THE “CONSORCIO-SANTIAGO” BUILDING 14 YEARS LATER

Enrique Browne

Architect

2007

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The Consorcio-Santiago Building (Enrique Browne and Borja Huidobro, Architects, 1990-

93) is located in the Las Condes neighbourhood, in Santiago, Chile. It has 26.751 m2

considering its underground 1. It reaches 17 floors and has 74 m in length, occupying half a

block on El Bosque Avenue.

The Consorcio Nacional de Seguros requested few but clear requirements. The building had

to have some 19.000 m2 on the floors ground floor and above. The open space floor plans

had to have some 1.200 m2 each, subdivided into at least two sectors. The first three levels

were to be for the company themselves (with their own entry) while the above would be

rented, or sold or posterior expansion of the company. It was suggested to utilize a “skin” with

insulating glass and panels of ACM2; a new material at the time and recently used in the

Interamericana building in the city centre (Alemparte y Barreda, Assoc. Architects, 1987-90).

However and above all, the image of the building had to endure time, that is, not become

outdated. With these indications, plus our own observations on the site, the neighbourhood,

the regulations and other factors, the project was realized.

The first that emerged was its floor plan with its form of a “boat”, which derives from the

alignment of its main facade with the principal axis that borders the building, namely El

Bosque Avenue on the west and Tobalaba Avenue with the San Carlos channel to the south.

Siding with the open angle between each avenue (148 degrees), the south face of the

building was eliminated, converting it in a tall vertex. This vertical “prow” symbolically marks

the starting point of the office area on El Bosque Avenue. The north-west corner also curves

itself as a welcoming gesture for the large pedestrian influx that approaches from Apoquindo

Avenue, where the underground station is. The curves at the ends create small exterior

squares on both corners of the city block ( Figure 1).

1 It has 2.5 underground floors for parking and equipment.2 ACM = Aluminium Composite Material.

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It was relevant to consider as well, that in the 1990’s the neighbours to the east were houses

for sale. Its unpredictable volume in the future made it convenient to hide that side. As such,

we proposed building a long volume of three levels, half attached to the neighbours according

to Regulations. This produced a tall corridor between this and the “boat”, making two

independent entries on the extremities: one for the Consorcio and another for the superior

levels. These entrances would be preceded by the exterior squares before mentioned. To

functionally separate both entrances without loosing the length, the entrance for the

Consorcio was left at ground level whilst the other at +1 level.

In normal weather, the biggest thermal problem in office buildings is over heating, given that 4

people – plus their equipment such as lights, computers and others – generate the heat

equivalent to a heater. Thus, the air conditioning system weighs a lot on the consumption and

energy costs. In Santiago the over heating increases a lot between October and March on the

west side. Adding up is the reverberation of the heat from the street and sidewalk pavements.

Additionally, are the unpleasant glares. The longest facade of the building had all these

problems, also present at a lesser extent on the north side.

The heat and glare issues were resolved using natural methods as much as possible, such

as vegetation and water. In the front area a reflective water pool of 48m in length and 430 m2

Figure 1: Site plan and Axis ( Consorcio Santiago Building )

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with sprinklers was installed. This avoids the reverberation and produces evaporation,

decreasing the temperature. Trees were also planted to cool the sidewalks and shade up to

the 3rd floor at least.

The two last floors were protected by a large shade overhang of width 4.5 m, which serves as

a visual crown of the building. In turn, it protects these floors from the northwest solar gain.

The overhang was fabricated out of inclined trellises that eliminate the direct solar incidence

on the insulating glass of 5.5 m height during most of the day. The sun on the glazing is only

after 5 pm. This made possible the reduction of the cooling thermal loads and decreased the

installed capacity of the air conditioning, with the respective energy saving during the life of

the building.

But the key was in the body of the building (floors 4 to 15). It was chosen to shade it with

vegetation. Three options were studied: “horizontal trellises” with deciduous creeping

plants to allow for more sun and light in winter; vertical “double green skin” with deciduous

creeping plants and deciduous “trees” (Figure 2).

Figure 2: Alternatives of solar vegetal protection

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About the type of plants, their growth speed, irrigation, thermal function and aesthetics, we

had empirical experience of over 15 years. “Horizontals” such as in House in Ch.Hamilton,

with table grapes as vegetation surface (1974), “verticals” such as in House in P.Harris,

(1982), or House in San Damián (1987), or in the frustrating El Agora Building, (1987), etc.

But with trees at height we did not have this experience. Because of this, the “double green

skin” (vertical trellis) was chosen. These were placed at 1,40 m from the exterior surface of

the building. This separation ensures ample chimney space for the ascending air currents

and gives plenty of room for generous garden planters below, with an automatic irrigation

system. Additionally, this separation allows for easy access by the facade cleaning trolleys

that also takes a gardener on board for the cuttings, disinfection and fertilization of the

greenery (Figure 2 and 3).

Previous experiences assured a growth of the creepers of at least 12m in height in 6 years

like in House in P.Harris. We choose, thus, to divide the big façade into three horizontal

green bands of 4 – 3 and 2 floors, marking out the separation of the bands with one floor

without greenery. As such the elevation was defined (Figure 4).

Figure 3: detail “double green skin” Figure 4: Thermal performance of the building

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To convince them of the solution, we invited the clients to see directly former experiences,

such as the House in P.Harris. Once this green solution was approved, the support of the

institution to the execution and maintenance has been constant. The specific design of the

vertical gardens was assigned to the landscape architect Juan Grimm, who utilized deciduous

creeping plants which emphasize the passage of the seasons of the year and their changing

colours, such as bouganvilleas, ampelopsis and plumbagos.

The “double green skin” solution signifies, in practical terms, vertically lifting the green

surfaces of the houses originally in the site, increasing these a bit from 2.674 m2 to 2.735 m2.

In other words, over than 70% of the total site size in both cases (Figure 5).

Figure 5: Vertical displacement of the green areas (Consorcio Building Santiago)

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As such, the building gives back to the city the vegetation that it took away, at the same time

making this greenery more visible. This cheers up the neighbourhood and oxygenates it,

mitigating the environmental pollution, especially of CO2. It offers in turn a changing aspect,

but of permanent validity. In fact architecture and vegetation behave differently in time. A

building looks its best when recently finished. Thus, the rush to photograph it quickly. Over

the years its appearance decays. They get dirty and the materials deteriorate, as well as

other problems. With nature the reverse happens. A recently planted park is only a hope. But

at 15 years it has gained a lot. Trees have grown, giving shade and forming spaces. The

green predominates as well as other values (Figure 6 and 7).

Side of a recently finished building Side of the building 15 years laterFigure 6: Building evolution in time

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Merging architecture and vegetation, making the latter a construction material, maintains

the building valid for an unlimited amount of time. With this, the main concern of the clients

was accomplished. On the other hand, the interiors becomes more attractive and domestic

(Figure 8). The vegetation can be regulated to the preferences of the users. Additionally, the

soft surface reduces the noise of the city.

Figure 8: Consorcio Santiago office interior (floors 6 and 14)

Figure 7: Nature evolution in time

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With all, the Consorcio-Santiago Building has become a landmark of the neighbourhood,

cherished by its inhabitants, neighbours and santiaguinos. This cam be proved. The

occupancy of the building have been permanently 100%. The company changed its old

logotype, kept for dozens of years, by another representing its building in Santiago (Figure 9).

In the opinion surveys carried out by newspapers and magazines, confirm the stated, and the

building has continually occupied a surprisingly high rank. It was chosen as the Best building

Decade of the 90’s in Chile (year 2002)3, then the Best Building of the last 30 years and

One of the Best 3 Buildings in Santiago, (2003)4 and selected as one of the 8 Best

Buildings in Santiago of all time, (2006)5.

Additional to its “environmental benefits”, the Consorcio-Santiago building has behaved

“energetically” better than thought. At least by the empirical studies carried out by the

engineer Joaquín Reyes. During the design, it was estimated that the “double green skin”

would reduce by 60% the solar radiation, with energy savings of 10%. For an International

Congress realized in 20026, the engineer Reyes carried out a comparative study of the

energy consumption of 10 recent corporative buildings in Santiago. However, it was unable to

3 Selection of the Vivienda y Decoración (Housing and Decoration) Magazine, Santiago, Chile, 21 of December,

2002.4 El Mercurio Newspaper survey. Santiago, Chile, 29 of December, 2003. 5 Selection Vivienda y Decoración (Housing and Decoration) Magazine N° 525. Santiago of Chile, 29 of July

2006.6 Reyes, Joaquín: “Impact of the Automation in the Energy Efficiency of Buildings”. CINTEC S.A. Presented in

Jornadas AADECA - Asociación Argentina de Control Automático (Argentinean Association of Automatic Control), 2002, Buenos Aires, Argentina.

Figure 9: New logotype of the Consorcio Company

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include the Consorcio-Santiago building due to the difficulty in obtaining monthly and annual

records from the different tenants, who had different agreements with the energy providing

companies. But this year was possible to get such data because the Consorcio company

were occupying most of the building. All costs previously considered were readjusted to the

year 2007 and were compared to typical floor of the Consorcio-Santiago building. The

results, although they have to be considered provisional, are much better than expected. The

Consorcio-Santiago has 48% less energy consumption than the average of the 10 originally

considered buildings. This reduction in energy consumption represents a monetary savings of

28% compared to the average of the other buildings (Figure 10). These percentages may be

a little exaggerated by circumstantial factors, such as location, height, relationship with

neighbouring buildings, interior occupancy density and others. Therefore, we compared a

floor of the Consorcio-Santiago building with “double green skin” versus another floor in the

same building without this protection. The previous results are confirmed, but attenuated. A

green protected floor consumes 35% less energy, with a cost reduction of 25% (Figure 11).

Average of 10 recent tall buildings in Santiago (air conditioned areas)versus

Consorcio Santiago Building (air conditioned areas with “double green skin”)

a) Energetic Consumption (2007) b) Economic Cost (2007)

Consortium - Santiago(Air conditioned surfaces with “double green skin”)

Average of 10 Buildings

(Air conditioned surfaces)

Consorcio - Santiago(Air conditioned surfaces with “double green skin”)

Average of 10 Buildings

(Air conditioned surfaces)

88,0 -

170,57

12,6

9.10-27,77%

Figure 10: Energetic Consumption 2007

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Figure 11:Consorcio Santiago Building. Floors with and without “double green skin”

As such, considering that the “double green skin” signifies a 20% savings in the annual

energy consumption – that is double of the initial thought – seems like a reasonable and

satisfactory estimate. Even more after an empirical research in architecture of 33 years of

“trial and error” work.

88,0

136,10

9,10

12,10 -24,79%-35,34%

a) Energetic Consumption (2007) b) Economic Cost (2007)

Floor without “double green skin”

Floor with “double green skin”

Floor without “double green skin”

Floor with “double green skin”

Winter Summer

Figure 12: Double green skin

Figure 11: Energetic Consumption 2007

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POSTSCRIPT

For reasons of clarity the previous evaluation of the Santiago-Consorcio Building focused on

its environmental quality and energetic behaviour. But other aspects could have been

mentioned. To be concise, only one more. With many years of functioning it was noticed that

the large Hall in the ground floor did not appropriately fulfil its representative role. The main

executives of the companies arrived by car to the underground parking, taking directly from

there the elevators to their offices. The same occurred with important guests for whom there

was reserved parking. As such, nearly none of them came through or saw the Hall. With this

noted, in 2001 it was decided to do new halls in the two underground parking levels, providing

better entries from those levels.

This operation also took advantage of solving the problem of those who went to the 2nd

underground level to smoke, something not allowed in the offices. Thus, they smoked in

between the cars, with danger and environmental dirtiness. In the new hall of this level, air

extractors where installed, vendor machines, money withdrawal points and other

commodities. Quickly the place converted in the regular but quick meeting point for the office

employees. Unfortunately, these services had to be cancelled, due to a company that has

parking on this level objected passing through there to use the elevators. This issues offers

lessons for future halls in office buildings.

Graphic 13: Hall First Underground Park Level. Graphic 14: Hall Second Underground Park Level

(2001) (2001)