In recent years, the term green roof has taken on a broad environmental and social meaning beyond its seemingly simplistic description. Green roof, living roof, vegetated roof, eco-roof – each synonym has become an epithet for reducing pollution and improving the urban environment, for alleviating stormwater runoff, and for maximizing the use of urban space. Green roof infrastructure, on the other hand, promises to become an increasingly important solution for building owners and city managers, providing a significant number of social, environmental, aesthetic, and economic benefits to the public and private sectors. This solution has been adopted in most Western European countries, USA Canada, Australia, China, Singapore, and many other countries, and more recently in Russia and former socialist countries, but on a limited scale.
WHAT IS A GREEN ROOF?
It stands to reason that the concept of a green roof as a way of adding ecological surface area and usable green space without taking up additional floor space is easy to understand and should be equally easy to implement. Consequently, many clients, municipalities, architects, landscape architects, and planners have begun to consider green roofs as an integral part of sustainable building practice.
A green roof can be defined as a flat or pitched (sloped) roof that supports vegetation on a roof or terrace, is designed to provide urban landscaping for buildings, people, or the environment, while acting as a stormwater management system. May also be defined as a roof garden with ornamental planting or fertile vegetation that is designed to grow naturally, using a substrate on an artificial structure, from at least one story. There is also another definition: a green roof is a vegetative roof system with a growing medium, supporting layers such as a root barrier, roof membrane, and drainage to restore green space loss. Green roofs are also referred to as eco-roofs, living roofs, or roof gardens.
However, they should not be confused with a traditional roof garden where planting is done in individual containers and pots located on an accessible roof terrace or deck. Green roofs have been proposed as an effective means to energy-saving policies in many countries with different climatic conditions. Their cooling and healing potential is highly dependent on the climate and building characteristics, and they are typically designed to improve energy savings in buildings and as sustainable infrastructure that provides a range of ecosystem services that counter many urban environmental problems. So green roofs are the cover for any built structure at any elevation, on any surface area such as a public building, parking lot, commercial or residential building, etc.-designed to support a layer of vegetation designed to mitigate stormwater, cool or maintain heat, or simply a usable, comfortable outdoor space that helps improve the urban environment.
TYPES OF GREEN ROOFS
Green roofs, vegetated roofs, or living roofs as they are known, can be classified according to the type of use, construction factors, and maintenance requirements, into three different types; extensive, semi-intensive, and intensive green roofs. The table below briefly presents the three types of green roofs
| Extensive green roof | Semi-intensive green roof | Intensive green roof | |
 |  |  |
| Поддръжка |  | | |
| Растителност | sedums (succulents), grasses, mosses, seasonal flowers | sedums (succulents), grasses, flowers, shrubs | sedums (succulents), grasses, flowers, shrubs, trees |
| Височина на системата | 15-25 cm. thin substrate layer | 25-50 cm. | 20-100 cm. deep soil layer |
| Тегло | 50-150 kg/m2 | <150 kg/m2 | 150 kg/m2 |
| Цена | $ | $$$ | $$$$ |
| Полза | ecological protective layer | landscape designed green roof | designed as a garden with aesthetic and ecological purpose |
| Достъпност | inaccessible or semi-accessible | Semi-accessible | Accessible |
| Напояване | little (at the beginning) or no irrigation | from time to time | regularly |
