Ten Innovations in North America’s

Prime Roofing & Exteriors


Innovation is key to remaining vibrant, relevant, and effective. As an industry, we have come a long way in a short period of time from the early German green roof experience. Innovation, which involves new ideas, devices, and methods, is nothing new to our industry.

Modular Green Roof Systems

A uniquely North American innovation, these systems are easy to install, often pre-vegetated in nurseries, and come in a wide range of styles with different performance characteristics. Most of them incorporate drainage systems, and are designed for maximum wind uplift resistance, locking into each other, into edging systems and even into the roofing membranes to stay put. In wind tunnel testing, modular green roofs have endured more than 110 mph without budging. Some are designed to biodegrade over time, while many are made of recycled high-density polyethylene. Many collect rainwater to make it available to the plants later, while some provide space for drip irrigation pipes.

Green Wall Systems Innovations

A tremendous amount of innovation has occurred since Patrick Blanc created his first living wall systems using hundreds of plants in wave-like patterns, anchored into a hydroponic felt based system, more than 15 years ago. Modularity has emerged in green/living wall systems, with opportunities to grow plants in a wide range of containers that hold growing medium, and are fixed to a frame attached to the wall. The early living walls were felt-based systems that fed nutrients to the plants through irrigation water.

The roots would grow through the felt, securing the plants, but also making plant replacement difficult. Now, there are many different technologies of the modular kind to choose from, which are much easier to manage from a maintenance perspective. There are also movable indoor living walls that recycle water and nutrients while purifying and humidifying the air, and providing aesthetic benefits. For those who can’t stand the thought of maintenance, there are a wide variety of non-living, moss based interior green wall systems on the market as well. Progress is also being made in keeping exterior green walls alive in northern climates, with the use of sensors that activate sophisticated irrigation systems. I expect we’ll see a lot more innovation from green wall suppliers in the future.

Blue-Green Roof Systems

These systems respond to the need for greater clarity of stormwater retention and detention benefits, particularly among the engineering community. Some of these systems incorporate horizontal aquifers that wick water back up into the plants for evapotranspiration. Others are designed to hold water above the waterproofing on flat roofs until it is released electronically or mechanically over dams placed around drains. In some cases, water sits within a grid structure with the green roof layers on top. In other cases, it simply sits on the waterproofing, below the green roof assembly which is installed over risers to create a gap.

The Purple Roof Concept is a new innovation that involves using a honeycomb structure above a thin layer of fibers that create friction that significantly and predictably delays the flow of excess water off the roof, even slope roofs. There are also mineral wool products that are used to capture and hold additional water beneath a green roof assembly. There are now many more options to increase stormwater retention and detention, beyond the capacity of the plants and growing media, than there were on the market just a decade ago.

Understanding Plant Performance

Green roofs, particularly extensive green roofs, are tough environments for plants to remain alive and healthy, particularly in arid climates. More than 20 years of research on a wide variety of plant species has significantly increased our knowledge of what type of conditions are most suitable for specific species and when irrigation is required and when it is not.

There is also a renewed interest in not only the survivability of plants, but also the biodiversity/habitat benefits of using native species on green roofs and walls.

Enhancing biodiversity requires specialized knowledge about the needs of the species for which one is trying to create habitat. Progress has been made, but more research in this field is needed especially about the use of native plants on rooftops. The knowledge about plant survival rests largely with researchers, manufacturers, green roof professionals and nurseries.

Food Producing Roofs

Ten years ago, there were just a few rooftop farms, and now there are dozens. Urban rooftop agriculture is by no means easy, but many of the design principles for these types of roofs are well established now, and successful business models have been implemented. These often involve supplementing food production with revenue from events, training, and tours, to name a few.

Detailed knowledge about growing media depth and composition, crop rotation, transportation, markets and more have been established, and some manufacturers, like Rooflite, have created products to support rooftop farms. Concerns over food security and food quality promise to drive forward the growth of rooftop farming, as well as the development of more vertical farms that are controlled-environment agriculture inside buildings.

As a society, we still have not come to terms with the very real threat that climate change and biodiversity loss poses to our food supply. Maybe a few shocks to the system are needed before real policy innovation takes place. “We know not the value of water, till the well runs dry,” said Benjamin Franklin.

Solar-Green Roofs

Although slow to take off in North America, there are numerous synergies between green roofs and solar photovoltaic (PV) panels. For example, green roof drainage layers and growing media are able to provide ballast, without roof penetrations, for solar panels to protect them against wind uplift, which can be the source of leaks. Green roofs are also able to cool ambient air temperatures and which increases the efficiency of the PV panel and increases solar energy production. A green roof will extend the life expectancy of waterproofing significantly so the solar panels don’t have to be removed in five or ten years to re-roof.

Solar panels can provide shade, which can facilitate plant growth underneath them. They can also capture and direct rainwater on a roof (see article from Sweden in this issue). Rooftop agrivoltaic research is also underway in Denver at Colorado State University. The research is exploring the potential benefits of food production on green roofs partially shaded by solar panels – an intriguing concept that could generate healthier crops using less water.

There are a variety of technologies that exist to successfully integrate solar production and green roofs. More work in needed across North America to establish an even playing field on incentives and policies to recognize the importance of integration rather than to promote competition for valuable roof space.

The Living Architecture Performance Tool (LAPT)

The LAPT was developed over five years with input from hundreds of academic and industry professionals. It was introduced to the market in 2018. The LAPT is a 110-point performance rating system that includes a comprehensive overview of all the performance benefits attainable from green roofs and walls across eight major categories, such as water, biodiversity and maintenance. It can be applied to a green roof, a green wall or a combination of both. Based on the same framework in USGBC’s LEED and ASLA’s Sustainable Sites, the LAPT provides a tool for designers wishing to get the most benefits for their projects.

The LAPT is a useful third-party review mechanism, to determine if a project is certified, silver, gold or platinum. Third party reviews are conducted by the Green Infrastructure Foundation, do not require excessive documentation, and are a fraction of the cost of other certification systems. To date, a handful of projects have been certified by this quality assurance framework, but the potential and need for more certification is huge. Click here to obtain a free copy of the LAPT.

Waterproofing and Quality Assurance Innovations

There have been new products adapted for green roofs, namely PUMA systems, (polyurethane methacrylate), which can be fluid applied at much cooler temperatures. Technical innovation was required to adapt PUMA systems to rooftops and moist climates. In terms of quality assurance, there have been advancements in the application of Electronic Leak Detection systems (see Brook’s article in this issue).

Social Equity

Research has shown us that poorer neighborhoods often coincide with a lack of useable green space, higher rates of asthma, and greater risk from heat waves and the urban heat island effect. Green roof and green infrastructure development has the potential to improve the quality of life for people living in these communities, in terms of employment, improved air quality, and a reduction in flooding and the urban heat island. With green infrastructure investment, public policy supports for various forms of home ownership, rent controls, and community self-determination are necessary. Otherwise, history has shown, that with quality-of-life improvements in a neighborhood, also comes the risk of gentrification.

Policies, Programs and Economics

Ten years ago, the words ‘green infrastructure’ was a term few people would understand. Now, the term green infrastructure, also known as natural infrastructure, is widely used in policy circles and recognized as a key strategy for managing storm water and climate change. Policy makers are beginning to acknowledge the need to monetize the eco-system benefits of green infrastructure, and to incorporate human health benefits too. The Green Infrastructure Charrette program by the Green Infrastructure Foundation combines innovative community scale design work, with an aggregate cost benefit analysis, in order to help make the case for these types of investments. Several charrettes have been completed and the reports are now available.

The growth of biophilic research, biophilic design and the WELL standard have helped put human health on the agenda because of the role of green infrastructure inside and around buildings. It turns out that if you can use biophilic design to help your employees feel better at work, this often translates into huge cost savings for companies that rely on people’s skills.

We now have green roof specific requirements for new buildings in cities ranging from New York and Toronto, to San Francisco and Portland, Oregon. In Toronto, the 2009 green roof bylaw has resulted in more than 4 million square feet of green roofs implemented across the city. Policy makers are waking up to the fact that green roofs offer solutions to multiple challenges in their communities. What is needed now, is for us to scale up the effort significantly if we are to obtain the full benefits from green roof and wall technology. Paul Hawken and his team at Drawdown have developed a global plan to reduce greenhouse gas emissions. Green roofs are one of 100 priority areas and the modeling calls for 9 to 11 percent growth per year by 2050. If green roofs grow from at 9–11 percent annually, 45–69 billion square meters of efficient roofing would be in place globally by 2050.

In order to accomplish this level of growth, we need the private sector to stand up and make green roofs the norm, rather than the exception. We also need billions of dollars in federal and state/provincial government infrastructure funding to install and maintain green roofs on existing buildings. To this day, there is still no technology that even comes close to delivering the wide range of public and private benefits that a green roof can. Let’s go after some of those infrastructure dollars!

These are a few of the many new developments in our industry, and no doubt, there will be many more to come. Green roofs and walls are hopeful in their nature. They demonstrate that we are capable of better, that we can innovate and change, and make investments in a healthier, more resilient future for our children, their children, and many creatures with whom we share the earth.


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