Green roofs and Green walls Introduction

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Planning of Green Roofs and Green Walls Andras Bela Olah PhD [email protected] m

Transcript of Green roofs and Green walls Introduction

Page 1: Green roofs and Green walls Introduction

Planning of Green Roofs and Green Walls

Andras Bela Olah [email protected]

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Lecture 1: Introduction

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Definition of green roof

Vegetation covered roof, where is a growing medium under the vegetation and the plants and the growing medium and the building composes one structural unit.

There can exist roofs, which are covered by vegetation without growing medium (for example a roof covered by climbing plants).

There can exist roofs, which are covered by vegetation, the plants are in growing medium, but they do not compose one stuctural unit (container gardens).

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Roof covered by climbing plants

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Container rooftop garden

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Historical facts about green roofs

The very first green roof was the Hanging Gardens of Babilon. There were many of them, and not only in Babilon. There were among them fake green roofs (without architectural spaces under them), but from technological and sociological point of view those were also emblematic (terraces of zikkurats, first aquaduct ever under the reign of Sin-ahhe-eriba etc.).

Besides such emblematic historical examples like the Hanging Gardens of Babilon and the sod roofs of Scandinavia the real green roofing started only in the 1960ties, when the usage of waterproofing membranes became common and widely used.

This green roofing movement started in Germany (West-Germany) and even nowadays the german green roofing industry is considered to be the best worldwide.

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Different types of green roofs

There used to be mentioned two groups: extensive and intensive green roofs. The main difference between them is the maintenance and the thickness of the growing medium. The extensive green roofs are not permanently irrigated and have thin growing medium (15 cm or less thickness). The intensive ones used to have thick „soil”, they are permanenly irrigated and occasionally fertilized.

Sometimes a third category is also mentioned: comprehensive green roofs.These have the advantages of the two other types, i. e. weight and maintenance of the extensive roofs and the quality of the intesive ones.

There is an other classification: pitched and flat green roofs.

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Extensive green roofs

The extensive green roofs are not permanently irrigated and have thin growing medium (15 cm or less thickness).

The main feature of them is the low maintenance: no permanent irrigation, checking the roof only once or twice per a year, for cutting the weeds.

The growing medium layer is very thin. This is very advantageous on the one hand, because the building structure does not have to bear extra strain. Thus, extensive green roofs can be widely applicated onto existing buildings.

Because of the thin „soil” layer, the material of it and the plants must be special. The plant types also determined by the local climate.

The main plant species used to be Sedum and mosses.

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Extensive green roofs

Sod roofs are vernacular in the scandinavian region. Because of its simplicity, low maintenance and the special local climate (high relative air humidity and high rate of precipitation in every season) these can be considered as an extensive green roof.

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Extensive green roofs

Extensive green roofs in Chicago (City Hall) and Stuttgart (green roof landscape). The rate of precipitation and the relative air humidity are significantly greater than in Budapest. These are so called Sedum-moss roofs. Among drier circumstances the Sedum becomes dominant.

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Extensive green roofs

Extensive green roofs in Budapest. The so called „Buffalo House” in the Budapest Zoo and the rooftop of the Antenna Hungaria office building (pics by Dr. László Gerzson). These are basically Sedum roofs due to the arid climate.

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Intensive green roofs

The intensive green roofs are permanently irrigated and have thick growing medium (at least 15 cm, but rather more thicker 40-50 cm, or in case of planting greater trees 80-100 cm is common). Permanent fertilisation is also common.

This type has more disadvantage, but its few advantages are unequivocal.

There can not be simply establish an intensive green roof on an existing building due to structural requirements.

The whole building structure must be stonger, which highly increases the price of the whole building process. The mainenance cost is also much higher.

Despite, this is a viable way to establish a new green area, which effects are similar to ordinary parks and gardens. These roofs can be used as real gardens.

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Intensive green roofs

The very first intensive green roof. The Hanging Gardens of Babylon. Established in ancient Mesopotamia. Waterproofing (natural bitumen and lead layers) and irrigating (canal system, Archimedes’ screws with more than 400 years before Archimedes ) was necessary.

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Intensive green roofs

An intensive green roof with the maintenance of an extensive one. Irrigation is determined by the local climate. In Singapore and in all rainforest zones the permanent irrigation is unnecessary.

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Intensive green roofs

Intensive green roof on the top and on the side of the Vancouver Public Library. The maintenance level is also low in temperate rainforest zone.

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Intensive green roofs in Hungary

Westend City Center in Budapest. Intensive green roof over a shopping mall and a railway station (pics by Dr. László Gerzson)

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Intensive green roofs in Hungary

Westend City Center in Budapest. Intensive green roof over a shopping mall and a railway station.

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Intensive green roofs in Hungary

Westend City Center in Budapest. Intensive green roof over a shopping mall and a railway station.

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Intensive green roofs in Hungary

Westend City Center in Budapest. Intensive green roof over a shopping mall and a railway station.

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Different types of green walls

There exist real green walls, where the wall itself contains also the growing medium and simply vegetation covered walls, mostly covered by climbing plants. A more simple solution is a special allee close to the facade of the given building.

The real green walls can be further separated into two subgroups: indoor green walls and outdoor green walls. Both of them is considered to be intensive, because they need continuous irrigating. That is why they can not be considered sustainable, excepting the case of the usage of greywater by residental buildings.

The outdoor green walls has an other problem due to the necessity of continuous irrigating: they can not be considered frost proof.

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Different types of green walls

Spalier, a not so widely known method for creating a green wall. Usually made from pear or apple trees.

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Different types of green walls

Deciduous climbing plant (boston ivy/Parthenocissus) covered buildings.

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Different types of green walls

Evergreen climbing plant (creeper ivy/Hedera) covered buildings.

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Different types of green walls

Outdoor green wall/vertical garden in Madrid (CaixaForum Madrid). Invented by Patrick Blanc.

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Different types of green walls

Indoor green wall/vertical garden in Budapest (Avis Green House office building, pic by Green Fortune).

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Thank you for your attention!