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This tool was developed in 2021 within the scope of the research project GENESIS PTDC/GESURB/29444/2017 financed by national funds through FCT - Foundation for Science and Technology. It determines the benefits and costs of applying a green roof or a green wall on your building compared to a conventional roof/wall cladding.

GREEN ROOFS

Extensive

Extensive green roofs are lighter solutions with low substrate thickness and  light vegetation as grasses and succulents.

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Technology

Extensive green roofs are multilayer solutions designed to cover partially or totally building roofs.  This system includes light vegetation (e.g. succulents, herbaceous), 8 to 15 cm of substrate, filter layer, drainage layer, root barrier, and waterproofing membrane. Extensive systems are only accessible for maintenance purposes. Although, they may have slight slopes. For more information regarding its application please check the ANCV or FLL technical guidelines for green roofs.

Notes

With an approximate weight of 80 to 180 kg/m2, this system may require a building structure reinforcement. The system requires little maintenance and supports short periods of drought. The installation of native vegetation from the climatic region where it will be installed should be privileged. However, depending on the selected vegetation, an automatic irrigation system may be required.

Main Benefits

Extensive green roofs can be combined with photovoltaic panels, allowing to improve their efficiency. allow to extend the roof in-service life, and depending on their characteristics, they can also contribute to improve buildings thermal comfort and reducing noise transmission.

Costs

Most costs are related to the installation process of the extensive green roof system (approximately 50 - 70 €/m2).  The installation cost is influenced by the type of substrate and vegetation chosen. And, depending on its location, its cost can be increased when using mechanical means of transport to the roof (e.g. crane).

Semi-intensive

Semi-intensive green roofs are intermediate solutions with a higher thickness than extensive green roofs  allowing to include  small and medium vegetation as grasses, succulents and shrubs.

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Technology

Semi-intensive green roofs are multilayer solutions designed to cover partially or totally building roofs.  This system includes medium-sized vegetation allowing the integration of herbaceous, subshrubs and shrubs. It contains 15 to 25 cm of substrate, filter layer, drainage layer, root barrier and waterproofing membrane. For more information regarding its application please check the ANCV or FLL technical guidelines for green roofs.

Notes

This system allows the application of a wider variety of plants than extensive green roofs. Therefore, it needs moderate maintenance. With an approximate weight of 150 to 350 kg/m2, it requires a building structure reinforcement and may allow pedestrian access. The installation of native vegetation from the climatic region where it will be installed should be preferred. However, depending on the selected vegetation, an automatic irrigation system may be required.

Main Benefits

Semi-intensive green roofs allow to extend the roof in-service life. Depending on their characteristics, they can also contribute to improve buildings thermal comfort and reduce noise transmission. Furthermore, they have the ability to retain more rainwater than extensive systems due to substrate thickness.

Costs

Most costs are related to the installation process (approximately 60 - 90 €/m2).  The installation cost is influenced by the type of substrate and vegetation chosen. And, depending on its location, its cost can be increased when using mechanical means of transport to the roof (e.g. crane).

Intensive

Intensive green roofs are  heavier solutions with higher substrate thickness than other green roofs  allowing to include  small, medium and high vegetation as grasses, succulents, shrubs and small trees.

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Technology

Intensive green roofs are multilayer solutions designed to cover partially or totally building roofs.  This system includes medium-sized and large vegetation allowing the installation of perennial, herbaceous, shrub and small trees. It contains more than 25 cm of substrate, filter layer, drainage layer, root barrier and waterproofing membrane. For more information regarding its application please check the ANCV or FLL technical guidelines for green roofs.

Notes

This system is usually designed for recreational purposes and allows the application of a wider variety of plants, similarly to plantations in natural soil. Although it needs frequent maintenance. It   may have also high demands on the substrate thickness, protection and drainage characteristics. It requires a building structure reinforcement and may allow pedestrian access. The installation of native vegetation from the climatic region where it will be installed should be preferred. However, depending on the selected vegetation, an automatic irrigation system may be required.

Main Benefits

Intensive green roofs have a deeper substrate which maximizes certain benefits compared to other green roof solutions. Therefore, they have an increased thermal and acoustic insulation potential and rainwater retention capacity. By allowing the installation of a wider variety of plants they also enhance biodiversity.

Most costs are related to the installation (over 100 €/m2) and maintenance processes.  The installation cost is influenced by the type of substrate and vegetation chosen. Its cost is higher when using mechanical means of transport to the roof (e.g. crane). The irrigation needs and plant maintenance are significantly higher than in other green roof solutions.

Costs

GREEN WALLS

Green Facades

Green facades are simpler solutions based on the application of climbing plants with or without a support structure.

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Technology

Green facades are formed by climbing plants that support themselves through their aerial roots, leaf tendrils and adhesion pads. This system can grow directly against the wall (direct system) or have a wire, mesh or trellis to support the vegetation weight (indirect system). Also, plants can be ground-based, when they grow in naturally grown soil, or have trays filled with substrate that are attached to the façade and climbing plants are placed to grow along certain areas of the wall. For more information regarding its application please check the ANCV or EFB websites.

Notes

Green façades have a limited plant selection and have an uneven growth. Direct systems are more economic as they do not include a support structure although the vegetation holds directly on the wall and may damage it.

Main Benefits

Green facades when fully grown help shading the walls reducing the heat gains in summer.  Also, depending on the vegetation thickness they can work as a noise barrier.

Costs

Direct systems are more economic to install than indirect systems, as they do not include a support structure. Their maintenance cost is low compared to other solutions, requiring occasional vegetation guiding. However, it depends on the vegetation types used and the local access conditions. Also, when the vegetation is ground-based, irrigation is often not installed.

Living Walls

Living  walls are modular or continuous solutions that allow covering the entire surface of the wall with a wider variety of plants that green facades.

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Description

Living walls are designed to cover partially or totally building walls with vegetation. These solutions have a support structure fixed to the wall. Continuous systems have a rigid support panel, a root resistant geotextile fabric and a permeable felt (hydroponic system) with individual pockets filled with inert growth medium for the vegetation. Modular systems include modules filled with growth medium, fixed to the support structure, where the plants are inserted. Irrigation is created in rows spaced in height. Drainage is carried out along the surface, avoiding the roots to soak. At the wall base a gutter is inserted for retaining and draining excess water.

Notes

Living walls allow for a greater diversity of vegetation than green facades. In addition, allow immediate coverage and uniform vegetation growth. Continuous living walls are usually lighter (with less than 30Kg/m2) than modular systems, allowing their application in new and existing buildings.

Main Benefits

Living walls maximize some benefits compared to green facades, enhancing the promotion of biodiversity and attributing greater aesthetic value to the property. Continuous systems contribute to improving the walls' acoustic properties. While, modular systems help to improve the thermal and acoustic characteristics of the walls.

Costs

Living walls are more expensive to install than green facades as they include more materials. Also, they are more costly to maintain,  requiring frequent pruning, plant replacement and irrigation (especially hydroponic systems).