ADVANTAGES OF GREEN ROOFS
WHY ARE GREEN ROOFS ESSENTIAL?
For many years planners, architects and landscape designers around the world have been seeking solutions which would allow them to make life in cities more friendly to humans. One of such solutions is introducing green plants on to the walls and roofs of buildings which have been dead so far. Benefits resulting from the application of green roof systems have been known for a long time.
Most of all green roofs significantly soothe the urban climate which varies from the climate of the surrounding areas to a large extent. Roof surfaces and building walls act as heat accumulators. This way a phenomenon called “islands of heat” is created which causes an increase in air temperature in centres of urban agglomerations by 1-2°C on average (in extreme cases up to 10°C) and a decrease in moisture.
By evaporation of accumulated water and reflection of solar radiation plants placed on roof surfaces create a form of air cushion with a higher moisture content and a lower temperature (a roof covered with bituminous roofing felt in summer heats up to 60-70°C, while a green roof heats up to only 25-40°C). A 2cm layer of greenery can retain approx. 50-60% of rainwater which then evaporates, and therefore it increases air moisture and takes the strain off urban sewage systems, enriching the air with oxygen and reducing CO2 content. A roof with a surface area of 15 m² produces oxygen for 10 people in a one year period. At the same time, it can absorb 10-20% of dust and gases in the air. Green roofs significantly reduce street noise (by approx. 20-30 dB) by reflection and partial absorption of sound.
Green roofs also act like an additional insulation of roofs – both thermal and physicalprotection of roofs from external damage (being damaged by wind, damaged by birds, changed due to solar radiation, etc.).
Such systems allow us to restore the biologically active surface area lost for buildings; this allows us to fully take advantage of small lots in city centres without colliding with local spatial management plans.
GREEN ROOF – PRACTICAL, ENVIRONMENTALLY FRIENDLY AND EFFECTIVE SOLUTION
Using plants on roofs and building facades constitutes a significant element of the architectural shaping of space. It allows us to hide installation devices situated on roofs, to create uniform compositions by combining greenery on various levels: plants in apartments, on terraces, roofs and in the area of buildings as well as to create typical plant elements distinguishing particular buildings.
One of the greatest architects of the 20th century Le Conbusier who called a roof “the fifth facade”, wrote that “(…) A roof – garden will be the favourite place in a house; moreover, for cities it means restoration of areas lost for buildings”. He believed that roof gardens will bring humans closer to nature and therefore, he included their construction as a priority in his new architecture program. Today, when we need an increasing number of houses, plants, offices, shops, streets and parking places, the message of Le Corbusier gains a special expression. Using new places where green surfaces can be created becomes essential.