it, is the method that they have to learned to control the
climate The shelter is the first man-made environment for human existence so it is
the most basic form by maintaining a level of attainable comfort on the part of human
beings.
There are four conditions of environmental elements that influencing human
comfort, these are solar radiation ambient air temperature relative humidity and
wind speed.
Nowadays architects design the buildings that are comfortable to live in as
well as utilitarian and attractive. The buildings are designed and built in direct response
to the natural environment, the available technology and the prevailing lifestyle. The
concept of climate-adapted building from both the human and energy viewpoints and
the development of new dynamic technologies have increased the potential for active
rather than passive envelope. Design to control the indoor environment and hence the
placing of less emphasis on mechanical equipment requiring nonrenewable energy
source.
A building's indoor thermal conditions should be more closely attuned to the
local climate. It is possible to use external climatic energy sources by filtering and
distributing them to occupied space via the envelope for end uses such as lighting,
cooling, heating and ventilation.
It is evident that human comfort is inextricably woven into building design and
the fabric and servicing of buildings. Buildings create environments. They provide the
temperature, humidity, lighting and ventilation necessary for people to live and work
productivity. The building envelope components can no longer be considered in
isolation, and it is necessary to examine at an early stage in the building design the
implications and interactions of.
Overall, the design objective should be to seek the solution with regard for
human well being which minimal over all costs are obtained with the greatest possible
energy savings.
To build responsively to the outside climate and reduce dependence on
mechanical systems is one of the most effective ways to save energy in residential
buildings.
Temperate, humidity levels, wind speeds and sunshine define the climatic
environment in which a building must operate. This climate is made up of four factors
as follow.
- Temperature
- Humidity
-Wind
- sun


HOT- HUMID CLIMATES
The hot-humid climates are in those areas shown on the accompanying map
where there is a relative humidity (open 90% ), heavy rainfall and a mean temperature
all the year round of over 64 F, but which may reach almost 100 F in the hot season.
The characteristics of this climate are oppressive, mostly dark-green vegetation all the
year round, often two wet seasons with the rain in coastal areas sometimes falling at
ninety degrees inclination. The glare is greater than in the torrid zones but may be duller
when the sky is overcast, ranging from 250-2,000 Ft.-lamberts, wind speeds may
reach 80 M.P.H. in open areas.
These conditions mean that buildings and humans need protection from rain and
sun, but because of the heavy humidity, air movement becomes a friend to dry and to
relieve acute discomfort. The humid zone demands shade externally by means of large
overhangs and other devices which also give protection from driving rain so that the
main walls of the building may be as open as possible to allow air movement through
the building.
In order to understand how to design for these conditions, an architect must
realize that there are three principle ways in which a body can lose heat: by radiation,
convection and evaporation. 1
In the humid zones where the diurnal temperature range is small by comparison,
due largely to water vapour in the air and considerable cloud formations, choice of
materials is not so greatly affected by rapid temperature changes. The effect of the
shadows cast by sunlight falling on to a building and the position of the sun at different
times of the day with its degree of penetration into a building are definite and
predictable. The design and effectiveness of sunshade devices and the measurement of
day lighting and reflection from adjacent surfaces may be determined. 2


Characteristics of hot-humid climates
Temperature (Daily range -average) Day-time air temperature dry season 20 F up wet season 10-15 F dry season 90 F up wet season 80-90 F
Night-time air temperature dry season 70-80 F wet season 75-80 F
Annual range Sky temperature Humidity 10-20 varies with season dry season 13-16 mb. wet season 20-25 mb.
Relative humidity dry season 20-55 % wet season 55-95 %
Rainfall Other characteristics of rainfall seasonal, 20-25 in. little or no rain in dry season 7 l/2"-10" ( 178-254 mm. )in wettest month
sky conditions, Depends on season, during rains as tropical, humid sky. Immidiately after rains, clear and blue, as island sky. Later in dry season bright with increasing dust in lower part of the sky, as
Ground conditions, General appearance desert sky. During rains, green as dry season progresses, vegetion dries and ground becomesbright-brown or reds.
Soil moisture soil Air movement monsoon Other characteristics May be damp in rains, but dries rapidly, risk of erosion. seasonal, fairly strong and steady during period change in relative humidity dry-wet season and vice-versa causes materials, especially timber, to shrink or swell excessively 3
Data from -Tropical Architecture in the dry and humid zones Table one page 18-19
I


CLIMATE BALANCED
The hot humid area presented two major problems to its inhabitants as follows:
1. The avoidance of excessive solar radiation
2. The evaporation of moisture by breezes.
The desirable would be to work with, not against, the forces of nature and to
make use of their potentialities to create better living conditions and utilizes all natural
resources favorable to human comfort which is called climate balanced".
The process of building a climate-balanced can be divided into four steps as
follows:
1. Climate data
Survey climatic elements at a given location about temperature, relative
humidity, radiation and wind.
2. Biological evaluation
Evaluate the climate impact in physiological terms by plotting the climate
data on the bioclimatic chart.
3. Technological solutions
Apply the technological solutions to climate-comfort problem
4. Architectural application
Combine the solutions with the architectural unity 4
A DETAILED ANALYSIS COVERING THE COMPLETE YEARLY CYCLE
CLIMATIC EVALUATION BY REGION
LOCAL WEATHER DATA
- Thermal analysis Diurnal cycle of the average hourly
temperatures and the degree days
- Solar analysis - The hours of sunshine
- The average amount of solar heat
striking a horizontal surface.
- The direction of the sun -altitude, azimuth
- Wind analysis - Wind directions and velocities
- Storm patterns and gale days
- Precipitation analysis The amount of precipitation
- The maximum rate of rainfall
- Humidity analysis - Average hourly percentage of relative
humidity
- Average and extremes in vapor pressure
EVALUATE THE CLIMATIC SITUATION OF A GIVEN LOCATION


Plotting of combined temperature and relative humidity data on the chart at
regular intervals will show the general characteristics of a region.
The hot humid area presented two major problems to its inhabitants as follows:
1. The avoidance of excessive solar radiation
2. The evaporation of moisture by breezes.
The desirable would be to work with, not against, the forces of nature and to
make use of their potentialities to create better living conditions and utilizes all natural
resources favorable to human comfort which is called" climate balanced".
When the climate is too hot for comfort, you instinctively seek the coolest spot
available, well shaded from the hot sun, to shield yourself from the liabilities of this
climate.
The basis for effective energy conscious design is responding to the liabilities
and assets in the climate which determine the mechanical system's loads and resulting
energy use.
For hot-humid climates, climatic liabilities are those factors ( of sun,
wind,temperature and humidity ) which make the seasonal conditions worse.
- Sun - can be a significant problem in hot climate.
- Temperature can be a liability in hot climates especially if it is too hot.
- Moisture can be a liability if it comes in the form of humidity, causing
such stickness that one cannot evaporatively
cool.
Climatic assets are those forces which make the seasonal conditions more
comfortable. These assets can be accomodated with simple design changes such as
siting, orientation, wall construction and window placement
- Wind
ventilation,
- can be an asset in hot humid climates to provide natural
allowing air conditioners to be shut off.
MICRO CLIMATE AND SITE INTEGRATION
The climatic condition of a specific site depends on the influence of the climate
zone and the site component.
EXTERNAL FACTOR
1. Landform
The angle of a sloped ground surface has a significant effect on the
micro-climate of a specific site The orientation of the slope determines the amount or
solar radiation which strikes the site and, to a certain extent, affects the air flow pattern
on the site.


The slope of the land also has an effect on the aspects of winds and
breezes. The wind speeds at the crest of a hill are greater than those on level land. The
speeds generally are lower on the lee side than on the windward size of a hill and
depend on the relative sloping angles of either side of the hill.
-Use land forms to protect against wind.
-Building adjacent to hill to form exterior use area.
-Use as a screening device.
-Slope exterior use areas for positive drainage and to avoid glare of sun
reflection.
-Use hill with building to form entry space.
2, Vegetation
Vegetation controls micro-climate by the filtration of solar radiation
impinging on a ground surface, altering wind speed and direction, and modifying the
moisture in the air .The more radiation that falls on the ground, the more that can be
absorbed and reradiated, thus causing alteration of ground temperature.
Trees can be used to reduce the amount of radiation falling on the
ground and shading the building nearby, trees are also be used as a windbreak or
screen to reduce the wind impact on a building During the season where natural
cooling is needed, proper planting of trees can increase the degree of cooling by
accelerating and channeling wind through an opening or guiding it in a desirable
direction.Trees also prolong the amount of water retained underground, This water
will ultimately be transpired or evaporated.
-Use to screen bad situation
-Use as visual screen
-Sun protection
-Wind protection
-Avoid glare of sun reflection and filtration of solar radiation
-Increase degree of cooling desirable direction modify moisture in the ai
-Landscaping to avoid blowing dust
3. Water bodies
The presence of significant water bodies on or near a site has
considerable influence on the temperature For the most part the variation in seasonal
and diurnal temperatures is much less as compared to sites away from water
bodies.Water bodies of all types are able to modify climate and reduce temperature
extremes.A major oprtion of solar energy is stored in water and only small percentage
of the energy is radiated off the water surface, as compared to land surfaces in which a
smaller percentage of solar energy striking the land is stored while a large portion of
that energy is radiated back into the atmosphere.Since water radiates a smaller
percentage of solar radiation than does a land mass it acts as a moderating influence
for abrupt variations in temperature of land nearby.
The different temperatures of water and land during day and night create
a movement of air mass. Air moves from warmer surface of water to land during the
night and from the warmer surface of land to water during the day.
Water bodies can be used to :
- Modify climate


- Reduce temperature extremes
- Create a movement of air mass/wind.
- Evaporative cooling to the air.
-Use breeze & evaporation from pool as cooling devic
-Use fountains & pool to reduce temperature.
4. HT. capacity
Energy falling on different surfaces will be reflected, absorbed and
reradiated at different rates. The surface with higher absorptivity will have a higher
potential to absorb energy in the form of heat. Once the solar energy strikes a surface,
part of it will be reflected back into the atmosphere, the other part will be absorbed. The
absorbed part can eventually be dissipated in four ways by heating the air through
convection, by radiation, by heating the attached materials and the evaporation of water.
The amount of heat due to absorption which is retained in a material depends greatly on
the mass or storage capacity of such material.
The nature of ground surface around a building has a very significant
impact on the ambient air temperature at the living level. It is necessary to pay attention
to this temperature around the building, which should be minimized or augmented
depending on whether one is dealing with mainly cold or mainly hot climat
Country area Cities area
Heat soil, plants
O
Dissipated through transpiration
from trees.
Heat concrete steel, brick, little water
O
Dissipated through heating the air and solid
materials of the subsurface.
THAILAND
Bangkok
- Latitude and longtitude ( ') 13 44N/100 30E
- Elevation (ft.) 39
- Winter
- Mean of annual extremes 57
-99% 61
- 97 1/2% 63
- Summer
- Design dry bulb
- 1% 97
- 2 1/2% 95
-5% 93
- Outdoor daily range ( F) 18
- Design wet bulb
- 1% 82
- 2 1/2% 82
-5% 81 5
Data from Ashrae Handbook 1977 Fundamentals chapter 23, Table 3, Page 23.22


AVERAGE TEMPERATURE:
Bangkok, Thailand
1988
Jan
Feb.
Mar.
Apr.
May
June
July
Aug.
Sep.
Oct.
Nov.
Dec.
cold cool comfort warm hot
cold = below freezing
cool = 40-60 F
comfort = 60-80 F
warm = 80-90 F
hot
= above 90 F


Maximum temperature,
Bangkok, Thailand
1988
Minimum temperature,
Bangkok, Thailand
1988
ft


sunshine duration ( hours ) Ave.temp.
Average temperature ,
Bangkok Thailand
1988
sunshine duration ,
Bangkok, Thailand
1988
month


Maximum relative humidity
Bangkok Thailand
1988
Minimum relative humidity,
Bangkok, Thailand
1988


Average relative humidity,
Bangkok,Thailand
1988
Rainfall,
Bangkok,Thailand
1988


Wind vclocih ,
Bangkok, Thailand
19SS
Wind Directiu.. ,
Bangkok Thailand
1988
Non 11
month
CU Nat e
pAT.A : DATA t>P.0C-S4$\H & $99 ^VISION ? CUHAToLOSA/ DIVISION


BASIC CLIMATE CONDITION
The basic climate condition is not comfort with almost periods of overheating
due to temperature although the humidity is within the comfort range.
- Too hot for comfort 83 % of the year
- Comfortable 17 % of the year
Climate and comfort are not purely a function of temperature and humidity. The
effects of solar radiation, wind moisture addition and diurnal temperature ranges
consignificantly improve individual and room comfort.
1. Temperature a liability
The major liability of this climate is that temperatures are high almost all
of the year which are liabilities to human comfort and require positive methods of
compensation by letting wind and humidity become assets.
2. Sun a liability when it's too hot for comfort
In this climate uncontrolled exposure to solar radiation can cause
significant cooling loads and severely reduce the amount of natural comfort available.
Proper design can shield interiors from overheating when temperatures are comfortable.
3. Wind an asset when it's too hot for comfort
In this climate winds can contribute to comfortable living by increasing
evaporative heat loss from the human body. Taking advantage of the winds for
controlled ventilation. The periods of natural comfort can be extended throughout the
warmer months, eliminating the need for air conditioning.
4. Moisture a liability when it's too hot for comfort
Humidity significantly reduces the comfort period. The poor placement
of fountains,pools, plants and other moisture producing elements can increase the
relative humidity and decrease the periods of comfort.


HOT- HUMID CLIMATES (THAILAND)
It is characterized by hot humid temperatures most of the year, totally passive (
non-mechanical ) comfort can easily be achieved. Methods of ensuring natural sun
control and natural ventilation are as follows :
- Natural sun control and natural ventilation to keep out direct sunlight and
maintain an adequate level of air movement.
- Houses raised for ventilation and flood protection
- Jalousies to catch wind and breezes.
- Lanais to screened perimeter porches for outdoor living.
- Sunshading
- Reflective roof
THE BIOCLIMATIC APPROACH
The major elements of climatic environment which affect human comfort can be
categorized as
- Temperature
- Humidity
- Radiation
-Wind
Means by which the body exchanges heat can be classified into four main
process
- Radiation 2/5 (Heat loss of the body )
- Conduction
- Convection 2/5
- Evaporation 1/5
Relation of human body to the climatic elements
Ivajoration Conduction Convection Sadiation
Human reaction
( Heat loss oi the holy)
Indices of comfort
(Operative temperature)
Main climatic
elements


The human being with a body temperature averaging 98.6 F seeking a
comfortable temperature condition. The desirable comfort zone indicated lies between
30 and 65 % relative humidity.
THE BIOCLIMATTC CHART
The bioclimatic chart was built up with dry-bulb temperature as ordinate and
relative humidity as abscissa. Any climatic condition determined by its dry-bulb
temperature and relative humidity can be plotted on the chart. If the plotted point falls
into the comfort zone we feel comfortable in shade. If the point falls outside the
comfort zone, corrective measures are needed. If the point is higher than the upper
perimeter of comfort zone winds are needed. And if the temperature is high and
relative humidity is low grains of moisture ( pound of air ) are needed.If the point is
lower than the perimeter of the comfort zone radiation is needed to counteract lower
dry-bulb temperature. 6
A good many of these measures may be achieved by natural means, by adapting
architectural design to utilize the climatic elements.


120
I 10
100
90
80
70
60
50
40
30
20
Bioclimatic chart (max.)
Bangkok Thailand
1988
M.R.T
shading line
btu./hour
Radiation
Freezing Line
10 20 30
40
60
70

-AO
80
90
I0(
rh.max


min. temp.
Bioclimatic chart (min.)
Bangkok, Thailand
1988
120
100
90
80
70
60
50
40
btu./hour
Radiation
Freezing Line
30
20
0 10
20 30 40 50 60
70 80 90 100
rh.min


120
1 10
100
90
80
70
60
50
40
30
20
Bioclimatic chart (ave.)
Bangkok ,Thailand
1988
btu./hour
Radiation
Freezing Line
T
0
10 20 30 40 50 60 70 80
90
!0(
rh.ave


temp.
Bioclimatic chart ( min., max.)
Bangkok Thailand
1988
Freezing Line
30 H
20
T
40
0
20
rli.min


120
1 10
100
90
80
70
60
50
40
30
20
Bioclimatic chart ( min., max., ave.)
Bangkok Thailand
1988
M.R.T.
btu./hour
Radiation
Freezing Line
20
40
60
80
100
RIM


It is the task of the architect to make utmost use of the natural means available
house, and to achieve a saving in cost by keeping to a minimum the use of mechanical
aids for the climate control. 7
The yearly temperature distribution is compressed into a very close range and
remains fairly constant on the side of extreme humidity. The temperature remains at
overheated levels most of the year.
Winds effects play an important part as relief from both high temperature and
humidity and even when temperature would be in the comfort range, vapor pressure
requires air movements The evaluation chart indicates that throughout the year shading
is required and air movements are needed to counteract vapor pressure indepedently of
the temperature situations. 8
The hot humid area presented two major problems to its inhabitants:
1. The avoidance of excessive solar radiation.
2. The evaporation of moisture by breezes.
To cope with these problems, we should design as follows
1. Allow free air movement.
2. Raised large gable roofs
- insulate against the sun.
- throw large areas of shadow over the dwellings.
3. Steep angle and extensive overhang of roofs protected against rainfall.
4. The floors were elevated
- keep dry.
- allow air circulation underneath.
The desirable would be to work with not against, the fources of nature and to
make use of their potentialities to create better living conditions and utilizes all natural
resources favorable to human comfort- called CLIMATE BALANCED".
The process of building a climate balanced can be divided into four steps as
follows;
1. Climate data survey climatic elements at a given location about temperature
, relative humidity radiation and wind.
2. Biological evaluation evaluate the climate impact in physiological terms and
plot the climate data on the bioclimatic chart.
3. Technological solutions apply the technological solutions to climate -
comfort problem
- in site selection
- in orientation
- shading calculations
- housing forms
- Air movements
- Indoor temperature balance


4. Architectural application combine the solutions to design architectural unity.
SOL-AIR ORIENTATION
The total problem of orientation for buildings is composed of many factors as
follows:
- Local topography
- Privacy
- The pleasure of a view
- Rduction of noise
- Climatic factors of wind and solar radiation
A large part of the architect's task is to position a building so as to take the best
advantage of the sun's value for thermal effect,hygiene and psychological benefits.
The sol-air" approach to orientation recognizes that air temperature and solar
radiation act together to produce one sensation of heat in the human body. 9
REGIONAL ORIENTATION CHART
The hot-humid zone requires orientation perpendicular to the axis of the
overheated period.
In many cases the living areas of a building must face orientations other than the
optimum zone. The west side should be protected from summer radiation.10
Once the proportion has been set up ,the optimum orientation can be evaluated
by drawing a parallelogram of the forces. The result will be an adjusted exposure for
the important sides.
The evaluation of orientation are as follows :
1. The times during which the living areas are used, specific hourly occupancy
2. The germicidal action of radiation.
3. The treatment of the exposed surface.


Suggested sun orientation for rooms
ROOM H HZ Z sz s sw w NW
B*lroom
living
Diiuag
Kitclun
Library
Laundry
Playground
Drying yard
Bathroom
Utility
Garag<
WorkjXop
TVrraco
SunporcX
SHADING DEVICE/SOLAR CONTROL
The skin of a building performs the role of a filter between indoor and outdoor
conditions, to control the intake of air, heat, cold, heat, sounds and odors.
It is generally agreed that air, temperature, wind are the best controlled within
the wall itself, while light is easier to control inside the building shell, and heat radiation
is the most efficiently halted before it reaches the building envelope proper. 11
Location, latitude and orientation all contribute to the formulation of an effective
device.
CONCLUSION ON SHADING EFFECTIVENESS
The sun protection effect for glass surfaces depends on several factors as
follows:
1. The reflectivity of solar radiation of the appied material and its color coating.
- light colors reflect sun impact
- dark colors absorb sun impact
Dark Medium Light Aluminium
Venetian Blind 0.75 0.65 0.56 0.45
Roller shade 0.81 0.62 0.41
Curtain 0.58 0.47 0.40


Surface
Reflectivity Percent of Solar Radiation
Polished aluminium 85
White-Lead Paint 71
Light Green Paint 50
Grey Paint 25
Black Matte 3
2. The location of the shade protection which influences the radiation and
convection heat impacts.
The exterior protecting devices dispose the connected and reradiated portion
of the energy to the outdoor air. The shade protection is dependent on its location, and
its effectiveness increase accordingly as it is positioned after on,or before the glass
surface in that order.
As an overall value one could conclude that the effectiveness increases 35
% by using outside shade protection instead of an inside one.
3. The specific arrangement of the applies shading method
The different methods of shade protection can only become categorized
under certain assumptions, such as to take certain values as a measure.
There are two kinds of shading devices as follows :
1. External shading devices
They are 30% more effective than internal shading devices because they
prevent solar radiation from reaching the building's interior.
The shape of the devices depends upon
- the orientation of the glass surface
- the severity of the overheated period
1.1 Horizontal devices
- depend primarily on the sun's altitude
shadow = ( depth of overhang ) ( sin o )
- horizontal shading is best used on south facing walls.
1.2 Vertical devices
- They are more efficient when located on east and west facing surfaces.


Combinations of vertical and horizontal elements can be use effectively to
control solar radiation. They can be either fixed or movable.
2. Internal devices
Less efficient than external devices because the solar radiation enters the
building and is trapped, causing interior heat gain.
Interior shades also can be used to reduce building heat loss in underheated
periods. 12
ECONOMY OF SHADING DEVICES
The importance of sun control can be shown by
1. Comparing the amounts of heat entering a building through its various
components.
2. The roof and the infiltration and the window conduction follow.13
DESIGN OF SHADING DEVICES
Depends on :
1. Time of year and day to shade
It is provided by a careful study of the average temperature data month
by month for 12 months and hour by hour for 24 hours.
2. The kind of shading device which will be effective on a particular side of a
building
It is provided when the month of the year and times of the day for which
shading is needed are plotted on the sun-path diagram of a particular place. The plotting
also provides the vertical and horizontal shadow angles needed to determine the total
depth of shading devices


FORM /. ENVELOPE / MATERIAL USE
The energy performance of the building envelope will be discussed in terms of
1. Size and Shape
An important consideration in building shape is the surface to volume
ratio (s/v ). Buildings with less surface exposed to the natural elements (lower s/v )
will be less susceptible to radiant and conductive heat gain or loss.
A large volume will possess a greater internal thermal inertia than a
smaller volume of similar shape. When there are large external temperature variations
the larger volume will have more inertia to overcome and less surface area to be affected
than a building that has a small volume. 14
The more exposed surface area there is the more potential for external
temperature influence.
Conclusions for basic form" of houses are as follows:
- The square house is not the optimum form in any location.
- All shapes elongated on the north-south axis work both in winter and
summer with less efficiency than the square one.
- The optimum lies in energy case in a form elongated somewhere along
the east-west direction.
Regional effects on house shapes
The optimum shape was defined as the one which has the minimum heat
gain in summer and the minimum heat loss in winter.
In the hot-humid region the sun attacks the east and west ends of a
house and forces it into a slender elongated structure The temperatures are not
excessive, and such a shape can be used beneficially for wind effect. But in larger
buildings, other factors play a more important part in forming the structure as follows:
- The logic of circulation
- Space needed
- Economy of organization
However some general principles about how to consider the shaping
tendencies of external climatic elements.
In the hot-humid zone buildings freely elongated in the east-west
direction are advantageous. Buildings located on the north-south axis recieve greater
penalty than they would in other climatic zones.


Performance of an air-flow envelope
The more perimeter area, the better the opportunity to admit daylight in
areas where heat loss is minimal and heat gain from light is a problem, it may be
beneficial to use a linear plan which allows maximum daylight and ventilation.
2.Surfaces
The emmisivity and absorptivity of materials is dependent upon the
particular wavelength of the incident radiation as well as the properties and temperature
of the surface.
As the emmisivity and absorptivity of a material increase the
reflectivity decreases. However, it can be assumed that the absorptivity and emissivity
are equal at the same temperature.
Surface Emissivity / Absorptivity Reflectivity
Low Temp. Solar
Radiation Radiation
Aluminum, bright 0.05 0.20 0.80
Asphalt pavement 0.95 0.90 0.10
Brass / copper dull 0.20 0.60 0.40
Brass copper, bright 0.02 0.30 0.70
Brick, red rough 0.90 0.70 0.30
Concrete, uncolored 0.90 0.65 0.35
Glass 0.90 - -
Paint, aluminum 0.55 0.50 0.50
Paint, white 0.90 0.30 0.70
Paint, brown red green 0.90 0.90 0.10
Slate, dark 0.90 0.90 0.10
Steel, galvanized 0.25 0.55 0.45
Tiles, red clay 0.90 0.70 0.30
3.Insulation
The value of insulation is in its ability to restrict the flow of energy. The
ideal insulator is to permit the smallest energy flow per unit thickness and unit weight
of the material.
If insulation is used excessively or improperly it may actually increase
energy consumption Buildings with high internal-heat gains may require a year-round


heat balance analysis of external and internal insulation required to achieve maximum
energy conservation.
Material Energy Resistance Energy capacity
Acoustic ceiling tile 2.381 0.128
Air space 0.909 0
Aluminum 0.0007 3.089
Brick face 4 inch 0.111 2.383
Carpet 2.2222 0.333
Clay die 4 inch 0.278 1.307
Concrete bik lw 8 inch 0.250 0.817
Door core 2.381 0.975
Dry wall 0.303 0.750
Earth 0.154 1.833
Felt 0.752 2.333
Glass block (wall) 2.500 1.667
Gypsum loth 0.870 1.083
Insulation rigid 2.778 0.347
Insulation roof deck 2.632 0.208
Perlite 0.667 0.750
Plywood 1.250 1.842
Rockwood Batt 3.704 0.067
Sand 0.188 1.742
Slate 0.100 2.330
Steel 0.003 4.790
Styrofoam 1.667 0.043
Urethane foam 5.882 0.048
Wood,hard 0.909 2.513
Wood, soft 1.250 1.733
Zonolite (loose) 2.564 0.058
4.Thermal mass
It is a measure of its energy or heat capacity The value of thermal mass
is its ability to delay heat flow.
A building with a high heat capacity has a high level of thermal inertia,
or temperature stability in response to sudden changes in heat flows. As a result,
extremes in diurnal exterior air temperatures will have much less affect on interior air
temperature of a massive building.
The impact of high internal loads will also be modified by the thermal
inertia.As the temperature of the building surfaces and contents increases above the
interior air temperature may be lagged beyond the building's normal hours of
occupancy and not impact on the users' comfort.


Combinations of insulation and passive construction materials can result
in very significant alterations to the heat-flow time lag. The placement of insulation can
have a great effect on the time lag of the composite wall. The placement of insulation
has such an effect because of the movement of heat into and out of the wall insulation.
1 5
Material Thickness U. Value Time lag
(inches) (btu/sq.ft./h) (hours)
Stone 8 0.67 5.5
12 0.55 8.0
16 0.47 10.5
24 0.36 15.5
Solid Concrete 2 0.98 1.1
4 0.84 2.5
6 0.74 3.8
8 0.66 5.1
12 0.54 7.8
16 0.46 10.2
Common brick 4 0.60 2.3
8 0.41 5.5
12 0.31 8.5
16 0.25 12.0
Face brick 4 0.77 2.4
Wood 1/2 0.68 0.17
1 0.48 0.45
2 0.30 1.3
Insulating 1/2 0.42 0.08
1 0.26 0.23
2 0.14 0.77
4 0.08 2.7
6 0.05 5.0


WIND
The direction and force of the wind is constantly being modified and changed
by the features of any building site and structure.
In overheated periods, wind can provide cooling of building surfaces and
natural ventilation of building interiors. Because wind direction often shifts from winter
to summer, building orientation may respond to both design conditions and the yearly
thermal requirement must again be assessed to establish the predominant design
conditions.
Wind exerts the greatest pressure when it is 90 degrees to the surface of a
building .The greater the pressure, the more the tendency will be for air to enter a
building.
To increase the usefulness of natural ventilation in overheated periods, an
orientation that accommodates wind conditions during those periods can be selected.
The precise angle which is most effective, however, is dependent upon the location of
the openings which allow air to flow in and out.
-As wind direction approaches can angle parallel to the building surface, the
convective gains and losses will increase the impact. These convective losses have on
total heat loss/gain is dependent on the resistance of a wall or glazed area.
-In the overheated environment, wind movement over, under and around the
building may provide additional convective cooling and thus becomes a desirable
design condition
-The pattern of wind flow around and through buildings depends on the
building's size, shape and orientation.
-As the height of a flat roofed building increases, the amount of air going
around the building increases while the air going over the building remains the same.
-As the pitch of the gable roof increase, more air going around the building. 16
Flow Patterns Inside Buildings
Natural ventilation can be utilized by
1. Orientation of building
2. Use of surrounds to create low and high pressure zones
3. Locating inlets in high outlets in low, pressure areas
4. Small inlet and large outlet sizes
5. Inlets which direct the flow to the living room
6. Undisturbed inside flow, open plan
Inside air speed satisfy bioclimatic requirements based on design temperature.
Directional effect of inlet attachments
Preplanning is the key to optimum use of natural ventilation Each buildind in a
residential development should be in the free sweep of the wind as far as possible. In
hot-humid climates, the placing of buildings in wind shadows of other buildings or, of
vegetation should be avoid.17
Although there are too many variables in the design of buildings to allow any
one set of standards for type, size, quantity and placement of windows for natural
ventilation it is possible to ascertain the most favorable conditions for a specific


building, and then to select the type of window and place it correctly to allow for
maximum use of natural ventilation. 18
INTERNAL FACTORS
The specific elements that require operating profiles for energy-usage evaluation
are:
- Lighting system
- People
- Equipment
- Mean radiant temperature
- Envelope gain
Lighting system
Sunlight in the humid tropics is strong in spite of cloudy skies. The clouds
recieve
the sun and overhang the ground with watery pressure, intercepting in themselves and
in the saturated air below them the greatest heats of the sun, but reflecting downward a
brillance which are apt to underestimate.
The tendency in humid tropical house design is to increase window and door
openings, but conditioned by the necessity to diminish both heat and glare which may
come from any part of the skies above and from the ground and nearby surfaces
catching the sun in the direction of the sun it should be well sheltered from sun and
glare, with light filtering through vegetion or screens, and with an abundance of air, for
ventilation continues to be necessary ; no sharp or burning light at close range. There
are as many ways of dealing with light as there are with ventilation.
Artificial lighting can be the greatest source of internally generated heat. Lamps
can be chosen that produce an appropriate amount of light per unit of heat. Incandescent
lamps are the greatest heat producers. High intensity discharge sources offer significant
reductions and are closely followed by fluorescents as producers of the least heat.
Illumination can be economized through light concentration at the task and
reduction of lighting in unnecessary areas. According to the I.E.S. general illumination
for working areas should be at least 10 % of supplementary illumination, but not less
than 20 footcandles. 19
The selection of efficient and appropriate light sources can reduce power
consumption Source efficiency can be determined by lumens per watt.
17-22 Lumens/watt for incandescent
56 - 63 " mercury
67 - 83 " fluorescent
85 - 100 " metal halide
105- 103 " high pressure sodium20


People
For healthy persons heat production is 400 BTUS per hour Irrespective of
the air temperature at a dry-bulb temperature of 70 F or 21 C and 45% RH., about
75% or 300 BTUS pre hour of this total heat production will be lost by convection and
evaporation.
The internal loads from lights, people and equipment are heat gains that are
independent of outdoor temperature variation and each one is represented as a
horizontal line above the zero axis on the load profile diagram.
The sensible heat gains and losses from infiltration and mechanical ventilation
vary in direct proportion to outdoor temperature changes and are represented as a
sloped line on the load profile diagram
Envelope Gain
The reflectivity of opaque surfaces is an important factor in the consideration of
solar heat gain.
- Light colored, smooth surfaces directly reflect solar radiation
- Darker surfaces - absorb more and reflect less heat gain is 30-
50% more than lighter surfaces (with similar
construction characteristics)
Glass surfaces transmit solar radiation directly and instantaneously into interior
spaces because:
1. Glass is a poor insulator against conductive heat loss.
2. Glass transmits a higher percentage of incident solar radiation than almost
any other envelope material.
3. Glass permits a substantial component of available natural light to enter the
building.
The preformance of the glazed unit will depend on specific glass properties as
follows :
1 .One-eight inch clear glass
The exact amount transmitted depends on the angle of incidence.
2. Heat absorbing glass
Reduces solar radiation transmitted into the interior without reducing
visibility levels.
3. Reflective glass
It is best used to prevent radiant heat gain in the overheated periods and
to reduce the cooling loads.
4. Insulating glass
It can modify the amount of radiation transmitted into the interior The
exterior pane should be selected for its heat-absorbing or reflecting
characteristics.
5. Glass block
It can be used to reduce radiant heat gain to the interior 35-75 %.
The angle of incidence of the sun's rays with the glass will affect the amount of
radiation transmitted into the building interior.


The relationship of transmitted radiation to angle of incidence is a linear one
until 60 and at which point it drops off sharply to 90 window can be designed for a
high angle of incidence during periods of overheating. 21
Mosquito Screening
Mosquito-screening keeps flying insects out but makes less headway than one
would expect. It prevents the entry of mosquitoes and flies, but it reduces air movement
and so increases temperature and it is held by many to induce a claustrophobic
atmosphere.
The compromise solution is to screen the bedroom and any other special room
such as a study room, and this appears to be a sensible alternative to whole-house
screening, which may be expensive and is open to the objection that to be successful. It
is pleasant to be in a screened room and success is possible if the screened openings are
large enough, 90% being the minimum under most conditions. The screen material
should be indestructible in ordinary use, rustroof andreasonably strong. A fully
screened house must be spacious and generously ventilation. 22


CASE STUDIES
Sophitel Central Hua-Hin Resort Hotel Thailand
Climate
For maintaining comfort indoors, the climate requires cooling almost all of the
year by allowing natural ventilation through the building.
Design Concept
The building are oriented to expose each living units to penetration by cooling
north-south breezes The buildings are two-three stories in height, raised above
basement areas.
The plan involves extensive exterior surface area, including balconies, exterior
entry stairs, exterior corridor ( single type ) and other exterior living spaces. These
features are arranged to provide sunscreen protection. The roof of the buildings is
designed to be steep slope to have enough air space inside to protect heat gain from
radiation to drain water from rain since the climate inThailand is hot and has rainfall
almost all of the year, besides this, as the pitch of the gable roof increase more air will
flow around the building and it will reduce room temperature .
Former Thai House
Design Concept
It is designed to be a one-storey building oriented in north-south The plan
involves exterior surface area as living or multipurpose area which has no panel in
order to
let the natural ventilation flow through. The roof of the building is designed to be a high
pitch gable (two levels). The upper one is steeper than the lower one as it is designed
to drain the water from rain and to have enough air space inside to reduce heat gain
from radiation. The lower one is designed to be a long overhang for shading the
building from sunlight and radiation.
Outdoor space is designed by using vegetation ( grass to absorb radiation
from sunlight and trees for shading ) and water body to reduce heat gain from outside
to inside
of the building.


CASE STUDY
Building
Sophitel Central Hua-Hin Resort Hotel
Factors Building Design
Virtues Defects
1. External Factor - Land form - Vegetation - Water body - HT. capacity - Using vegetation ( grass trees ) - Shading - Temperature modification through transpiration - Modification of temperature variation and temperature extreme - Using water body - Stability of diurnal temperature - No attempt in using landform and HT.capacity
2. Building Envelope Interfere - Form / Envelope - Material use - Shading device / Solar control - Orientation - Building placement - Good Ventilation - Orientation north south - Planning single corridor - Stratification - Cross Ventilation through most building envelope - Solar heat gain protection - Large volume of roof ventilation - Overhang force from sun protection - Material - wood panel has low resistant and easy to have deterioration by natural climatic systems and by termite attack. - roof tile concrete has high ability to radiate the heat out of surface but it has a high ability to absorb too.
3. Internal Factor Interior heat gain - Interior heat gain from equipment ( aircon.) is not much because this building is design to have the natural ventilation. - No insulation for building envelope.


CASE STUDY
Building Former Thai House
Factors Building Design
Virtues Defects
1. External Factor - Land form - Vegetation - Water body - HT. capacity - Using vegetation ( grass trees ) - Shading - Temperature modification through transpiration - Modification of temperature variation and temperature extreme - Using water body - Stability of diurnal temperature - Create air movement - Using water body sometimes it will increase relative humidity during the time that is too wet too comfort - No attempt in using landform and HT. capacity
2. Building Envelope Interfere - Form / Envelope - Material use - Shading device / Solar control - Orientation - Building placement - Good Ventilation - Orientation north south - Stratification - Cross Ventilation through most building envelope - Solar heat gain protection - Large volume of roof ventilation - Overhang force from sun protection - Material - wood panel has low resistant and easy to have deterioration by natural climatic systems and by termite attack. - roof tile clay handmade reddish brown has low ability to radiate the heat out of surface.
3. Internal Factor Interior heat gain - No interior heat gain from equipment ( aircon.) because this building is designed to have natural ventilation and heat gain from other equipments lighting system and people is not much as this building is a residential building. - No insulation for building envelope.


DESIGN GOALS
As we know from the study, we can make the conclusions about how to design
the room temperature within comfort zone in hot-humid climates areas especially
Thailand,
which needs to have the exclusion of solar heat from buildings by using the
principles apply in the exclusion of solar heat as follows :
1. Shading
To prevent direct sunshine from falling on those parts of the building which
have immediate contact with the interior. Achieved by using :
- overhang eaves
- shading devices canopies, pergolas
(For Bangkok Thailand need the combination shading device as sunlight
comes from all orientations even in north orientation )
2. Reflectivity and Absorptivity
Reflectivity and absorptivity are two extremely important characteristics of a
building in hot-humid climates with a surface having good reflective properties will
reduce the cooling load significantly by using the reflective qualities of various top
surface finishes so that as little as possible of the radiant heat of the sun is absorbed by
the building
White washed white painted polished or smooth surfaces are good
reflectors.
( high R. value )
3. Ventilation
Providing for full air movement and convection in roof spaces and wall cavities
thus preventing reservoirs of hot air from building up.
We can design to have good ventilation by using the principles as follows:
1 .Outside of the building, use of surrounds to create ventilation and pressure
zones)
- Landform
- Vegetation
- water body
- Orientation and Planning
- Pitch of the roof
- Raise the building up to let the air flow between the ground and the
floor of the building.


2. Inside of the building
- Location and size of inlets and outlets
- Space from floor to ceiling
- Louvre door window
- Design the panel and the balcony that can let the air flow through
Besides these, there is the significant method that can create air movement when
there is no wind which is called Air Flow Chimney Effect The concept of this
method is to create air movement from inside of a room to a chimney or the louvre
wall where the hot air is created The hot air in the chimney or the louvre wall will flow
up and it will bring the colder air inside of the room instead of it. This w ill make the
air movement from
one place to another place that it will help to reduce the inside room temperature when
there is no natural wind.
4. Thermal Capacity
Using materials which do not store up heat from the sun. (low U.value high
R.value ) and using the insulation to restrict the flow of energy.
- U. value is a factor that shows the numbers of btus. of thermal energy which
pass through a section of material.
- R. value represents the ability of a material to resist thermal transfer.


BIBLIOGRAPHY
AIA Research Corporation with Syska & Hennessey, Energy Inform Designing for Energy
Conservation April ,1978
AIA Research Corporation Regional Guidelines for Building Passive Energy Conserving
Homes, Washington D.C.
Baneiji K. Ranjit, Energy Economy in Design Huntington New York : Robert E. Krieger
Publishing Company, INC.,1981.
Davis and Schubert, Alternative Natural Energy Sources in Building Design New
York,N.Y.:Van Nostrand Reinhold Publishing Company,1977.
Fry Maxwell and Jane Drew Tropical Architecture in the Dry and Humid Zones ,
Malarba Florida : Robert E. Krieger Publishing Company 1982.
Giffels Associates Inc. Solar Energy & Housing Design Concepts AIA Research
Corporation, 1975.
Koenigsberger, O.H.E.T.A.L., Manual of Tropical Housing and Building- Part 1 :
Climate Design,London :Longman Group Limited .
Loftness Vivian, Identifying Climatic Design Regions & Assessing Climatic Impact
on Residential Building Design, AIA Research Corporation, Washington D.C.20006
1977.
National Academy of Sciences, Solar Radiation Considerations in Building, Planning
and Design, Washington D.C.: Printing and Publishing Office, 1976.
Olgyay Victor, Design with Climate : Bioclimatic Approach to Architectural
Regionalism, Princeton Newjersey : Princeton University Press, Fourth Printing ,1973.
Olgyay, Aldar and Victor, Solar Control and Shading Devices, Princeton N.J.:Princeton
University Press, 1976.
Ruck Nancy C., Building Design and Human Performance New York : Van Nostrand
Reinhold 1989.
White E.T., Concept Sourcebook : A Vocabura)ry of Architectural Forms, Tucson,
Arizona : Architectural Media ,1975.


1 Maxwell Fry and Jane Drew Tropical Architecture in the Dry and
Ilumid Zones ( Malarba Florida : Robert E. Krieger Publishing Company 1982 )
12-13.
2 Ibid., 17.
3 Ibid., 18-19
4 Victor Olgyay Design with Climate : Bioclimatic Approach to
Architectural Regionalism ( Princeton, New Jersey : Princeton University Press ,
1973 ) 11-12.
5 ASHARAE Handbook 1977 Fundamentals ( Atlanta Ga.:
ASHARAE ,1973 ) 23.22.
6 Victor Design with Climate 22.
7 Ibid., 23.
8 Ibid., 30.
9 Ibid., 54
10 Ibid., 61.
11 Ibid., 63.
12 AIA Research Corporation with Syska & Hennessey Energy Inform
Designing for Energy Conservation ( 1978 ) 62-63.
13 Victor Design with Climate 72.
14 AIA Energy Inform ,51.
15 Ibid., 52-54.
16 Ibid., 42-47.
17 Victor Design with Climate 104-111.
1 8 Ranjit K. Banerji, Energy Economy in Design ( Huntington, New
York : Robert E. Krieger Publishing Company,INC.,1981 ) 62.
19 AIA., Energy Inform 121.
20 Ibid., 122.


21 Ibid., 59-60.
22 Maxwell,
Tropical Architecture 54.




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