Thermal Comfort and Energy in Santiago. Confort.pdf · Chilean standard NCh 1079.Of 77....

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Abstract The construction in Chile, until now, has not considered aspects with respect to the climatic conditions where it is wanted to construct, being similar of north to the south. Recently last year the Ministry of Housing, introduced regulation in building code about the insulation in ceilings, consequent with improving the living standard of the population, like one first measure.

Chile presents 9 different climatic zones, thus it is necessary to develop diverse designs in the construction, according to the local climate.

Many factors affect the living standard of the people, like thermal comfort, acoustic conditions, natural lighting, and internal humidity among others. This study considers only thermal comfort in Santiago, and corresponds to an analysis of low cost houses, which in the last periods have had deficient behaviors.

This study was made for a brick house; the ones that are actually built for low-income people, of 43 m², with different insulations, and then compare it with wooden houses, like the ones that Fundación Chile is developing. The results shows that, the consumption in energy for heating, decreases with only insulation in ceiling in 15%, in walls and ceiling 38% and in wooden houses 48%. Despite this, in summer is necessary to study vertical shading and ventilation system during the night, because in all afternoon the houses are over thermal comfort.

In addition different material for the wall, like adobe, dense brick, and normal brick with more thickness were studied nevertheless, limit values for the comfort are exceeded in summer and in winter the heating is necessary.

In this study, only two months were considered. January represents the summer and July the winter. Average values for each month were used.

Introduction Geography Chile is a republic whose territory extends along the western and southwestern South America. It limits in the north with Peru, in the east with Bolivia and Argentina, and in the south and the west with the Pacific Ocean. It is extends about 4.230 km long, from Latitude 17,30°S to 56,30°S along the Longitude 70°. The total area is 756.096 km² and the width between 90km and 400km from the west to east.

Geography of Chile is very peculiar, two chains of mountain cross the country in all its longitude (Cordillera de la Costa and Cordillera de los Andes), leaving a narrow valley between both, where most of the cities are constructed. The

Thermal Comfort and Energy in Santiago. Utilization of Climatic Design for Low-Cost houses

Paula Colonelli Pérez-Cotapos. Forest Engineer, specialized in Wood Industry (Universidad de Chile) Project Engineer, Fundación Chile

Paula Colonelli Pérez -Cotapos

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population groups in low zones, lower than 700 m. above sea, only 10% lives on the altitude about 2.000 m.

The population is about 15 million (estimated for 1999). Strong earthquakes are frequent in all parts of Chile; this is an important condition to consider for construction.

Figure 1.- Transversal section of latitude 33.3°S.

Cordillera de la Costa Valley Cordillera de los Andes

Climate The climate is generally smooth, due to the influence of the sea and to the protective wall of the Cordillera de los Andes. The cold current of Humboldt and the Cabo de Hornos are responsible for thermal inversion, having the north, lower temperatures than would correspond, and in the south higher than be expected (see table 1). Also they modify the regime of winds that affect in an important way the climate of the country.

Table 1.- Comparison between theoretical and real temperatures. City Iquique Coquimbo Valdivia Pto. Natales

Latitude 20°S 30°S 40°S 50°S T° Theoretical (°C) 23.1 18.1 12.0 5.7 T° Real (°C) 18.3 14.4 11.8 6.8 Deterrence +4.8 +3.7 +0.2 -1.1 Source: Rodriguez (1972)

The strong evaporation of the Pacific Ocean, produces great amount of clouds that move towards the continent, and the currents when arriving at the coast usually modify their course, because of these and other causes, the precipitation is not equal. Although it increases from north to south, it is not constant from year to year. There are noticeable periods of drought or rain, and the topography and regional conditions create numerous microclimates.

Chilean standard NCh 1079.Of 77. Architecture and construction - Climatic zoning for dwellings for Chile and recommendations for architectural design, divide Chile, into 9 climate zones, which can be seen in the table 2.

Table 2.- Chilean Climate Zone (Nch1079)

Zone Description

Northern Coast

Desert zone with climate predominantly maritime; small temperature variations; clouds and humidity dissipate at noon, no rain in the north, very little rain in the south; almost no vegetation.

Northern Desert Desert zone: without rain, dry and hot; high solar radiation; cold nights; no vegetation; strong winds.

Northern Transverse Valley

Semi-desert zone: long and hot summers; microclimates in the valleys; small rains increasing to the south; high solar radiation high temperature variations; vegetation increasing.

Central Coast

Maritime climate: moderate temperatures; short winter (4 to 6 months); clouds in summer dissipate at noon; important rains; predominantly westerns winds; salty and relatively humid environment.

Central Interior

Mediterranean climate: moderate temperatures; short winter (4 to 5 months); rains and frost increasing to the south; intense solar radiation in summer; moderate temperature variation; increasing to the east; predominantly southwestern winds.

Southern Coast Maritime climate: rainy with moderate to cold temperatures and long winters.

Southern Interior Rainy and cold zone with short summer with moderate solar radiation. Extreme South Very rainy and cold zone with very short summer and different

microclimates.

Andean Zone Dry atmosphere with great daily temperature variation; great differences in latitude, altitude and climate conditions.

Thermal Comfort and Energy in Santiago

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Santiago The area of study is Santiago de Chile, the capital, located at latitude 33,3°S and 543m above sea level. The climate in Santiago (central interior) presents moderate temperatures, short winter (4 to 5 months) rains, and intense solar radiation in summer, moderate temperature variation and predominantly southwestern winds. The conditions for Santiago are the following:

Table 3.- Climate data for Santiago, Quinta Normal

Rad

iatio

n, M

J/m

,day

Sun

shin

e h/

day

Rai

nfal

l, m

m/m

onth

Tem

pera

ture

, C

Rel

ativ

e hu

mid

ity, %

Source: FACH, Anuario Metereológico 1992

Construction and Architecture The actual construction in Chile is similar to construction in Europe and the United States, but simplified in aspects such as thermal insulation and double-glazing is not used. Recently, in 1999, the Ministry of Housing introduced, some obligatory U values for roofs into the National Building Code.

Common materials used for construction of houses in 1998 are illustrated in Table4.

Table 4.- Material used for construction of houses (percentage of the total units)

Material Total Chile

Santiago

Brick 54% 52%

Concrete 28% 45%

Wood 14% 2%

Total 96% 99%

Problem The quality of construction in Chile is quite deficient, especially for low cost houses, the design does not take climatic factors of the place into consideration.

The principal problems in that type of houses are: § Inadequate thermal comfort (too cold in winter and hot in summer) § High humidity and indoor condensation in winter § Insufficient natural lighting § No proper acoustic insulation § Lack of ventilation § Uniform Design

That problem damages the living standard of these persons and the low temperatures in winter affect the health, principally for the children. In addition, a considerable

Paula Colonelli Pérez -Cotapos.

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amount of pollution and humidity are produced indoor due to heating systems, which consist of kerosene stoves, without chimney.

Objective The purpose of this project is to improve the thermal conditions for low-cost houses in Santiago. For this reason the following specific objectives have been developed: § To evaluate the effect on the thermal comfort, different materials in the walls,

in summer and winter. § Evaluation of the effect in the thermal comfort, insulation in walls and

ceilings, in summer and winter. § To determine the saving of energy that can be achieved with the use of

insulation in winter. § To compare the thermal comfort of a wooden house with a brick house § To improve thermal comfort in summer with shade.

Method In order to fulfil the requirements the following activities were made: § Determination of thermal comfort values for Santiago § Obtaining of recommendations for the thermal comfort of Santiago. § Determination of low-cost insulation for the walls § Determination of heat load in the house and air change. § Accomplishment of simulations of the thermal comfort (winter and summer),

for brick houses without insulation, with insulation in ceiling, with insulation in ceiling and external wall, and for wooden houses.

§ Simulation of the use of shading in the windows for the insulated brick houses.

§ Evaluation

The study was made for January and July, representing summer and winter respectively, because they are the months in which the extreme temperatures and solar radiation appear.

Tools Used § Mahoney Table was used to obtain thermal comfort values for Santiago and

general considerations about design recommendations for layout, spacing, air movement, openings, size of walls and insulation, roofs insulation etc.

§ Bioclimatic Chart of Givoni, was used to obtain thermal comfort for Santiago, and some design recommendations.

§ Solar Diagrams, for analyse of solar position and radiation in Santiago § Aiolos software, for Natural ventilation in Buildings, to determine the air-

change rates. § DEROB programme was used to obtain thermal behaviour of material. Based

on analysis of simulations results, recommendation will be made for future improvement of low cost housing design for Santiago.

Site description The design chosen, consists of a typical two-storey building of 43m², for low-income people. It includes, according to the new regulations, thermal insulation in ceiling. It corresponds to twin houses, constructed in double modules, as illustrated in figures 2 and 3:


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Figure 2.- Frontal façade of the House

Figure 3.- Back facade of the House


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Base Case The house is constructed of 140mm brick, in all external walls. The windows are single–glass (normal in Chile). The ceiling consists of 8mm of gypsum board with 80mm of glass wool (14kg/m3) according with the actual thermal regulation introduced at Chilean building code in 1999. The roof is made of corrugated fibre cement sheets.

Figure 4.- Frontal façade from DEROB

Figure 5.- , Back façade and adiabatic wall (from DEROB)

The focus of the project in Santiago because the program of the government is to build about 60.000 low-cost houses per year, and most of them will be built in Santiago. The orientation of the window corresponds to north south, and the project will be located in a vacant area.

For the analysis of the different compositions, volume 3 that corresponds to the ceiling is not considered, because it is an uninhabited area. Volume 1 corresponds to the ground floor and the volume 2 to the second floor. The internal divisions were not considered.

The dividing wall between the two houses was considered adiabatic, that there is no heat transfer between the houses. For this reason the wall was simulated adding to it 1000mm of glass wool to obtain a low conductance, as it can be observed in the table.

Description of Simulations The following cases were defined (table 6), for the configurations of the elements see table 5.

In all the cases the ground floors, doors and windows were the same. The second floor of concrete (element code 08), except in wooden houses, where the second floor corresponds to element 09.

For shade were considered horizontal elements of 30cm of length, on all the windows. The assigned properties were: absorptance: 72%, transmission: 0%, emittance front: 90%, and emittance back: 90%.


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Table 5. - Element Configurations

Code

Type Thickness mm

Material (From outside to

inside)

Absorptance

front/back

Emittance front/back

01 External Wall 140 Brick 72/72 90/90

02 External Wall Insulation 1

140 20 8

Brick Polystyrene Gypsum

70/70 87/87


140 40 8


70/70 87/87

04 External Wall Wooden Frame

9 50 20 10

Plywood Glass wool Air at 21 C Gypsum

70/70 87/87

05 Adiabatic Wall 1000 70

Glass Wool Brick

70/70 87/87


Glass Wool Gypsum

70/70 87/87

07 Ground Floor

300 80 70 1.4

Earth Sand Concrete PVC Vinyl

45/45 85/85

08 Intermediate 120 Reinforced Concrete 45/25 85/90

09 Intermediate Floor Wooden

40 16

180 10

Light Concrete with polyst. Plywood Air at 21°C

70/70 87/87

10 Ceiling 80 8

Glass Wool Gypsum

70/25 90/90

11 Ceiling Without insulation

8 Gypsum 70/70 87/87

12 Door 3 39 3

High Density Fibreboard Air at 21°C

13 Roof 5 Fibre Cement 72/72 90/90

14 External Wall Adobe

250 Adobe 70/70 87/87

15 External Wall Dense Brick

140 20 8

Dense Brick Polystyrene Gypsum

70/70 87/87

16 External Wall 20mm Brick

200 Brick 70/70 87/87

16 types of elements were defined, for the configuration of the houses, 4 types of external walls, 2 adiabatic walls, 1 for the first floor, 2 for the second floor, 2 ceiling structures, 1 type of door, and 1 roof. In the following table these elements are defined, code number has been given to them for their denomination.


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Table 6.- Cases Considered in the study

Case

Season

Material Insulation Ceiling

External Wall

Adiabatic Wall

Obser.

W 00 Winter Brick 14 No 10 01 05

W 01 Winter Brick 14 Ceiling 11 01 05 Base case

W 02 Winter Brick 14 Ceiling Wall

11 02 05

Wooden W Winter Wood Ceiling Wall

11 04 06

W 03 Winter Brick 20 Ceiling 11 16 05 Case W01, but thickness of external wall 200mm

W 04 Winter Dense Brick

Ceiling Wall

11 15 05 Case W02, with dense brick in external wall.

W 05 Winter Adobe Ceiling 11 14 05 Case W01, but with adobe external wall.

S 00 Summer Brick No 10 01 05

S 01 Summer Brick Ceiling 11 01 05 Base case

S 02 Summer Brick Ceiling Wall

11 02 05

Wooden S Summer Wood Ceiling Wall

11 04 06

S 03 Summer Brick 20 Ceiling 11 16 05 Case W01, but thickness of external wall 200mm

S 04 Summer Dense Brick

Ceiling Wall

11 15 05 Case W02, with dense brick in external wall.

S 05 Summer Adobe Ceiling 11 14 05 Case W01, but with adobe external wall

S 02 S Summer Brick Ceiling Wall

11 02 Summer Shade in all windows

S 02 A Summer Brick Ceiling Wall

11 02 Summer Low air changing

S 02 SA Summer Brick Ceiling Wall

11 02 Summer Low air changing, and shade in all windows

Properties of Materials Table 7, shows the thermal properties of material used.

Table 7.- Properties of material used.

Material Conductivity Sp. Heat Density

(W/mK) (Wh/kgK) (kg/m3)

Concrete 1.7 0.24 2300

Air Space at 21 C 0.024 0.28 1.201

Earth 1.4 0.22 1300

Sand 0.58 0.24 1500 Gypsum Ch. 0.24 0.23 650

Reinforced concrete 1.63 0.24 2400

Brick 0.6 0.2 1400

Fibrocement 0.23 0.2 1000

PVC Vinyl 0.4 0.26 1400

Glass Wool 0.038 0.24 14

High density fibreboard 0.13 0.37 1000

Polystyrene Expanded 0.043 0.47 10

Plywood 0.102 0.75 560

Light Concrete with polystyrene 0.088 0.3 260

Adobe 0.75 0.24 1700

Dense Brick 1.2 0.24 2000 The characteristics for all materials were taken from NCh853 and, when not

available there, from course material (Thermal properties of building materials). Table 8, shows the air change rates and internal load, obtained from the software


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Ailos, for normal conditions, and for low air changing respectively. The internal loads were based on that 5 people, 2 adults and 3 children, occupy the houses.

Table 8.- Normal and Low Air change rates considered and internal loads Summer

Volume 1 Volume 2 Volume 3 Hours H. Load N Ach L Ach H. Load N Ach L Ach H. Load NL Ach

1:00 - 7:00 0 4 2 375 4 2 0 2

8:00 - 11:00 290 9 5 290 4 2 0 2 12:00 - 13:00 190 25 5 0 21 5 0 2 14:00 - 20:00 210 11 5 210 11 5 0 2 21:00 - 0:00 313 4 2 313 4 2 0 2

Winter

Volume 1 Volume 2 Volume 3 Hours I. Load N Ach L Ach I. Load N Ach L Ach I. Load NLAch

1:00 - 7:00 0 2 2 375 2 2 0 2 8:00 - 11:00 290 3 2 290 2 2 0 2

12:00 - 13:00 190 8 2 0 7 5 0 2 14:00 - 20:00 210 4 2 210 4 5 0 2 21:00 - 0:00 313 2 2 313 2 2 0 2

NAch: Normal air change rate LAch: low air change rate

Results The diagram of Mahoney indicates that all the year the nights, in Santiago are below the comfort, being cold, most of during the months June, July and August. Despite this, during the day in the months of March, April, October November and December (during autumn and the spring), the thermal comfort is reached. However, in summer (January and February), it is very warm and in the winter from May to September the days are cold, under the 20 °C. (see annex)

With these climatic conditions one sees clearly the need to introduce in the houses elements that allow to increasing of the indoor temperature in winter, and, in summer, reducing the heat from solar radiation during the day. During the night they are under the comfort and do not imply preoccupations.

Table 9.- Mahoney Diagram Diagnosis °C Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Monthly mean max 29.7 28.1 26.7 21 16.2 12.8 13 17.5 19.5 23.7 25.1 28.6 Day comfort, upper 28 28 28 28 25 25 25 25 25 28 28 30 Day comfort, lower21 21 21 21 20 20 20 20 20 21 21 22 Thermal stress, day H H O O C C C C C O O O Monthly mean min 13.7 12.2 12.1 8.9 7.3 4.6 3.1 4.9 6.6 8.4 10.5 11.6 Night comfort, upper 21 21 21 21 20 20 20 20 20 21 21 22 Night comfort, lower 14 14 14 14 14 14 14 14 14 14 14 14 Thermal stress, night C C C C C C C C C C C C H = Hot O = Comfort C = Cold

Givoni diagram for January and July indicates the same, cold winter where heating is required, and in summer cooling, ventilation and high inertia is required.


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Figure 6.- Givoni Diagram

As shown in table 10, the recommendations of Mahoney for Santiago, requires

heavy walls, floor, and roof, over 8 hours of time -lag, orientation North and South and openings, around 20% of the wall.

Table 10.- Mahoney recommendations.

Item

Recommendations

Layout Orientation north and south (long axis east–west)

Spacing Compact layout of estates

Air movement No air movement requirement

Openings Medium openings, 20–40%

Walls Heavy external and internal walls

Roofs Heavy roofs, over 8h time-lag

Size of opening Small openings, 15–25%

Position of openings

In north and south walls at body height on windward side, Openings also in internal walls

Walls and floors Heavy, over 8h time-lag

Roofs Heavy, over 8h time-lag As it is observed in the table, for low cost houses presented here, is very difficult

to obtain time -lag over 8 hours, in the external walls, although an increase of 1.2 h, can be observed in the table 10, by the use of 20 mm of polystyrene and 8mm of gypsum (code 02). The increase produced with 20mm additional of polystyrene (code 03), was considered insignificant reason why it was decided not to choose it.

The same it happens in the ceiling structure, however for the ground floor obtain 9.2h, which is sufficient.

Summer (January)

Winter (July)


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Table 11.- Conductance and Time Lag of the elements

Code

Type Thickness mm

Material Conductance W/m² °K

Time Lag

01 External Wall 140 Brick 4.285 2.270


140 20 8


1.366

3.414


140 40 8


0.835

3.647

04 External Wall Wooden Frame

9 50 20 10

Plywood Glass wool Air at 21 C Gypsum

0.630 0.541


Glass Wool Brick

0.038 12.574


Glass Wool Gypsum

0.035

11.107

07 Ground Floor

300 80 70 1.4

Earth Sand Concrete PVC Vinyl

2.519

9.180

08 Intermediate Floor 120 Reinforced Concrete

13.581 1.718

09 Intermediate Floor Wooden

40 16 180 10

Concrete with polyst. Plywood Air at 21°C Gypsum

1.255

1.950

10 Ceiling 80 8

Glass Wool Gypsum

0.468 0.223

11 Ceiling Without insulation

8 Gypsum 29.996 0.016

12 Door 3 39 3

High Density Fibreboard

Air at 21°C High Density Fibreboard

5.286

0.083

13 Roof 5 Fibre Cement 45.994 0.009

14 External Wall Adobe 250 Adobe 3.000 6.338

15 External Wall Dense Brick

140 20 8

Dense Brick Polystyrene Gypsum

1.478 3.250

16 External Wall 20mm normal Brick

200 Brick 3.000 3.984


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Results from Simulations

Materials As observed in the chart in winter, the wooden house presents the highest temperatures, while the adobe and the normal brick house of 14 cm without insulation lowest. The increase of thickness of the brick (W01-W03) improves the temperature in winter only 0.3°C for the average, and during the night for the two studied seasons the difference is of 0.6°C.

During the night, adobe (in winter) presents behaviour similar to the brick walls with insulation and wood. However, during the day the values are smaller.

Figure 7. - Temperature in winter, ground floor with different materials.

Winter - Air Temperature Ground Floor - Volume 1

5

6

7

8

9

10

11

12

13

14

15

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

W 01 W 02 W 03 W 04 W 05 Wooden W

Table 12.-Extreme temperatures and average in winter, Ground Floor with different materials.

Winter

Case W 01 W 02 W 03 W 04 W 05 Wooden W

Max 11.2 11.7 11.1 11.6 10.8 12.9

Min 5.4 6.4 6.0 6.4 8.0 6.1

Average 8.9 9.7 9.2 9.7 9.8 10.0 There is no difference when increasing the density of the brick (W02-W04). The

values for both seasons are practically the same.

Figure 8.- Temperature in summer, Ground Floor with different materials.

Summer - Air Temperature Ground Floor - Volume 1

18

20

22

24

26

28

30

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

S 01 S02 S 03 S 04 S 05 Wooden S


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Table 13.-Extreme and average temperatures in summer, Ground Floor with different materials. Summer

Case S 01 S02 S 03 S 04 S 05 Wooden S

Max 28.5 28.6 28.2 28.5 28.1 29.8

Min 19.1 19.8 19.7 19.8 20.1 18.9

Average 24.3 24.5 24.4 24.5 24.5 24.5

Winter As seen in the figure 9, the wooden house presents a better thermal comfort in winter for ground floor and second floor. This difference takes place from 8 in the morning. Despite that, all the cases are below thermal comfort.

Figure 9.- Temperature in winter, Ground Floor with different materials.

Winter - Air Temperature Ground Floor - Volume 1

1

3

5

7

9

11

13

15

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

W 00 W 01 W 02 Wooden W Outdoor

The effect of insulation in the ceiling is observed clearly in the temperature of the

second floor (1.2°C), mainly at night, when the ventilation of the house decreases. The high variations of the temperature take place because of greater air change supposed for that hour. The house with insulation in the walls and ceiling is better than the brick house without insulation but is worse than wooden house.

Figure 10.- Temperature in winter, Second Floor with different materials.

Winter - Air Temperature Second Floor - Volume 2

1

3

5

7

9

11

13

15

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

W 00 W 01 W 02 Wooden W Outdoor


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In second floor, it is observed that the wooden house has 1.9°C higher temperature than the insulated brick house and 2.4°C higher temperature than the house with insulation in the ceiling. Respect to the averages of temperature during the day, the wooden house surpasses with 2.3°C the house without insulation, with 1.5°C the insulated ceiling case and only with 0.5°C the case with insulated walls and ceiling.

Table 14.- Temperature for winter, in all cases, extreme values.

Ground Floor

Case W 00 W 01 W 02 Wooden W

Max 11 11.2 11.7 12.1

Min 5.2 5.4 6.4 6.5

Average 8.7 8.9 9.7 9.7

Second Floor

Case W 00 W 01 W 02 Wooden W

Max 11.9 11.9 12.4 14.3

Min 5.9 7.1 8.5 8.1

Average 9.0 9.8 10.8 11.3

Energy When economically evaluating the different insulations and materials of the houses, significant differences are found between the different cases. The simulations were made with respect to the energy required to obtain at least 22°C to the interior of the house during the 24 hours of the day. The calculations were made for 90 days and the price kerosene 0.41U$/liter, that corresponds to the current price in Chile. (1kg of kerosene produces 10Kcal/kg, ρ =0.8)

Of the figure11, it is possible to deduct that the wooden house reduces the energy cost, with a 48% in comparison to the brick house without insulation. The new Chilean legislation with respect to the insulation of ceilings gives a reduction of 15%.

These houses have a cost of U$12.350, the cost of energy during 10 years without insulations corresponds to 36%, however for the wooden house it is only 18%, witch is very important to consider in the future, because these houses are for low income people, where in many cases the expenses of heating are often excluded from the monthly budget. If it is considered that the monthly income is of US400, and heating is used during 8 hours, the result is that during the months of winter the cost of heating corresponds to 12,4% for the brick house without insulation and would be reduced to half in the wooden houses.

Figure 11.- Consumption of Energy for Heating for al least 22°C, during 90 days in winter.

- 50

100 150 200 250 300 350 400 450

Compsumption of Energy U$ and kWh for winter season

U$ 447 378 275 233

kWh/m² 175 148 107 91

W 00 W 01 W 02 Wooden W

100%85%

52%61%


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Summer In summer, it is important to analyse the maximum values above 28°C, because this is limit for the thermal comfort, in agreement with Mahoney tables, nevertheless Givoni shows 25°C, as maximum values for thermal comfort, for less than 60% of relative humidity. The figure 12, shows that the wooden house is warmer, approximately 1° of maximum, than other cases, for both floors.

Figure 12.- Temperature in summer, Ground Floor with different materials.

Summer - Air Temperature Ground Floor - Volume 1

12

14

16

18

20

22

24

26

28

30

32

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

S 00 S 01 V1 S02 Wooden S Outd_Temp

From (the) 11:00 in the morning until 18:00 in the evening, all cases are outside thermal comfort in both volumes. Therefore it is important to analyse a system of shading..

Figure 13.- Temperature in summer, Second Floor with different materials.

Summer - Air Temperature Second Floor - Volume 2

12

14

16

18

20

22

24

26

28

30

32

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

S 00 S 01 V2 S02 Wooden S Outd_Temp

Table 15.- Temperature for summer, in all cases, extreme values.

Ground Floor

Case S 00 S 01 S 02 Wooden S

Max 28.6 28.5 28.6 29.8

Min 19.0 19.1 19.8 18.9

Average 24.3 24.3 24.5 24.5

Second Floor

Case S 00 S 01 S 02 Wooden S

Max 30.1 29.4 29.5 31.0

Min 19.7 19.9 20.6 19.2

Average 24.8 25.2 25.5 25.2


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Shade in Summer To study shading it was decided to analyse the brick house, with insulation in external walls and ceiling.

For shading were considered horizontal elements on all the windows of 30cm of length. The assigned properties were: absorbance: 72%, transmission: 0%, emittance front: 90%, and emittance back: 90%.

Figure 14.- Temperature in summer, in ground and second, with shading.

Summer - Air Temperature Shade

18

20

22

24

26

28

30

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

V1 S02 V2 S02 Vol 1 S 02S Vol 2 S 02S

As it is observed in table 16, the differences found by the use of shading were only of 0,2 °C on both floors. Therefore one may conclude, that shading does not have effect on the temperature in our case.

Table 16.- Temperature for summer, for shade used, extreme values. Normal Ach.

Ground Floor – Volume 1

Case S 02 S 02 S Difference Max 28.6 28.5 0.2 Min 19.8 19.7 0.1 Average 24.5 24.5 0.1

Second Floor – Volume 2

Case S 02 S 02 S Difference Max 29.5 29.4 0.2 Min 20.6 20.5 0.2 Average 25.5 25.4 0.1

It was decided to decrease the air changes, because one may think that air changes are more important in the behaviour of temperature than the effect of shading. But results indicate it is almost the same temperature in the house with shade and the one that it does not have.

Nevertheless, the values in the case of low air changes are higher than in the case with normal air change, and in temperature average for volume 1 (ground floor) the difference founded is 1°C, and for volume 2 (second floor), is 1.4°C.


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Figure 15.- Temperature in summer, in ground and second floor, with shade, Low Ach.

Summer - Air Temperature Shade - Low Air Changing

18

20

22

24

26

28

30

32

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Tem

per

atu

re °

C

Vol 1 S 02 A Vol 2 S 02 A Vol 1 S 02SA Vol 2 S 02SA

Table 17.- Temperature for winter, for shade used, extreme values. Low Ach.

Ground Floor – Volume 1 Case S 02 A S 02 S A Difference

Max 28.8 28.6 0.2

Min 21.6 21.5 0.1

Average 25.6 25.5 0.1

Second Floor – Volume 2

Case S 02 A S 02 S A Difference

Max 30.0 29.8 0.2

Min 23.7 23.5 0.2

Average 26.9 26.8 0.1 Differences in the use of shade are founded in the solar radiation from 18Wh/h to 6:00AM to 72 Wh/h at midday, in the ground floor (Volume 1)

Figure 16.- Solar radiation ground floor, in summer.

Radiation ABS

0

50

100

150

200

250

300

350

400

450

0 2 4 6 8 10 12 14 16 18 20 22 24Hours

Wh

/h

S 02 S 02 S


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Figure 17.- Solar Views, during January. (from DEROB)

6:00AM

9:30 AM

15:00PM

18:30 PM

8:30AM

12:00AM

16:00PM

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Discussions and Conclusions Material According to the recommendations given by Mahoney, for Santiago, elements of heavy time lag are required, over 8h. Due to the adobe was studied, with the purpose of analysing the results in the house in January and July. As indicated in table 11, external walls with 250mm of adobe present a time lag of 6.33h, three times the normal brick structure (140mm). The graphs show in general a lower temperature during the day with the walls made with adobe and higher in the night, being the daily oscillation of temperature for this material, minor than all the cases.

In the case of the wood structure the opposite happens, the daily oscillation of temperature to the interior of the house is the greater one, reaching 10.9°C and 6.8°C in summer and winter respectively, (adobe 8°C and 2.8°C). The time lag in this case is of 0.541, explaining the high thermal oscillation. Despite this, the structure presents the best conditions for the winter, because quickly it obtains the external temperature during the day and during the night the losses are smaller, than in a structure without insulation. This is because this material presents a low conductance 0.630(W/m²K). In summer however, this capacity to accumulate heat to the interior of the house is not wished, because the gains by radiation are high by the time of the year, and as they are not lost through the walls, the temperature indoor, is higher than in all the other studied cases. § Elements with elevated time lag are required to decrease the daily

oscillation of temperature, and to improve thermal comfort in the warm season.

§ Low conductance is required, to increase the temperature in the cold season.

Winter A decrease in the use of energy required for heating in the months of winter can be obtained easily, 15%, only considering the insulation in the ceiling, as the new Chilean regulation indicates, but 48%, if it is constructed in wood.

This point would have to be studied with greater detail, because it is a relevant aspect in the standard of life of the low-income people.

Despite of it, until now it is difficult to obtain thermal comfort with passive measures for low-cost houses, because structure a low conductivity for the external walls is required.

The solution in brick is impossible to apply in these low cost houses, because in this material is necessary have double walls for obtain low conductance as is required. Although the wooden houses, that are being develop by Fundación Chile improve the thermal conditions, but heating in winter is required anyway, in agreement with Rodriguez (1972). § For the zone of Santiago, it is necessary to consider heating in winter, to

obtain thermal comfort. § The new Chilean legislation with respect to the insulation of ceiling,

lowered the energy by 15% of the required in winter (to obtain 22°C during the 24 hours of the day)

§ With the use of wooden house with thermal insulation, the energy requirements decreased by 48% with respect to a house without insulation.

Summer During 18 hours daily approximately, in all the studied cases, the temperature indoors is on thermal comfort, defined for Mahoney. Unfortunately during all afternoon, the house is very warm, the wooden especially. Different walls, with higher time lag, like adobe, causing improvements in summer, but in winter they are not appropriate. A possible solution is to find new types of shading, as it is discussed ahead, and to increase ventilation during the night. § A solution for Santiago consists of wooden houses or structure of brick

with insulation in ceiling and walls. Nevertheless shading solutions must be studied.

§ Ventilation in summer must be considered during the night


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Shade in Summer North-facing windows receive sunlight only early in the morning and in the evenings during the summer.

This happens from 6:00 in the morning to 8:30 on North facade, to seeming again to 16:30. By this time, the house is in comfort, reason why the effect of shade is not required. (Figure 17)

South facing windows receive most sunlight (9:30-15:30), but in summer the sun is high in the sky and can be blocked by canopy or overhang. At this time, the sun altitude is near 90°, which indicates, that the incident radiation to the interior of the house is low, as it is possible to see in the following equation I surf = cosθ IDN, if θ ≈ 90°, cosθ≈0.

Added to this, the surface of windows in the south façade is only a 12.5% of the wall, that is why one can conclude that reducing radiation with the use of shading causes changes of temperature in local points only and in relation to the volume this is insignificant.

West and east-facing windows are much more exposed to the sun in summer, according to Littlefair (1999), but in our case the house does not present windows in these orientations.

§ For this orientation and this house, rather than to design horizontal shade, it is more relevant with another type of shade, mainly vertical. However more important is to increase the ventilation as the diagram of Givoni shows, and as the simulation results shows, when diminishing the air changes, the temperature is increased up to 1,4°C.


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References Alvarez, S. Et al. Natural ventilation in Buildings, a design handbook. Derob-Lth for MS window, User Manual version 99.02 Fuerza Aerea de Chile, Dirección General de Aeronáutica Civil 1992 Anuario Metereológico. Koenigsberger, O.H. et al.- 1974 Manual of Tropical housing and building. Part one: Climatic Designe; London. Littlefair, P. 1999 Solar Shading of Building. BRE report 364. Ministerio de Vivienda y Urbanismo 1999 Reglamentacion Térmica. Ordenanza general de urbanismo y Construcción. Muller, E. 1996 Arquitecture, Thermal Comfort and Energy in Chile. Lund University, Sweden NCh 849.Of87.- Aislación Térmica. Transmisión Térmica. Terminología, magnitudes, unidades y símbolos. NCh853.Of91. – Acondicionamiento ambiental térmico-envolvente térmica en edificios- calculus de resistencias y transmitancia termicas. NCh 1079.Of77.- Zonificación climatico habitacional para Chile y recomendaciones para el d iseno arquitectónico. Olgyy, A. Et al. 1976 Solar control and shading devices. Rodriguez ,G. 1972 El Clima Chileno y su relación con la contruccion habitacional.Revista del Idiem, vol. 11, N°3. Sarmiento, Pedro 1999 Energia Solar en Arquitectura y Construccion, Universidad Federico Santa Maria.

Acknowledgements I would like to thank:

The Architecture, Energy and Environment 2000 course Staff for their dedication and good disposition, given during the accomplishment of the course. Especially to Hans Rosenlund, who helped me with my problems with the language, and to Laura Liuke, Erik Johansson and Marie Claude Dubois .

Fundación Chile for the support offered during the course, especially Emilio Moreno, Paula Bosch and Valentina Leyton.

SIDA, for making possible my participation in the course.


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Annexes

LocationLongitude -70.4 °

Latitude -33.3 °Altitude 520 m

Air temperature °C Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec High AMTMonthly mean max. 29.7 28.1 26.7 21 16.2 12.8 13 17.5 19.5 23.7 25.1 28.6 29.7 16.4Monthly mean min. 13.7 12.2 12.1 8.9 7.3 4.6 3.1 4.9 6.6 8.4 10.5 11.6 3.1 26.6

Monthly mean range 16 15.9 14.6 12.1 8.9 8.2 9.9 12.6 12.9 15.3 14.6 17 Low AMR

Relative humidity % Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonthly mean max am 72 75 85 89 91 93 94 94 92 75 72 60 1 <30%

Monthly mean min pm 41 41 44 46 58 71 66 53 56 39 41 35 2 30–50%

Average 56.5 58 64.5 67.5 74.5 82 80 73.5 74 57 56.5 47.5 3 50–70%

Humidity group 3 3 3 3 4 4 4 4 4 3 3 2 4 >70%

Rain and wind Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec TotalRainfall mm 0 0.5 13.2 41 129.5 170.3 23.3 57.7 20.7 0 7.8 0 464

Wind, prevailing S S S S SE SE SE SE SE SE S S N, NE, E, SE,

Wind, secondary SE SE S SE S S S S SE S N SE S, SW, W, NW

Diagnosis °C Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec AMTMonthly mean max 29.7 28.1 26.7 21 16.2 12.8 13 17.5 19.5 23.7 25.1 28.6 16.4Day comfort, upper 28 28 28 28 25 25 25 25 25 28 28 30Day comfort, lower 21 21 21 21 20 20 20 20 20 21 21 22

Thermal stress, day H H O O C C C C C O O OMonthly mean min 13.7 12.2 12.1 8.9 7.3 4.6 3.1 4.9 6.6 8.4 10.5 11.6 H = Hot

Night comfort, upper 21 21 21 21 20 20 20 20 20 21 21 22 O = Comfort

Night comfort, lower 14 14 14 14 14 14 14 14 14 14 14 14 C = Cold

Thermal stress, night C C C C C C C C C C C C

For AMT = 16.4Comfort limits

Humidity group Lower Upper Lower Upper Lower Upper Lower Upper Lower Upper Lower Upper L U L U1 26 34 17 25 23 32 14 23 21 30 12 21 23 32 14 232 25 31 17 24 22 30 14 22 20 27 12 20 22 30 14 223 23 29 17 23 21 28 14 21 19 26 12 19 21 28 14 214 22 27 17 21 20 25 14 20 18 24 12 18 20 25 14 20

Meaning Indi- Thermal stress Rainfall Humidity group Monthly mean rangecator Day Night

Air movement essential H1 H 4H 2–3 <10°C

Air movement desirable H2 O 4Rain protection necessary H3 >200mm

Thermal capacity necessary A1 1–3 >10°COutdoor sleeping desirable A2 H 1–2

H O 1–2 >10°CProtection from cold A3 C

Indicators Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec TotalH1 0 0 0 0 0 0 0 0 0 0 0 0 0H2 0 0 0 0 0 0 0 0 0 0 0 0 0H3 0 0 0 0 0 0 0 0 0 0 0 0 0A1 1 1 1 1 0 0 0 0 0 1 1 1 7A2 0 0 0 0 0 0 0 0 0 0 0 0 0A3 0 0 0 0 1 1 1 1 1 0 0 0 5

NightDay NightAMT >20°C AMT <15°C

DayDay Night

Santiago, Quinta Normal

AMT 15–20°CDay Night


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Layout0–10

5–120–4 Compact courtyard planning

Spacing11–12 Open spacing for breeze penetration

2–10 As above, but protection from hot and cold wind

0–1 X Compact layout of estatesAir movement

3–120–5

6–122–120–1 X No air movement requirement

Openings

0–1 0 Large openings, 40–80%

11–12 0–1 Very small openings, 10–20%

Any other conditions X Medium openings, 20–40%Walls

0–2 Light walls, short time-lag

3–12 X Heavy external and internal wallsRoofs

0–5 Light, insulatted roofs

6–12 X Heavy roofs, over 8h time-lagOutdoor sleeping

2–12 Space for outdoor sleeping requiredRain protection

3–12 Protection from heavy rain necessarySize of opening

0 Large openings, 40–80%1–12

2–56–10 X Small openings, 15–25%

0–3 Very small openings, 10–20%

4–12 Medium openings, 25–40%Position of openings

3–121–2 0–5

6–120 2–12

Protection of openings

0–2 Exclude direct sunlight

2–12 Provide protection from rainWalls and floors

0–2 Light, low thermal capacity

3–12 X Heavy, over 8h time-lagRoofs

10–12 0–2 Light, reflective surface, cavity3–12

0–9 0–56–12 X Heavy, over 8h time-lag

External features

1–12 Space for outdoor sleeping

1–12 Adequate rainwater drainage

Light, well insulated

Rooms single banked, permanent provision for air movementRooms double banked, temporary provision for air movement

In north and south walls at body height on windward side

As above, openings also in internal walls

Medium openings, 25–40%

X

11–12

0–1

0

1–2

X Orientation north and south (long axis east–west)11–12

Thermal Comfort and Energy in Santiago. Confort.pdf · Chilean standard NCh 1079.Of 77....

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Transcript of Thermal Comfort and Energy in Santiago. Confort.pdf · Chilean standard NCh 1079.Of 77....