Menu

Literature Review Thermal Performance

Literature Review
Thermal Performance:
Introduction
Roofs can represent up to 32% of the horizontal surface of built-up areas CITATION RFa05
l 16393 (Evapotranspiration rates from extensive green roof plant, 2005). Thermal performance of a building refers to the process of modelling the energy transfer between a building and the surroundings. CITATION Mat15
l 16393 (Thermal Performance of Buildings: Case Study and Experimental Validation of Educational Building, June 2015) Understanding the thermal performance of buildings calculates the cooling load and hence it helps to estimate the capacity, size and selection of an air conditioning apparatus. For an unconditioned building, it calculates the temperature variation within a building. These are very essential and enable us to determine the effectiveness of the design of the building CITATION JKN
l 16393 (Handbook on Energy Conscious buildings). The design load is based on inside and outside design condition CITATION Mat15
l 16393 (Thermal Performance of Buildings: Case Study and Experimental Validation of Educational Building, June 2015) s. It is based on the estimation of steady state approach of various building elements such as wall, roof, door, etc. and the estimation of overall heat transfer rate. CITATION Mat15
l 16393 (Thermal Performance of Buildings: Case Study and Experimental Validation of Educational Building, June 2015)Heat transfer modes
There are three modes of heat transfer: conduction, convection and radiation.

Conduction: This occurs at molecular level when a temperature gradient exists in a medium, which can be solid or fluid. Heat is transferred along that temperature gradient by conduction. CITATION Mat15
l 16393 (Thermal Performance of Buildings: Case Study and Experimental Validation of Educational Building, June 2015)Convection: happens in fluids in one of two mechanisms: random molecular motion which is termed diffusion or the bilk motion of a fluid carries energy from place to place. Convection can be either forced through for example pushing the flow along the surfaces or natural as that which happens due to buoyancy forces. CITATION Mat15
l 16393 (Thermal Performance of Buildings: Case Study and Experimental Validation of Educational Building, June 2015)Radiation: Occurs where heat energy is transferred by electromagnetic phenomenon, of which the sun is a particularly important source. It happens between surfaces at different temperature even if there is no medium between them as long as they face each other. CITATION Mat15
l 16393 (Thermal Performance of Buildings: Case Study and Experimental Validation of Educational Building, June 2015)
Conduction
The conductive transfer is of immediate interest through solid materials. However, conduction within fluid is also important as it is one of the mechanisms by which heat reaches and leaves the surfaces of solid. CITATION Chr09
l 16393 (Heat transfer, 2009) Moreover, the tiny voids within some solid materials contain gases that conduct heat, albeit not very effectively unless they are replaces by liquids, an event which is not uncommon. Provided that a fluid is still or very slowly moving, the following analysis for solids is also applicable to conduct heat flow through a fluid CITATION Chr09
l 16393 (Heat transfer, 2009).
15849601075055
Figure 1 shows, in schematic form, a process of conductive heat transfer and identifies the key quantities to be considered: One dimensional conduction

Q: the heat flow by conduction in x- direction (w)
A: the area through which the heat flows, normal to the x- direction (m2)
dT/dx: the temperature gradient in the x- direction (K/m)
k: the thermal conductivity (W/mK)
Q = kA T1-T2
L
Thermal conductivity of the particular heat conducting substance and, like other properties depends on the state of the material, which is usually specific by its temperature and pressure. CITATION Chr09
l 16393 (Heat transfer, 2009). The dependence on temperature is of particular importance. Moreover, some materials such as those used in building construction are capable of absorbing water, either in finite pores or at the molecular level, and the moisture content also influences the thermal conductivity. CITATION Chr09
l 16393 (Heat transfer, 2009).The value of thermal conductivity varies significantly with temperature, even over the range of climatic conditions found around the world CITATION Chr09
l 16393 (Heat transfer, 2009).
S.N. Name of building Fabrics Density Kg/m3 Mean Temp. Thermal Conductivity K.Cal/hr/°CM
1 Brick 1820 45.6 0.697
2 RCC (Mix 1:2:4 by weight) 2288 42 1.360
3 Cement Mortar 1648 45.6 0.808
4 RCC Brick 1920 42.5 0.945
5 Lime Concrete 1446 41 0.628
6 Mud Phuska 1922 42 0.446
7 Brick Tile 1892 41 0.586
8 Cement Plaster 1762 42 0.620
9 Cinder Concrete 1406 43 0.590
10 Cellular Concrete 704 42 0.162
11 Foam Concrete-1 704 42 0.128
12 Foam Concrete-2 250 40.8 0.054
13 Window Glass 2350 59.5 0.701
14 A. C. Sheet 1520 44.1 0.240
15 Timber Various 720 41 0.124
16 Gypsum Board (with layer of Hessian Cloth) 939 41 0.035
17 Vermiculite (loose) 264 42.0 0.059
18 Dolomite Brick 675 53.9 0.092
19 Crushed Dolomite 688 51.2 0.027
20 Thermocole 22 41 0.027
21 Foam Glass 160 41 0.047
22 Foam Plastic 24 29 0.027
23 Saw Dust 188 42 0.044
24 Soft Board 249 33 0.040
25 Wall Board 262 37 0.046
26 Chip Board 432 35 0.058
27 Chip Board (perforated) 352 35 0.057
28 Particle Board 750 37.20 0.084
29 Coconut Pith Insulation Board 535 44.0 0.052
30 Bartex Insulation Board 329 59.6 0.058
31 Jute Felt 291 37 0.044
32 Mineral wool slab 192 43.1 0.035
33 Crown Fiber Glass 32 40.1 0.032
34 G. I. Sheet 7520 50 52
Table 1Thermal Conductivity (K-Value) of Building (S K Gupta1, 2015)Radiation
While both conduction and convection transfers involve the flow of energy through a solid or fluid substance, no medium is required to achieve radiative hewat transfer. Indeed, electromagnetic radiation travel most efficiently through a vacuum, though it is able to pass quiet efficiently through many gases, liquid and through some solids, in particular, relatively thin layer of glass and temperate plastics. CITATION Chr09
l 16393 (Heat transfer, 2009)7810501430655
Figure 2 Illustration of electromagnetic spectrum

The above fig. Indicates the name applied to particular section of the electromagnetic spectrum where the band of thermal radiation is also shown. This indicates:
The rather narrow band of visible light:
The wide span of thermal radiation, extending well beyond the visible spectrum. CITATION Chr09
l 16393 (Heat transfer, 2009)Our immediate interest is thermal radiation. It is of the same family as visible light and behaves in the same general fashion, being reflected, refracted and absorbed. CITATION Chr09
l 16393 (Heat transfer, 2009) These phenomenons are of particular importance in the calculation of solar gain, the heat inputs to buildings from the sun and radiative heat transfer within combustion chamber. CITATION Chr09
l 16393 (Heat transfer, 2009)Another property of the surfaces in this relationship: its absorbtivity. This has been taken to be equal to the emissivity. This is not always realistic. An ideal emitter and absorber is referred to as a ‘black body ‘, while a surface with an emissivity less than unity is referred to as ‘grey’. CITATION Chr09
l 16393 (Heat transfer, 2009)5689606747510
Table 2Representative value of emission
Radiation heat exchange between two surfaces of temperature T1 and T2:
CITATION Chr09 l 16393 (NaserSayma, 2009)What is a cool roof?
150495256476533432752688590A cool roof is one that reflects most of the incident sunlight and efficiently emits some of the absorbed radiation back into the atmosphere, instead of conducting it to the building below. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) As a result the roof literally stays cooler, with lower surface temperatures, keeping the building at a cooler and more constant temperature. The term, ‘cool roof’ refers to the outer layer or exterior surface of the roof which acts as the key reflective surface. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) These roofs have higher solar reflectance than a typical roof surface. The term ‘cool roof’ encompasses an extensive array of roof types, colours, textures, paints, coatings, and slope applications CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l).
Figure 4 Cool white roofs

Figure 3 Effect of roof construction on Indoor temperature

Properties of cool roofs
The two primary thermal properties that characterize roofs are solar reflectance and emittance. Surfaces with low solar reflectance absorb a high fraction of the incoming solar energy. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) A fraction of this absorbed energy is conducted into ground and buildings, a fraction is convicted to the ambient air, and a fraction (termed emissivity) is radiated back to the sky. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) For equivalent conditions, the lower the emissivity of a surface, the higher will be its steady-state temperature. Surfaces with low emissivity cannot effectively radiate to the sky and, therefore, get hot. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l)Solar Reflectance
When solar radiation is incident on an opaque surface, some of the energy is reflected. Solar reflectance is the ratio of solar energy that is reflected by a surface to the total incident solar radiation on that surface. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) Solar reflectance is measured on a scale from 0 to 1. A reflectance value of 0 indicates that the surface absorbs all incident solar radiation, and a value of 1 denotes a surface that reflects all incident solar radiation CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l). The term ‘albedo’ is often used inter-changeably with solar reflectance. High albedo or reflective surfaces stay much cooler than low albedo or less reflective surfaces. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l)Thermal Emittance
Thermal emittance is the relative ability of a material to reradiate absorbed heat as invisible infrared radiation. Emittance, measured from 0 to 1, is defined relative to a black body with an emittance of 1. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) . Emittance tends to remain constant over the lifetime of a roof. Energy that is not reflected by the roof is absorbed by it. This absorbed heat will eventually be re-radiated (or lost through conduction) by the roof. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) . A roofing material with higher thermal emittance will re-emit absorbed thermal energy more quickly than a material with a low emittance. A cool roof minimizes the solar heat gain of a building by first reflecting a considerable amount of incoming radiation and then by quickly re-emitting the absorbed portion. As a result, the cool roof stays cooler than a traditional roof of similar
Construction. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l)Solar Reflectance Index (SRI)
Though most roofing materials have a fairly high thermal emittance, in order to accurately determine a roofing product’s ‘coolness’, or its ability to shield the building beneath it from heat, both solar reflectance and thermal emittance must be measured. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) It is important to note that it is possible for a roofing material to have a very high emittance value and a reflectance value ranging from low to very low, or vice versa, although such materials would typically not be considered cool roofs. A high emittance value alone will not result in a cool roof nor will a high reflectance value alone. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l). The Solar Reflectance Index (SRI), which incorporates both solar reflectance and emittance in a single value, quantifies how hot a surface would get relative to standard black and standard white surfaces. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) .The Solar Reflective Index (SRI) is a measure of the ability of the constructed surface to reflect solar heat, as shown by a small temperature rise. It is defined so that a standard black (reflectance 0.05, emittance 0.90) is 0, and a standard white (reflectance 0.80, emittance 0.90) is 100. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) Once the maximum temperature rise of a given material has been computed (for example, the standard black has a temperature rise of 50°C in full sun, and the standard white has a temperature rise of 8.1°C), the SRI can be computed by interpolating between the values for white and black. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) .Given this definition, it is possible for a material (with both, a high reflectance and a high emittance) to have an SRI greater than 100. The SRI formula is supported by a significant number of case study analyses by Lawrence Berkeley National Laboratory (LBNL) and is recognized by the industry as an accurate representation of the trade off between emittance and reflectance. SRI internalizes an emittance-reflectance
Trade off into a single number simplifying the comparison of roof products. SRI is calculated according to ASTM E 1980-01. Reflectance is measured according to ASTM E 903, ASTM E 1918, or ASTM C 1549. Emittance is measured according to ASTM E 408 or ASTM C 1371. An easy-to-use SRI calculator developed by Lawrence Berkeley National Laboratory requires the solar reflectance and thermal emittance values to calculate SRI. According to ECBC cool roof requirement, roofs with slopes less than 20 degrees slope shall have a initial solar reflectance of at least 0.7 and an emittance of 0.75 . ASHRAE 90.1 defines Cool roofs as having a minimum solar reflectance of 0.70 and a minimum thermal emittance of 0.75. The 2007 version of ASHRAE 90.1 adds an alternative of achieving a minimum SRI of 82. CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l)
Figure 5 Understanding cool roof and its thermal properties
Different type of cool roof technique
Shading the roof is a very important method of reducing heat gain. Roofs can be shaded by providing
Roof cover of concrete or sheet or plants or canvas or earthen pots etc. CITATION Mal11
l 16393 (SHADING: PASSIVE COOLING AND ENERGY CONSERVATION IN BUILDINGS, 2011) .Shading provided by external means, particularly a roof, should not interfere with nighttimes cooling. A cover over the roof, made of concrete or galvanized iron sheets, provides protection from direct radiation. CITATION Mal11
l 16393 (SHADING: PASSIVE COOLING AND ENERGY CONSERVATION IN BUILDINGS, 2011) .Disadvantage of this system is that it does not permit escaping of heat to the sky at nighttimes. A cover of deciduous plants and creepers is a better alternative. Evaporation from the leaf surfaces brings down the temperature of the roof to a level than that of the daytime air temperature. CITATION Mal11
l 16393 (SHADING: PASSIVE COOLING AND ENERGY CONSERVATION IN BUILDINGS, 2011) .At night, it is even lower than the sky temperature. Covering of the entire surface area with the closely packed inverted earthen pots, as was being done in traditional buildings, increases the surface area for radiative emission Insulating cover over the roof impedes heat flow into the building. CITATION Mal11
l 16393 (SHADING: PASSIVE COOLING AND ENERGY CONSERVATION IN BUILDINGS, 2011). However, it renders the roof unusable and maintenance difficult. Another inexpensive and effective device is a removable canvas cover mounted close to the roof. During daytime it prevents entry of heat and its removal at night, radiative cooling. Painting of the canvas white minimizes the radiative and conductive heat gain CITATION Mal11
l 16393 (SHADING: PASSIVE COOLING AND ENERGY CONSERVATION IN BUILDINGS, 2011)
Figure 6 some methods of shading the roof
Insulation over the roof
Insulation acts as a barrier to heat flow and is essential for keeping your home warm in winter and cool in summer. A well-insulated and well-designed home provides year-round comfort, cutting cooling and heating bills by up to half. This, in turn, reduces greenhouse gas emissions. CITATION Max13
l 16393 (Passive design Insulation, 2013). Insulation can help with weatherproofing and eliminate moisture problems such as condensation; some types of insulation also have soundproofing qualities. Insulation products come in two main categories — bulk and reflective — which are sometimes combined into a composite material. CITATION Max13
l 16393 (Passive design Insulation, 2013).

To compare the insulating ability of the products available, we need to look at their R-value, which measures resistance to heat flow. The higher the R-value, the higher the level of insulation. Products with the same R-value have the same insulating performance if installed as specified. CITATION Max13
l 16393 (Passive design Insulation, 2013). The appropriate degree of insulation depends on climate, building construction type, and whether auxiliary heating and/or cooling is to be used. Material R-values are supplied with bulk insulation and refer to the insulating value of the product alone. The higher the R-value the better the thermal performance CITATION Max13
l 16393 (Passive design Insulation, 2013).
Insulation types and their applications
Bulk insulation mainly resists the transfer of conducted and convected heat, relying on pockets of trapped air within its structure. Its thermal resistance is essentially the same regardless of the direction of heat flow through it. CITATION Max13
l 16393 (Passive design Insulation, 2013) Bulk insulation includes materials such as glass wool, wool, cellulose fiber, polyester and polystyrene. All bulk insulation products come with one material R-value for a given thickness CITATION Max13
l 16393 (Passive design Insulation, 2013) INDEX c “2” z “16393” .

.
Figure 7 Bulk insulation traps air in still layers.

Reflective insulation mainly resists radiant heat flow due to its high reflectivity and low emissivity (ability to re-radiate heat). It relies on the presence of an air layer of at least 25mm next to the shiny surface. The thermal resistance of reflective insulation varies with the direction of heat flow through it. CITATION Max13
l 16393 (Passive design Insulation, 2013).Reflective insulation is usually shiny aluminum foil laminated onto paper or plastic and is available as sheets (sarking), concertina-type batts and multi-cell batts. Together these products are known as reflective foil laminates, or RFL. CITATION Max13
l 16393 (Passive design Insulation, 2013)
21196307067550Dust settling on the reflective surface greatly reduces performance. Face reflective surfaces downwards or keep them vertical. CITATION Max13
l 16393 (Passive design Insulation, 2013) The anti-glare surface of single sided foil sarking should always face upwards or outwards CITATION Max13
l 16393 (Passive design Insulation, 2013)..

.
Figure 8 Reflective insulation and heat flow.

Composite bulk and reflective materials are available that combine some features of both types. Examples include reflective foil faced blankets, foil backed batts and foil faced boards. CITATION Max13
l 16393 (Passive design Insulation, 2013)Broken China mosaic terracing
Well-graded broken pieces of glossy glazed tiles an inexpensive and conducive cool roofing option are provided by Well-graded broken pieces of glossy glazed tiles . Broken pieces of glazed tiles (preferably white) are embedded in wet mortar to provide a smooth surface that does not undulate. The joints are then grouted using cement mortar with waterproofing materia CITATION Env1
l 16393 (C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l) l.

Cool colour roof coating
Reflective roof is a design concept that aims to reduce the effect of heat gain on building roofs during sunny days CITATION Akb08
l 16393 (WhiteRoofsCooltheWorld, Directly OffsetCO2 and DelayGlobalWarming., 2008).This design consists of a single or multiple layers comprising different materials. The physical properties of the material surfaces are the major factors that affect roof behavior, particularly if it is cool or not. Several reasons support the use of cool roofs:
Enhance indoor thermal comfort of spaces without air- conditioning.
Extend the service life of a roof by reducing roof operating temperature.
Reduce energy consumption.
Reduce the trapped heat in the atmosphere by reflecting solar rays back into the sky, which can delay climate change.
Figure 10 Dark vs. Cool roof surface

Figure 11 Dark vs. Cool roof surface. Temperatur
Various colors can function as a reflective component. CITATION Urb10
l 16393 (GuidelinesforSelectingCoolRoofs.U.S. DepartmentofEnergyBuildingTechnologiesProgramandOak RidgeNationalLaboratory., 2010)suggested that any colored surface that can reflect more of the invisible solar rays is considered a cool dark color or cool color. For example, alight-colored surface reflects 80%, a reflective dark-colored surface reflects 40%, and and a normal dark-coloured surface reflects 20% of the incoming sunlight.

Cool roofs are typically white, and can be divided into single ply or liquid applied CITATION Mac09
l 16393 (BeyondMitigation,PotentialOptionsfor Counter-BalancingtheClimaticandEnvironmentalConsequences oftheRisingConcentrationsofGreenhouseGases., 2009). Typically liquid applied products include white paints, acrylic coatings, polyurethane, or elastomeric. CITATION Kar14
l 16393 (Passive cooling techniques through reflective and radiative roofs in tropical houses in Southeast Asia: A literature review, 2014)All the researchers agreed that the best cool-roof products in tropical climates considerably reduce the maximum solar heat gain by reflecting solar radiation by about 90%.However; reflective roofs lose its reflectivity, owing to the accumulation of dirt and weathering conditions, particularly in large cities. The use of reflective roofs is an effective strategy during hot months, but not during cold months. Moreover, highly reflective roofs result in visual discomfort and glare, and as such, its use is not advisable for areas near flight paths. Thus, the site topography and building regulations limit its application in some cases. CITATION Kar14
l 16393 (Passive cooling techniques through reflective and radiative roofs in tropical houses in Southeast Asia: A literature review, 2014)While application procedures prescribed by the manufacturer may vary from product to product.

Inverted earthen pots
In this system burnt clay pots were placed in inverted positions and covered with mortar of Lime, Surki and Building rubbish. The thermal and humidity insulating properties of the layer was felt almost immediately. CITATION Sar06
l 16393 (BPRI (Burnt-Pot Roof Insulation), the novel method of roof insulation in Bangladesh, 2006). The system is known as ‘Burnt-Pot Roof Insulation’ abbreviated as BPRI. Burnt clay pots are manufactured in the country for the purpose of marketing yogurt and these pots have been found suitable for this purpose. CITATION Sar06
l 16393 (BPRI (Burnt-Pot Roof Insulation), the novel method of roof insulation in Bangladesh, 2006) Other materials used are: Polythene sheet, Lime, Surki, Building rubbish and Cement. The clay pots are placed in inverted positions and covered with mortar of lime, surki and building rubbish. The air trapped inside the pots act as insulator and their use considerably reduces the weight of the material and their cost. Polythene sheet acts against leakage of humidity or water. After observing its initial success and extremely low co CITATION Sar06
l 16393 (BPRI (Burnt-Pot Roof Insulation), the novel method of roof insulation in Bangladesh, 2006) s t..The system has been explained in the fig
Figure 13 burnt pot roof installation
Advantages of BPRI :
Burnt Pot Roof Insulation (BPRI) has got a number of advantages over the conventional Lime-terracing. Some of these are:
(i) BPRI is extremely cheap. The cost of civil works depends upon a number of factors like the cost of materials, labor, transport, storage etc., all of which varies from place to place and from time to time. So, it is not possible to find the comparative costs on global basis.

(ii) The construction of conventional lime-terracing needs expert masons, skilled workers and experienced beaters. It is possible to make BPRI by the semi-skilled laborers.
(iii) The weight per unit area of BPRI is about 50% of the conventional lime-terracing.
(iv) Quite often the house-owners construct buildings by vertical phasing. In such case, every time the building is extended vertically the owners need to remove the old layer of insulation. BPRI is suitable for such purpose because of its extremely low cost.
(v) Lime-terracing needs to be removed and re-applied after every 15 to 20 years. It has been found that the process of its removal involving heavy beating damages the reinforced concrete roof. BPRI is free from such hazards. CITATION Sar06
l 16393 (BPRI (Burnt-Pot Roof Insulation), the novel method of roof insulation in Bangladesh, 2006)Green Roof
A typical green roof consists of a lightweight soil mixture and a drainage layer. A fabric
Filter keeps these layers separated and a special layer under the drainage protects the
Underlying structure from the vegetation roots. High-quality waterproofing is
Required in order to prevent water leakage. The height of each layer depends on the
Requirements of the selected vegetation. The role of the drainage layer can be simply to
Control the moisture of the soil and allow proper drainage, since in many cases saturated
10572752948940Soil will permanently damage the roots. In some types of green roof the drainage layer is designed to retain rain or irrigation water in order to keep the soil mixture wet, creating an environment suitable or water-demanding vegetation CITATION The09
l 16393 (Green Roofs in Buildings:Thermal and Environmental Behaviour, 2009).
Figure 13 typically green roof structur
Regarding the construction properties, the heights of the layers and the maintenance
Requirements of roof gardens, two main categories are mainly reported: extensive and
Intensive green roofs CITATION Dun04
l 16393 (Planting Green Roofs and Living Walls, Timber Press Inc, 2004). However, the limits between these
Categories are not always clear CITATION The09
l 16393 (Green Roofs in Buildings:Thermal and Environmental Behaviour, 2009).
Green roof properties
Being part of the building shell, a green roof influences thermal flux through the area it
Occupies. In contrast with every other building element, the gardening layers of the green
Roof (soil and vegetation) are a living system that interacts both with the building and the
Environment in a variety of different ways. The most important benefits of green roofs can
Be summarized as follows:
energy conservation for heating and cooling;
reduction in the urban heat island effect;
absorption of air pollutants and dust;
attenuation of storm water run-off;
extension of life for waterproofing layers; attractive open space (aesthetic benefits);
provision of wildlife habitat;
replacement of vegetation and habitat lost during urban expansion;
reduction of urban noise;
Social and psychological benefits. CITATION The09
l 16393 (Green Roofs in Buildings:Thermal and Environmental Behaviour, 2009)On the other hand, among the major disadvantages of green roofs are the relatively high
Initial cost and the additional building load that must be supported. In the case of existing
Buildings, this limits the choice of green roof type to the extensive type, which in many
Cases does not need additional support.. CITATION The09
l 16393 (Green Roofs in Buildings:Thermal and Environmental Behaviour, 2009)
Figure 15 The Energy Balance fore Green Roof
Works Cited
BIBLIOGRAPHY (DGIS), U. D.-G. (2013). ALTERNATIVE BUILDING TECHNOLOGIES IN MADHYA PRADESH. Development Alternatives.

(EDS), E. D. C o o l R o o f s f o r C o o l D e l h i : D e s i g n M a n u a l. Delhi: Bureau of Energy Efficiency (BEE).

Artaic, L. A. (2018). Mosaic Tile Installation Information: Artaic. Retrieved from Artaic: https://artaic.com/mosaic-tile-resources/mosaic-installation-instructions/
Dr. Umamaheshwaran Rajasekar, P. K. (2015). HANDBOOK ON ACHIEVING THERMAL COMFORT WITHIN BUILT ENVIRONMENT VOLUME II. Taru Leading Edge, India.

Karam M. Al-Obaidin, M. I. (2014). Passive cooling techniques through reflective and radiative roofs in tropical houses in Southeast Asia: A literature review. Malaysia: Elsevier B.V.

Maleki, B. A. (2011, December). SHADING: PASSIVE COOLING AND ENERGY CONSERVATION IN BUILDINGS. International Journal on “Technical and Physical Problems of Engineering” , Pages 72-79.

Mathew Joseph 1, V. J. (June 2015). Thermal Performance of Buildings: Case Study and Experimental Validation of Educational Building. MBC College of Engineering ; Technology, Kerala, India1;Amal Jyothi College of Engineering, Kerala, India2. Kerala, India: International Journal of Advanced Research in Electrical,Electronics and Instrumentation Engineering.

Max Mosher, C. M. (2013). Passive design Insulation.
NaserSayma, C. L. (2009). Heat transfer. Ventus PublishingApS.

Nayak, J. K. Handbook on Energy Conscious buildings. IIT Mumbai.

R., F. (2005). Evapotranspiration rates from extensive green roof plant. Pennsylvania State University. Pennsylvania: Pennsylvania State University.

S K Gupta1, N. N. (2015). Thermal Performance of Wall ; Roof – Efficiency of Building Materials. Gurgaon: International Journal of Science and Research (IJSR).

Sarma, B. ;. (2006). BPRI (Burnt-Pot Roof Insulation), the novel method of roof insulation in Bangladesh. Bangladesh: KU Studies. Special edition. 01-05.

Shah, M. (n.d.). Cool Roof Demonstration Project. Retrieved from Manasi Shah: http://mansi-shah.weebly.com/cool-roofing-demonstration-project.html
Theodosiou, T. (2009). Green Roofs in Buildings:Thermal and Environmental Behaviour. ADVANCES IN BUILDING ENERGY RESEARCH (Volume 3), 271–288.

Thermal Comfort. (n.d.). Retrieved from http://thermalcomfort.co.in/promoting-cool-roof-and-passive-ventilation-concepts-indoor-temperature-comfort
VARANASHI, S. P. (2014, May). Clay pots for a roof keep the house cool. The Hindu .