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Why are green lawns a necessity?

A rapid and unrestrained development of urban agglomerations changes the way of living of their inhabitants. On the one side, we create high and marvelous buildings made of concrete and glass, together with communication arteries, comfortable and fast means of transportation. On the other hand, the areas under the construction of new parks, squares and lawns are continually restricted. Therefore, so much people want, from time to time, to leave the city facilities and rest within nature.

For many years, city-planners, architects and designers of green areas have been searching for solutions, which would make living in cities more friendly for the man. One of them assumes the introduction of plants to the formerly dead areas, such as walls and building roofs. The advantages, which are brought by green roofs in our cities have been known very long:

:: they ease the city climate which, to a large degree, differs from the climate of the surrounding areas. The building roofs, walls and other surfaces act as heat accumulators. As a result, the so-called “islands of heat” phenomenon is created, which entails a rise in air temperature in the centres of agglomerations in average for 1 – 2 °C (in extreme cases, even up to 10°C) and the lowering of its humidity. At the same time, the plants, through steaming away the amassed water and reflecting the sun rays, create a certain type of “airbag” on the surface of the roof, which has higher humidity and lower temperature (a roof covered with bituminous roofing paper heats up to 80 – 100°C in the summer, whereas a green roof only to 25 - 40°C). A two-centimetre layer of green plants is able to collect nearly 50 – 60% of rainfall, which is subsequently steamed away, thanks to which they increase air humidity and relieve city drainage systems. Moreover, plants enrich city air with valuable oxygen and decrease the amount of CO2. A roof of the size 15 m2 produces in the period of one year an amount of oxygen sufficient for 10 people. At the same time, it can collect 10 – 20% of dust and gases from the air,

:: they alleviate street noise by partial reflection and absorption of about 20 – 30 dB,.

:: they act as an additional insulation to the roof, both thermal and protecting the surface of the roof against external defects (breaking by wind, defects caused by birds, changes in the effect of sunray action etc.),

:: they enable to recover the biologically active surface lost in construction. This allows to fully use small parcels in city centres without colliding with the local plans of spacious arrangement,

:: moreover, the use of plants on roofs and building elevations is one of the elements of architectonic shaping of the space. This allows for hiding installation devices located on the roof, creating uniform compositions through joining plants on various levels: plants in flats, on terraces and in the surrounding of the building, creating characteristic plant elements which would distinguish the buildings.

One of the biggest designers of the XX century, Le Corbusier, who named the roof “the 5th elevation”, wrote about them in such manner: “… The roof – garden will be the favourite place in the home, and, apart from this, will be the city’s recovery of all area lost in construction? He claimed, that gardens on roofs will draw the man close to nature, and, therefore, he put their construction on a top place in his programme of new architecture. Today, when we need more and more houses, factories, offices, shops, streets, and parking spaces, the message of Le Corbusier takes on a new, special meaning. Using new space, where green areas may be created, becomes a necessity.

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