passive cooling.pdf

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Passive cooling of outdoor urban spaces. The role of materials

L. Doulos, M. Santamouris *, I. Livada

Group Building Environmental Studies, Section Applied Physics, Physics Department, University of Athens, Panepistimioupolis,

Athens 157 84, Greece

Received 18 September 2003; received in revised form 22 January 2004; accepted 27 January 2004

Available online 4 May 2004

Communicated by: Associate Editor Volker Wittwer

Abstract

This paper presents the results of a comparative study aiming to investigate the suitability of materials used in

outdoor urban spaces in order to contribute to lower ambient temperatures and fight heat island effect. The study

involved in total 93 commonly used pavement materials outdoors and was performed during the whole summer period

of 2001. The thermal performance of the materials was measured in detail using mainly infrared thermography pro-

cedures.

The collected data have been extensively analysed using statistical techniques. Comparative studies have been

performed in order to identify the major advantages and disadvantages of the materials studied. Materials have been

classified according to their thermal performance and physical properties into ‘cool’ and ‘warm’ materials. The impact

of color, surface roughness and sizing has been analysed as well.

The study can contribute to selection of more appropriate materials for outdoor urban applications, and thus assist

to fight the heat island effect, decrease the electricity consumption of buildings and improve outdoor thermal comfortconditions.

2004 Elsevier Ltd. All rights reserved.

Keywords: Passive cooling; Pavement materials; Outdoor comfort

1. Introduction

The continuously growing size of the urban envi-

ronment and the careless development of buildings and

open spaces have a major impact on the urban micro-climate. The building’s energy behavior and perfor-

mance are heavily influenced by the density of the

building space. The observed ‘heat island’ effect is

mainly influenced by urban design, namely the canyon

radiative geometry, anthropogenic heat and the mate-

rial’s street physical properties (Santamouris, 2001; Oke

et al., 1991). The emitted infrared radiation from the

various buildings and street surfaces impinges on the

surroundings surfaces and is entrapped inside the can-

yon. Besides, the total amount of the absorbed solar

radiation is increased due to multiple reflections between

the buildings (Santamouris and Assimakopoulos, 1997).Also the anthropogenic heat increases the intensity of

the ‘heat island’ effect through the use of fuels from ei-

ther mobile or stationary sources. Finally the incident

solar radiation and every available heat form can in-

crease the storage of sensible heat in the city’s structure

during the daytime. The stored heat is released into the

urban atmosphere during the night period. Therefore

the total amount of the energy balance is increased and

air temperatures become greater (Santamouris et al.,

1998).

A more positive thermal balance can be achieved by

reducing the thermal gains in the urban environment

* Corresponding author. Tel.: +30-1-727-6934; fax: +30-1-

729-5282/81.

E-mail address: [email protected] (M. Santamouris).

0038-092X/$ - see front matter 2004 Elsevier Ltd. All rights reserved.

doi:10.1016/j.solener.2004.04.005

Solar Energy 77 (2004) 231–249

www.elsevier.com/locate/solener

http://mail%20to:%[email protected]/http://mail%20to:%[email protected]/


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and in particular by reduction of the absorbed solar

radiation. The role of building materials is decisive for

the reduction of the thermal gains and overheating. The

thermal performance of the building materials is mainly

determined by their optical and thermal characteristics;

the albedo to solar radiation and the emissivity to long

wave radiation are the most significant factors. The useof appropriate materials, the so-called ‘‘cold’’ materials,

can improve thermal comfort conditions during the

summer period. They are characterized by a high

reflectivity factor to the short wave radiation and high

emissivity factor to the long wave radiation. They reduce

the amount of solar radiation absorbed by the building

envelopes and urban structures and keep their surfaces

cooler. Respectively, they are good emitters of long wave

radiation and release the energy that has been absorbed

as short wave radiation. Using ‘‘cold’’ materials in urban

environmental planning contributes to lower surface

temperatures that affect the thermal exchanges with theair (Akbari et al., 1992, 1997; Bretz and Akbari, 1997).

In this paper, the surface temperature distribution of

the total number of 93 selected materials is presented. A

theoretical analysis is followed aiming at the investiga-

tion of the thermal performance of the selected building

materials. Also, a methodology for their classification in

‘cold’ materials is been developed. An experimental

campaign was set up at an open space at the National

and Kapodistrian University campus in Athens, during

August 2001. For the theoretical analysis the selected

materials were grouped according to their construction

material, their surface texture and surface color (Table

1). The measurements were obtained through infrared

(IR) thermograph imaging.

2. Materials for pavements and their role in the thermal

balance of the urban environment

The use of appropriate materials to reduce heat is-

land and improve the thermal characteristics of the ur-

ban environment has gained increasing interest during

recent years. Many research works have been carried out

to evaluate the possible energy and environmental ben-

efits when light colored surfaces are used. Research triesto investigate the impact of the materials optical and

thermal characteristics on the urban temperature as well

as the possible energy conservation during the summer

period. A detailed guide on light colored surfaces has

been published by US EPA (Akbari et al., 1992). Re-

search shows that important energy gains are possible

when light color surfaces are used in combination with

the plant of new trees.

The use of materials define the global albedo of the

cities. Typical albedo of European and American cities

are close to 0.15–0.30. Much higher albedo have been

measured in some North African cities (0.45–0.6). Taha

(1997) has compiled data given by (Taha, 1994; Kung

et al., 1964; Dabberdt and Davis, 1978; Vukovich, 1983;

Brest, 1987; Coppin et al., 1978; Rouse and Bello, 1979;

Mayer and Noack, 1980; Steyn and Oke, 1980; Aida,

1982; Oguntoyinbo, 1970, 1986) for snow free urban

albedos for several cities and has published the difference

between the urban and rural albedo. Cantat (1989) hasestimated the albedo of various types of surfaces as well

as their temperature in the major Paris area, It is found

that urban areas have a much lower albedo while the

albedo in Paris is to about 16% lower than in the sur-

rounding rural areas.

Various studies have been performed to understand

better the thermal and optical performance of materials

used for pavements and their impact to the city climate.

Lower surface temperatures contribute to decrease the

temperature of the ambient air as heat convection

intensity from a cooler surface is lower. Such tempera-

ture reductions can have significant impacts on coolingenergy consumption in urban areas, a fact of particular

importance in hot climate cities.

Yap (1975) has reported that systematic urban–rural

differences of surface emissivity hold the potential to

cause a portion of the heat island. Robinette (Santa-

mouris, 2001) reports relative temperatures of 38 C

over grass, 61 C, over asphalt, and 73 C over artificial

turf. Santamouris (2001) reports asphalt temperatures

close to 63 C and white pavements close to 45 C.

Oke et al. (1991) have simulated the effect of the

optical and thermal characteristics of ‘urban’ materials

to the heat island intensity during the night period. They

report that the role of emissivity is minor. As the emis-

sivity increased from 0.85 to 1.0 there was a slight in-

crease of 0.4 C of DT between the urban and rural

environment for very tight canyons, where there was

almost no change for higher view factors. On the con-

trary, the effect of the thermal properties of the materials

was found to be much more important. For a flat land, it

is found that if the urban admittance was 2200 J/m 2/K,

and the rural one was 800 units lower a heat island

of about 2 C was developed during the night period,

while when the urban admittance was decreased to 600

J/m2/K, a cool island of over 4 C was formed during

night.In an other study, Asaeda et al. (1996) have reported

the experimental results of a study where the impact of

various pavement materials used commonly in urban

environments were tested during the summer period.

They found that the surface temperature, heat storage

and its subsequent emission to the atmosphere were

significantly higher for asphalt than for concrete and

bare soil. At the maximum, asphalt pavement emitted an

additional 150 W per square meter in infrared radiation

and 200 W per square meter in sensible transport com-

pared to a bare soil surface. They also found that the

rate of infrared absorption by the lower atmosphere

232 L. Doulos et al. / Solar Energy 77 (2004) 231–249


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over asphalt pavement was greater by 60 W/m2 than that

over the soil surface or concrete pavement. Gustavsson

and Bogren (1991) measured the influence of road con-

struction on road surface temperature. On a test road,

they had found a nocturnal maximum difference of 1.5

C between beds consisting of blast furnace slag and

those consisting of gravel.

Berg and Quinn (1978) reported that in mid-summer

white painted roads with an albedo close to 0.55 have

almost the same temperature with the ambient envi-

Table 1

Description of the studied materials (Bl stands for black, Bli for black inlays, Br for brown, Gn for green, Gr for gray, R for red, Wh

for white, Whi for white inlays)

Material

number

Construction

material

Surface color Surface

texture

Material

number

Construction

material


texture

1 Mosaic Green Smooth 48 Concrete Bl–Whi Smooth

2 Mosaic Wh–Bl Smooth 49 Concrete Wh–Bli Smooth

3 Mosaic Light–Br Smooth 50 Concrete Black Rough

4 Mosaic Gray Smooth 51 Concrete Black Smooth

5 Mosaic White Smooth 52 Concrete Red Rough

6 Mosaic Brown Smooth 53 Concrete Red Smooth

7 Mosaic Red Smooth 54 Concrete Red–Whi Smooth

8 Mosaic Black Smooth 55 Concrete Red–Bli Smooth

9 Concretea Red Smooth 56 Pebble Green Rough

10 Concretea Black Smooth 57 Pebble Dark–Gr Rough

11 Granite Red Smooth 58 Pebble Gray Rough

12 Granite Black Smooth 59 Pebble Light–Gr Rough

13 Concretea Orange Smooth 60 Asphalt Black Rough

14 Concretea Brown Smooth 61 Concrete White Rough

15 Concretea

Gray Smooth 62 Concrete White Rough16 Concretea Gray Rough 63 Concrete White Smooth

17 Concretea White Smooth 64 Concrete Wh–Whi Smooth

18 Concretea White Rough 65 Concrete Or–Whi Smooth

19 Granite White Smooth 66 Concrete Orange Rough

20 Granite Wh–Bl Smooth 67 Concrete Orange Rough

21 Granite Green Smooth 68 Concrete Or–Whi Smooth

22 Granite Wh–Gn Smooth 69 Concrete Green Rough

23 Marble White Smooth 70 Concrete Orange Rough

24 Marble Wh–Bl–R Rough 71 Concrete Dark–Gn Rough

25 Marble Wh–Bl Smooth 72 Concrete Green Smooth

26 Marble Wh–Bl Rough 73 Pebble Gr–Wh Rough

27 Marble White Smooth 74 Concrete Wh–Blue Smooth

28 Marble White Rough 75 Pebble Wh–Gn–R Rough

29 Marble Wh–Bl Smooth 76 Pebble White Rough30 Marble White Smooth 77 Pave stone Red Rough

31 Marble White Smooth 78 Pave stone Gray Rough

32 Marble Pink Smooth 79 Pave stone Brown Rough

33 Marble Light–Br Smooth 80 Stone Black Rough

34 Marble Red Smooth 81 Stone Brown Rough

35 Marble Wh–Bl Smooth 82 Stone Gray Rough

36 Marble Dark–Gr Smooth 83 Stone Green Rough

37 Marble Gray Smooth 84 Stone Black Rough

38 Pebble Brown Rough 85 Stone Brown Rough

39 Pebble Light–Br Rough 86 Stone Brown Rough

40 Pebble Bl–Br Rough 87 Stone Green Rough

41 Pebble Light–Br Rough 88 Stone Brown Rough

42 Pebble Red Rough 89 Stone Brown Rough

43 Pebble Wh–Br Rough 90 Stone Brown Rough

44 Concrete Gray Smooth 91 Stone Brown Rough

45 Concrete Gray Rough 92 Stone Red Rough

46 Concrete Gray Rough 93 Stone Red Rough

47 Concrete Gray–Whi Smooth

a The size of the material tile is 30 cm · 30 cm.

L. Doulos et al. / Solar Energy 77 (2004) 231–249 233


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ronment, while unpainted roads with albedo close to

0.15 were approximately 11 C warmer than the air.

Taha et al. (1992) have measured the albedo and

surface temperatures of a variety of materials used in

urban structures. They found that white elastomeric

coatings having an albedo of 0.72 were 45 C, than black

coatings with an albedo of 0.08. They also report that awhite surface with an albedo of 0.61 was only 5 C

warmer than ambient air whereas conventional gravel

with an albedo of 0.09 was 30 C warmer than the air.

3. Implementation of the experimental measurements

3.1. Instrumentation and description of the experimental

site

The basic experimental equipment used for the

implementation of the measurements consists of aninfrared camera to measure surface temperatures.

Measurements were also performed by using a precise

contact thermometer in order to take into account

minor errors associated with reflected infrared radiation

and the non-complete knowledge of the material’s

emissivity.

The surface temperature measurements were taken

on an hourly basis from 9:00 to 18:00 (local time). The

ambient meteorological conditions, recorded from ameteorological station at the university campus, were

characterized by high air temperatures, low relative

humidity (Figs. 1 and 2) and clear sky. Wind speed and

direction were also measured. Wind speed was always

low during the experimental period (


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pebble and mosaic) of different surface color materials

(white, gray, black, red, brown and green) and of dif-

ferent surface texture materials (with smooth surfaces,

rough surfaces and anaglyph surfaces with marks and

designs). The tiles had a size of 40 cm · 40 cm. In order

to compare the thermal performance of material tiles

made of the same construction material, surface colorand texture but different size, a number of some extra

concrete tiles sized 30 cm· 30 cm were studied. The

sampling tiles were placed on an especially modulated

platform covering a surface of 40 m2 (Fig. 3). The

platform was horizontal and insulated from below. The

heat transfer effects between the platform and the sam-

ple materials were eliminated because of the platform’s

insulation.

3.2. Thermograph imaging method

The surface temperatures of the sample materialswere measured with an IR camera, that is an infrared

condition monitoring system (AGEMA Thermovision

570, 7.5–13 lm wavelength). The IR-camera measures

and images the emitted infrared radiation from an object

(Fig. 4). The fact that radiation is a function of the

object’s corresponding surface temperature (Planck’s

law equation (1)) makes it possible for the thermal

camera to calculate and display this temperature(Gaussorgues, 1994; Thermovision, 1997). The mea-

sured infrared radiation is also function of the object’s

emissivity.

Q ¼ erT 4 ð1Þ

Q is the object’s long wave radiated energy (W/m2), e is

the object’s emissivity that is a function of wavelength,

the direction of observation relative to the surface

and the surface temperature (Gaussorgues, 1994), r is

the Stefan–Boltzmann’s constant (5.67 · 108 W/m2/K4)

and T is the object’s surface temperature (K) (Wolfe and

Zissis, 1997).

In the present study, the emissivity values given by

Gaussorgues (1994) and Wolfe and Zissis (1997) have

been used during the experimental procedure. The

emissivity of most of the materials has been also mea-

sured using hot plate techniques and no significant dif-

ferences have been found. In practice, the emissivity

values for the total number of the studied materials were

close to 0.9. (Fig. 5).

4. An analysis for the study of the thermal performance of

the tested materials

Due to lack of uniformity in the surface temperature

distribution at same studied materials, the measured

surface temperatures correspond to the average tem-

perature values of the total horizontal surface. The IR

monitoring system estimated these values automatically.Fig. 3. The site of the experimental campaign with the modu-

lated platform.

Fig. 4. Visible and infrared image of selected building materials.



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The most important reasons for the existence of non-

uniform surface temperature distribution are the color

contrast, the surface roughness and the tile’s heat

transfer effects (Fig. 6).

The estimated mean hourly surface temperature val-

ues for each material tile are given in Table 2 and in

statistical box plots (Figs. 7–20). Table 2 gives the mean

daily, the absolute maximum and the absolute minimum

surface temperatures for every material tile within 9:00

to 18:00. The box plots (Figs. 7–20) show the mean daily

surface temperature and the mean daily temperature

range of the material tiles. They are presented separately

Fig. 5. Radiation contributions to the general measurement situation.

Fig. 6. Same examples of material tiles characterized by non-uniform surface temperature distribution due to color contrast

(a), roughness (b) and heat transfer phenomena (the arrows shows the direction of the incident solar radiation) (c).



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for the total number of the materials according to their

construction material (Figs. 7–14) and their surface

color (Figs. 15–20). The lower and upper lines of the box

plots are the minimum and the maximum values of the

corresponding mean hourly surface temperature values.

The line inside the box is the average surface tempera-

ture value. The materials with the smallest average sur-

face temperature are presented at the left part of each

graph, while the warmest materials are presented at the

right part. Because of the large number of the studied

Table 2

Mean daily and absolute maximum surface temperatures during the experimental period of August 2001 within 9:00 to 18:00

Material

number

Mean daily

surface tem-

perature (C)

Absolute

maximum

surface

temperature

Absolute

minimum

surface

temperature

Material

number

Mean daily

surface tem-

perature (C)

Absolute

maximum

surface

temperature

Absolute

minimum

surface

temperature

1 34.8 39.5 23.9 48 41.8 48.1 27.2

2 35.5 40.6 23.7 49 35.2 40.3 23.1

3 35.5 40.7 23.6 50 43.7 50.4 28.9

4 37.5 43.3 24.7 51 44.4 52.0 27.6

5 33.3 37.7 22.2 52 39.9 45.9 26.1

6 36.9 42.5 23.7 53 39.1 45.5 24.8

7 38.5 44.8 24.9 54 37.9 43.7 24.6

8 42.1 49.6 26.1 55 41.1 48.2 25.5

9 37.8 43.8 24.6 56 44.0 50.9 28.9

10 44.0 51.6 27.5 57 45.2 52.7 28.5

11 40.1 46.6 26.7 58 40.6 46.9 26.8

12 43.9 51.7 27.9 59 40.1 46.3 26.0

13 37.3 42.7 25.2 60 46.7 54.0 30.3

14 39.5 45.8 25.5 61 33.9 38.1 23.715 37.6 43.0 25.6 62 33.2 37.5 23.1

16 38.7 44.6 25.7 63 34.7 39.2 24.1

17 33.2 37.7 23.1 64 32.6 37.2 21.9

18 34.5 39.3 23.5 65 37.4 42.9 24.4

19 32.5 36.8 22.8 66 38.9 44.9 25.2

20 35.2 40.4 23.7 67 38.9 44.8 25.3

21 36.2 41.4 24.6 68 37.6 43.2 24.7

22 38.3 44.3 25.1 69 38.4 44.3 24.9

23 33.4 38.0 23.4 70 37.3 42.9 24.3

24 34.1 38.4 24.2 71 42.8 50.0 26.6

25 31.6 36.1 22.5 72 37.7 43.7 23.9

26 32.6 36.9 23.2 73 38.1 43.6 25.1

27 29.7 33.4 21.0 74 37.7 43.3 24.5

28 32.8 37.2 23.0 75 36.9 42.0 24.629 34.5 39.9 23.7 76 33.6 38.0 23.0

30 30.1 34.2 21.1 77 43.2 49.6 28.8

31 32.2 36.6 22.0 78 42.7 49.2 28.2

32 38.3 44.5 26.1 79 40.6 46.3 27.1

33 32.4 37.5 22.1 80 43.3 50.4 28.5

34 41.4 48.3 28.2 81 40.3 46.9 26.3

35 37.6 43.2 25.6 82 42.4 49.3 28.3

36 43.1 50.7 29.0 83 40.3 47.2 26.0

37 39.1 45.7 26.4 84 41.4 48.2 26.7

38 40.8 46.7 27.4 85 37.8 43.8 24.4

39 40.6 46.7 26.7 86 38.6 45.0 25.1

40 39.9 45.8 26.7 87 38.1 44.3 25.2

41 38.9 44.7 26.1 88 35.4 40.8 23.4

42 39.5 45.1 26.6 89 33.9 38.6 22.5

43 36.3 41.1 24.7 90 35.4 40.8 23.3

44 38.0 43.1 26.0 91 40.5 46.7 27.3

45 38.7 44.2 25.9 92 42.0 48.8 27.9

46 38.6 43.8 26.8 93 42.5 49.2 27.7

47 37.9 43.5 25.1



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materials a selection of the most commonly used ones

was done.

The minimum values of the mean daily and the

absolute maximum surface temperatures were observed

10

15

20

25

30

35

40

45

50

55

60

No 5

White

No 1

Green

No 2

White

Black

No 3 Light

Brown

No 6

Brown

No 4 Gray No 7 Red No 8 Black

Surface color

T e m p e r a t u r e ( ° C )

Mean surface temperature

Temperature range

Fig. 7. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the material tiles

made of mosaic.

10

15

20

25

30

35

40

45

50

55

60

No 19 Whi te No 20 Whi te-

Black

No 21 Green No 22 White-

Green

No 11 Red No 12 Black

Surface color



Temperature range


made of granite.

10

15

20

25

30

35

40

45

50

55

60

No 17

White

No 18

White

No 13

Orange

No 15

Gray

No 9 Red No 16

Gray

No 14

Brown

No 10

Black

Surface color

T

e m p e r a t u r e ( ° C )


Temperature range


made of concrete (30 cm ·30 cm).



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for the white colored material tiles. On the contrary the

maximum corresponding values were noticed in the dark

colored material tiles. Namely, the mean daily surface

temperatures ranged between 29.7 C (for the white

marble tile no. 27) and 46.7 C (for the asphalt tile no.

60). Furthermore the absolute maximum temperatures

varied from 33.4 and 54 C for the same corresponding

materials.

From a first point of view it seems that from the

white colored materials the ones made of marble pre-sented the lowest value of the mean daily surface tem-

peratures. The observed differences in the measured

surface temperatures for the white colored materials are

due to the surface texture. In general the smooth sur-

faced materials present lower surface temperatures than

the ones with rough surface or anaglyph schematics

(Fig. 15).

Continuously, the black colored materials had the

largest surface temperatures from the total number of

the material tiles. The material tile made of asphalt

presented the greatest surface temperature because of its

black and rough surface. Large surface temperatures

10

15

20

25

30

35

40

45

50

55

60

No 64

White

No 61

White

No 49

White

No 44

Gray

No 69

Green

No 66

Orange

No 52

Red

No 71

Dark

Green

No 51

Black

Surface color

T e m

p e r a t u r e ( ° C )


Temperature range

Fig. 10. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the material

tiles made of concrete (40 cm ·40 cm).

10

15

20

25

30

35

40

45

50

55

60

No 27White

No 30White

No 25WhiteBlack

No 31White

No 33Light

Brown

No 26WhiteBlack

No 28White

No 23White

No 24WhiteBlackRed

No 29WhiteBlack

No 35WhiteBlack

No 32Pink

No 37Gray

No 34Red

No 36DarkGray

Surface color



Temperature range

Fig. 11. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the materialtiles made of marble.

10

15

20

25

30

35

40

45

50

55

60

No 78

Gray

No 77

Red

No 79

Brown

No 60

Black

Surface color

T e m

p e r a t u r e ( ° C )


Temperature range

Fig. 12. Mean daily surface temperature and temperature

range, within 9:00 to 18:00 for the period of August 2001, for

the material tiles made of pave stone.



10/19

were also observed in tiles made of pebble with dark

gray and dark green surface color (no. 57, 44 C, no. 56,

45.2 C). This was caused by the existing surface

roughness at the pebble tiles (Fig. 17).

10

15

20

25

30

35

40

45

50

55

60

No 76

White

No 43

White

Brown

No 75

White

Gn

Red

No 41

Light

Brown

No 42

Red

No 40

Black

Brown

No 59

Light

Gray

No 58

Gray

No 39

Light

Brown

No 38

Brown

No 56

Green

No 57

Dark

Gray

Surface color

T e m

p e r a t u r e ( ° C )


Temperature range

Fig. 13. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the material

tiles made of pebble.

10

15

20

25

30

35

40

45

50

55

60

No 89

Brown

No 88

Brown

No 90

Brown

No 85

Brown

No 87

Green

No 86

Brown

No 81

Brown

No 83

Green

No 91

Brown

No 84

Black

No 92

Red

No 82

Gray

No 93

Red

No 80

Black

Surface color



Temperature range

Fig. 14. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the materialtiles made of stone.

10

15

20

25

30

35

40

45

50

55

60

No 27 Marb le No 19 Grani te No 5 Mosaic No 76 Pebb le No 61 Concrete

Construction material



Temperature range



the white colored material tiles.

10

15

20

25

30

35

40

45

50

55

60

No 4 Mosaic No 44

Concrete

No 37 Marble No 58 Pebble No 82 Stone No 78 Pave

stone




Temperature range



the gray colored material tiles.



11/19

10

15

20

25

30

35

40

45

50

55

60

No 84

Stone

No 8

Mosaic

No 36

Marble

No 80

Stone

No 12

Granite

No 51

Concrete

No 57

Pebble

No 60

Asphalt




Temperature range

Fig. 17. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the black

colored material tiles.

10

15

20

25

30

35

40

45

50

55

60

No 9

Concrete

No 7 Mosaic No 42

Pebble

No 11

Granite

No 34

Marble

No 93 Stone No 77 Pave

stone




Temperature range

Fig. 18. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the red colored

material tiles.

10

15

20

25

30

35

40

45

50

55

60

No 1 Mosaic No 21 Granite No 87 Stone No 69

Concrete

No 83 Stone No 56 Pebble


T e m p e r a t u r e ( ° C

)


Temperature range

Fig. 19. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the green




12/19

In order to study the impact of the size of the

building materials on their thermal performance during

the daytime period a comparison analysis was per-

formed for material tiles made of concrete. Two different

groups of concrete tiles were measured and studied with

respect to their size (30 cm · 30 cm, 40 cm · 40 cm). The

two groups had the same surface color and texture. The

t -test (Livada and Asimakopoulos, 2002) was applied on

the mean daily surface temperatures and it was found

that the surface temperatures were statistical equal

(confidence level a ¼ 0:05). Table 3 gives the mean dailysurface temperatures of the two groups. From this

comparison, can be assumed that the size of the tiles

does not affect the thermal balance of the studied

materials during the day.

Fig. 21 shows the surface temperature distributionfor a number of representative building materials to-

gether with the air temperature during the hot day

period of the 7th August 2001. The selected material

consist of white colored tiles made of marble (no. 27)

and concrete (no. 49) and black colored tiles made of

concrete (no. 51) and asphalt (no. 60). The maximum

difference (22.5 C) between surface temperatures was

Table 3

Comparison of the measured surface temperatures in the case of

concrete tiles with the two different sizes (30 cm ·30 cm, 40

cm·40 cm)


texture

Mean daily surface tem-

perature (C)

(30· 30) (40· 40)

Black Smooth 44.0 44.4

Gray Smooth 38.7 38.7

Gray Rough 37.6 38.0

Red Smooth 37.8 37.9

Orange Smooth 37.3 37.4

White Smooth 34.5 33.9White Rough 33.2 33.2

10

15

20

25

30

35

40

45

50

55

60

No 33 Marble No 3 Mosaic No 85 Stone No 66

Concrete

No 79 Pave

stone

No 38 Pebble


T e m p e r a

t u r e ( ° C )


Temperature range

Fig. 20. Mean daily surface temperature and temperature range, within 9:00 to 18:00 for the period of August 2001, for the brown


20

25

30

35

40

45

50

55

60

09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

Time


No 60 Asphalt(Black)

No 51Concrete(Black)

No 49Concrete(White)

No 27Marble(White)

Air Temperature

Fig. 21. Distribution of surface temperatures within 9:00 to 18:00 of 7th August 2001, between selected material tiles.



13/19

observed for the tiles made of marble and the asphalt at

14:00 LT.

It is often that in the urban environment the building

materials are not always chosen according to their sur-

face color. The most commonly used construction

materials are asphalt, concrete, pebble and pave stone.

However, from the experimental procedures it wasfound that the thermal performance of these materials is

not satisfactory. Figs. 15–17 and 20 show that tiles made

of concrete, pebble and pavestone were warmer than the

other materials. The marble tiles were the coldest from

the total number of the studied materials. Therefore, the

use of materials made of marble in the open urban areas

is thermally more efficient than the use of concrete,

pebble and pave stone materials.

5. A comparative analysis between the surface material

temperatures and the ambient air temperature

The concluding remarks, comparing the material

mean surface temperatures with the mean ambient air

temperature (31.2 C, Fig. 1) during the experimental

time period, are the following:

(A) The majority of the materials studied were

characterized by greater average surface temperatures

than the average air temperature. Only the white colored

tiles made of marble (no. 27 and no. 30) were cooler than

the ambient air. The surface temperatures varied from

29.7 to 30.1 C correspondingly for the two material

tiles.(B) The warmest (38.1 C) light-colored material tile

was the one made of pebble with white and green surface

color (no. 73). The maximum temperature difference

between the light colored materials and the ambient air

was estimated equal to 6.9 C.

(C) In the case of the dark colored materials the

maximum temperature difference was observed for the

one made of asphalt (no. 60) equal to 15.5 C. Besides,

the coldest dark colored material was that made of stone

(no. 84) with average surface temperature of 41.4 C and

a temperature difference with the ambient air of 10.2 C.

6. Statistical analysis of the material surface temperatures

on a 24-h basis

A further investigation of the thermal performance of

the studied materials is attempted through a statistical

analysis. The analysis was based on a number of mea-

surements performed on a 24-h basis during the period

from 9:00 of 14th August 2001 to 9:00 of 15th August

2001. The 24-h period has been divided in three different

subperiods, namely 9:00 to 3:00, 11:00 to 15:00 and

22:00 to 3:00.

6.1. Analysis of the mean surface temperature of building

materials within 9:00 to 3:00 (LT)

The total number of the studied building materials

was separated into nine different groups with respect to

their construction material. Namely each group was

consisted from material tiles made of the same con-struction material but different surface color. F -ANO-

VA test (Livada and Asimakopoulos, 2002) of the means

was applied on the mean surface temperatures within

9:00 to 3:00 LT, in order to study the statistical signifi-

cant differences that caused by the differences in the

surface color.

Table 4 shows that the F -values for each of the

studied group are smaller than the critical values F 0:05 at

a confidence level of 0.05 (a ¼ 0:05). It was found thatthe color of the building materials in each group does

not affect the estimated mean surface temperatures.

A similar methodology was applied on the meansurface temperatures of building materials categorized

into six different groups according to their surface color

(Table 5). Namely, in this case the F -values of mean

surface temperatures were estimated for same colored

materials but of different construction material.

Similar results were obtained in this case. The mean

surface temperatures of the studied building materials

with the same color but of different construction

Table 4

F -ANOVA test of mean surface temperatures for nine groupsof materials, with respect to their construction material and of

different color

Building materials F F 0:05

Mosaic 0.405


14/19

material were found statistically significant at the con-

fidence level of 0.05 (a ¼ 0:05).As a result it could be mentioned that the balance

between the absorbed and the emitted heat during a 24-h

day period appears to be the same for the total number

of the studied materials. However, examining the daily

temperature profile (Figs. 22 and 23) of the materialswith black surface color and with white surface color,

high temperature differences are observed especially

during midday hours.

6.2. Analysis of the mean surface building material

temperatures during the midday hours

In order to investigate the thermal behavior of the

building materials during the day the surface tempera-

tures were studied within the period of 11:00 to 15:00 of

14th August in the daytime. Namely, the mean surface

temperatures and their standard deviation were calcu-

lated and the F -ANOVA test was applied on the surface

temperature values considering the two different cate-

gories according to their construction material (Table 6)

and surface color (Table 7) (Livada and Asimakopoulos,

2002).

As far as the mean surface temperatures of same

construction materials are concerned, these were found

statistically significant different except for those materi-

10

15

20

25

30

35

40

45

50

55

60

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9

Time


No 12Black

No 11 Red

No 22WhiteGreen

No 21Green

No 19White

Fig. 22. Distribution of hourly surface temperatures, within 9:00 of 14th August 2001 to 9:00 of 15th August 2001, for material tiles

made of granite.

10

15

20

25

30

35

40

45

50

55

60

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 5 7 8 9

Time


No 51Black

No 71DarkGreen

No 52Red

No 44Gray

No 61White

Fig. 23. Distribution of hourly surface temperatures, within 9:00 of 14th August 2001 to 9:00 of 15th August 2001, for material tiles

made of concrete.

Table 6

F -ANOVA test of mean surface temperatures, within 11:00 to

15:00 of 14th August, for nine groups with respect to their

construction material and of different color


Mosaic 6.91 >2.32

Granite 10.55 >2.62

Concrete (30· 30) 8.61 >2.32

Concrete (40· 40) 5.70 >1.63

Marble 15.81 >1.86

Pave stone 1.013 1.94

Stone 5.69 >1.94



15/19

als made of pave stone (Table 6). From the pave stone

material group, only three different colors were studied

(red no. 77, gray no. 78 and brown no. 79) where simi-

lar mean surface temperatures were measured during

the day (varying from 40.7 to 43.8 C). Furthermore, the

differences of the mean surface temperatures for thesame colored materials are statistically significant for

each group (Table 7). As a result both the construction

material and color should be taken into account for the

lowest surface temperatures.

In an attempt to define ‘‘cold’’ and ‘‘warm’’ materials

the multiple statistical test of Tukey and Kramer were

applied on the mean surface temperature values (Livada

and Asimakopoulos, 2002). This was to examine the

significance of the mean surface temperatures differ-

ences, within the daytime hours, for each pair of the

studied materials.

The Tukey and Kramer test became more reliable

with the performance of the t -test of the mean surface

temperature differences for all the possible pairs of the

studied building materials as both of these statistical

tests are applied at the same confidence level (Livada

and Asimakopoulos, 2002).

The concluding remarks are as follows:

1. For building materials made of mosaic as ‘‘cold’’ can

be considered the white, the white–black, the green

and the brown surface colored materials (no. 5, no.

2, no. 1 and no. 6).

2. For those made of the granite as ‘‘cold’’ can be con-

sidered the white and the white–black surface coloredmaterials (no. 19 and no. 20).

3. For those made of the concrete as ‘‘cold’’ can be con-

sidered all the white colored materials (no. 17, no. 18,

no. 49, no. 61, no. 62, no. 63 and no. 64).

4. For those made of the pebble as ‘‘cold’’ can be con-

sidered the white, the white–brown and the white–

green–red surface colored materials (no. 76, no. 43

and no. 75).

5. For those made of the marble as ‘‘cold’’ can be con-

sidered the white, the brown (beige) and the white

with black shades surface colored materials (no. 27,

no. 33 and no. 29).

6. For those made of the stone as ‘‘cold’’ can be consid-

ered the brown surface colored materials (no. 88, no.

89 and no. 90).

The same statistical test was performed between the

different colored construction tiles. The corresponding

results are the following:

(A) For black surface colored materials the lowest tem-

peratures were observed at those made of mosaic,

concrete and marble (no. 8, no. 48 and no. 37).

(B) For white surface colored materials the lowest tem-

peratures were observed at those made of mosaic,

concrete, granite, pebble and marble (no. 5, no.

64, no. 19, no. 76 and no. 27).

(C) For gray surface colored materials all of them ex-

cept for those made of pebble (no. 58) and pave

stone (no. 78) presented low temperatures.

(D) For green surface colored materials the lowest tem-peratures were observed at those made of mosaic

and granite (no. 1 and no. 21).

(E) For brown surface colored materials the lowest tem-

peratures were observed at those made of mosaic

and stone (no. 6 and no. 89).

From the combination of the above comparisons

turned up seven tiles (Table 8), which can be considered

the tiles with the lowest temperatures.

The same multiply comparison by Tukey and Kra-

mer statistical test was applied for the 21 sampling pairs

of materials that turned up from the above table (Livada

and Asimakopoulos, 2002). The corresponding results

show that the mean surface temperatures for the green

colored mosaic tile, the brown colored mosaic tile and

the brown colored stone tile (marked with * in Table 8)

are statistically significant higher than the others at a

confidence level of 0.05 (a ¼ 0:05).Finally as ‘‘cold’’ materials can be considered, from

the colder to warmer, the white marble, the white

Table 7

F -ANOVA test of mean surface temperatures, within 11:00 to

15:00 of 14th August, for the six groups of building materials,

according to their color and of different construction material

Surface material color F F 0:05

White 2.16 >1.90

Gray 4.02 >1.94

Black 2.90 >2.12

Red 2.50 >2.05

Green 7.18 >2.44

Brown 4.00 >2.12

Table 8

Mean surface temperatures and deviation for ‘‘cold’’ materials

as they assumed by statistical tests with respect to their con-struction material and surface color within 11:00 to 15:00 of

14th August

Material–surface color Surface tem-

perature (C)

Deviation

Mosaic–white (no. 5) 32.32 5.162

Mosaic–green (no. 1) 33.92 5.812

Mosaic–brown (no. 6) 34.98 6.932

Granite–white (no. 19) 31.46 5.353

Concrete (40·40) and White

with marble inlay (no. 64)

32.36 6.523

Marble–white (no. 27) 29.1 4.625

Stone–brown (no. 89) 33.6 7.655



16/19

granite, the white mosaic and finally the white concrete

with marble inlay. In this comparison the surface texture

was not taken into account.

6.3. The impact of the surface texture on the thermal

performance of the materials

In order to investigate the impact of the surface

texture on the mean surface temperatures, 24 different

pairs of same colored and construction building mate-

rials but of different texture were studied for the period

of 11:00 to 15:00 within the 14th August.

The F -test of the variance differences was applied for

each of the studied pairs in order to define a proper

equation of t -test of the differences of the mean values

(Table 9) (Livada and Asimakopoulos, 2002).

The standard deviations for each of the studied pair

of building material were considered statistically signif-

icant equal at a confidence level of 0.05 (a ¼ 0:

05).

Afterwards the statistical test of the means (t -test)

was applied for all the samples with the same size and

with statistical equal standard. For all the cases the jt jvalues were smaller from the critical value t 0:05 at the

0.05 confidence level in the two tailed test.

Therefore the material’s surface texture does not af-

fect statistically the measured surface temperature during

the daytime (9:00 to 15:00). ‘‘Cold’’ building materials

can be considered independently of the surface texture.

6.4. Analysis of the mean surface building material temperatures during the night period

In order to investigate the thermal behavior of the

building materials during the night the surface temper-

atures were studied within the period of 22:00 of 14th

August to 3:00 of 15th August in the nighttime. Simi-

larly as above, the mean surface temperatures and their

standard deviation were calculated and the F -ANOVA

test was applied, considering the two different categories

according to the construction material (Table 10) and

the color (Table 11) (Livada and Asimakopoulos, 2002).

According to the construction material the mean

nocturnal surface temperatures were found statistically

significant different only for marble and stone (confi-

dence level a ¼ 0:05) (Table 10). According to the samecolored materials, the differences of the mean surface

temperatures are statistically significant for every group

(confidence level a ¼ 0:05) (Table 11).

Table 9

Various material pairs comparison to examine the surface texture impact in the measured surface temperatures

Construction material Surface color–texture Surface mean

temperatures (C)

Deviation jt -testj

Concrete (30 cm·30 cm) Gray, smooth without schematic (no. 15) 36.74 6.97 0.98

Gray, rough without schematic (no. 16) 38.44 8.39

White, smooth without schematic (no. 17) 32.06 5.93 1.05

White, rough without schematic (no. 18) 33.76 7.25

Concrete (40 cm·40 cm) Gray, smooth without schematic (no. 44) 38.14 6.70 1.86


Red, smooth without schematic (no. 53) 39.86 11.85 0.144

Red, rough without schematic (no. 52) 40.16 9.99



White, smooth with inlay (no. 64) 32.36 6.52 1.246

White, rough with schematic (no. 63) 34.36 6.37

Orange, smooth with schematic and inlay (no. 65) 37.7 9.37 0.943Orange, rough without schematic (no. 66) 39.6 10.94

Green, smooth with inlay (no. 72) 38.66 13.93 2.23

Green, rough with schematic (no. 71) 44.28 17.69

Orange, rough with schematic (no. 70) 37.88 11.56 0.811

Orange, rough without schematic (no. 66) 39.6 10.94

Black, smooth with schematic (no. 50) 44.26 12.05 0.855

Black, smooth without schematic (no. 51) 46.28 15.86

Marble White, smooth with black shades (no. 25) 31.38 5.78 1.667

White, rough with black shades (no. 24) 33.76 4.41

White, smooth (no. 27) 29.1 4.63 1.363

White, anaglyph (no. 28) 32.0 6.31



17/19

The Tukey–Kramer test was applied again on the

mean nocturnal surface temperature values for those

materials made of marble and stone. The concluding

remarks are the following:

1. For building materials made of marble, the white

with black and red shades (no. 24) and the white

(no. 28) surface colored materials could be character-

ized as ‘‘warm’’ materials, while the light brown (no.

33) surface colored material could be characterized as

‘‘cold’’ material.

2. For building materials made of stone, the brown (no.89, no. 91) and the red (no. 93) surface colored mate-

rials could be characterized as ‘‘warm’’ materials,

while the brown (no. 88) and the red (no. 92) surface

colored materials could be characterized as ‘‘cold’’

materials.

As a result it could be mentioned that the construc-

tion material determines the thermal balance during the

night (by affecting the emissivity), while the surface color

determines significant the thermal balance only during

the day (by affecting the albedo).

The same statistical test was performed between the

different colored construction tiles. The corresponding

results are the following:

(A) For black surface colored materials low tempera-

tures were observed for all the construction materi-

als, except for those made of asphalt (no. 60). Theconstruction material made of asphalt defined as

the ‘‘warmest’’ of all.

(B) For white surface colored materials, the rough with

schematics concrete (no. 63) could be characterized

as ‘‘warm’’ material, and the light brown marble

(no. 33) as ‘‘cold’’. The light brown marble was con-

sidered in the group with the white surface colored

materials.

(C) For gray surface colored materials, the cement

with the smooth surface (no. 46) and the pave

stone (no. 78) could be characterized as ‘‘warm’’

materials. For the rest gray surface colored materi-als, the mean surface nocturnal temperatures were

similar, so no material could be characterized as

‘‘cold’’.

(D) For green surface colored materials, the pebble (no.

56) could be characterized as ‘‘warm’’ material.

(E) For brown surface colored materials, the pebble

(no. 38) could be characterized as ‘‘warm’’ material.

6.5. The impact of the surface texture on the thermal

performance during the night period

In order to investigate the impact of the surfacetexture on the mean surface temperatures during the

night, the same pairs (as given in Table 9) of same col-

ored and construction building materials, but of differ-

ent texture, were studied for the period within the 22:00

of 14th August to 3:00 of 15th August.

The F -test of the variance differences was applied for

each of the studied pairs in order to define a proper

equation for the t -test of the differences of the mean

values (Table 12) (Livada and Asimakopoulos, 2002).

The mean nocturnal surface temperature comparison

according to the texture of the materials indicates,

showed in some cases statistically significant differences(confidence level a ¼ 0:05) (Table 12). In particular, forboth concrete and marble, the differences were caused

due to the low surface temperatures measured in the

smooth surface materials during the night, while the

corresponding tiles with rough surface had warmer

surface.

Generally the smooth surface materials appear to be

colder than the rough materials during the night. For 24-

h time period the light brown marble (no. 33) and the

brown stone (no. 90) could be characterized as ‘‘cold’’

materials.

Table 10

F -ANOVA test of mean surface temperatures, within 22:00 of

14th August to 3:00 of 15th August, for nine groups with re-

spect to their construction material and of different color


Mosaic 2.03 2.22

Green 10.97 >2.49

Brown 11.72 >2.30



18/19

7. Conclusions

The materials’ thermal balance is determined mainly

by their reflectivity to solar radiation and their emis-

sivity to the long wave radiation during the daytime. As

the emissivity values for the total number of the studied

materials were close to 0.9, the observed differences in

the mean daily surface temperatures are mainly caused

by the different albedo factors of the total number of the

studied materials. The physical characteristics of the

material tiles that affect their albedo are the color,

the surface texture and the construction material. The

rough and dark colored surfaces tend to absorb more

solar radiation than the smooth, light colored and flat

surfaces. Therefore the dark colored surfaces are warmer

than the light colored.

From the study of the total number of the pavement

materials according to their surface color material it was

found that the light colored tiles were cooler than the

others. As expected the white colored tiles were the

coldest, while the black colored were the warmest.

Afterwards from the analysis of the building materials

according to their construction material it was found

that tiles made of marble, mosaic and stone were cooler

than the other ones. Besides, from the analysis based on

the material textures, the tiles with smooth and flat

surface were cooler than the tiles with rough and ana-

glyph surface. Finally studying the impact of sizing it

Table 12

Various material pairs comparison to examine the surface texture impact in the measured nocturnal surface temperatures

Construction material Surface color–texture Surface mean

temperatures C

Deviation jt -testj

Concrete (30 cm· 30 cm) Gray, smooth without schematic (no. 15) 17.87 0.539 0.211




Concrete (40 cm· 40 cm) Gray, smooth without schematic (no. 44) 18.22 1.001 0.321


Red, smooth without schematic (no. 53) 17.42 0.57 2.51

Red, rough without schematic (no. 52) 18.51 0.562



White, smooth with inlay (no. 64) 17.08 0.662 3.82

White, rough with schematic (no. 63) 18.73 0.455

Orange, smooth with schematic and inlay (no. 65) 17.83 0.707 0.76


Green, smooth with inlay (no. 72) 17.13 0.679 1.43

Green, rough with schematic (no. 71) 17.82 0.718

Orange, rough with schematic (no. 70) 18.02 0.722 0.37


Black, smooth with schematic (no. 50) 18.62 0.822 3.38

Black, smooth without schematic (no. 51) 16.85 0.827

Marble White, smooth with black shades (no. 25) 15.6 1.452 2.19

White, rough with black shades (no. 24) 16.93 0.759

White, smooth (no. 27) 16.18 0.722 3.72

White, anaglyph (no. 28) 18 0.711

Fig. 24. Definitions of ‘cold’ and ‘warm’ materials.



19/19

was concluded that for the material tiles with the same

construction material, surface color and texture but

different geometry characteristics (surface size and

thickness) the differences in the surface temperatures are

not statistical significant during the daytime period. The

observed non-uniform temperature distribution on some

materials’ surfaces was caused by their surface colorcontrast; the surface roughness and the heat transfer

phenomena. Therefore as ‘‘cold’’ materials can be

characterized those having a smooth and light colored

surface and construction materials made of marble,

mosaic and stone. Similarly as ‘‘warm’’ materials could

be defined those having a rough and dark colored sur-

face and construction materials made of pebble, pave

stone and asphalt (Fig. 24).

The use of ‘‘cold’’ materials is important in the urban

environment and especially in cities with hot climate.

The use of ‘‘cold’’ materials contributes to the reduction

of the air temperature due to heat transfer phenomena.However ‘‘warm’’ materials instead of ‘‘cold’’ are used

to the urban environments structure. This use is caused

either due to economic and esthetic reasons, or by bad

environmental planning. As a result, the temperature in

the urban environment is raised and the demand for

cooling load in the buildings is getting greater.

References

Aida, M., 1982. Urban albedo as a function of the urban

structure––a model experiment. Boundary Layer Meteorol.

23, 405–413.

Akbari, H., David, S., Dorsano, S., Huang, J., Winnett, S.,

1992. Cooling our Communities. EPA, USA. pp. 43–52.

Akbari, H., Bretz, S., Kurn, D.M., Hanford, J., 1997. Peak

power and cooling energy savings of high-albedo roofs.

Energy Build. 25, 117–126.

Asaeda, T., Ca, V.T., Wake, A., 1996. Heat storage of

pavement and its effect on the lower atmosphere. Atmos.

Environ. 30 (3), 413–427.

Berg, R., Quinn, W., 1978. Use of light colored surface to

reduce seasonal thaw penetration beneath embankments on

permafrost. In: Proceedings of the Second International

Symposium on Cold Regions Engineering. University of

Alaska, pp. 86–99.

Brest, C.L., 1987. Seasonal albedo of an urban/rural landscapefrom satellite observations. J. Appl. Meteor. 26, 1169.

Bretz, S.E., Akbari, H., 1997. Long-term performance of high-

albedo roof coatings. Energy Build. 25, 159–167.

Cantat, O., 1989. Contribution a l’ etude des variations du bilan

d’ energie en region parisienne. Ph.D. Thesis. University of

Paris Sorbonne, 362 pp.

Coppin, P., Forgan, B., Penney, C., Schwerdtfeger, P., 1978.

Zonal characteristics of urban albedos. Urban Ecol. 3, 365.

Dabberdt, W.F., Davis, P.A., 1978. Determination of energetic

characteristics of urban–rural surfaces in the greater St.

Louis Area. Boundary Layer Meteorol. 14, 105.

Gaussorgues, G., 1994. Infrared Thermography. In: Microwave

Technology Series 5. Chapman & Hall. pp. 36–45.

Gustavsson, T., Bogren, J., 1991. Infrared thermography in

applied road climatological studies. Int. J. Remote Sensing

12, 1811–1828.

Kung, E.C., Bryson, R.A., Lenschow, D.H., 1964. Study of a

continental surface albedo on the basis of flight measure-

ments and structure of the earths surface cover over North

America. Mon. Weather Rev. 92, 543.Livada, I., Asimakopoulos, D., 2002. Introduction to the

Applied Statistics. Simetria Press, Athens.

Mayer, H., Noack, E.M., 1980. Einfluss der schneedecke auf die

strahlungsbilanz im grossraum Munchen. Meteorol. Run-

dsch. 33, 65.

Oguntoyinbo, J.S., 1970. Reflection coefficient of natural

vegetation crops, and urban surfaces in Nigeria. Quart. J.

Roy. Meteorol. Soc. 96, 430.

Oguntoyinbo, J.S., 1986. Some aspects of the urban climates of

tropical Africa, WMO, pp. 110–135.

Oke, T.R, Johnson, G.T., Steyn, D.G., Watson, I.D., 1991.

Simulation of surface urban heat islands under ‘ideal’

conditions at night––Part 2: Diagnosis and causation.

Boundary Layer Meteorol. 56, 339–358.Rouse, W.R., Bello, R.L., 1979. Shortwave radiation balance in

an urban aerosol layer. Atmos. Ocean. 17, 157.

Santamouris, M., Assimakopoulos, D.N. (Eds.), 1997. Passive

Cooling of Buildings. James and James Science Publishers,

London.

Santamouris, M. (Ed.), 2001. Energy and Climate in the Urban

Built Environment. James & James Science Publishers,

London.

Santamouris, M., Papanikolaou, N., Georgakis, C., 1998.

Study on the ambient and surface temperature in Omonoia

Square, Athens, Greece. Internal Report, Group Building

Environmental Studies, Physics Department, University of

Athens, Athens, Greece.

Steyn, D.G., Oke, T.R., 1980. Effects of a scrub fire on the

surface radiation budget. Weather 35, 212.

Taha, H., Sailor, D., Akbari, H., 1992. High albedo materials

for reducing cooling energy use. Lawrence Berkeley Lab

Rep. 31721, UC-350, Berkeley, CA.

Taha, H., 1994. Aircraft-based albedo measurements over the

South Coast Air Basin. In: Taha, H. (Ed.), Analysis

of Energy Efficiency of Air Quality in the South Coast

Air Basin––Phase II, Rep. no. LBL-35728, Lawrence

Berkeley Laboratory, Berkeley CA, pp. 43–59

(Chapter 2).

Taha, H., 1997. Urban climates and heat islands: albedo,

evapotranspiration, and anthropogenic heat. Energy Build.

25, 99–103.Thermovision 570, 1997. Operating Manual. AGEMA Infrared

Systems.

Vukovich, F.M., 1983. An analysis of the ground temperature

and reflectivity pattern about St. Louis, Missouri, using

HCMM satellite data. J. Appl. Meteor. 22, 560.

Wolfe, W., Zissis, G., 1997. The Infrared Handbook. IRIA

Series in Infrared & Electro-Optics. Infrared Information

Analysis Center Environmental Research Institute of Mich-

igan a DTIC-sponsored DoD Information Analysis Center,

pp. 1.28–1.32.

Yap, D., 1975. Seasonal excess urban energy and the nocturnal

heat island––Toronto. Arch. Meteorol. Geoph. Bioklima.,

Series B 23, 68–80.


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