"Extensive pre-planting systems for storm management with planted roofs are the mainstream of roof greening in North America today, and biodiversity is increasingly the focus of planting roofs." Recently, Dr. Liao Jiaxin, a North American planting roofing expert and global consultant of Freudenberg Planting Roofing, was a guest of China Flower News, sharing the development trend of planting roofing in North America, analyzing the current roof greening technology in the region, and bringing a set of greening system solutions that have been verified for more than 40 years, covering thousands of roof greening projects around the world, without fear of heat and cold.
2500 square meters of roof greening at broadway technology center in Vancouver, Canada
From the service upstream, we can enjoy the transformation of the service city ecology
In the past 50 years, north American roof greening has transitioned from "design for enjoyment" to the pursuit of "green, ecological roof", and its demand has transitioned from an improved type to a rigid demand type, which is inseparable from policy support and technological changes.
According to Liao Jiaxin, from 1950 to 2000, the three-dimensional greening in North America was mainly concentrated in landscape roofs and roof gardens, and its design concepts and design ideas were creative expressions of architects and landscape architects, they were real gardens, focusing on repairing neat soft and hard landscape elements, planting trees, shrubs, flowers, focusing on improving the beauty and comfort of roof space, mainly used in hotels, office buildings, underground parking lots and other places, intended to improve rental returns. Roof greening such as Rockefeller Center in New York, Kaiser Center in Oakland, California, and Sheraton Central Hotel in Toronto, Canada were typical representatives at that time, laying a good foundation for promoting the development of roof greening in North America.
Rockefeller Center, New York
Kaiser Center, Oakland, California, USA
Sheraton Toronto Hotel, Canada
Vancouver Public Library
Since 2000, green roofs and ecological roofs have become the main direction of roof greening development in North America, and they advocate bringing nature back to the city, and began to plant informal extensive landscapes dominated by hardy plants on the roofs of municipal office buildings, business buildings, industrial areas, and multi-family houses to enhance environmental benefits.
This is largely based on addressing the environmental, economic, and social challenges facing North American cities, and with policies and incentives, this low-cost, low-maintenance, and many benefits for central cities has become mainstream. Dearborne Motor Company in Michigan, Toronto City Hall, etc. are typical representatives of the earliest large-scale extensive roof greening, and the green roof completed by Chicago City Hall in 2003 has planted 3,000 kinds of plants, saving $5,000 in electricity bills per year.
Chicago City Hall
Dearborne Motor Company, Michigan, USA
Toronto City Hall
Rainwater management is the biggest mission of roof greening
In North America, research on roof greening also focuses on its benefits, accounting for 80%, R&D technology, policies and incentives account for 5% each, and planning, design and maintenance account for 10%. Studies have shown that planting roofing can slow down the peak of water flow and strengthen rainwater management, which is an effective choice for sponge cities, while thin and light simple planting roofs can be as effective as heavy garden-type planting roofs.
Heavy rains are a major challenge for Urban Areas in North America, with flash floods destroying buildings and infrastructure, leading to waterway erosion, urban runoff bringing pollutants into rivers and oceans, and integrated sewage overflows (CSOs) that severely impact the environment, and slowing down torrential water flows has become an important support for their promotion of roofing.
Liao Jiaxin's recommended Xifulai ® rainstorm-proof planting roofing system, with a thickness of only 82 cm, a saturated load of 66.5 kg per square meter, and a water storage capacity of up to 43.3 liters per square meter, which adds a blue-green roof of a blue water storage box, and by controlling the flow of the discharge layer, excess rainwater can remain on the roof for up to 48 hours.
Blue-green roofing
Liao Jiaxin stressed that both the American planting roofing standard ASTM and the German planting roofing standard NSI/SPRI & FM Global emphasize the test tests of windproof, fireproof and root resistance. From the perspective of planting roofing market research, from 2009 to 2018, the area of roof greening planting in North America increased by 5% to 15% every year. The Energy and Environmental Design Pioneer Awards (LEED) also include many of these indicators as rating scores, which are involved in the rating of green buildings.
Extensive preplantation system
Simple extended pre-planting systems are mainstream
According to Liao Jiaxin, simple extended planting roofing accounts for 59% of the North American roof greening market due to low load, low maintenance cost, and ecological environmental protection; garden planting roofing accounts for only 15% due to high growth requirements and high maintenance costs, 15% without clear definition, and 11% semi-intensive.
From the perspective of planting methods, the pre-planting system can immediately achieve green roofing, rapid installation, high survival rate, low maintenance, easy inspection and maintenance of roofing membranes, minimum wind erosion and other advantages accounted for 86%, while the on-site planting (modules, cuttings, sowing) system due to the initial low coverage, long construction period, long grow-out time, construction costs, high maintenance costs, accounted for only 14%.
The Xifulai pre-planting system recommended by Liao Jiaxin only needs ® to lay the root resistance layer, water filtration layer, water retention layer and planting layer layer by layer, and the construction is simple and fast. The lightweight and economical system is only 56 mm thick, with a saturated load of 55.5 kg per square meter and a water storage capacity of 32.5 liters per square meter. Most importantly, it can last for decades, even hundreds of years, with little maintenance after planting, and is widely used in different climates without fear of extreme heat and cold.
Biodiversity is of increasing concern
"North America is losing biodiversity, 33 percent since 1970, nearly 3 billion birds over the past 50 years, and 30 percent of plant pollination networks, most likely due to habitat loss and pollution." Liao Jiaxin said that it is precisely because of this that the current planting roof emphasizes the design of biodiversity.
Liao Jiaxin proposed a set of design ideas to increase biodiversity planting roofing. She believes that increasing the thickness of the substrate, changing the ratio of the substrate, and meeting the growth needs of as many different types of plants as possible; providing diverse terrain, creating shady areas in the all-sun roof, increasing the diversity of habitats; incorporating rocks, logs, and branches into the design to attract birds and insects to inhabit; providing nesting opportunities, water sources, etc. are all effective ways to increase biodiversity.
The LavalLeenre School in Canada and the Maisonneuve Golf Park in Montreal, Canada, use this design idea to create a beautiful landscape with different levels of the Hefroe ® Biodiversity Pre-planting System with a thickness of 185 mm, a saturated load of 190 kg per square meter, and a water storage capacity of 68 liters per square meter, which attracts many small animals to settle down.
Summer landscape of Letendre School in Laval, Canada
Autumn view of Letendre School in Laval, Canada
Spring view of the Maisonneuve Golf Park in Montreal, Canada
Autumn view of the Maisonneuve Golf Park in Montreal, Canada
Source: China Flower News