Green screen: these new offices in Chile incorporate parrones or planted pergolas as a simple means of environmental control.

Chile's extreme geography encompasses an enormous diversity of climates, from the arid deserts of the north to the cold, wet south. Most of the population lives in a Mediterranean central belt and the vernacular architecture of this region reflects the archetypal practice of mediating between interior and exterior domains, with buildings traditionally organised around cool patio courtyards and wide, covered verandas. Adding a further layer of lush visual and physical texture, plant-covered pergolas (parrones) are also used to diffuse light, temper the climate and create shade.

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As well as being ecologically appropriate and environmentally responsive, planted screens are an adaptable and economical means of reducing energy use in buildings. Santiago-based architect Enrique Browne has revived and reinterpreted the tradition of parrones in several projects, from his own atelier (AR January 2000) to larger-scale office buildings (AR February 1999).

Here, in the coastal city of Concepcion, Browne applies parrones principles to a mid-rise office block for an insurance company. The site occupies the corner of a somewhat higgledy-piggledy plaza dominated by a small, historic church. The new building rounds off the composition of the square, its entrance placed directly on axis with the church entrance; God and Mammon in momentary equilibrium.

Two contrasting elements make up a crisp, yin-yang composition. A long, thin box clad in ribbed steel and incised with long, thin window slits rises above a shorter, fatter glass-skinned block wrapped in an external layer of timber louvres. Both steel and timber are produced locally, so the architecture connects with a sense of place. The disparate sibling blocks are united by a great flat roof that hovers protectively out over the street, like a huge hat brim. Inside, open-plan office space is wrapped efficiently and economically around a core of circulation and services. The two lower floors contain public offices, with corporate spaces above. A double-height entrance hall with a striated stone floor adds an honorific touch.

Incorporated within the timber louvres are troughs for planting that will gradually become established on the north (sunny) side, screening and diffusing the sun's glare. The cascading greenery will form an eye-catching addition to the urban skyline, animating the facade of the building as the planting changes colour and intensity with the seasons.

Responding to challenging climatic and urban conditions, Browne's latest project, like his other buildings, shows that decent environmental conditions can be achieved in a modest, unrhetorical way. And, as the greenery takes hold, this is architecture that seems destined to improve with age. C.S.

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