Jerusalem is joining the world's cities in promoting 'green roofs': rooftop gardens designed to lower energy costs, purify the air and provide homes for plants and animals.
Up until a few months ago, the roof of the main building at the Jacob Sapirstein Junior High and High School for Boys in Ramot, Jerusalem, was a typical Israeli roof, covered with sheets of insulation and a tangle of pipes. Now it is covered with a variegated garden that is not only more pleasing aesthetically but will also reduce noise, flooding and energy costs.
Last year there was a significant increase in "green roof" projects throughout Israel, a result of growing awareness of the importance of urban replanning, particularly in regard to buildings. The Jerusalem municipality has put together a plan to create green roofs in the city, starting with school buildings. Israel Electric Corporation is planning green roofs for power facilities, and a sewage treatment plant with a green roof in the capital's Har Homa neighborhood is in the planning stage.
In cities such as London, Chicago and Singapore green roofs are being installed on top of office buildings, train stations and private homes. In London, one of the City's major large law firms recently created a green roof on top of each of its three high-rise office buildings.
A U.S. study published last month warned of an increase in so-called extreme heat events in large cities, partly due to a lack of vegetation. The study's authors said that green roofs can help to diminish these periods of high temperatures.
Three green roof projects were part of this year's Houses from Within in Jerusalem, during which buildings and other sites of special interest are open to the public over a weekend. The event took place on October 8-9. Joining the Ramot school were the roof of an underground parking garage in the Har Hotzvim industrial park, designed by Kolker, Kolker, Epstein Architects and that of the Society for the Protection of Nature's Jerusalem Bird Observatory and Research Center, located near the Knesset.
Green roofs consist of vegetation planted in a growing medium on top of layers of waterproofing and insulation. Some, such as the SPNI observatory, are called "living roofs" because the plants are irrigated by rainwater only.
According to Eyal Ronen of Hasin Dvorachek Ronen Architects, a member of the team that is behind the school's green roof, the most important part of the green-roof construction process is keeping water and roots from getting into the building below by using the right protective materials.
Ronen, who also teaches a course on green roofs at Bezalel Academy of Art and Design in Jerusalem, notes some of the environmental benefits of a roof such as the one at the school: They reduce energy use inside the building by providing insulation from both heat and cold. The vegetation filters pollutants, improving air quality. By absorbing and delaying rain runoff significantly, the roofs diminish the force of flood waters in urban areas.They also help to reduce noise pollution and contribute to the preservation of plants and animals. "In this small garden at the school we are already seeing birds and insects. It's a sign the local animal community has adopted the place," Ronen says.
According to Yoni Hollander, principal of the Sapirstein school, municipal officials proposed the green-roof idea to the school. "We were enthusiastic but what was especially important to us was finding a way to involve our students in the planning."
School administrators contacted Ronen and Roni Lev, Ronen's co-teacher at Bezalel and coordinator of the art school's environment and sustainability program. Ronen and Lev, together with the high-school students, formulated various ideas for developing the roof and passed them on to architect Arie Kotz, who represented the municipality. The team cooperated with a roofing company, and about six months ago the first green roof in a Jerusalem school was completed and dedicated.
The school's roof garden is modest in size, and compromises were made with regard to artificial irrigation and the use of chemical fertilizers, but it is already providing insulation for the building. In addition, the project has increased the students' environmental awareness.
"We have an environmental ideology and this was a way to implement it," says Yehuda Neuman, principal of the middle school.Park green
The green roof near the entrance to Har Hotzvim, on top of an underground parking garage, and the adjacent park, are nearly the only green areas in the industrial zone. The parking lot belongs to a 20-story building that is still under construction.
The entire building was originally planned to conform with Israeli standards for "green construction," but in the end the developers abandoned the idea.
"The main purpose of this roof is efficient use of the land rather than meeting goals such as conserving energy," explains architect Amir Kolker, whose firm designed the project. "I don't really like the term 'green construction.' It's as though you've done something special and as far as I am concerned it should be taken for granted," Kolker says.
The roof of an adjacent building is partially covered in vegetation. Kolker says he hopes it will attract cafes and restaurants catering to people who work in the area.Eyeing the Knesset
The roof of the bird observatory has a more unequivocally ecological orientation. "Open areas in cities are disappearing; green roofs can provide a comfortable habitat for various kinds of flora and fauna," says Amir Balaban of the SPNI.
Soil from the Jerusalem area was placed on the roof of the research center and planted with bulb plants that can store large amounts of water, such as asphodels, squills and Hyacinth squills. "We have managed to achieve nine months of flowering without irrigation," says Balaban proudly. "There are already insects such as ladybugs and spiders as well as several species of reptile, including one snake species. We're looking for more roofs that can be transformed into living roofs, including that of the Knesset."
Israel Electric Corp. began taking an interest in green roofs after realizing the potential for saving energy and for noise reduction. IEC is mapping buildings that might be suitable for a green makeover, with a pilot program slated to begin shortly at a company facility in Tel Aviv.