Green is the new grey, or at least it should be…

Published on
July 5, 2022
June 30, 2022

During some of our recent conversations with clients and other network partners, such as engineering groups, developers and design-build contractors, questions have been raised about what technologies could drive + accelerate “green design” with impact, at scale.

What in the PTC's view, could be one of the next 'big things'?

Earlier this month France mandated green (yes, indeed with plants!) roofs on commercial buildings, albeit with caveats, this law will be implemented July 1st 2023. Many cities, primarily in Europe and some in the US, already mandated green/solar roofs (or hybrid solution) in some shape or form. Some European insurance companies offer clients to reduce (insurance) premiums contingent upon installing a green roof, thereby mitigating and reducing the risk of hail damage + better insulated houses (flipside = high repair costs involved!). The challenge that we see in market with Climate/ESG tech is tying the value proposition into a tangible ROI. Yet, here’s a substantial one.

The grey roof(top) on new developments, is often “overseen” as a sizeable opportunity: a bare concrete/singly ply roof with water tanks, buried under the building (in CBD’s, with tight lot lines) and pipes. It surely does its job, but it’s not very appealing, is it? Grey rooftops have one single function: To keep the elements of nature outside.

They convey water, rush excessive storm water into pipes and push it downstream. This traditional grey system has no other function than getting rid of excessive water as quickly as possible, no aesthetic value, nor environmental benefits. It actually does more harm than good. And data shows that storm events are increasing (across globe) and seem to be increasing in the foreseeable future. As an example, multiple studies in 2018 and 2019 showed that summer storms in the United States are increasing in frequency AND that hurricanes and storms are getting wetter. A Nasa study from late 2018 supports the assumption that the global warming is pumping up the number of extreme storms over the tropical oceans around the equator (30 degrees North and South).

In such instances usable water (on the roof) is being treated as a waste product and at the same time the amount of water pushed downstream is stressing our sewers and harming our rivers and bays (on increasing levels), especially if you look from a city-wide scale perspective. But, isn’t it time to go a different route? Doing more of the same might solve the water problem on a short term, but it has no added value. There’s some very interesting technologies in market that have spent considerable amount of capital + human resources in scientific research. Europe is leading the way, by incentivizing such efforts from multiple angles…

Why are we wasting all of the storm water on a rainy day (on the roof), just to open the valves a few days (sunny day) later to irrigate a dry landscape? Why are our air-conditioners running overtime, while green infrastructure could (help) cool the city? Plants have the ability to absorb heat and cool the air by evaporating the water they caught.

The credo should be: “It’s time to turn grey into green”. At scale this is powerful and we are seeing some really promising tech in our network.

No alt text provided for this image

So many shades of green, the first inning.

You probably have seen some examples of amazing green parks on roofs of large buildings. In case you haven’t: it might be worth to google “The Meadow on the old Chicago main post office” or “Salesforce Park” in San Francisco. Parks like these are absolutely stunning and may even be an ideal image for the future, but you don’t have to go all out to help and find a tangible ROI. If you have tight lot lines, expensive $/Sq.Ft, low allowable outflow (dictated by county) then there are +EV “green” solutions to explore. Including secondary benefits for owner + tenants.

Not the entire roof has to be green. Besides the size, there are also different types of systems with pro’s and con’s. You have “traditional” green roofs that hardly bring value (from an ROI/ownership perspective), blue-roofs, blue-green and (Dutch) polder-system roofs. Different systems and manufacturers, but we expect only a few to become the "winners" in the market over time.

Why isn’t every rooftop green yet?

Just like most innovations, building a well-functioning green rooftop requires education, knowledge and commitment. The engineers have to sign off, the budget needs to stay in place, the roof is always installed last obviously, so the green will easily be value engineered if needed…Unless, it’s part of the storm water calculations and embedded into the permit (and potentially freeing up space underground for an additional parking spot or apartment). There have been examples of such projects in the US and Europe.

But most importantly, owners need to be convinced of the list of benefits of a green roof (and it’s storm water capabilities).

So, Cheers! To a green future with rooftop barbecues, peaceful reading getaways by a rooftop river and your new favorite Instagram-able picture spot.

Should you wish to learn more about the opportunities “on the roof”, we have a number of technologies in our network + extensive knowledge in this niche industry. Please do reach out and we’d happy to partner with you. and

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