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The Literary Caf Bustamante ParkThe Skylight Influence on The Environmental Performance of The reading area MArch Enviromental desing

ABSTRACT: In 2007 the Chilean government came out with the newthermal regulation that is divided in 3 stages, been the third one based onthe application of the new buildings regulation in aspects of thermalperformance, with new U-values to walls, roofs and windows. On the otherhand, been this project constructed during the same year that these newapplications were applied and constructed by the same government, it is

absolutely relevant to understand the actual environmental performance onthis building .This is why the results made through qualitative andquantitative analysis are so relevant and reveal a great lack of anyenvironmental strategy application in this public building whose mainfunction is to provide a comfort learning space for the community.Nevertheless much of that comfort is obtained from mechanic heating andcooling system

.INTRODUCTION:

Chile has experienced serious problems of power provision during the

last few years, and the coming years do not seem very fruitful with theArgentine gas provision cuts in the short and medium term. On the otherhand the power policies of the Government have not yet managed to clarifywhich is going to be the direction the country is going to take in terms ofenergy sources, making it difficult to unravel the future of the countryenergy problems.

The subject of the Sustainable Architecture has settled in the discussion,and it sounds stronger than ever in Chile. The government has created anEnergy Efficiency Program promoted by the Ministry of Economy. Thisprogram subsidizes the cost that implies the development andimprovement of buildings to make them energy efficient.

However, been a project recently developed by the Chilean government,no study has been made to determine the actual environmentalperformance of the building, therefore ignoring all the energy problems inwhich the country is living today. This study will analyse the actualperformance of the building, focusing in the skylight influence in thereading area and comparing this area to the Cafe area. The study attemptsto understand the environmental performance in terms of its thermal andlighting behaviour between these two areas.

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OBJECTIVES:

The main objective of this research is the application of all theenvironmental analysis tools that will be required to find out the actualperformance of an existing building located in Chile that was recentlybuilt and in which no environmental strategies were considered.

Therefore the most probable outcome will be the implementation ofnew strategies in order to improve the environmental performance ofthis building.


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3. Climate Analysis

Latitude 3326'

Longitude 7037

Figure 1 Figure 2

Santiago Sky conditions during occupancy Hours 9:00 -20:00 mon-sun

Santiago averages temperatures during the year

The Literary cafe is located in Santiago City, the Capital of Chile.Santiago is the principal city; located almost in the middle of the country.The latitude is the main element that determines the Chilean climate.Santiago counts with a Mediterranean climate, being the summer seasonsince December through February (the thermometers go up to 30C in thisseason) and winter since May through August, and the annual average is of14C.

During the year there is a 52% of clear sky condition over Santiago whichmeans that any system of illumination based on natural lighting could be

useful.

During almost haft of the year (47%) the external temperature is belowthe comfort range, this means that heat loss must be prevented during thisperiod. On the other hand the other haft of the year (42%) the externaltemperature is in the comfort range, which means passive cooling systemcould be viable in this period.

.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%clear sky overcast sky

Direct radiationSolar protection

Direct radiationSolar protection

HOURS

Figure 5

Figure 3

Figure 4

C


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3.1 Site microclimate analysis

N WINTER SOLSTICE

EQUINOX SOLSTICE

SUMMER SOL STICE

The Literary Coffee Bustamante is located in the middle of BustamantePark which is surrounded by residential buildings (fig.6). The project isgenerated from translucent central space, contained by two lateralvolumes, closed, consolidating the continuity of the park throughout itsentire axis(fig.7).

The rectangular shape of the building has and orientation mostly north-south, being these two facades the main entrances which have largewindows facing south and north, these last, exposed to the penetration ofsun light. On the other hand, the two lateral volumes are made of pureconcrete and they contain service areas. The prevailing winds come fromthe south east making the south facade permeable to winds current. Thenoise pollution from the main street is absorbed by the trees and thelateral concrete walls from the east and west facades

Winter winds

Noisepollution

Noisepollution

SOLAR ANGLES:

winter solstice: 34.5 equinox solstice: 58.3 summer solstice: 79.7

The orientation benefits of not having

any overshadow issue by thesurrounding building. On the otherhand, the surrounding trees areacting as a natural layer helping toblock the direct sun in summer timeand letting it inside in winterseason.

(apendix.1)

Figure 6

Figure 7


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4. The Literary caf

Architect: Germn Bannen LayLocation: Park Bustamante, Bustamante n335,Santiago, Chile.

Build surface: 630.05 msqYear: 2007/2008

Plan ground floor

Plan firstfloor

4.1 Architectural Concept:

The geometry and the translucent elements reinforce the continuity of thepark.The central cover was developed with a perimetral louvre window,recovering the idea of the Colonial Prgola that was part of the park before.

4.2 Design strategies:

This is not a building that stands out for its application of environmentalstrategies neither for its performance in such field, but nevertheless, thereare some basic strategies that were implemented in it, one of these is theorientation to the north facade, mostly glazed, through this facade is wheremost the solar gains are won to heat the building in winter. On the otherhand, the east and west facades are made of pure concrete thusminimizing the noise pollution. (fig. 9,10)

Plan First Floor

N

N

Figure 8

Figure 9

Figure 10


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4.3 Activities:

The building is developed in two levels: the ground level connects thepark with the cafeteria and multiple activity hall, where workshops haveplaced every weekend, stand publishing books, metropolitan newspaper,launchings, and newspaper and periodicals library. This level counts with

public toilets and an area of services for the personnel of the building .In thefirst floor there is the reading area, this is a free plant with sofas, armchairs,and reading tables, with books .In this level is located the reception, aleading desk, administration, a the library, and a children section speciallydesigned. (fig.10, 11, 12).

North Facade

South Facade

West Facade

East Facade

Croos Section 1

Croos Section 2

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16


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4.4 Building materials:

The predominant material of this building is concrete; the thermal mass ofthis material has been the way of trying to achieve insulation on the externalswalls. The material also has been used in the roof. The only area in whichinsulation has been implemented is in the roof, this has been made of one

layer of polystyrene with wood ceiling that is visible in the reading area.On the other hand, the north and south facades are completely glazed withsingle glass except for the toilets area, the staff service and the offices. Theskylights that are located on the reading area are made of polycarbonate(fig.17,18)

5. Qualitative analysis:

The indoor environment should be designed and controlled so thatoccupants comfort and health are assured. There are individualdifferences in perception and subjective evaluation, resulting in a baselevel of dissatisfaction within the building population. (CIBSE Guide

A, M.Humphreys), 2006: page 1.1)

5.1 Occupants survey:

Eventhough, most of the time the literary cafe building runs withmechanical ventilation in summer and heating in winter, this surveyhas been structured with the main objective of analysing theoccupants satisfaction or dissatisfaction with the internal condition ofthe building as it is and obtain a general perception of occupants opinion in two specific areas: the caf and the reading area (fig.15).Nevertheless it must be born in mind that in some of the surveys the

mechanical system could have been turned on at the moment theywere answered. On the other hand the inquiry covered the peoplethat were in the literary cafe in summer as much as in winter making atotal of 42 people considered in the questioning.

SKYLIGHT: (U- VALUE: 3.40 W/M2 K)

Polycarbonate: double layer, 16 mm

EAST AND WEST FACADE

WINDOWS:

(U-VALUE: 1.63 W/M2 K)

Exterior frame: aluminium

Interior frame: aluminium

Double glazing

ROOF (U-VALUE: 0.26 W/M2 K)

Metal deck: 2 mm

Asphalt layer: 0.5 mm

Concrete: 150 mm

Polystyrene: 100 mm

Wood ceiling: 20 mm

EXTERNAL WALLS: (U-VALUE

1.03 W/M2 K)

Concrete: 250 mm

WINDOW (U-VALUE: 5.60

W/M2 K)

Exterior frame: aluminium

Interior frame: aluminium

Single glass

High emissivity glass

Figure 17

Figure 18 Figure 19


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5.2. Survey Results:

Reading area:SUMMER:

Temperature light air

WINTER:Temperature light air

SUMMER: WINTER:Air-condition: heating

According to the survey, there seemed to be a discomfort during summerwith the low temperatures in this area. 28% of the people complained ofcertain discomfort in terms of feeling cold in summer. On the other hand in

terms of brightness most of the people felt comfortable with the light, only a20% claimed to be slightly bright in excess in summer. In terms of ventilationthere seems to be excess of air conditioning during this period. Theperformance of the building in winter seems to be much better, in terms oflighting and ventilation. Nevertheless, 28% of the people complained of beingcold in excess in this season. When inquired on air-conditioning, peopleexpressed a discomfort on the heating system and on the intensity of the air-conditioning during summer (fig.20). On the other hand, there is a strongdependency on the heating system in winter.

Figure 17

Caf area:SUMMER:

Temperature light air

WINTER:Temperature light air

Air-condition: heating:SUMMER: WINTER:

The cafe area seems to be most affected by the overuse of air-conditioning in summer. However, the occupants seemed satisfied withmost of the lighting and the air conditioning but at the same time most ofthe comfort in this area relays on the heating system in winter.(fig.21)

Do you think the Reading caf is a suitableplace to read?

In general, the majority of the people feels that the reading cafe is asuitable place to read. Nevertheless, they are some issues the buildinghas, regarding the use of air condition in excess in summer, creating lowtemperatures and heat loss in winter that seems to be managingthrough heating systems. In terms of lighting, there seems to be abrightness issue in the reading area in summer.

Figure 20 Figure 21

Figure 22


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6. Skylight Typology:

The skylight in general is used to bring light into a space where the naturallight cannot reach through as a vertical translucent element. They also canbe used as a great source of ventilation and heat gains . The geometry ofthe skylights turn to change accordingly to the purpose of the design, interms of what and how is wanted to illuminate.

The skylight design for this building has a conceptual background ratherthan an environmental strategy; it was based on recovering the idea of theColonial Prgola (that was located in the park as part of the recovery plan)(fig.24).In this particular case the geometry of the skylight is quite simpleallowing the light to come directly (fig.25), without any reflecting element orshape that could reduce the impact of the direct light or solar radiationrather than the material itself. The translucent material is made ofpolycarbonate with thin steel straps that keep the material rigid. (fig.25,26)

Figure 23

Figure 24

Figure 25

Roof plan

Figure 26 Figure 26


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7. Quantitative analysis: daylight performance:

Lighting in a building has three purposes:

To enable the occupant to work and move about in safety To enable tasks to be performed correctly and at an appropriate pace To create a pleasing appearance.

Accordingly to CIBSE guide the comfort criteria for the reading roomsare to maintain the illuminance at a minimum of 500 lux. (CIBSE Guide A,M.Humphreys (Oxford Brookes University), 2006: page 1.8.1)

7.1. Computer daylight simulation:

The simulation was made to analyse the daylight performance in thecafe and reading area to find out if these areas complied with theminimum requirement they were supposed to achieve according to

their activities. (fig.27,28,29,30)

area

DaylightFactor(average)

DaylightFactor(minimum)

uniformityratio

illuminanceovercast/average

illuminancesunny/average

CIBSErecommendation(minimum)

CAFAREA 4.68% 0.49% 0.2 747.3 lux 1811.2 lux

50-200 lux (diningrooms)

areas

DaylightFactor(average)

DaylightFactor(minimum)

uniformityratio

illuminanceovercast/average

illuminancesunny/average


READING A REA 11.25% 3.09% 0.2 947.46 lux 8887.95 lux

500 lux (readingareas

Reading area

Cafe area

Figure 27

Figure 28

Figure 29

Figure 30


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Cafe area overcast condition Reading area overcast condition

Cafe area sunny day Reading area sunny

Both areas are well illuminated, fulfilling the minimum standard ofIlluminance requirements from CIBSE guide (fig.31,32,33,34), the mainissue lies in the lack of lighting uniformity. Studies were made also in sunnydays where the illuminance levels in the reading area exceeded dramaticallythe standard levels, being the main reason the light coming down from theskylights (fig.37).

Considering that the caf area is near the glass wall, the depth of theroom seems to be too long to provide efficient light on the side of this area,creating dark spaces in the joints between floor and the walls near this area.

In the reading area there is also a lack of uniformity, but in this case, the

main reason lies on the fact that it is receiving a great amount of daylightfrom the skylight, creating a big contrast between the area near the glassand in the balcony area, therefore in sunny days glade became an issue inthis area, contrast studies were conducted .

Having identified the two main problems, regarding the uniformity ratio inboth areas and glare issues in the reading area, computer simulation wereconducted having the main goal of findind out possible solutions to dressthese issues.)

The contrast ratio show glare problems in the morning in the reading areaTime:9:30 AM Date:21 of December .Acording to CIBSE code for interior lighting been the guideline of 10:3:1

CONTRAST RATIO 9.5 : 1.5 :1 CONTRAST RATIO 16 : 1 : 22

Sky surfaces visible at direct angles

Indirect light bounce in the ceiling

and then goes back to desk

Summer

Equinox

Winter

9:00 am

view

12:00 pm 16:00 pm

Heliodom testingConfirm glade issueIn the reading area

Figure 31 Figure 32

Figure 33 Figure 34

Figure 35 Figure 36

Figure 37

(appendix.2)

Figure 37


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The main changes made were based on changing the transmittance of theskylight materials in the reading area and the windows in the first floor ofthe south facade to a lower transmittance level to avoid contrasts issueswith the main objective of improving the uniformity ratio in these two areas.On the other hand, skylights were provided for the cafe area,(fig.40)creating a semi-translucent opening in the floor of the reading area with the

objective of providing natural lighting to the caf area . Therefore, afterthese changes the uniformity ratios were improved to a 0.5 in the readingarea and in the cafe area to a 0.6. (fig.38,39,42)

areasDaylight Factor

(average)

DaylightFactor(minimum) uniformity ratio

illuminanceovercast/ average

illuminance sunny/average


CAF AREA 5.27% 3.29% 0.6 747.3 lux 1511.2 lux50-200 lux (diningrooms)

READINGAREA 7.78% 4.09% 0.5 947.46 lux 2880.95 lux 500 lux (readind areas

(appendix.3)

Figure 38

Figure 39

Figure 40

Figure 41

Figure 42


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8. Quantitative analysis thermal performance:

8.1. Computer simulation:

After having a global view of the daylight performance of the building, thenext stage was to approach an understanding of the thermal

performance. In terms of what is the role of the skylights in the readingarea and how their thermal performance affect the entire building, also tofind out how the external envelope behave in different seasons withoutmechanical ventilation and heating. For this analysis, the simulationswere concentrated in the comparison of the two areas; the reading andcafe areas, been the first one above the second one.

North facade south facade reading area

Simulations Summary table:

Numbers aims of simulations

N1 performance of the envelope : only materials and infiltration.N2 performance of the building including ventilation.

N3 performance of the building including ventilation and internal gainsN4 Performance of the building without skylight, to study the impact of solar gains.

N5performance of the building with skylight and improvement in materials and

ventilation

Materials Summary table:structure materials U-values W /M2 K orientationext. Walls Concrete 1.03 east, west

inter. Wallsplaster wall with foamedinsulation 0.894 inside

windows single glass 5.60 north and southwindows2 Double glazing 1.63 east and westskylights Polycarbonate 3.40 ceiling

roof

Concrete with metal deck,insulation: Polystyrene andWood ceiling 0.26

Figure 30top of the building

After applying the materials to the TAS 3D model, the preliminary conclusionregarding the materiality of the building it can be inferred that the north and thesouth facades are mostly exposed to the external condition, being the mainreason the low U-values of the windows in those facades.

Simulation N1: only materials and infiltration.

The reading area seems to be just the 30% of the year in the comfortrange. On the other hand the Caf area overhead by a 5% the comfortrange of the reading area in the entire year. However the predominanttemperatures in both areas, are the ones below the comfort range.

Simulation N2: effect of ventilation in summer (no internal gains)

The introduction of ventilation in summer has the effect of bringing down a10% the temperatures over the 25 C, and keeping the same percentage in

the temperatures below the comfort range in the reading area.Nevertheless, the comfort range percentage has increased in almost a 25%in the caf area and brought down almost a 10% the temperatures over thecomfort rage. Therefore, the introduction of ventilation helps to reduce thetemperature above the comfort range in this case.

Figure 43

Figure 44

Figure 45


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Simulation N3: effect of ventilation in summer and internal gains.

This case is the closest to the actual performance of the building in apassive mode, and it showed overheating problems in both areas with theintroduction of occupants. On the other hand, it evidenced that almost50% of the temperatures in the caf area are reaching the comfort range,being one of the main reasons this area is always much colder than thereading area, but the introduction of occupants helped to stabilize thetemperatures in this area.

Simulation N4: building without skylight

Peak day with skylight Peak day without skylight

The main aim of the simulation without skylight was to find out which wasthe real impact in the thermal performance of the solar radiation comingdown through the skylight located in the first floor over the reading area.The temperature change between these two cases is of 6 C in thereading area and 2 C in the cafe area during the hotest day of the year.

Simulation N5: with skylight, improvement in materials, ventilation andinternal gains

In this simulation, it has been demonstrated that through the improvement ofthe U-value of the materiality in the skylight, glazing and creating moreopening windows in the south facade the comfort range increasedconsiderably in both areas. On the other hand, the actual performance of

the building only allows 2 months of the year to have a free runningbuilding (without air-conditioning or heating).On the other hand, with theintroduction of the following changes, the free running period could beextended to a 4 months.

Actualperformance

Improvementperformance

Figure 44

Figure 49

Figure 46 Figure 47

Figure 48

Figure 45

Figure 50

(appendix.4).

Temperatures in occupancy Hours 9:00 -20:00 mon-sun

Th Li C f B P k


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9. Quantitative analysis: ventilation performance

The aim of this study is to evaluate whether natural ventilation isachieved in the terms of air flow and air change in the main spacewhere the reading and caf areas are. For this study the Optiventprogram was used to analyse the building behaviour in different

seasons .

Summer: temperatures outdoor 28 C/ indoor 36 C

Equinox: temperatures outdoor 17 C/ indoor 24 C

Winter: temperatures outdoor 1 C/ indoor 15 C

On the CISBE guide the suggested that the air supply rate for a readingroom it should be of 10 litres per second of fresh air per person. The readingarea was simulated for 30 people being the fresh air rate 30 litres per second(0.30 m3/S). Therefore, it can be concluded that most of the time the air flowrate is achieved with the existent ventilation, nevertheless in summer season

the levels achieved of air flow for cooling seem to be barely reaching what isrequired. However, must be taken into account that the glass door has beentaken as the main inlet and outlet of this building for this simulation being themain reason why this building does not have big openings therefore in acommon situation these doors will be kept closed most of the time.Therefore to improve this situation the creation of more opening windowsshould be considered.

Figure 51

Figure 52

Figure 52

The Literar Caf B stamante Park


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10. Conclusions:

From this study it can be concluded that the building has certain thermaland lighting issues. According to the survey, it seems to be a discomfort interms of excess use of the air conditioning during summer, causingextreme temperature changes between outdoor and indoor of the buildingin summer. On the other hand, most of the people feel comfortable with

the light performance of the building and the air quality.

However, analysing the building in more details, there is an issue onthe daylight uniformity of the reading and caf area, created by theamount of light coming from the skylight in the reading area. On the otherhand, in the caf area the daylight uniformity issue comes from the lackon light coming from the glass located in the south facade.

In terms of thermal performance, through the simulations, it has beenconcluded that external envelope has thermal problems being the mainissue the permeability of the external envelope regarding the typology of

glazing used in the south facade where most of the heat loss is goingthrough and in a secondary aspect the poor insulation of the building thatis related directly to the low U-values of the concrete used on the building.

10.1 Suggested improvements:

From this study, suggestions had been made to improve theperformance of the building in terms of passive design, regarding onthermal and lighting aspects.

In lighting aspect changing the transmittance of the skylight in thereading area and the windows in the first floor of the south facade to alower transmittance material, this will allow to improve the uniformity ratioin this area. On the other hand secondary skylight can be provided inthe floor of the reading area to bring light indirectly to the cafe area in thisway improving the uniformity ratio of the caf area.

In terms of thermal aspect, change the south facade single glaze to adouble glazing, thus avoiding excessive heat loss. As well as reducing thetransmittance of polycarbonate in the skylight.

In aspect of ventilation, create opening windows in the south facade that

will improve the flow rate in summer and it also will help to maintaintemperature in the comfort range in the months of march, April, Octoberand November, when these improvements will have the biggest impact inthe building, allowing the building have two more months of free runningin terms of air-conditioning or heating in the year.

The Literary Caf Bustamante Park


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11. References:

[1] Humphreys, Michael, & Nicol Fergus. 2006. CIBSE, 7th Edition. Place: Printed in Great Britain by Page Bros. (Norwich) Ltd.

[2] Michael J. Holmes *, Jacob N. Hacker.2007. Climate change, thermal comfort and energy: Meeting the design challenges of the 21st century .Place:

Arup, 13 Fitzroy Street, London W1T 4BQ, UK. Available from: http://www.sciencedirect.com[3]Tamura Y.2004.wind effects on buildings and urban environment. Proceeding of ISWE1-the first international symposium on wind effects on buildings

and urban environment/Tokyo/8-9 March 2004.

[4]Benson Lau. The luminous environment in the Elephant and Rhino Pavillon in London Zoo.Ph.Darwin College.May 2000.

[5]Benson Lau. K14 CSP Glare Phenomenon 2 organisation: Department of Architecture & the Built Environment, Nottingham University.

[6] Besser Daniela. 2010. Victor Miller Building.The atriums influence on the environmental performance of the classrooms.

[7] Cafe literario parque Bustamante.Agustin Infante K. organisation: Plataforma Arquitectura.2008.[viewed 10 march 2011].Available from:

http://www.plataformaarquitectura.cl/2008/06/26/cafe-literario-parque-bustamante/[8] Plan Nacional de Accin de Eficiencia Energtica 2010-2020. Organisation: AChEE.[viewed date: 10 april 2011].Available from:

http://www.ppee.cl/576/channel.html
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