PHNOM PENH (Khmer Times) – Rising seven stories above the Chroy Changva Peninsula, the Yellow Tower is distinctive for two reasons; its capsular curved-glass elevator shaft and its “vertical garden,” the lush coat of climbing plants that covers its facade.
The unusual building, completed three years ago, was designed by a pool of five architects and houses office space and a penthouse residential suite. For Phnom Penh’s burgeoning skyline, where ‘green’ buildings usually refers to construction sites covered in green protective mesh, the tower stands as a rare example of a “living wall.”
And in the capital’s tropical climate, it makes a lot of sense.
By adding a vertical garden, “the building becomes more energy efficient, which leads to a decrease in carbon emissions,” explains Kim Gjemmestad, one of the tower’s owners. “[It] also mitigates the urban heat island effect, absorbs and filters storm water, reduces pollution and acts as a carbon sink.”
He estimates that the living wall reduces air conditioning costs by 30 to 50 percent, while attracting birds, bees, geckos and dragonflies – increasing the city’s biodiversity.
Creating a vertical garden is both cheap and straightforward, said Mr. Gjemmestad. “Simply install inexpensive fishing net and stretch it out with some help of steel wires pulled vertically from the ground to top floor,” he explains. “Then plant aggressive climbing plants on the ground floor, and they’ll climb up and create a massive wall that can reach 50 meters height. You’ll start to see results after a couple of months.”
Following a visit to the Yellow Tower, Russian architect Yara Podolitskaya said she was impressed with the building’s design and energy-saving properties.
“The green wall acts as a protective barrier, shielding the building from direct sunlight,” she said. “Electricity in Cambodia is very expensive and the use of air conditioning is not an effective solution. [This building’s] space is bright, windy and stays cool even on the hottest day.”
Camille Teyssier, an IT consultant at Borama Consulting, works with her colleagues in an open-space office with a terrace on the fifth floor of the Yellow Tower. She sees many intangible benefits in the tower’s design, and reckons there should be more green walls in the city.
“Being in an eco-friendly building, surrounded by nature, has positive effects both on our performance and state of mind,” she said.
Just as a green wall insulates the side of a building from the city’s oppressive heat, a green roof can shield it from above. Green roofs are constructed by planting vegetation on a specially-prepared rooftop surface comprising an impermeable layer, drainage mats and an irrigation system.
Jasmine Terrace Hotel, in Boeung Keng Kang 1 commune, was a pioneer of this ecofriendly design concept. The boutique hotel’s green roof, carpeted in flowering plants, goes largely unnoticed by guests. But it was never intended as a traditional garden.
“Our green roof keeps the rooms cool and in this way we save power on air-conditioning,” said Ms. Ung Penny, the hotel’s operation manager. “Moreover, it has the function of deadening sounds, so when it rains, for example, it’s not noisy.”
She said the “living roof” required a significant initial investment, costing more than the installation of the hotel’s swimming pool. It also requires maintenance – including regular weeding. But despite the costs, the energy savings make for a high return on investment.
Ung Nareth, the Cambodian owner and architect of the hotel, said since covering the roof with plants his electricity bill has dropped to $400 a month, less than half its previous amount.
Mr. Nareth said he learned about environmental building design and permaculture by reading up on examples and practices in Europe.
“Since here in Cambodia I couldn’t find all the necessary materials to make a green roof, I recycled Styrofoam boxes to create a simple but effective drainage system,” he said. “We also had to choose the right kind of soil, which couldn’t be too heavy, and to change the structure of the roof in order to support the weight.”
The hotel’s first attempt at creating a green roof ended unceremoniously, Ms. Penny admits. Initially, they tried planting jasmine, like the hotel’s name, but the heat proved too much for the fragile shrub, which withered under the blazing sun. So they switched to portulaca, whose Khmer name “pka mong dob” means “the 10 o’clock flower” as these succulent plants blossom at that time day.
The vines that climb 25 meters up the walls of the Yellow Tower wrap around the building’s porthole windows, which overlook the Mekong River. (Photo: Kim Gjemmestad)
The flowering “living roof” of the Jasmine Terrace Hotel, a pioneering green roof initiative. (Photo: Courtesy Jasmine Terrace Hotel)