Passive techniques in office building design for warm humid climate

SEMINAR ON PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR WARM HUMID CLIMATE

Submitted by:

SRUTHY P B090085AR

Guided by:

DR. NASEER M.A.

In partial fulfillment for the award of the Degree of

BACHELOR OF ARCHITECTURE

DEPARTMENT OF ARCHITECTURE

NATIONAL INSTITUTE OF TECHNOLOGY CALICUT November 2013

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

ACKNOWLEDGEMENT I am greatly indebted to my guide Dr. Naseer M A for having made available his valuable time, support and guiding me in the right direction throughout this Seminar. I would like to thank our HOD Dr. Anil Kumar P P and seminar co- ordinator Ar. Bimal P for facilitating this course. I thank Ar. Sarah George for giving me valuable inputs time to time.

I would also like to thank my friends for giving their inputs on the subject and my family and loved ones for being supportive throughout, and God, for making all of this possible.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

ABSTRACT Passive design can be referred to a way of designing buildings that takes advantage of the prevailing climate and natural energy resources, such as daylight, wind and thermal buoyancy, to achieve a comfortable environment while minimizing energy use and reliance on mechanical systems A proper architectural design of a building envelope can significantly lower the energy usage through day lighting, reduced HVAC loads, etc.

The chief goal of building is to provide a healthy and comfortable shelter, therefore energy saving should not disregard these. Thermal comfort improves concentration, workmanship and enthusiasm enhancing productivity and quality, whereas a poor thermal environment results in sickness. Conventionally thermal comfort is achieved by energy intensive mechanical air conditioners. Passive cooling if employed properly is an excellent alternative, which provides a comfortable and healthy environment.

The building design in a warm and humid climate should aim at reducing heat gain by providing shading, and promoting heat loss by maximizing cross ventilation.

Dissipation of humidity is also required to reduce discomfort.

This paper summarizes the requirement of passive techniques, growing energy demand in office buildings, suitability of passive techniques in warm humid climate and also the advantages of various passive cooling options in office buildings. Few case studies of passive cooling systems are also presented to provide confidence in stake holders to practice passive cooling. However, these cases lack universal validity because many factors like thermal adaptation, clothing behaviour, activity level, age and sex affect the thermal comfort, and the performance of passive cooling system is a function of numerous site related parameters even though of the same climate.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CONTENTS

1 INTRODUCTION................................................................................................... 11 1.1

Relevance ...................................................................................................... 11

1.2

Aim ................................................................................................................ 14

1.3

Objectives ...................................................................................................... 14

1.4

Scope ............................................................................................................. 14

1.5

Methodology ................................................................................................. 15

1.5.1

Elements of organization ....................................................................... 15

2 GENERAL CONSIDERATIONS .......................................................................... 18 2.1

Climate .......................................................................................................... 18

2.1.1

Climatic elements................................................................................... 18

2.1.2

Climate types ......................................................................................... 20

2.2

Comfort: ........................................................................................................ 21

2.3

Thermal comfort ............................................................................................ 22

2.4

Warm humid climate and building comfort .................................................. 23

3 ENERGY CONSUMPTION AND BUILDINGS .................................................. 28 3.1

Increasing energy consumption by buildings ................................................ 28

3.2

Office buildings and energy consumption .................................................... 29

3.3

Energy requirements of office buildings ....................................................... 31

4 PASSIVE TECHNIQUES ...................................................................................... 33 4.1.1

Design for Minimising Cooling Requirement ....................................... 33

5 PASSIVE TECHNIQUES IN OFFICE BUILDINGS OF WARM HUMID CLIMATE ............................................................................................................... 37 5.1

Site and Building envelope ........................................................................... 37

5.1.1 4

Orientation ............................................................................................. 37

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 5.1.2 5.2

Building form ......................................................................................... 40

Ventilation ..................................................................................................... 41

5.2.1

Cross ventilation .................................................................................... 41

5.2.2

Rain Protection and Ventilation ............................................................. 42

5.3

Cooling .......................................................................................................... 42

5.3.1

Ventilative Cooling ................................................................................ 42

5.3.2

Thermal mass cooling ............................................................................ 45

5.3.3

Radiant Cooling ..................................................................................... 46

5.3.4

Indirect Evaporative Cooling ................................................................. 47

5.3.5

Wind Tower ........................................................................................... 48

5.3.6

Advanced passive cooling...................................................................... 49

5.4

Dehumidification ........................................................................................... 50

5.5

Shading .......................................................................................................... 51

5.5.1

Shading of walls:.................................................................................... 51

5.5.2

Shading of windows ............................................................................... 52

5.5.3

Deep porches and verandas .................................................................... 55

5.6

Lighting ......................................................................................................... 56

5.6.1 5.7

Building Materials ......................................................................................... 59

5.7.1 5.8

Innovative Day lighting systems:........................................................... 57

Thermal Mass......................................................................................... 60

Landscaping .................................................................................................. 60

5.8.1

Green roof (vegetated roof) ................................................................... 61

5.8.2

Water elements....................................................................................... 62

6 DESIGN FEATURES FOR BUILDING ELEMENTS IN AN OFFICE BUILDING ............................................................................................................. 64 6.1

Wall ............................................................................................................... 64

6.1.1 5

Lightweight concrete (LWC) walls ....................................................... 64

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 6.1.2

Ventilated or double skin walls.............................................................. 65

6.1.3

Walls with latent heat storage ................................................................ 65

6.2

Roof ............................................................................................................... 65

6.2.1

Masonry roofs ........................................................................................ 66

6.2.2

Lightweight roofs ................................................................................... 67

6.2.3

solar chimney and wetted roof ............................................................... 67

6.2.4

Thermal Roof insulation system ............................................................ 69

6.3

Fenestration (windows and doors) ................................................................ 70

6.3.1

glazing types .......................................................................................... 71

6.3.2

Louvers .................................................................................................. 71

7 CASE STUDIES ..................................................................................................... 75 7.1

Indian Naval Academy, Ezhimala- administrative block.............................. 75

7.1.1

Site and topography ............................................................................... 75

7.1.2

Planning ................................................................................................. 75

7.1.3

Sustainable features ............................................................................... 76

Passive design ...................................................................................................... 77 7.2

Office-cum-laboratory for the West Bengal Pollution Control Board, Kolkata ……………………………………………………………………………...78

7.2.1

General description ................................................................................ 78

7.2.2

Design features....................................................................................... 78

8 CONCLUSION ....................................................................................................... 82 8.1

6

passive technique guidelines for offices in warm humid climate ................. 84

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

LIST OF FIGURES Fig 1.1 Psychometric chart .......................................................................................... 11 Fig 1.3 Break-up of energy consumption category wise, ............................................ 12 Fig 1.2 Increase of energy use in the commercial sector, UNDP, India ...................... 12 Fig 1.4 Energy need in a typical office building .......................................................... 13 Fig 2.1 The psychometric chart ploting the combination of temperature and humidity ...................................................................................................................................... 19 Fig 2.2 A wind frequency diagram, a ‗wind rose‘. ...................................................... 19 Fig 2.3 The four modes of heat exchange .................................................................... 22 Fig 2.4 The comfort temperature tends to follow the outdoor temperature. Data from Pakistan, Europe, and Humphreys which have varying climate ...................... 22 Fig 2.5 Relation between comfort temperature and wind speed .................................. 23 Fig 2.6 Factors affecting thermal comfort ................................................................... 23 Fig 2.7 Bioclimatic chart for warm humid climate ..................................................... 24 Fig 2.8 Variation of comfort temperature with in a tropical warm humid climatic region over the months ..................................................................................... 24 Fig 2.9 Wind tower ...................................................................................................... 26 Fig 3.1 Pie chart on energy consumption by various sectors ....................................... 28 Fig 3.2 Peak cooling load in office building (Hong Kong, Lam and lii, 1999) ........... 29 Fig 3.3 Energy consumption by all building types in India (Retail and private offices shown) .............................................................................................................. 30 Fig 3.4 Growth of electricity consumption in commercial sector ............................... 30 Fig 3.5 electricity requirement for an office building .................................................. 31 Fig 4.1 The orientation and spatial organisation of a Thai house ................................ 33 Fig 4.2 A schematic of a roof section showing an example of a combined use of insulation, a ventilation space and ................................................................... 34 Fig 5.1 Orientation with longer facades on N-S .......................................................... 37 Fig 5.2 orientation for different climatic regions ......................................................... 37 Fig 5.3 Average daily solar radiation received on North orientation in Bhubaneswar 39 Fig 5.4 Average daily solar radiation received on South orientation in Bhubaneswar 39 Fig 5.5 Average daily solar radiation received on East orientation in Bhubaneswar .. 39 Fig 5.6 Average daily solar radiation received on West orientation in Bhubaneswar . 39 7

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Fig 5.7 doomed roof air cooling .................................................................................. 41 Fig 5.8 Examples of opening design to encourage ...................................................... 43 Fig 5.9 Examples of solar chimney configurations: vertical (a) and inclined (b)........ 44 Fig 5.10 Wind-assisted ventilation (a); buoyancy dominated, wind-opposed ventilation (b); and wind dominated, ............................................................. 45 Fig 5.11 A schematic of a radiant cooling system which involves cooling the roof by nocturnal radiation ......................................................................................... 46 Fig 5.12 A schematic of the cool radiant panel system tested in Thailand .................. 46 Fig 5.13 A schematic of the Cool roof system............................................................. 47 Fig 5.14 Wind tower .................................................................................................... 48 Fig 5.15 passive space conditioning ............................................................................ 49 Fig 5.16 courtyard, INA administrative block ............................................................. 49 Fig 5.17 Dehumidifying window (a) and its operation (b) .......................................... 51 Fig 5.18 green wall ...................................................................................................... 51 Fig 5.19 Solar PV panels and louvers as wall shading ................................................ 52 Fig 5.20 Details of HSA & VSA ................................................................................. 52 Fig 5.21 External shading for windows as an effective means of shading .................. 52 Fig 5.22 Horizontal & vertical fins as an external shading device .............................. 53 Fig 5.23 Design of a shading ....................................................................................... 54 Fig 5.24 Comparison of daylight penetration between multiple overhangs and single overhang ........................................................................................................ 55 Fig 5.25 Shading through sun proof fabric and verandahs .......................................... 55 Fig 5.26 Fixed types of jalis for shading...................................................................... 56 Fig 5.29 Typical light pipe ........................................................................................... 57 Fig 5.30 Daylight control ............................................................................................. 58 Fig 5.31 roof garden ..................................................................................................... 60 Fig 5.32 Shading with trees ......................................................................................... 61 Fig 5.33 Shading through landscaping......................................................................... 62 Fig 6.1 Wetted roof ...................................................................................................... 67 Fig 6.2 Various roof systems, sample nos. from Table 6.1 ......................................... 68 Fig 6.3 Roof insulation ................................................................................................ 69 Fig 6.4 Different types of thermal insulation ............................................................... 69 Fig 6.5 Different louvers .............................................................................................. 71 8

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Fig 6.6 movable louver types ....................................................................................... 72 Fig 6.7 Some adaptive interventions applied to windows, doors and balconies to promote higher adaptive use, as found in KD, KA and RS. (A, B): Bamboo blinds hung on balcony .................................................................................. 73 Fig 7.1 INA administrative block ................................................................................ 75 Fig 7.2 Administrative block, rear ............................................................................... 75 Fig 7.3 Corridor ........................................................................................................... 75 Fig 7.4 Corridor ........................................................................................................... 76 Fig 7.5 Jali work .......................................................................................................... 76 Fig 7.6 Courtyard ......................................................................................................... 76 Fig 7.7 Skylight ............................................................................................................ 77 Fig 7.8 Roof detail ....................................................................................................... 77

LIST OF TABLES Table 2.1 Summer indoor climatic data ....................................................................... 25 Table 3.1 Annual energy consumption by various building types in India ................. 28 Table 3.2 Breakdown of annual electricity consumption for a base case generic office building .......................................................................................................... 31 Table 5.1 Average solar radiation intensity on various facades of a building in warm & humid climate ............................................................................................ 38 Table 5.2 Example of Solar angles to be cut on various cardinal directions in warm & humid climate building ( case of city of Bhubaneswar) ................................ 53 Table 5.3 Recommended daylight factors for interiors as per Bureau of Indian Standards........................................................................................................ 57 Table 5.4 Desirable reflectance levels in a room ......................................................... 57 Table 5.5 Comparison of temparatures in summer of two buildings with black and white roof ....................................................................................................... 59 Table 5.6 Maximum indoor temperature for different roof materials ......................... 60 Table 6.1 Various roof types and their U values ......................................................... 70

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CHAPTER 1

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

1 INTRODUCTION 1.1 RELEVANCE Relevance of passive techniques in the present world Climate has always challenged man in his quest for a better life. The elements of weather have affected all spheres of man's activities and have shaped his instinctive responses leading to largely disruptive effects to the natural environmental equilibrium. (Daroda, 2011) The search for habitable dwellings which offer comfort, security and relief brings into focus the need for buildings which respond to particular local climatic and environmental conditions. (Daroda, 2011) The so-called International Style which ignores traditional age-old solutions to problems posed by local climate while relying instead on the use of high technology materials such as reinforced concrete frame and glass walls simply fails as an architectural solution. For example, a 3 x 3m glass wall in a building exposed to solar radiation on a warm, clear tropical day will let in approximately 2000 kilocalories per hour. To maintain the microclimate of a building thus exposed within the human comfort zone, two tons of refrigeration capacity is required. Such a reliance on energy-consuming solutions at a time when the earth is experiencing severe climate change due to global warming is truly a reflection of the failure of the architect to live up to his responsibility towards the client and the environment. (Daroda, 2011) Fig 1.1 shows the psychometric chart which identifies the comfort zone, defined as the range of

Fig 1.1 Psychometric chart

temperatures and humidity within which people feel comfortable under calm wind

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 conditions. In general, as temperature increases, tolerance to humidity decreases, and vice versa. (Daroda, 2011) As living standards rise people want to install heating and/or cooling equipment to improve thermal comfort, achieve the desirable thermal comfort. For buildings not adapted to the climate, the amount of energy to run the equipment, and its cost, will be excessively high, and it will have a negative impact on the environment.

Climatic Design of Buildings, 2000)

(Rosenlund,

A good or at least acceptable, indoor climate can often be

achieved with little or no extra input of energy. This is where passive techniques in building design come into picture.

Relevance of passive techniques in office buildings, -Indian context Buildings are mushrooming in our country without sufficient consideration for the site and its climate. Fog 1.2 shows increasing energy consumption in India over the years. (UNDP/GEF EE

Improvements

in

Buildings,

2010)

Consequently this affects the need

for

artificial

comfort

techniques to make the space livable. Buildings in the India consume about 30% of the electricity consumption, for heating, cooling,

lighting

and

Fig 1.3 Increase of energy use in the commercial sector, UNDP, India

running equipment such as computers. The energy consumption in buildings is expected to further increase because of improving standards of life and increasing world population. Thus causing tremendous ill effects to the environment we live in. This is not just the case of a residential building but more on office and commercial

Fig 1.2 Break-up of energy consumption category wise,

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buildings.

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Energy consumption in office buildings is one

of

the

highest

compared

to

the

consumption of other building types. (The fig 1.3.

shows

the

break-up

of

energy

consumption category wise for a state in India.).

((NPC), 2009)

Thus an alternative for

better comfort levels with least or no ill

Fig 1.4 Energy need in a typical office building

effects to the environment have to be identified and passive techniques in buildings becomes relevant there. The use of more passive techniques will reduce the energy load consumed by office buildings.

Fig 1. 4. Shows the energy need for various purposes in a typical office building in India. ((NPC), 2009)

Relevance of passive techniques in warm humid climate, -Indian context Climate is the term used to describe the long-term weather patterns of a particular place, including factors such as rainfall and humidity Depending on the combination of these factors, different climate classifications can be given to various regions of the world. (Daroda, 2011) The climate of any region is affected by latitude and elevation as well as nearby oceans and ocean currents.

Warm and humid climate Warm and Humid climate is characterized by high relative humidity, around 70-90 %, and high precipitation levels, about 1200 mm per year. The temperatures usually vary between 25–35 ºC in summers; while in winters, temperatures vary between 20–30 ºC.

(Shivani singh sachan, 2013)

The building design in a warm and humid climate should aim

at reducing heat gain by providing shading, and promoting heat loss by maximizing cross ventilation. Dissipation of humidity is also required to reduce discomfort Climate is a big challenge in warm humid climate especially. The dominant factor affecting thermal comfort is the relative humidity; even an increase in air movement might not significantly improve the body‘s ability to lose heat to the atmosphere if the air is saturated or close to saturation. So this paper will be trying to explore deeper

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 into the solutions for better comfort conditions in office buildings of warm humid climate through passive nature.

1.2 AIM To study the various passive techniques that can be used to increase the comfort levels and decrease the energy consumption in office buildings of warm humid climates.

1.3 OBJECTIVES 1. To understand the concept and relevance of passive techniques in the present world with increased energy consumption and growing energy crisis 2. To understand the comfort needs for office buildings in warm humid climate and how well it can be achieved through passive techniques 3. To study and analyze various methods of passive techniques that can be used in office buildings of warm humid climate through various case studies and research publications

1.4 SCOPE 1. The area of study of the seminar will be limited to passive techniques used in office buildings of warm humid climate with more emphasis on sub-tropical region 2. The seminar may not deal with technical details of any of the proposed techniques; however the ideas behind the techniques will be studied.

3. Researches are still undergoing on various passive techniques that could be used in warm humid climate and being a topic with huge scope, there could be other techniques which are not dealt with in this seminar 4. The outcome of the study may be of some help (partially or fully) in on-going Thesis project ‗ National Institute for Research and Development in Defence Shipbuilding‘

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

1.5 METHODOLOGY

1.5.1

ELEMENTS OF ORGANIZATION

Objective

Derivative

Source

Warm humid

Types of warm humid climate

Journals,

climate and comfort

based on region, comfort requirement

research publications

for each case Office building

energy

requirements

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Total activity

energy

analysis

consumption, and

requirement for each

DEPARTMENT OF ARCHITECTURE, NIT C

energy

Journals, research publications, literature case studies

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 from journals

Passive design strategies

Detailed

study

of

office

Journals,

buildings in warm humid climates

research publications,

and the type of passive techniques

literature case studies

that can be effectively implemented

from journals

in design Analysis and deriving guidelines

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Thesis oriented, guidelines for the buildings

DEPARTMENT OF ARCHITECTURE, NIT C

Journals, research publications

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CHAPTER 2

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

2 GENERAL CONSIDERATIONS 2.1 CLIMATE “It is not practicable to plan a building exclusively on economic, functional or formal grounds and expect a few minor adjustments to give a good indoor climate. Unless the design is fundamentally correct in all aspects, no specialist can make it function satisfactorily.

Climate must be taken into account when deciding on the overall concept of a project, on the layout and orientation of buildings, on the shape and character of structures, on the spaces to be enclosed and, last but by no means least, the spaces between buildings. In other words climate must be considered at the early design stage.”

- Koenigsberger (1974)

The traditional architecture varies from place to place depending on how people protect themselves from hostile weather conditions. The building design for arid climate is clearly different to the design for hot and humid climate. In this respect although the building accommodate the functions of shelter against hostile weather conditions, a private place for resting and sleeping, their form differs with climate.

(Anicet Vincent, 2004)

Climate: Climate encompasses the statistics of variation in temperature, humidity, atmospheric pressure, wind, precipitation,

atmospheric

particle

count

and

other

meteorological variables in a given region over long periods of time.

There are various climatic elements affecting thermal comfort namely temperature, humidity, precipitation, wind etc. (Anicet Vincent, 2004) 2.1.1

CLIMATIC ELEMENTS

Temperature: The DBT, dry bulb temperature (°C, °F or K), is probably the most commonly used unit to describe climate. Air temperature is measured with a dry bulb thermometer 18

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 protected from solar and heat radiation. This data is generally available in meteorological records as monthly means, maximum and minimum values (both normal and extreme). The wet bulb temperature (WBT) is the temperature at which vapour saturation occurs. (Rosenlund, Climatic Design of Buildings, 2000)

Humidity: Air contains a certain amount of vapour, which is called air humidity. It can be specified as absolute humidity in grams per kg or m3, or as partial vapour pressure

(kPa).

however

the

More

common

expression

is

relative

humidity – RH (%) which describes the portion

of

vapour

in

relation

to

saturation. Hotter air can contain more vapour than colder, and when cooled to the limit – the dew point – the surplus condenses. Relative humidity can be

Fig 2.1 The psychometric chart plots the combination of temperature and humidity

measured with electronic hygrometers or with a simple sling hygrometer including a dry bulb and a wet bulb thermometer. (Rosenlund, Climatic Design of Buildings, 2000)

Wind: At local level wind is the most irregular and varying component of the climate. It is affected by topography, vegetation and surrounding buildings; closeness to the sea may create on and offshore winds. Wind is described by its speed and direction and is measured with an anemometer. (Rosenlund, Climatic Design of Buildings, 2000) The fig 2.2 shows a wind frequency diagram, a ‗wind

Fig 2.2A wind frequency diagram, a ‘wind rose’.

rose‘. The length of the lines describes frequencies from different directions, and the thickness describes wind speed intervals, according to a scale and a legend. The figure in the middle is the percentage of calm. (Rosenlund, Climatic Design of Buildings, 2000) 19

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Precipitation: Precipitation may vary considerably between seasons. Data on monthly means, extreme values and maximum precipitation during 24 hours are commonly found.

Combinations with other elements could be interesting in relation to building design, e.g. at strong winds it rains ‗horizontally‘ (driving rain). (Adamson, 1993)

Solar radiation and sky conditions: The sun may be described as the ‗engine‘ of the climate since it supplies a large amount of energy to the earth. The sun‘s path is regular and depends on the latitude and the time of the year. The season also determines the total amount of irradiation through the length of the day. High altitudes give more intense solar radiation, because there is less absorption in the relatively thinner layer of atmosphere.

The position of the sun may be determined with the help of solar diagrams. There is one diagram for each latitude, making it possible to read the altitude (vertical angle) and the azimuth (horizontal angle) of the sun at every hour of every day of the year.

The relation between direct and diffuse radiation varies with the sky conditions.

Humid air or overcast skies increase the diffuse part. Overlays to the solar diagram may give data on solar radiation on horizontal or other surfaces, but corrections for cloudiness and humidity must always be considered. Reflections from the ground and adjacent buildings, and shading from adjacent buildings and vegetation, affect the total solar radiation. (Rosenlund, Climatic Design of Buildings, 2000) 2.1.2

CLIMATE TYPES

One of most commonly used classification system for describing the climate is Köppen‘s. The classification below mainly follows Köppen,with main groups given in parentheses if they deviate. (miller, 1971)

Cold climate (Cold Temperate, Sub-arctic and Arctic): The average temperature of the coldest month is below 0°C; some subgroups have dry seasons. In arctic areas all months may have average temperatures below zero; elsewhere summer averages may reach 22°C. (miller, 1971)

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Temperate climate Temperate climates have average temperatures ranging from 0–18°C for the coldest, and 10–22°C for the hottest month. Subgroups are defined by differences in rainfall distribution. (Rosenlund, Climatic Design of Buildings, 2000) Hot-arid climate (Desert and Steppe) Deserts have average temperatures above 0°C in winter and above 18°C in summer.

Subgroups are defined by differences in rainfall distribution over the year Warm-humid climate (Equatorial) Minimum average monthly temperature is above 18°C and subclasses are defined by differences in seasonal rainfall distribution. A warm-humid climate has a fairly constant temperature, both over the day and over the year. Humidity and cloudiness make diffuse solar radiation important, and the potential for radiative sky cooling is lower. Seasons are often determined by rainfall and winds.

[ (Rosenlund, Climatic Design of

Buildings, 2000)

Warm and Humid climate is characterized by high relative humidity, around 70-90 %, and high precipitation levels, about 1200 mm per year. The temperatures usually vary between 25–35 ºC in summers; while in winters, temperatures vary between 20–30 ºC. (Shivani singh sachan, 2013)

2.2 COMFORT: The human being, like other bodies, exchanges heat with its environment through conduction (by direct contact), convection (transported by air), radiation (mainly shortwave visual light and long-wave heat) and evaporation/ condensation (heat released through change of state of water, also called latent heat). (Rosenlund, Climatic Design of Buildings, 2000)

Factors influencing the heat balance are environmental, such as air and

mean radiant temperatures, vapour pressure and air motion, but also individual, such as metabolic rate and clothing. The thermal equilibrium must be maintained within narrow limits for survival, and the range of comfort is even narrower.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Comfort

is

a

subjective

experience, and not all people agree about optimal comfort. To handle comfort, it was necessary to define some kind of index, or a ‗comfort

zone‘

where

the

majority of people experience well-being.

1997).

(american Society of Heating,

Fig 2.3 shows the four

modes of heat exchange.

Fig 2.3 The four modes of heat exchange: conduction,

2.3 THERMAL COMFORT A healthy and comfortable thermal environment of indoor workspace makes the occupants comfortable with improved work efficiencies and well-being. Thermal sensation refers to subjective thermal perception as how the person feels the environment e warm, neutral, cold etc. Different environmental parameters, activity level and clothing worn by the occupants affect thermal sensation experienced by a person. The word ―thermal comfort‖ is defined by American Society of Heating,

Fig 2.4The comfort temperature tends to follow the outdoor temperature. Data from Pakistan, Europe, and Humphreys which have varying climate

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Refrigerating and Air- Conditioning Engineers (ASHRAE), as the condition of mind which expresses human satisfaction with the thermal environment.

Fig 2.6 Factors affecting thermal comfort

Fig 2.5 Relation between comfort temperature and wind speed

2.4 WARM HUMID CLIMATE AND BUILDING COMFORT Warm and Humid climate is characterized by high relative humidity, around 70-90 %, and high precipitation levels, about 1200 mm per year. The temperatures usually vary

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 between 25–35 ºC in summers; while in winters, temperatures vary between 20–30 ºC. (Shivani singh sachan, 2013) In fig 2.7 Showing bioclimatic chart for warm humid climates, the new comfort zone is shown on the right of the original one.

Fig 2.7 Bioclimatic chart for warm humid climate

Before a decision is made to adopt a design strategy from other climates into hot humid climates, one must understand the climatic conditions of the site and their

Fig 2.8Variation of comfort temperature with in a tropical warm humid climatic region over the months

impact on the building. For building design purposes two different warm-humid 24

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 climates should be considered, a tropical and a subtropical climate. In order to evaluate building design strategies a detailed analysis into both are essential.

The warm humid climate which is mainly characterized by an elevated temperature and high relative air humidity, air flows in building theoretically needed to restore comfort, therefore, the buildings should be designed to provide cross ventilation.

Table 2.1summer indoor climatic data

(Bhatia, 2002)

The air temperature and humidity combined in the enthalpy have a strong

impact on perceived air quality, and perceived air quality determines the required ventilation in ventilation standard. Air movements inside a building depend not only on external wind velocity, but also largely on the most of architectural parameters.

Architectural means for achieving this aim include such conventional design element as position and orientation of building, roof shape, balcony configuration, type and location of windows, partition and furniture arrangement. Changes in these elements can modify interior airflow magnitudes and patterns. (Al-Tamimi, 2011)

Though it is difficult to define comfort precisely, it is evident that comfort is the result of three variable factors: temperature, humidity, and air movement (described in detail above) in general, for the warm, humid region (sub-tropical belt) comfort conditions are achieved when the room temperature is between 24 and 30 C, relative humidity between 45 and 65%, and with an air movement of 0.07 to 0.11 m/s (George Havenith, 2002)

25

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 The building design in a warm and humid climate should aim at reducing heat gain by providing shading, and promoting heat loss by maximizing cross ventilation.

Dissipation of humidity is also required to reduce discomfort. Thus, we can,

Resist heat gain by: 

Decreasing surface area of the building exposed to the outside.



Using materials that take a longer time to heat up.



Providing buffer spaces between the outside and the inside.



Increasing shading of the building in general.



Using materials that reflect heat.

Promote heat loss by: 

Appliances used are well ventilated.



Proper ventilation occurs throughout the day.

Humidity levels have to be reduced as much as possible, by: 

Wind Tower (Fig 2.9) (Shivani singh sachan, 2013)

Fig 2.9 Wind tower

26

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CHAPTER 3

27

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

3 ENERGY CONSUMPTION AND BUILDINGS

3.1 INCREASING ENERGY CONSUMPTION BY BUILDINGS Buildings account for over one third of India‘s total electricity consumption which is mainly in the residential and commercial sector. That is 30% energy consumption is contributed by buildings In India, and 66% building stock is yet to be constructed.

(Astrid Roetzel,

Fig 3.1Pie chart on energy consumption by various sectors

2013)

Energy consumption in the building sector is function of the type of construction, usage pattern, the climatic region and the energy consuming devices installed in the buildings. Different types of energy end-use in buildings such as lighting, space heating, space cooling, plug-in loads and appliances all together account for the overall energy consumption pattern of the building. Energy consumption is not only Table 3.1 Annual energy consumption by various building types in India

28

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 dependent on the type of the end use appliances but also on the operational efficiency and maintenance of these end use appliances. Building design and material can have a significant impact on the energy consumption levels of a particular end-use application. (Jones Lang, 2007)

3.2 OFFICE BUILDINGS AND ENERGY CONSUMPTION In warm humid climate due to the need for more cross ventilation it becomes more energy consuming to use active systems of cooling for office buildings. The average annual energy intensity for office buildings is 1.57 kWh/m2 (Harvey, 2010)

Fig 3.2 Peak cooling load in office building (Hong Kong, Lam and lii, 1999)

Key features for energy consumption in office buildings 

the standards to which the building and its services are designed



the proportion of open-planned offices; these tend to use more energy, particularly for lighting



the presence of air-conditioning.



design which maximises the use of form and fabric to control the internal environment



design which minimises the provision, capacity and use of building services



the quality of construction, installation and commissioning.



occupancy hours and, to a lesser extent, densities



the amount of office and other equipment installed and its intensity of use



matching standards and operating hours of services and equipment to usage



effective maintenance

29

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 

Unoccupied space.



Mainframe computer rooms, communications rooms and extensive dealing rooms, and their air-conditioning.



Catering kitchens and sports and leisure facilities. (GUIDE, 2000)

Fig 3.3 Energy consumption by all building types in India (Retail and private offices shown)

From fig.3.3 we can observe that the energy consumption by office buildings both Private and government offices have increased considerably over the years. (Jain, 2007)

Fig 3.4 Growth of electricity consumption in commercial sector

30

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

3.3 ENERGY REQUIREMENTS OF OFFICE BUILDINGS A healthy and comfortable thermal environment of indoor workspace makes the occupants comfortable with improved work efficiencies and well-being in an office building.

Cooling Electricity for mechanical cooling is significant, but seldom as much as that for the pumps and fans which distribute the cooling. Cooling plant and the associated pumps need to be carefully managed to run only when there is genuine demand, and small 24-hour loads should be independently cooled. (pitt, 2012) Lighting Increasing open plans in the offices increases the overall floor area of a room and thus increasing the requirement for artificial lighting.

(pitt,

Table 3.2 Breakdown of annual electricity consumption for a base case generic office building

2012)

Computing Various

electronic

equipment and computers are extensively used in offices and a major portion of enrgy requirement is for the running of these.

Fig 3.5 electricity requirement for an office building

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CHAPTER 4

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

4 PASSIVE TECHNIQUES Passive design can be referred to a way of designing buildings that takes advantage of the prevailing climate and natural energy resources, such as daylight, wind and thermal buoyancy, to achieve a comfortable environment while minimizing energy use and reliance on mechanical systems. (Shamim Ara Hassan) A proper architectural design of a building envelope can significantly lower the energy usage through day lighting, reduced HVAC loads, etc. Innovations such as the self-shading envelopes are being explored by researchers (Suresh B. Sadineni, 2011) 4.1.1

DESIGN FOR MINIMISING COOLING REQUIREMENT

In hot humid climates, a significant amount of energy can be saved if cooling needs can be minimised. In general, to achieve this, solar and conductive heat gains should be contained, and natural ventilation promoted for cooling and humidity removal. (Ar Aniza Abdul Aziz, 2000)

Some of the key strategies for minimising cooling needs involve

appropriate orientation and spatial organisation, shading, and appropriate use of materials, colours, textures and vegetation. (Suresh B. Sadineni, 2011) 4.1.1.1 ORIENTATION AND SPATIAL ORGANISATION Orientation and spatial organisation affect the ability of a building to ventilate and receive solar radiation. To minimise solar gain and maximise ventilation, traditional buildings in hot humid climates usually employ spread-out plans and permeable internal organisation However work is still required to overcome the challenge of applying such orientation and spatial organisation to commercial buildings in high-density areas, such as high-rise offices, so that a balance is struck between comfort, energy use and commercial feasibility.

(Torwong

Chenvidyakarn, 2005)

33

DEPARTMENT OF ARCHITECTURE, NIT C

Fig 4.1 The orientation organisation of a Thai house

and

spatial

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 4.1.1.2 SUN SHADING Solar gain through windows is often a major component of the heat gains of a building. Also, solar radiation on the opaque parts of the building envelope raises the surface temperature of the envelope and contributes to the heating of the interior environment. (Torwong Chenvidyakarn, 2005) Effective shading can be provided by various means, including dedicated shading devices, nearby structures, vegetation and special glasses. Generally, external shading devices are considered the most effective, since they intercept solar radiation before it passes through the building envelope into the interior space. An appropriately orientated high-pitched roof which affords self-shading and allows only one side of it to receive direct solar radiation at a time is another possible shading technique (Torwong Chenvidyakarn, 2005)

4.1.1.3 MATERIAL, COLOUR AND TEXTURE For many regions in hot humid climates, modern materials produced using technologies imported from colder and drier climates, such as plasterboards, lightweight concrete blocks and insulations have become prevalent. To minimise thermal impact from solar radiation, multiple layers of materials may be required to make up a building envelop. A layer of insulation, such as foam or glass fibre, is probably required to cut effectively conductive heat transfer through opaque surfaces which receive strong solar radiation. In addition, a ventilation gap may be beneficially provided between the different layers of the envelope materials to vent excessive heat accumulated within. (Torwong Chenvidyakarn, 2005)

Fig 4.2 A schematic of a roof section showing an example of a combined use of insulation, a ventilation space and

34

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 In addition to the use of traditional and imported materials, a number of new materials have been developed in hot humid climates, usually from local raw materials, such as agricultural wastes. Examples include particleboards from a mixture of rice straw and rice husks. (Torwong Chenvidyakarn, 2005) 4.1.1.4 VEGETATION Vegetation can be an effective means of moderating the temperature around a building and reducing the building‘s cooling requirement. Vegetation in the form of trees, climbers, high shrubs and pergolas, for example, can provide effective shading for the building‘s walls and windows. (Torwong Chenvidyakarn, 2005) 4.1.1.5 COOLING TECHNIQUES Even with the best effort to reduce heat gains, cooling requirement may not be eliminated. In such cases, a range of passive cooling techniques may be employed to help achieve thermal comfort. Key cooling techniques for hot humid climates involve appropriate utilisation of natural ventilation, thermal mass and heat dissipation by radiation and evaporation. (Torwong Chenvidyakarn, 2005) 4.1.1.6 DEHUMIDIFICATION TECHNIQUES In hot humid climates where the humidity level is often above the comfortable limit, dehumidification is an important part of thermal comfort strategy. Typically, dehumidification in these climates is accomplished by mechanical airconditioning.

However, this can be highly energy consuming, as often to reduce moisture to a required level, humid intake air has to be cooled to a temperature below that required for thermal comfort. Efforts should be made to integrate passive dehumidification techniques with appropriate passive cooling systems to develop viable alternatives to conventional air-conditioning. (Torwong Chenvidyakarn, 2005)

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CHAPTER 5

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

5 PASSIVE TECHNIQUES IN OFFICE BUILDINGS OF WARM HUMID CLIMATE Passive techniques involve designing buildings and selecting construction materials in a way that reduces heat absorption and conduction through the roof and walls. The goal of these systems is to minimize, or eliminate if possible, the use of mechanical air conditioning systems to decrease energy consumption. Agrawal in his study postulated that by using proper passive design concepts at least 2.35% of the world energy consumption could be avoided. (Jorge L. Alvarado, 2009) Special considerations for implementing passive techniques have to be taken in warm humid climate.

5.1 SITE AND BUILDING ENVELOPE 5.1.1

ORIENTATION

Building orientation could provide reductions minimizing

in

cooling

solar

loads

penetration

by and

absorption through windows, walls and roofs.

(Los Alamos National Laboratory

Sustainable Design Guide, 2002)

Designers could

follow some simple rules concerning solar exposure. In solar passive design features, orientation is a major design

Fig 5.1 Orientation with longer facades on N-S

consideration, mainly with regard to solar radiation, daylight and wind.

In tropical climate like India long facades of buildings oriented towards North—South are preferred. Fig 5.2 shows 37

the

various

orientation

for

Fig C 5.2 orientation for different climatic regions DEPARTMENT OF ARCHITECTURE, NIT

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 different climatic region.

(Daroda, 2011)

East and West receive maximum solar radiation

during summer. In predominantly cold regions, also North South long facades are advisable, as South orientation receives maximum intensity of solar radiation in winter months (Nagan, 2010) Far from the polar and equatorial regions, for example, the highest intensity of solar radiation is on east- and west-facing walls in summer and south-facing walls in winter. This promotes a strong preference for the north–south orientation of main facades and glazing. Moreover shading systems, in particular for windows, are usually used to reduce solar heat gains but this leads to a reduction in natural daylight and hence an increase in energy consumption for artificial lighting 5.1.1.1

(Nagan, 2010)

SIMULATION OF AN OFFICE IN BHUBANESWAR

The below figures shows the solar radiation received on each facade of the building orientation which were modelled in Eco-tect software. South orientation receives maximum solar radiation during winters which is preferable. East and West receive maximum solar radiation during summer. West is a crucial orientation because high intensity of solar radiation is received during summers, when the internal gains are also at its peak. Thus, designers need to be very careful while designing West facade and spaces behind West facade. (Nagan, 2010) Orientation also plays an important role with respect to wind direction. At building level, orientation affects the heat gain through building envelope and thus the cooling demand, orientation may affect the daylight factor depending upon the surrounding built forms, and finally the depending upon the windward and leeward orientation fenestration could be designed to integrate natural ventilation. (Nagan, 2010) An example of average Solar Radiation received on various facades in warm & humid climate zone of Bhubaneswar City

38

DEPARTMENT OF ARCHITECTURE, NIT C

Table 5.1Average solar radiation intensity on various facades of a building in warm & humid climate

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

Fig 5.3 Average daily solar radiation received on North orientation in Bhubaneswar

Fig 5.4 Average daily solar radiation received on South orientation in Bhubaneswar

Fig 5.5 Average daily radiation received on orientation in Bhubaneswar

Fig 5.6 Average daily solar radiation received on West orientation in Bhubaneswar

39

DEPARTMENT OF ARCHITECTURE, NIT C

solar East

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 5.1.2

BUILDING FORM

Building form can affect solar access and wind exposure as well as the rate of heat loss or heat gain through the external envelope. The volume of space inside a building that needs to be heated or cooled and its relationship with the area of the envelope enclosing the volume affect the thermal performance of the building. (Nagan, 2010) The general design considerations regarding building form should be: 

Contain the exposure of external elements by means of compact building envelope and careful consideration of the treatment of different elevations



Use sheltering and buffering

5.1.2.1 COMPACTNESS: The building form also determines the air flow pattern around the building directly affecting its ventilation. The compactness of the building is measured using the ratio of surface area to volume (S/V). The depth of a building also determines the requirement for artificial lighting. The greater the depth, higher is the need for artificial lighting. The circular geometry has the lowest S/V ratio thus the conduction gains from the building envelope as well as solar gains from windows are least, in circular geometry in comparison to other building geometries which is most energy efficient in warm & humid climate. (Nagan, 2010)

5.1.2.2 SHELTERING OR SELF-SHADING: Built form, which is designed such that it is self-shaded through massing or articulation results in sheltered built forms, and cuts off a large amount of direct solar radiation. In warm & humid climate, the envelope should be designed so that it

40

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 remains shaded for the greater part of the day; the external walls should be so planned that they shade each other. (Nagan, 2010)

5.2 VENTILATION The tropical humid climate which is mainly characterized by an elevated temperature and a high relative air humidity, air flows in building theoretically needed to restore comfort, therefore, the buildings should be designed to provide cross ventilation. As found by Fanger and Toftum, the air temperature and humidity combined in the enthalpy have a strong impact on perceived air quality, and perceived air quality determines the required ventilation in ventilation

standard.

(Linden,

2008)

Fig 5.7 doomed roof air cooling

Air

movements inside a building depend not only on external wind velocity, but also largely on the most of architectural parameters. Architectural means for achieving this aim include such conventional design element as position and orientation of building, roof shape, balcony configuration, type and location of windows, partition and furniture arrangement. Changes in these elements can modify interior airflow magnitudes and patterns (Nagan, 2010) Air movement within enclosed spaces is essential. It brings the air in contact with the skin and at the same time replaces the warm and saturated air next to the skin, thus cooling the body.

5.2.1

CROSS VENTILATION

Cross ventilation is of utmost importance for buildings located in hot, humid regions.

It can be achieved as follows:

41

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 

Making the inlet slightly smaller in size than the outlet so that there will always be a lower pressure within the room and air flow will thereby be assured (Venturi Effect)



Providing ventilators below or at ceiling level (for pitched roofs) so that air entering the room through windows, after picking up heat and becoming lighter in density, will rise to the ceiling. If ventilators are provided the warmer air will escape ('Stack Effect') and allow more cool air to flow in through the window (Ashfaque Ahmed Chowdhury, 2007)

5.2.2

RAIN PROTECTION AND VENTILATION

In warm humid regions the temperature may be quite high during the rains and, of course, accompanied by high humidity. In this situation ventilation is very important for comfort during the rain. Therefore, the design of the building should enable natural ventilation also during the rainy period, even when accompanied by high winds, with effective prevention of water penetration through the open window or doors. (Rosenlund, Climatic Design of Buildings, 2000) A combination of wide balconies or verandas and shutters with details which enable air flow but block rain can be a good solution. Covered balconies are very useful anyway, to enable outdoor activities during unfavorable warm periods. Such balconies can therefore be very useful in hot, humid, rainy regions. A common feature in many vernacular buildings in hot, humid regions is a veranda surrounding the building.

Often, the veranda is formed by structurally extending sloping roofs beyond the walls, but they can also have a structural system separated from that of the roof.

(M. Haase a,

2008)

5.3 COOLING 5.3.1

VENTILATIVE COOLING

Ventilation provides cooling by enabling convective heat transfer from a warm building‘s interior to a cool exterior. Also, sufficiently high indoor air velocities give

42

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 the occupants direct physiological cooling. In a natural system, ventilation can be accomplished by either wind, buoyancy or a combination of wind and buoyancy.

5.3.1.1 VENTILATIVE COOLING BY WIND This technique relies on wind force to produce pressure differences between the interior and exterior of a building, which in turn lead to internal air movement and heat removal from the interior. Sufficiently high indoor air velocities can also increase appreciably convective heat transfer from the occupants‘ skins and clothing and the rate of skin evaporation, the net effect of which is physiological cooling. With an indoor air speed of around 1.5-2.0 m/s, ventilation can provide comfort in regions and seasons when the maximum outdoor air temperature does not exceed about 2832ŕš?C, depending on the humidity level and the acclimatisation of the population (Torwong Chenvidyakarn, 2005)

Several investigations agree that, in general, to achieve effective ventilation in hot humid climates at least two large operable windows should be provided on different walls, preferably one opposite the other, with one of them intercepting the prevailing wind (Fig 5.8 a). When the windows cannot be orientated to face the wind, wind deflectors, which may be in the form of appropriately placed internal partitions, can be employed to channel air through the occupied zone (Fig 5.8 b) Obstruction of the air path should be minimised (Fig 5.8c). Furthermore, windows should be at the body level to increase potential for physiological cooling (Torwong Chenvidyakarn, 2005)

Fig 5.8 Examples of opening design to encourage

5.3.1.2 VENTILATIVE COOLING BY BUOYANCY This technique relies on temperature differences between the interior and exterior of a building to

43

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 produce pressure gradients across the vents and drive the ventilation. Such temperature differences are usually a result of the heating by the occupants, lighting and other internal heat sources.

While buoyancy-driven ventilation may be used to keep the interior temperature from rising excessively above the exterior and supply sufficient fresh air, the movement of indoor air achieved by this technique is usually insufficient to provide physiological cooling: computer simulations have shown houses fitted with ventilation chimneys being able to achieve a maximum indoor air velocity of only about 0.1 m/s, for instance

Fig 5.9 Examples of solar chimney configurations: vertical (a) and inclined (b)

In general, to maximise the heat removal potential of buoyancy-driven ventilation, the vent area should be maximised, along with the vertical distance between the inlet and outlet. Additional buoyancy can be provided to increase the heat removal rate without raising the interior temperature by using solar radiation to heat a part of the ventilation path that is sufficiently separated from the occupied space. Such techniques may be implemented in the form of the so-called solar chimney (Fig 5.9), for example, which appears to have potential in hot humid climates where solar radiation is high.

(Torwong

Chenvidyakarn, 2005)

Work on the solar chimney shows that the optimum width of a chimney is independent of solar intensity, but is dependent on the height of the chimney itself, the size of the room inlet and the size of the chimney inlet. Furthermore, greater flow 44

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 rates can be achieved when the chimney is inclined appropriately according to the latitude in which it is used or made of a low-emissivity material to minimise radiative heat loss through its walls (Torwong Chenvidyakarn, 2005)

Fig 5.10 Wind-assisted ventilation (a); buoyancy dominated, wind-opposed ventilation (b); and wind dominated,

5.3.1.3 VENTILATIVE COOLING BY COMBINED WIND AND BUOYANCY The presence of wind can reduce or enhance the cooling potential of buoyancy-driven flows. Wind will assist buoyancy when the inlet is located on a windward side and the outlet is located on a leeward side (Fig 5.10 a). The result is a greater indoor air velocity and greater cooling. In contrast, wind will oppose buoyancy if the inlet is placed on a leeward side while the outlet is on a windward side. In this case, if the magnitude of the wind-produced velocity is smaller than the buoyancy-produced velocity, the net flow will be reduced along with the cooling effect (Fig 5.10 b).

However, if the wind-produced velocity exceeds the buoyancy-produced velocity, the net flow will be greater, although the flow regime will be reversed following the direction of the wind (Fig 5.10 c). Greater cooling may be expected as a consequence.

Such interaction between wind and buoyancy highlights the need for locating the ventilation inlet and outlet appropriately to optimise the cooling potential of natural ventilation. (Torwong Chenvidyakarn, 2005) 5.3.2

THERMAL MASS COOLING

Thermal mass can be utilised in several ways. The mass may be integral to the building envelope to provide direct cooling, or it can be remote, such as the earth under or around a building, through which fresh air is passed and cooled before entering the occupied space. Traditionally, thermal mass is used in hot humid climates 45

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 predominantly in public buildings of social/religious importance, such as temples, whose heavy masonry envelopes also satisfy the need for durability. Appreciable reduction of the indoor temperature can be achieved in such buildings, with indoor air maxima about 3๐C below outdoor air maxima having been observed in some cases.

For modern buildings in hot humid climates, small-scale experiments and computer modelling suggest that thermal mass can make an appropriate envelope material for spaces used primarily during the day, computer simulations suggest that this technique may also have potential in hot humid climates where night-time temperatures are generally higher and diurnal temperature swings smaller. A reduction in the indoor temperature of about 3-6๐C below the exterior air may be achievable, depending on the local climate, the amount of mass, its distribution and the ventilation details. (Torwong Chenvidyakarn, 2005) 5.3.3

RADIANT COOLING

When two surfaces of different temperatures face one another, radiative heat exchange will occur between them. Radiant cooling relies on this mechanism to dissipate heat from a building or an occupant‘s body. One of the more common radiant cooling systems uses the roof of a building as a radiator to dissipate heat to the night sky. This process cools the roof, which in turn serves as a heat sink for the occupied space underneath.

(Torwong Chenvidyakarn, 2005)

Fig 5.11 A schematic of a radiant cooling system which involves cooling the roof by nocturnal radiation

To enhance the performance of such a system further, a desiccant bed can be incorporated in the roof structure to dehumidify the passing air. More work is still required to optimise the cooling

46

DEPARTMENT OF ARCHITECTURE, NIT C

Fig 5.12 A schematic of the cool radiant panel system tested in Thailand

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 potential of this technique in hot humid climates.

5.3.4

INDIRECT EVAPORATIVE COOLING

Water left on a surface of a building has a natural tendency to evaporate in order to achieve phase equilibrium with the water vapour in the surrounding air. As it evaporates, every gramme of water extracts about 2550 J of heat from its environment. Indirect evaporative cooling uses this principle to provide cooling, while keeping the evaporation process outside the building to avoid elevating the indoor humidity level. Indirect evaporative cooling can be achieved by several means, notably a roof pond, a spray of water over a roof surface and a roof garden.

(Torwong

Chenvidyakarn, 2005)

5.3.4.1 ROOF POND This system collects water on the roof of a building and lets it evaporate. The evaporation cools the roof which then serves as a heat sink for the interior. A roof pond system has been tested in the hot humid climate of Mexico, which has an insulation floating on the water surface to shield it from solar radiation during the day, and which circulates the water over the insulation at night to remove heat absorbed in the water by convection, evaporation and radiation (Torwong Chenvidyakarn, 2005)

Fig 5.13 A schematic of the Coolroof system

5.3.4.2 ROOF SPRAY Where collection of water on the roof is not possible, for structural reasons for instance, water may be sprayed onto the roof surface as an alternative to the roof 47

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 pond. Case studies show that this technique has some potential in warm humid climates, with a reduction in the indoor air temperature of about 1-4ŕš?C being possible 5.3.4.3 ROOF GARDEN A roof garden can provide cooling in several ways. The plants shade the roof, and together with the substrate layer, act as insulation. Also, the substrate layer and roof structure combined serve as thermal mass that delays heat transfer from the exterior while absorbing heat from internal sources.

Furthermore, the evapotranspiration process provides cooling. Case studies in hot humid climates show that roof gardens have significant cooling potential, with a reduction in the roof surface temperature of about 10-30ŕš?C being achievable, depending on the roof construction, planting details and surrounding conditions (Torwong Chenvidyakarn, 2005)

5.3.5

WIND TOWER

The hot ambient air enters the tower through the openings in the tower and is cooled when it comes in contact with the cool tower and thus becomes heavier and sinks down. When an inlet is provided to the rooms with an outlet on the other side there is a draft of cool air. After a whole day of heat exchange, the wind tower becomes warm in the evening (Dr Anupama Sharma, 2003)

Fig 5.14 Wind tower

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 5.3.6

ADVANCED PASSIVE COOLING

5.3.6.1 EARTH AIR TUNNELS: Daily and annual temperature fluctuation decreases with the increase in depth below the ground surface. At a depth of about 4m below ground, the temperature inside the earth remains nearly constant round the year and is nearly equal to the annual average temperature of the place. A tunnel in the form of a pipe or otherwise embedded at a depth of about 4m below the ground will acquire the same temperature as the surrounding earth at its surface and therefore the ambient air ventilated through this tunnel will get cooled in summer and warmed in winter (L. Pires a, 2013)

Fig 5.15 passive space conditioning

5.3.6.2

VENTILATED COURTYARD AS A PASSIVE COOLING STRATEGY

The inclusion of an internal courtyard in building design is attributed to the optimization of natural ventilation in order to minimize indoor overheating conditions. However, the efficiency of this strategy greatly depends on the design details of the building composition in providing appropriate

airflow

pattern

to

the

courtyard. (I. Rajapaksha, 2003) From the results of thermal measurements, a

49

DEPARTMENT OF ARCHITECTURE, NIT C

Fig 5.16 courtyard, INA administrative block

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 significant correlation between wall surface temperatures and indoor air temperatures is evident. A reduction of indoor air temperature below the levels of ambient is seen as a function of heat exchange between the indoor air and high thermal mass of the building fabric. However, this behaviour is affected by indoor airflow patterns, which are controlled through the composition between envelope openings and the courtyard of the building. (Voss, 2006) A relatively better indoor thermal modification is seen when the courtyard acts as an air funnel discharging indoor air into the sky, than the courtyard acts as a suction zone inducing air from its sky opening. The earlier pattern is promoted when the courtyard is ventilated through openings found in the building envelope. (I. Rajapaksha, 2003) Given the ambient wind climate, and when the measured effective ventilation rate is established, CFD simulations could be used as an appropriate design tool in deriving the corresponding opening composition Thus, the potential of courtyards to act as passive cooling can be correlated with a building composition in terms of airflow rate and pattern (Zambrano1, Malafaia1, 2, & Bastos1, 2006)

5.4 DEHUMIDIFICATION In warm humid climates where the humidity level is often above the comfortable limit, dehumidification is an important part of thermal comfort strategy. Typically, dehumidification in these climates is accomplished by mechanical airconditioning.

However, this can be highly energy consuming, as often to reduce moisture to a required level, humid intake air has to be cooled to a temperature below that required for thermal comfort.

An alternative passive technique uses a double-glazing window unit, whose gap is filled with louvres coated with a silica powder desiccant (Fig5.17). At night, humid exterior air is passed through the gap between the glass panes to allow the desiccant louvres to remove moisture from the passing air, before the dried air is delivered to the occupied space. Then, during the day, the moisture absorbed in the desiccant louvres is driven out using direct solar heating, which regenerates the system.

Chenvidyakarn, 2005)

50

DEPARTMENT OF ARCHITECTURE, NIT C

(Torwong

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

Fig 5.17 Dehumidifying window (a) and its operation (b)

5.5 SHADING External shading is the most effective ways of shading, as it cuts off direct sunlight during summer

and

allows

winter

sunlight to enter inside the space.

However,

in

cloudy

weather or if not designed properly,

Fig 5.18 green wall

these can reduce daylight availability inside the space. For such cases, external moving shading devices are preferred. (Nagan, 2010) 5.5.1

SHADING OF WALLS:

Shading walls from direct sun can be one of the simplest and most effective ways of reducing the heat load on a building. Clever use of shade can dramatically improve the comfort conditions inside and reduce reliance on expensive air conditioning systems. As in the warm & humid climate, the East and West facades receive maximum solar intensity especially in summers, shading the East and West facades is a challenge. As eastern and western walls heat significantly in summers, overhangs

51

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 may not be enough. The entire east and west walls have to be shaded to protect from the strong summer solar intensity (Nagan, 2010) 5.5.1.1 VERTICAL SHADING Vertical shading is the most advisable form of shading to cut the intensive solar heat gains for east and west walls especially in summer. It is some form of vertical light blocker that is placed at the external edge of the overhang or porch roof, extending all the way to the ground

Fig 5.19 Solar PV panels and louvers as wall shading

5.5.2

SHADING OF WINDOWS

In the non-conditioned buildings shading device plays a crucial role in the

thermal

window.

performance

Windows

on

of

a

facades,

facing different cardinal directions, should be provided by the shading devices which can cut the direct

Fig 5.21 External shading for windows as an effective means of shading

incident solar radiation for the critical solar angles. (Nagan, 2010) Horizontal Sun Angle (HSA) This is the horizontal angle between the normal of the window and the Sun azimuth angle at a given time as shown in the fig. 5.20 52

DEPARTMENT OF ARCHITECTURE, NIT C

Fig 5.20 Details of HSA & VSA

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 The horizontal sun angle at critical hours can be cut by the vertical fins provided as external shading device. (Nagan, 2010) Vertical Solar Angle (VSA) It is the angle that a plane containing the bottom two points of the window and the centre of the Sun makes with the ground when measured normal to the shaded surface Table 5.2 Example of Solar angles to be cut on various cardinal directions in warm & humid climate building ( case of city of Bhubaneswar)

as shown in the fig. The vertical solar angle at critical hours can be cut by the horizontal fins provided as external shading device. (Nagan, 2010)

Fig 5.22 Horizontal & vertical fins as an external shading device

5.5.2.1 EXAMPLE TO DESIGN A SHADING DEVICE FOR A WINDOW For a window of height 1.5 m and width 3m, design shading device to cut the HSA of 450 and VSA of 600.

Design of shading device to cut the VSA

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 The vertical solar angle of 600 can be cut by providing a single horizontal overhang of length 841mm or it can be cut by providing two horizontal projections each of length 408mm placed at a distance of 750mm as shown in the figure.

The length and spacing can be calculated either by the drafting softwares like autocad, sketchup etc. by graphical method or it can be manually calculated by the mathematical formula given below – Depth of shading device = Spacing between the shading device x tan (90 -VSA) For a given VSA either of the values for Depth or Spacing between shading overhangs can be selected to get the value of other one.

Design of shading device to cut the HSA The horizontal solar angle of 450 can be cut by providing a single vertical fin of length 2907mm or it can be cut by providing four vertical fins each of length 657mm placed at a distance of 657mm as shown in the figure.

The length and spacing can be calculated either by the drafting softwares like autocad, sketchup etc. by graphical method or it can be manually calculated by the mathematical formula given below – Depth of vertical fins = Spacing between the vertical fins x {tan (90 -HSA)}

Fig 5.23 Design of a shading

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 It is always desirable to break single overhang with larger depth into multiple overhangs of smaller length. It enhances the amount of daylight penetration in the space. The figure

in

right

shows

the

comparison between amount of daylight

penetration

for

two

shading devices, one with single deep overhang and the other with multiple smaller overhangs

(Nagan,

Fig 5.24 Comparison of daylight penetration between multiple overhangs and single overhang

2010)

5.5.3

DEEP PORCHES AND VERANDAS

These are excellent at reducing the solar heat gain in a building because they completely shade the walls. They also cut the solar intensity creating cool spaces even without plants or shrubs 5.5.3.1 SUN-PROOF FABRIC COVERS: For porches, or sails these can be attached to the building itself, and are a good seasonal solution. It is possible to get fabrics and shade cloth that cut out more than 95% of sunlight, and have guarantees of 20 years minimum lifespan. These are put up at the start of the shading season, taken down at the end. In addition to their function of blocking sunlight, fabric sails can be visually exciting. A row of triangular sails, for example, tilted so they overlap each other, and provides excellent shade and visual interest. (Nagan, 2010)

Fig 555.25 Shading through sun proof fabric and verandahs

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

5.6 LIGHTING Day lighting has a major effect on the appearance of space and can have considerable implications on energy efficiency, if used properly. Its variability is subtly pleasing to the occupant in contrast to the relatively monotonous environment produced by artificial light. It helps to create optimum working conditions by bringing out the natural contrast and colour of objects.

(Nagan, 2010)

The presence of natural light can

bring a sense of wellbeing and awareness of the wider environment. Day lighting is important particularly in commercial and office buildings that function during the day.

Fig 5.26 Fixed types of jalis for shading

Integration of day lighting with artificial light brings about considerable savings in energy consumption. A good day lighting system, has number of elements most of which must be incorporated into the building design at an early stage. This can be achieved by considering the following relation to the incidence of day light on the building. (Nagan, 2010) 

Orientation, space organization and geometry of the space to be lit



Location, form & dimension of the fenestrations through which day light will enter



Location & surface properties of internal partitions that affect the day light distribution by reflection

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 

Location, form and dimensions of shading devices that provides protection from excessive light and glare



Light and thermal characteristics of the glazing materials

Table 5.3 Recommended daylight factors for interiors as per Bureau of Indian Standards SP:41(S&T). DF 1%=80 lux. Design sky illuminance 8000lux

Table 5.4 Desirable reflectance levels in a room

5.6.1

INNOVATIVE DAY LIGHTING SYSTEMS:

5.6.1.1 LIGHT PIPES: Light tubes or light pipes are used for transporting or distributing natural or artificial

Fig 5.27 Typical light pipe

light. In their application of day lighting, they are also called as sun pipes, solar pipes, solar light pipes, or day light pipes.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Generally, it may refer to ―a tube or pipe for transport of light to another location, minimizing the loss of light.‖ They make it possible to transport daylight through thick roof structures and attics.

They are easier to install in retrofit applications than skylights. For practical reasons, light pipes are limited to smaller light collection areas. (Nagan, 2010) 5.6.1.2 DAY LIGHTING CONTROL: Day lighting controls are devices that regulate the level of illumination provided by electric lights in response to the presence of day light. They usually consists of a sensing device that monitors either the total light level in the space or the available day light level at the day light aperture, and a control module which receives signal from sensor then switches or dims the electric lighting to maintain the needed illumination with minimal energy use. Day lighting controls also help to achieve uniform luminance throughout the space and reduce Fig 5.28 Daylight control

conditions of over lighting.

(Nagan, 2010)

For spaces that receive significant day light, Daylight Harvesting Controls can be used to keep lights off, or to dim lights. The simplest systems simply turn off the lighting circuit when a pre-determined level of illumination is achieved through daylight. Because these systems require a high level of daylight throughout the space, systems that turn off only a portion of the lights are often more effective. For example, two lamps in a four-lamp fixture might be turned off, or the row of fixtures nearest the windows might be turned off in response to daylight Control techniques: 

On/off day light switching is the most economical approach, but may create light level changes in work areas. It is most successful in circulation areas and non-critical work areas. (Ex; multilevel switching schemes)

58

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 

Dimming systems have higher costs, but will be more acceptable in high work areas. (Ex: Dimming ballasts

5.7 BUILDING MATERIALS Building materials have a significant influence on the achievement of comfort conditions within enclosed spaces. They should be durable (not easily deteriorate in a hot, humid climate) and be good heat insulators. Materials such as bricks, concrete blocks, stone, reinforced cement concrete, asbestos cement sheeting, clay tiles, stabilised earth blocks, steel, aluminium, copper and brass are recommended for use.

When using these materials, if possible, a hollow space should be provided within the wall thickness. This air space acts as a good insulator and heat transmission within the building by conduction is minimised. It is advisable to construct the room to be used Table 5.5 Comparison of temparatures in summer of two buildings with black and white roof

at night with lighter walls {so that they can lose heat easily in the evening) and those to be used during the day with thick walls {so that solar heat transmission within the room will be delayed Colour also plays an important role in minimising heat transmission within a building. Light colours {whitewash or white painted surfaces) are known to reflect solar rays of all wave lengths, red, green, and brown are poor reflectors. Black does not reflect at all and absorbs and converts to heat solar radiation of all wave lengths. Consequently, light colours are recommended for external use.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 5.7.1

THERMAL MASS

Thermal mass refers to the high heat capacity materials that can absorb heat, store it and release it later. They include building components such as walls, partitions, ceilings, floors and furniture of a building that can store thermal energy. It helps in the regulation of indoor temperature by absorbing and progressively releasing the heat gained through both external and internal means. This leads to delaying/reducing the peak indoor loads and decreasing the mean radiant temperature (Torwong Chenvidyakarn, 2005) Table 5.6 Maximum indoor temperature for different roof materials

5.8 LANDSCAPING Vegetation

should

be

extensively and judiciously used to provide shade to the building

walls

surroundings

and so

its that

incoming air is cooled before entering the building.

Fig 5.29 roof garden

Energy-efficient landscape approach Energy-efficient landscape approach can be described as building-scale design intervention intended to improves the energy use of a building (Panagopoulus, 2008) where vegetation serves as passive means for minimising temperatures around buildings as well as reducing overall UHI (Yeang, 2006: 224). Although it is at building-scale effects, 60

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 What constitute energy-efficient landscaping?

According to Yeang (2006: 140), it

encompass

any

kind

of

accessible areas in built forms that

noticeably

available

for

integration with vegetation i.e. roof surfaces, building facades, terraces, sky- courts and the built forms facades(trellis, pergola).

Fig 5.30shading with trees (Nagan, 2010)

5.8.1

GREEN ROOF (VEGETATED ROOF)

Various studies observed that the conversion of dark-coloured roofs into green roofs may contribute significant effects in improving climatic condition In term of climate control, rooftop vegetation can be as effective as ground vegetation as it provides hospitable environment for plant life. Likewise, various types of vegetation (even hardy plants) can adapt to the rooftop environment and its role of climate control is similar as at ground level. In fact, their evaporative cooling potential could be more significant because it is exposed closer to the sun and wind at these areas (Yeang, 2006: 140-141). Indeed, green roofs can also function as passive cooling elements by its potential of energy saving. A study by Susca et al. (2011) demonstrated the reduction of energy saving approximately 40-110%.

Meanwhile, experiments on vegetated roofs by Sandifer (2009) and Shaharuddin et al.

(2011) show a significant reduced temperature differences between green roof and concrete roof. In addition, other than urban cooling, rooftop vegetation also benefited as storm water reduction (Shaharuddin et al., 2011; Susca et al, 2011), removal of air pollution and promote urban biodiversity. (Sudaporn Chungloo, 2006)

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 5.8.2

WATER ELEMENTS

Apart from vegetation, the use of water elements should also be meticulously designed to meet climatic needs of certain area. The geometry, location and the surrounding landscapes influences the evaporative cooling potential of water bodies (Sun and Chen, 2012).

It should be noted that only sufficient amount of water body coverage

should be taken into design to optimise its evaporation rate and to avoid excessive humidity in ambient temperature. At larger scale, incorporating water into urban design in humid regions should be adequately proportioned for evaporation and must not to overload the already heavy humidity of hot-humid tropics (Nagan, 2010)

Fig 5.31 shading through landscaping

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CHAPTER 6

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

6 DESIGN FEATURES FOR BUILDING ELEMENTS IN AN OFFICE BUILDING Passive building energy efficiency technique is more effective to buildings such as offices that are unoccupied during the night when the thermal mass can be cooled with night-time ventilation

6.1 WALL Walls are a predominant fraction of a building envelope and are expected to provide thermal and acoustic comfort within a building, without compromising the aesthetics of the building. The thermal resistance (R-value) of the wall is crucial as it influences the building energy consumption heavily Conventionally, based on the materials used in construction, walls can be classified as woodbased walls, metal-based walls and masonry-based walls. There are other types of advanced building wall designs that are applied to improve the energy efficiency and comfort levels in buildings (Suresh B. Sadineni, 2011)

6.1.1

LIGHTWEIGHT CONCRETE (LWC) WALLS

Lightweight concrete (LWC) refers to any concrete produced with a density of less than 2000 kg/m3. For structural purposes, the LWC density often ranges between 1600 and 2000 kg/m3 along with a strength grade of 15 MPa. Whereas for thermal insulation purposes the density is often less than 1450 kg/m3 along with strength grade as low as 0.5 MPa. The thermal resistance of light weight concrete can be improved by mixing with light weight aggregates. (E. Prianto, 2006)

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 All kinds of LWC walls are particularly useful in countries where concrete construction is predominant and the use of insulation in walls is not a common practice. Also, they can be constructed faster using less skilled labour

(Suresh B. Sadineni,

2011)

6.1.2

VENTILATED OR DOUBLE SKIN WALLS

An air gap between two layers of masonry wall braced with metal ties constitutes a ventilated or double skin wall. They are also called cavity walls. There are two basic kinds of ventilated walls, one with forced ventilation in the cavity, and the other with natural ventilation (stack effect). Most commonly, ventilated walls are used to enhance the passive cooling of buildings Although, energy savings for all the wall designs increase with the increase in width of the air gap, however, further increase over 0.15m yielded only diminishing returns. A typical summer cooling energy savings of 40% can be achieved with a carefully designed ventilated wall.

6.1.3

WALLS WITH LATENT HEAT STORAGE

The phase change material (PCM) is incorporated in light weight wall structures to enhance the thermal storage capacity. PCMmaterial is impregnated commonly in gypsum or concrete walls. Porous material such as plasterboard has better PCM impregnation potential than pumice concrete blocks. The thermal heat storage in PCM based walls depends on the amount (weight %) of PCM material impregnated in the wall material (Suresh B. Sadineni, 2011) In a separate study, experimental results on PCM based composite wall boards showed a decrease in maximum room temperature by 4.2 â—ŚC

6.2 ROOF roof is the most exposed to impacts of solar radiation, as it receives sunlight for practically

65

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 the whole of the day, and in the tropics the angle of incidence is close to the normal in the hotter parts of the day. Heat gain through roof elevates ceiling surface temperature and causes radiant heat load on the occupants. The term ‗roof‘ includes the roof structure, the outer covering, and layers of insulating materials or membranes and the ceiling.

Some passive cooling techniques could be implemented in tropical climates as result of modification in roof architecture. These include a compact cellular roof layout with minimum solar exposure, domed and vaulted roofs, naturally or mechanically ventilated roofs, micro ventilated roofs, high roofs and double roofs. Other methods such as white-washed external roof surfaces to reduce solar absorptivity, roofs covered with vegetation to provide humidity and shade, and usage of high thermal capacity materials such as concrete to minimize peak load demand are also gaining popularity. Roof shading is one way of reducing the impact of solar radiation on the roof surface. Economical roof shading is usually achieved with local material such as terracotta tiles, hay, date palm branches, inverted earthen pots, etc. which can usually contribute to a 6 ◦C drop in the indoor temperature (Ashok Kumar, 2008)

6.2.1

MASONRY ROOFS

During tropical summers, they tend to exhibit unfavorable thermal characteristics such as higher soffit temperature and longer heat retaining capacity that affect the indoor air comfort conditions and increase energy costs. The indoor temperatures exceed 40 ◦C due to high roof temperatures of about 65 ◦C. Higher soffit temperatures make them emit long wavelength infrared radiation towards the occupants. Even worse is that it might continue into the night due to the heat capacity of the slab. This problem of high roof temperatures can be mitigated by employing roof shading, cool roof coatings or compound roof systems. A compound roof system developed with a combination of radiation reflectors and thermal insulation demonstrated substantial lowering of the heat conducted through a concrete roof (Suresh B. Sadineni, 2011) 66

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 6.2.2

LIGHTWEIGHT ROOFS

Lightweight aluminum standing seam roofing systems (LASRS) are popularly used on commercial and government buildings as they are economical. However, they are wind sensitive due to weak seam-clip connection and also have bad thermal characteristics. Two easy ways to improve thermal characteristics of these roofs are by adding thermal insulation and using light colored roof paint. It was determined that the lighter colored surfaces such as white, off-white, brown and green yielded 9.3%, 8.8%, 2.5% and 1.3% reduction in cooling loads compared to a black-painted LASRS surface. Recent investigations have revealed that the LASRS with glass fiber insulation does not suit well for hot and humid climates due to the interstitial condensation in the glass fiber layer Photovoltaic roofs (Suresh B. Sadineni, 2011) 6.2.3

SOLAR CHIMNEY AND WETTED ROOF

From the experimental results, water spraying on the roof together with the solar chimney can reduces indoor temperatures by 2.0–6.2 1C compared with ambient air, and by 1.4–3.0 1C compared with the controlled cell. From the experimental result of utilizing the solar chimney during the period of high solar radiation and high ambient temperature, the difference between temperature at the inflow into the solar chimney and temperature at the outflow from the solar chimney tends to decrease. Water

Fig 6.1 wetted roof

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 spraying on the metal ceiling does not only decreases temperature in the room but also increase the temperature difference and increases the related air flow rate from room to the solar chimney too.

(Sudaporn Chungloo, 2006)

The Fig 6.2 shows various types of roof

details and their corresponding U values are given in Table 6.1 (Suresh B. Sadineni, 2011)

Fig 6.2 Various roof systems, sample nos. from Table 6.1

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 6.2.4

THERMAL ROOF INSULATION SYSTEM

The thermal insulation for roofs has been of growing importance lately, because on an average as much as 60% of the thermal energy leakage occurs through the roofs. Roof insulation has the potential for saving both cooling and heating loads 6.2.4.1 THERMAL INSULATION Thermal insulation is a material or combination of materials, that, when properly applied, retard the rate of heat flow by conduction, convection, and radiation.

It retards heat flow into or out of a building due to its high thermal resistance. The proper use of thermal insulation in buildings reduces not only the energy usage but also downsizes the HVAC system during design (Suresh B. Sadineni, 2011)

Fig 6.3 roof insulation

Fig 6.4 different types of thermal insulation

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Table 6.1 Various roof types and their U values

6.3 FENESTRATION (WINDOWS AND DOORS) Fenestration refers to openings in a building envelope that are primarily windows and doors. The fenestration plays a vital role in providing thermal comfort and optimum illumination levels in a building. They are also important from an architectural standpoint in adding aesthetics to the building design Heat gain through window is determined by the overall heat loss co-efficient U-value (W/m2-k) and solar energy gain factor, and is much higher as compared to that through opaque wall. Direct sunlight can cause glare. Incorporation of shading elements with windows help in: keeping out the sun‗s heat, block uncomfortable direct sun, and soften harsh daylight contrasts. Shading devices are therefore necessary to allow glare free natural light. Shading devices are also critical for visual and thermal comfort and for minimizing mechanical cooling loads. Shading devices for windows and walls moderate heat gains into the building (Indraganti, 2009) A simulation study was carried out on 10 different glazing types applied to five different climatic zones in India It was observed that the annual energy savings by a window is dependent on not just the thermal conductivity (U-value) and the solar heat gain coefficient (SHGC or g-value) of the window but also on its orientation, climatic

70

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 conditions and building parameters such as insulation level, floor area, etc.

(Suresh B.

Sadineni, 2011)

6.3.1

GLAZING TYPES

6.3.1.1 AEROGEL GLAZING Their high performance, low density and outstanding light diffusing properties make them an appropriate choice for roof-light applications (Suresh B. Sadineni, 2011) Shading devices for windows are of various types like: 

Moveable opaque (roller blind, curtains etc) can be highly effective in reducing solar gains but eliminate view & impede air movement



Louvers (Adjustable or fixed) affect the view and air movement to some degree

 6.3.2

Fixed overhangs LOUVERS

6.3.2.1 FIXED LOUVERS They can be designed as fixed and can be cost effective and can become an integral

Fig 6.5 differnt louvers

part of the building aesthetic but does not cope with changing altitude of sun.

Summers can be exceedingly hot in warm & humid climate; consequently from an early date, openings in buildings were partially closed by means of open-work

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 coverings made from stone, stucco, ceramic or wood. These coverings reduce the heat gain to the building and also add aesthetic value to the building.

They can cope well with the sun‗s changing altitude and can also be adjusted as per the angle of sun‗s altitude, but can be very costly and also requires high operation and maintenance.

6.3.2.2 MOVABLE LOUVERS They can cope well with the sun‗s changing altitude and can also be adjusted as per the angle of sun‗s altitude, but can be very costly and also requires high operation and maintenance. (Nagan, 2010) Some adaptive interventions applied to windows, doors and balconies to promote

Fig 6.6 movable louver types

higher adaptive use, as found in KD, KA and RS. (A, B): Bamboo blinds hung on balcony openings and (C) Planter box extension to windows to reduce glare and sunlight and curtains and to improve privacy, (D, E, F) : Metal grill gates to main doors and metal grill enclosures to balconies to improve safety, privacy and cross ventilation. (G) Additional door shutters with mosquito screens and vents for

72

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 improved cross ventilation, (I) RCC Jalis applied to corridors for safety, sun control and cross ventilation. (A study of the effectiveness of passive climate control in naturally, 2007)

Fig 6.7 Some adaptive interventions applied to windows, doors and balconies to promote higher adaptive use, as found in KD, KA and RS. (A, B): Bamboo blinds hung on balcony

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

CHAPTER 7

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

7 CASE STUDIES 7.1

INDIAN

NAVAL

ACADEMY,

EZHIMALA-

ADMINISTRATIVE BLOCK Location: ezhimala, Kannur Year of establishment: 2009 Climate: Warm humid climate Site area: 2500 acres Architect: Ar. Namita Singh 7.1.1

Fig 7.1 INA administrative block

SITE AND TOPOGRAPHY

Hilly terrain sloping towards the Arabian sea. The building at the topmost level is the commodores bungalow and everything else comes in hierarchy to it gradually merging with the sea. The residential area is zoned at the top most part of the hill and Administrative area is situated on the lower side. There is a natural pond in the site

Fig 7.2 administrative block, rear

created by quarying from the site

7.1.2

PLANNING

All the buildings on site recieve good view of the sea- practical due to the terrain and zoning 

The whole campus is designed based on site specific considerations- least cut and fill



Fig 7.3 corridor

The principle of campus design here is Cluster type with a variety of exterior and interior spaces

75

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 

The institutes academic and administrative section are the focal point and that binds the residential zone and the physical training zone.



In the main administrative area all the buildings are connected by a shaded pathway- enhancing walkability



Utmost consideration have been given to the climatic aspects and build to use more passive cooling techniques



The buildings are made with single corridor mainly and the corridors are covered by jali work.



Atrium is present in almost all buildings of the

Fig 7.4 corridor

campus considering the climatic aspects. 

Individual buildings are majorly planned with courtyards

Fig 7.6 courtyard

7.1.3

SUSTAINABLE FEATURES

Minimal

use of artificial lighting and air

conditioning in the building The materials and roofing creates cooler interiors Organization of courtyards, longer open corridors and rooms having one side full ventilation is effective for ventilation and natural lighting 76

DEPARTMENT OF ARCHITECTURE, NIT C

Fig 7.5 jali work

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Skylights used in underground passages giving it ample lighting

PASSIVE DESIGN Minimized the use of glass to only entrances of administrative block Maximized

locally

available

material

use

and

construction style Administrative block: exterior is cladded with rough stone and sloping roof made of steel rafters and clay roof tiles with additional insulation given by clay ceiling tiles Corridors are semi open with different types of stone jaalis through which filtered light penetrates and direct heat reduced For decreasing the cost and minimize clay tiles, metal sheets with same texture are used with high insulation layers.

Darker flooring and walls provides cooling effect Similar flooring pattern is followed throughout Steel framed windows and ventilators are provided extensively

Fig 7.8 roof detail

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DEPARTMENT OF ARCHITECTURE, NIT C

Fig 7.7 skylight

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

7.2 OFFICE-CUM-LABORATORY FOR THE WEST BENGAL POLLUTION CONTROL BOARD, KOLKATA Building/project name: Office-cum-laboratory building for West Bengal Pollution Control Board Climatic zone: Warm and humid Building type: Office-cum-laboratory building Architects; Ghosh and Bose & Associates Pvt. Ltd Year: 1999 An office building in a tight urban setting that uses innovative planning and detailing to achieve energy efficiency 7.2.1

GENERAL DESCRIPTION

The building of the WBPCB (West Bengal Pollution Control Board) has put to use a number of technologies that aim to promote a more sustainable built environment.

7.2.2

DESIGN FEATURES



Optimum orientation of plan form



Solar passive features include optimum window disposition and sizing to allow maximum daylighting, while minimizing adverse thermal effects



Design for switching circuits for lights based on a computer- simulated lighting grid



Energy-efficient lighting techniques have been adopted



Shading devices are specifically designed for different wall orientations to control the glare and also reduce the thermal load on the building



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Techniques evolved to treat waste water

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 7.2.2.1 ARCHITECTURAL DESIGN The functional requirements of the design were broken down into three basic components. 

Fully air-conditioned laboratory wing with state- of-the-art laboratories



A ventilated, non-air-conditioned office wing providing office space



An ancillary wing housing entrance lobby, cafeteria, auditorium, training centre, library, and guest rooms

7.2.2.2 PASSIVE SOLAR DESIGN Orientation The West Bengal Pollution Control Board building had used orientation to be a positive feature of the adverse site. The site was not suitable in this respect, being a long narrow plot facing north-west and south-east. A conventional plan would have exposed large glazed areas to south-east, north-west and south-west, resulting in the useless glare of direct sunlight and excessive heat gain.

By effective architectural design, the key laboratories and office spaces are oriented north-south for both daylighting, good ventilation and optimum thermal condition Fenestration design The highlights of the solar passive features are optimum window disposition and sizing to allow maximum daylighting, while minimizing adverse thermal effects.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 However, indiscriminate increase of glazing area to achieve this is counterproductive, causing glare and over-heating of the building. The glare from uncontrolled daylight necessitates the use of curtains and blinds with a resultant increase in the use of artificial lighting and cooling load 

The shading devices, and window size and disposition vary according to the orientation of the walls.



In addition, at the initial design stage, the architects ensured appropriate depth of the plan to maximize daylight penetration into the interior

7.2.2.3 DESIGN OPTIMIZATION To arrive at an optimum solution, the entire interior was computer- simulated to test the light levels (at 1-m grid intervals) and thermal performance (with different window sizes) 

This provided the following results



Finalization of window sizes after this exercise. Since suitably- oriented windows were important from the points of view of solar incursion and wind direction, maximum glazing was provided in the north-south direction, and minimum in east and west directions.



Design to include the advantage of solar heat in winter while its reduction in summer through shading devices.



Suitability of orientation for ventilation, in a city like Kolkata.



Reduction of cooling load for air-conditioned laboratory area. The staircase and toilet blocks are located in the part of the building, which unavoidably faces west

Scientific design of shading devices The shading devices were designed specifically for different wall orientations to control the glare and reduce the thermal load on the building. 

For windows facing north, vertical louvres normal to the wall, capped by a horizontal member of the same width on top are enough to provide the required shading.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 

Windows facing south were generally shaded with horizontal louvres.

Normally these horizontal louvres should extend much beyond the window, possibly to other windows at the same level, to avoid sunlight coming partly from the corners. Hence, instead of extending the horizontal members to any distance beyond the window on either side, two vertical louvres were provided at the two extremes.



For windows oriented east and west, the recommended shading device is a combination of horizontal and vertical louvres. The horizontal louvre is normal to the wall but the vertical louvre is inclined at 30 degrees towards the south, away from the normal to the wall. This has the advantage of letting in the winter sun during early mornings, on the east façade and of completely cutting off the summer sun from morning to evening

The total saving (approximately 39.8%) is achieved by controlling window sizes/shading devices. Solar passive techniques with respect to orientation and depth of plan have led to a saving of about 2.6% over a conventionally-designed building.

Hence, due to a combination of correct orientation, depth of plan, window, and external shading, it is anticipated that the designed Pollution Control Board building at Salt Lake will save approximately 41.5% energy more than a conventionally designed building of the same size annually. (Sustainable habitats)

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

8 CONCLUSION A healthy and comfortable thermal environment of indoor workspace makes the occupants comfortable with improved work efficiencies and well-being. The building design in a warm and humid climate should aim at reducing heat gain by providing shading, and promoting heat loss by maximizing cross ventilation. Dissipation of humidity is also required to reduce discomfort. Energy consumption in the building sector is function of the type of construction, usage pattern, the climatic region and the energy consuming devices installed in the buildings.

Special considerations for implementing passive techniques have to be taken in warm humid climate.

Planning aspects Orientation and spatial organisation affect the ability of a building to ventilate and receive solar radiation. To minimise solar gain and maximise ventilation, traditional buildings in hot humid climates usually employ spread-out plans and permeable internal organization. In tropical climate like India long facades of buildings oriented towards North—South are preferred.

Built form circular geometry in comparison to other building geometries which is most energy efficient in warm & humid climate. In warm & humid climate, the envelope should be designed so that it remains shaded for the greater part of the day; the external walls should be so planned that they shade each other.

Ventilation cooling and dehumidification Different types of ventilation can be given and ventilation is most required for cooling and dehumidification in warm humid climates. Rain protection has to be considered while providing ventilation Shading

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 Various shading methods can be followed suitable to the climate and use of building.

External shading is the most effective ways of shading, as it cuts off direct sunlight during summer and allows winter sunlight to enter inside the space.

Lighting Lighting is of extreme importance in office buildings. Various daylighting systems can be used instead of active systems Materials and finishes Materials like stone, adobe blocks, cob walls have high U values and greater time-lag.

This can be an advantage for buildings used in daytime since it can prevent the heat from entering inside for a longer time. Smooth and light colour for exterior can help to reflect the solar radiation without allowing transmitting inside. Light colour walls and roof can reduce the heat from entering inside.

Various landscaping techniques and other techniques can be used for bringing in passive energy usage in buildings and reducing the use of non-renewable/ active energy sources in the rising situation of energy crisis.

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

8.1 PASSIVE TECHNIQUE GUIDELINES FOR OFFICES IN WARM HUMID CLIMATE

Features

Guidelines

Site and orientation

N- S facing longer faรงade, orient buildings to shade each other along with considering wind flow.

Built form

Compact form, circular most compact, decide on the depth of the building to get required natural lighting, providing courtyards are recommended or else longer rectangular buildings with single corridor

Ventilation

Orient the building and fenestrations opening towards the windward direction

Cooling

Use different types of cooling techniques, ventilative cooling, cooling by thermal mass, evaporative cooling. Windows have to be designed for effective use of venturi effect and stack effect. Advanced cooling techniques to be used

Dehumidification

Incorporate wind towers in design, use dehumidification window technique

Shading

Shading of east and west walls and shading of windows have to be done.

Type of shading device have to be chosen with respect to the orientation and shading requirement. Shading devices have to be designed for the windows with calculation

Lighting

Depth of the building should not be more than the ability for natural lighting to reach. Use light pipes and day light control technique for the work spaces of offices

Materials and construction

Roofs: Use insulating roofs, roofs which have least U values are the best( Clay tile + cavity+ insulation + ceiling tiles) Walls: Walls which have least U value have to be used, double skin walls and hollow brick, etc. can be used Fenestration: should use materials which have least U value and K value, recommended glazing types to be used

Landscaping

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Trees and water elements have to be used, green roofs, roof garden, shading of west and east walls etc. to be used

DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

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DEPARTMENT OF ARCHITECTURE, NIT C

PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 REFERENCES 1. (NPC), N. P. (2009). State-wise Electricity Consumption & Conservation Potential in India. Bureau of energy efficiency (BEE).

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PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 12. Astrid Roetzel, A. T. (2013). Impact of building design and occupancy on office comfort and energy performance in different climates. Building and Environment.

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PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 24. Jain, P. M. (2007). Buildings and Energy In India. NME-ICT Workshop.

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PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013 37. Sudaporn Chungloo, B. L. (2006). Application of passive cooling systems in the hot and humid climate:The case study of solar chimney and wetted roof in Thailand. Building and Environment.

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PASSIVE TECHNIQUES IN OFFICE BUILDING DESIGN FOR SEMINAR WARM HUMID CLIMATE 2013

SRUTHY P ―Panchami‖ Chungam kallithodi road P.O Feroke Kozhikode, Kerala, India Phone: +91 7736481820 Email: Sruthy. Moon@gmail.com

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DEPARTMENT OF ARCHITECTURE, NIT C