07/23/2010 16:06

Vertical gardens, a new craze sweeping landscape architecture firms in Europe, have finally arrived in Israel.

Picture a city of the future, in which the outside of buildings are enveloped in green, wrapped in a living, breathing garden. Inside office buildings, special wall hangings bursting with live flowers and ferns will act as a natural air-conditioners, at the same time humidifying and purifying the air. Suddenly, workers complaining of dry eyes and headaches will be cured by the calming presence of greenery, as the plants cleanse toxins from the air.

“The goal is to insert a little bit of nature into the concrete city,” says Richard Rozenbaum, owner of Rozenbaum Advanced Gardening Systems in Jerusalem. “In areas where there wouldn’t be enough room for gardening because of the crowding of the buildings, you can suddenly build a huge gardening area.”

When I walk into Rozenbaum’s “showroom,” a gardening shed with a two-meter-tall vertical garden, I leave the dry heat of summer behind and am immediately embraced by moist, pungent air that makes me feel like I’ve stepped into a jungle.

Vertical gardens, a new craze sweeping landscape architecture firms in Europe, have finally arrived in Israel. Green walls are a type of “isolated gardening,” also known as container gardening, which means that the garden isn’t connected to the ground. Rozenbaum builds two types of green walls, filled with begonias, small palms, ferns and other common house plants. The smaller, outdoor walls are built using perlite, a material made from volcanic rock that is incredibly light and porous. He builds the perlite vertical gardens just 10 cm. deep, which is more than enough room for the roots to open and flourish. The material also makes watering and fertilizing easier, because it doesn’t absorb the way regular dirt does.

“You could grow a tree in this stuff,” Rozenbaum explains. “Without this product, it would be impossible to create vertical gardens.”

INDOOR VERTICAL gardens, which Rozenbaum envisions will become a fixture in office lobbies, use technical, nondisintegrating fabric that resembles tarpaulin, stretched over a PVC board. The roots love the fabric, opening up in an area that is only two cm. thick. “We had to move this wall a few weeks ago for a gardening convention in Tel Aviv,” says Rozenbaum. “It’s been growing for six months, and when I moved it I couldn’t believe my eyes. You should have seen the amount of roots, it was tremendous!” “Roots don’t need earth,” Rozenbaum insists when I tell him the way he gardens goes against everything I’ve ever learned about growing plants. “NASA has done a lot of experiments with this, and they found they could even grow plants on Mars. I swear, you don’t need earth!” Rozenbaum’s passion for the ability of these vertical gardens to solve climate problems in the cities is contagious. He paints pictures of whole cities lowering the temperature through green walls, office lobbies transformed into jungles. In fact, he was so excited to show off his green wall that he accidentally scheduled the interview for the same time as his daughter’s bat mitzva.

After pushing it up a few hours, Rozenbaum could barely contain his pride and passion for this new type of gardening, which he touts as “the solution of natural air conditioning.” Cities suffer from a climate phenomenon known as “urban heat island,” which means that the temperature in the city is much higher than the surrounding area. Many factors contribute to this: idling cars, belching factories, a higher concentration of air conditioners and more areas covered in black asphalt, which absorbs heat during the day and releases it at night.

Next time you enter a city, see if you can notice the change. According to the US Environmental Protection Agency, a city with more than a million people averages between one and three degrees Celsius warmer than its surroundings. This difference is even more noticeable in the evening, when cities can be as much as 12º warmer due to the heat released by all of the asphalt.

Green roofs or green walls on the outside of buildings are an effective but expensive tool in the fight against urban heat islands. They can lower the temperature of the air inside the building by 2º.

They can also make the buildings last longer, by absorbing acid rain and direct UV rays that lead to cracking and carbonization of the exterior. Indoors, studies of Rozenbaum’s wall found that it can lower the temperature of a room by as much as 10º, according to research done at Tel Aviv University.

“This wall sweats; it’s always donating humidity to its environment,” explains Rozenbaum. “In France, the government has started to push the whole subject of green walls inside buildings, because there have been reports that the quality of the air inside of office buildings is worse than the air outside. These plants have the ability to cleanse toxins out of the air. And we can build walls that are maybe less aesthetic but have plants that are known to absorb toxins. Having a green wall actually helps with health problems, because people who complain about headaches, or dry or red eyes, will be able to feel a difference in the quality of the air.”

But it’s not just air-conditioning and purification: Green walls are an effective tool to combat the greenhouse effect, because plants consume a large amount of carbon dioxide. Generally, 10 square meters of a green wall consumes the same amount of CO2 per year as a four-metertall tree. Depending on which plants are chosen, green walls can also consume nitrous oxide and sulfur dioxide, two common air pollutants.

If it sounds like these green walls are the be-all and end-all for global warming, the prohibitive cost will bring you back to reality, and keep them from catching on too quickly. Rozenbaum’s standard minimum price for two square meters is NIS 6,000 per square meter (before tax). As the size of the vertical garden increases, the cost per square meter decreases. For example, a wall that is 10 square meters will cost about NIS 2,000 for each square meter.

And though vertical gardens are simple in theory, they are expensive and complicated to build. They must be watered 24 hours a day, seven days a week, by a drip irrigation system. Because of the complexity of the watering system monitor, Rozenbaum needs to visit between once a week and once every few months to check the water and the system, at NIS 500 per visit.

Larger systems require a special computer that monitors the makeup of the water to ensure that it isn’t too salty or has other impurities. The computer also has a dampness sensor that can adapt the amount of water coursing through the irrigation system to correspond with the exact amount the garden needs, depending on heat, direct sunlight or air temperature.

This system will send Rozenbaum an SMS if anything goes wrong.

“We’re very excited about saving water, because you can really control the water on a vertical garden,” says Rozenbaum.

“We were able to insert a [water measuring] system that is incredibly precise. The hope is that there’s no wasted water.”

Because the water is recycled, the water efficiency of a vertical garden is much higher than a normal garden. An average vertical garden requires half a liter to one liter per day for each square meter. In the summer, a regular garden requires roughly five liters for one square meter.

In an office building, Rozenbaum points out, you can collect the condensed water from air-conditioning units and use that to water the plants. Of course, with a successful green wall, you’ll be using the air-conditioning less, anyway.

“Plants and green spaces fight against the high heat inside the city, but then there’s also the aesthetic reasons,” says Rozenbaum. “You take a simple wall, and you can garden it. When you see a 15-meter-high wall filled with blooming flowers, it’s just simply… you’re left with an open mouth. There are a lot of new gardening ideas that are arriving in Israel, but this is the solution that is most suitable for the Israeli climate.”