When we first installed our green roof at Good Earth Plant Company fifteen years ago in 2007, all the information about the long-term impact came from Europe. There weren’t many green roofs in the United States, just a few in the northern United States and southern Canada. There were very few studies conducted on them, none in our Southern California region.

Times change, and we are much more enlightened about the positive impact of green roofs on the immediate environment and their contribution overall. We love green roofs and everything they stand for at Good Earth Plant Company. We have now built several green roofs in the decade since then, from private homes in Del Mar, Encinitas, and Santa Monica, to the “Fallen Star” art installation at UCSD, to the spectacular green roof at Sharp Memorial Hospital in Kearny Mesa.

When we learned about the third annual World Green Roof Day 2022 coming up on Monday, June 6, from our friends at Greenroofs.com, we wanted to get involved and do our part to support the movement to spread the gospel of green roofs.

What Is World Green Roof Day?

World Green Roof Day is the idea of green roof veterans and London residents Chris Bridgman and Dusty Gedge. Gedge are both board members of the UK-based Green Roof Organisation (did the spelling give it away?), which created the British green roof code of practice. Chris and Dusty work every year to help World Green Roof Day grow and educate people worldwide on the benefits of green roofs to our climate, cities, and wellbeing. Dusty is also an accomplished nature photographer focusing on birds, just like my father, Bob Mumford.

Why World Green Roof Day? “Towns and cities globally are going green to adapt to climate change. Green roofs also provide vital wildlife habitats and make life better for everyone.

“By celebrating green roofs, there is hope across the globe that we can all come together and enjoy green spaces and all they have to offer,” said Chris and Dusty on the WGRD website.

You don’t need to convince your Eco-Warrior friends here in San Diego.

Cooling benefits of a green roof

Yes, a green roof requires an upfront investment for the additional engineering to hold the weight load, the green roof itself, and the need to irrigate it for the first few years. But a green roof’s benefits are long-lasting both for its owner and especially for our planet. We’ve written about those benefits many times in previous blog posts like this one.

Green roofs are uniquely suited to fight one of the growing dangers of climate change: the urban heat island effect. We’re glad to see the increasing attention to the dangers of this problem in our cities. This week, the news organization Axios reported several cities taking aggressive action to mitigate this threat, but too many others ignore the problem.

In urban areas covered with many asphalt streets, concrete, and lots of dark rooftops, these materials absorb and retain heat. They can raise the temperature by 10 degrees. Often, the problem is made worse in neighborhoods with a lack of green spaces and trees, affecting lower-income communities. And to save money, the City of San Diego keeps chopping down trees!

Combine this with climate change, and it’s a serious threat. A heatwave last year in the Pacific Northwest caused 1,400 deaths. Scientific studies and even the U.S. Environmental Protection Agency (EPA) are urging cities to pursue sustainability and cooling measures. Los Angeles, Phoenix, and Miami are taking it seriously enough to name Chief Heat Officers.

These cities have proposed cooling and misting centers, sealants and reflecting coatings on streets and buildings, and planting trees. New York has a “cool roof” program to paint rooftops.

How about considering more green roofs?

Green roofs can cool our cities and our planet

New studies are looking at the civic benefits of green roofs to an entire region.

A recent study of green roofs in Chicago used satellite photos to assess their ability to reverse warming trends. It found green roofs with diverse plant species provide more significant cooling benefits, a hopeful sign.

A study from Reed College shows the capacity of Portland, Oregon, to reduce the overall daily temperature through green roofs for a cost between $50 and $115 million and improve Portland’s deteriorating stormwater system. Would this have saved those 1,400 lives last year?

San Diego Mayor Todd Gloria is among U.S. mayors who signed the Cities Race to Zero pledge to achieve net-zero greenhouse gas emissions by 2050 to hold off the worst effects of climate change. I was glad to see “adding greenery to roofs” on the city’s website as part of “Our Climate, Our Future” initiative. It’s a start!

A green roof with about four to six inches of growing media (referred to as an “extensive system”) may reduce a building’s cooling needs by 25 percent and prevent heat loss by 26 percent. This can be a substantial energy savings as every one degree Fahrenheit can reduce electricity use for air conditioning by eight percent through lowering temperatures, another climate change benefit.

Green roofs harness the cooling power of plants to lower temperatures. Investing in green infrastructure creates jobs and saves lives, improving our economy and our health. They’re part of the solution.

Raising the green roof at Good Earth Plant Company

We aren’t able to talk about the details just yet, but we are working with partners right now planning what would become our biggest green roof project EVER – 15 years after we planted our own humble green roof. Keep your eye on the blog for more news.

Along the way, I became certified as a Green Roof Professional (GRP), and we’re always up for a conversation about green roofs. Want to talk about it? Give us a call at Good Earth Plant Company, and let’s figure out what works for you. Or email me at jim@goodearthplants.com. There’s no bigger way to enrich your life with plants than looking up!