Dialogue with Stakeholders

Interview with Roland Weber: Cool high-rises in hot Summers with Passivhaus and Green Facades (08/2018)

Rhein-Main TV (Edmund Stössel):
Good evening dear viewers! Nice that you are back in a new episode of “on a word”, despite these summery temperatures. This is exactly what our current topic is about! Most people feel discomforted by this hot weather. If you are not already equipped with plenty of fans or an air-conditioner at home, you also think about: How can I cool my flat down, what would be necessary? How do I have to build residential in the future? Therefore, I am very pleased to welcome someone who had a vision regarding this topic. Not only at affordable costs, but also in the framework of Passiv House constructions: it’s Roland Weber, CEO, and founder of Green Towers. Good evening Mr. Weber! Green Towers, that’s easy to guess, is about green towers, green in the sense of planted towers. We will go into that in a moment. First of all, I would like to convey your vision compactly to our viewers. How did the idea arise to work and develop high-rises in combination with greenery?

Roland Weber (Founder of Green-Towers): Yes, the green story has frankly said very long roots. It all started in an NGO in the Frankfurt Westend 40 years ago, where we made an effort to give roadside trees more water. A lot of citizens thought about how can we make Frankfurt more livable and greener? It was an important topic.

Of course, later life brought me in entirely different areas: More recently in Russia, I built up the technical side of Europe’s biggest high-rise contractor and found out that there is a significant room for improvement in the industry. These high-rises consume energy lavishly, especially, when they are constructed in beautiful glass facdes, which we like aesthetically.

We soon understood that the Passive House technology in Darmstadt is a unique opportunity in high-rises to save approx. 80-90% of energy and 50% of the Carbon footprint. If we have a closer look at the future, we can predict that over three billion people flow into the cities within three decades. That means that cities will grow by half of the current population of our planet. Consequently, skyscrapers will become a bigger topic.
In this respect, ´Passive House´ is first and foremost a technical matter; it’s about the correct construction, the right shadowing and also well-thought building services.

Regarding economic efficiency, there is a payback, an ROI. Passive House in high-rises is as efficient as in single-family houses. Nothing new in principle. As I said, long roots. They also went back to more than ten years ago regarding the need for passive design: I came across it when we planned a city in Libya. Full of enthusiasm I founded the Green Casting Group in Dubai, cooling by plants and through shading with local deset plants was part of the story. Well, as it is with such technology companies, sometimes life goes in another direction. My opportunity to build up Europe’s largest high-rise contractor provided me with a sense of what is overall cost-efficient and what works in high-rise design and construction.

The green facades are a rather old topic, rooting in my early years. Using green facades well can offer a lot more potential than what we see in our contemporary systems in the market. Especially in high-rise construction, we have virtually no ecomomic large scale options. There is the pioneer Stefan Böri with his trees on the balcony. Also, there is another pioneer, Patrick Blank, who refined the concept of planted, green walls. However, both are relatively expensive.

If we have a look at this heat now, these hot ´tropical nights´ in Frankfurt, in Berlin, where it is 7 degrees warmer at night than in the surrounding; suburban areas, where it does not cool down, and people can’t fall asleep anymore – all this is nothing lofty or abstract. Green facades can cool down cities by two or three degrees. In summer this can change a lot. It can be even more when we think about narrow-standing high-rises or enclosed courtyards. At the same time, this has not only a rational, measuralbe side but also an important psychological influence – as we can see in the next pictures.

Rhein-Main TV: Exactly! To make it more tangible and real, you brought some additional images with you. The first one shows Frankfurt’s skyline. On the left-hand side, we can see a Green Tower or rather two Green Towers. Also, the greenery of the Commerzbank tower is revealing, too.

Weber: Sure. We should not forget to say that we weren’t the only ones with such thoughts. However, it’s easy to see: This was our competition entry for Frankfurt’s old police headquarters. We were participating as project developers with our twin towers. As a technology company, we become active project developers. Thus, we can control and determine future steps and avoid dilution. You can see that the iconic architecture fits well into the skyline. Our vertical garden, a vertical forest even – located on the north side and planted with ivy, speaks directly to the city. This we’ll see better and more precise on the following pictures. The topic of a vertical garden, a vertical forest shows an entirely different language of high-rise facades and architecture in contrast to the traditional glass and steel structure, located on the left and the right.

Rhein-Main TV: Because it was too far away, we can have a more detailed look on this now and see how a garden or in this case a balcony is going to look like from your point of view. On this graph of yours – of course also for you dear viewers – it is clearer. It perhaps seems like there are only simple balcony boxes – however, in the background next to these people is planted in the same height. Would one have to imagine it like this: The whole house is continuously from top to bottom then provided with green?

Weber: Exactly! It’s not about to plant some primroses. Important are aesthetical reasons, as well as technical aspects to cool down parts of the city.

We are mainly working with climbing plants which are innovative in high-rises. Of course, what does innovation mean? The old Romans already had climbing plants, surely ivy on their mansions. Yet, in our opinion, this is the ideal solution for high-rises: climbers are robust, easy to handle, don’t cost too much and in contrast to the other established systems on the market they have a low-maintenance.

This is our backbone. As seen in the pictures, the vertical garden speaks in two ways: to the city, and also to the tenants.

It’s not only about measuring something – like the two degrees – it’s also about the psychological part. This is quite strong. Just a simple example: When I am sitting in a street café, and there is some greenery surrounding me, traffic and other noises around me seem quieter to me. That is mostly a psychological effect. You feel less disturbed. Also, there are among noise many other factors, playing in. Including dust filtration, pollution, emissions and also stormwater retention. Yet, let´s not get too technical. The most important things are lifestyle and wellbeing: that is the main thing for us.

Rhein-Main TV: What effects greenery and plants have on not only a lifestyle but also emissions, will be topic in a moment. Here we show a picture of an ivy façade.

Weber: Yes, this ivy façade here really is a very plain, simple and scrubby one. In this street in the Frankfurt Westend we already have a hanging façade for years. It worked perfectly well during hot summers and cold winters. And It shows nicely that its roots cope well above ground. Thereby let´s assume without expensive gardeners taking much care about it.

Rhein-Main TV: So, this is also a barrier, which has this psychological effect, right?

Weber: Yes. I mean, at that moment we had midday heat, at the peak of our recent heat wave. Normally, one wouldn´t like to stay on the balcony or near the window for long. However, with its shade, it already made it all more livable.

Rhein-Main TV: I often used this terminology now: Passiv House. For all of you, who aren’t so deeply into it: What is unique about it and for instance when it comes to cooling capacity: What did you improve there regarding high-rises?

Weber: Fortunately, we did not have to reinvent the bicycle. We can benefit what the Passivhaus Institute has created.

Our vision is about the necessity to do it. I recognised this for myself far before that: I mentioned my passive architecture in Lybia and Dubai from over a decade ago. However, Passiv Houe brought it to perfection. It’s about efficient construction, about isolation, it also is much about the cladding. The beauty about Passiv House is: everyone is talking about making the world green – now I am speaking as an engineer – but in the end, you always ask yourself: What is the real impact, the added-value at which cost? The good thing about Passiv House – It makes this 100% transparent.

Rhein-Main TV: What does this exactly mean? Transparency regarding figures and how to save energy in the end?

Weber: We exactly know every figure and information, in contrast to the best global standards, on how we can save 80%-90% of energy. Additionally, we have a Return on Investment. Also, they are perfect in their scientific research: Without it, I could have never explained my vision. It is an own scientific world – I guess there are about 50-60 engineers and PhD- physicists who are constantly refining their formulaes.

Rhein-Main TV: Cooling is a central topic, which interested a lot of people at the moment. Passive House standard stands for a well-balanced temperature, independently of the season. With vertical greenery, the cooling effect is even more significant.

Weber: Yes, first of all: Passive House makes every action easily measurable: when I have a certain amount of energy consumption, a certain amount of CO2 will be produced. This chain is transparent. We also work parallel to Passive House: The green façade is not necessary for the Passiv House technology. Passiv House is, first and foremost a technical storyline. When there is a heat wave, you close the windows; they are well-isolated and well-shadowed: It is just a very technical side of things, which is working very well and doesn’t need a lot of cooling. This works not only in winter but also in the summertime. We believe that green facade something that cities should do more. Singapore is a thought leader, for instance when it comes to building regulations: They have financial incentives for project developers. When planning with green facades, they get benefits. This is undoubtedly a factor that makes things easier. A good example on how to responsibly and effectively incentivise the finance industry.

Rhein-Main TV: That´s correct, but we are still far away from these legislative proposals. In addition to this, there is another psychological effect. I can imagine, if you are presenting these things on a conference, some people might say: Well, a garden in 200m height: How should we do this, who should take care of it? That must be a lot of effort! How does this concept work?

Weber: That is precisely the key question when things get serious. At the first glimpse, everybody loves green, but when reallity kicks in: How does it work? There are plenty of good experiences. We got a lot of valuable inspiration from the whole research in Berlin and its green networks.

Also, our architects, based in Chicago had a big influence. Chicago is well-experienced with extreme climate. They have many stormy roof gardens on their high-rises: They are located in wind tunnel gorges, which is the worst condition for plants.

Picture: Courtesy by Ted Wolf, Chicago

In Berlin they researched very thoroughly green facades – also other cities do a lot (I mentioned Singapore). Our experience is strongly influenced by the American system, which scientifically categorises plants. Frankfurt has a climate, which is relatively mild. We then choose plants, which are stronger than basic theoretical requirements, just to be safe.

Concerning maintenance: there will be drip irrigation, which doesn’t carry significant costs. Climbing plants require low maintenance. They perhaps need to be taken care of annually. A bit more when you want the facade to bloom, and the whole tower to change colour: This can happen in fall and in spring.

Rhein-Main TV: There is no problem to change a towers colour?

Weber: No. On the south side, we do have Forsythia, which by exception is no climbing plant, but everyone knows them from our front gardens in February and March: When everything is dull and grey, these plants make the whole tower boldly yellow:

Picture: Todd Halamka Architects, Chicago

That’s how we see our tower. The yellow Forsythia only needs pruning once a year. Blue in summer will be Wisteria, also on the south side. This we will have to prune twice a year.

The other ones –wild wine and ivy- are easy to handle. The green facades, we have in Westend – like my parents planted them on their houses after the war too – all grew largely being left alone. Understandably, sometimes a neighbour asked to keep it away from their house, which of course we then did. Either allow it or keep it off. However, apart from this, it all worked by itself where it was planned.

Besides, here we see the fall colors of the wild wine:

So again: What cools our city down effectively? What works?

Street-trees do work easily and, in our view, climbing plants on high rises will do this job equally well. They have extremely low maintenance and only need little watering. A bit of effort is necessary, but it is not a significant expense.

Rhein-Main TV: So how is it, when we stick to the costs, it is a concept, what you’ve been trying to make that is affordable for everyone. How is that combinable? When we have a closer look at the picture from before: Wonderfully laid out, the tower is twisting a bit with some plants too, which individually don’t make a big difference. But something like this in Frankfurt’s city centre: How should this be affordable?

Weber: Overall affordability, in general, is not an easy topic: there are many things, coming into play. First of all, a twisting architecture, an iconic architecture, even with us is a bit more expensive, then a cheap box. Yet through my Russian experience with all these big sites, we developed methods, which also makes iconic architecture ´affordable´, without the usual high extra cost for iconic buildings.

And as said: building green doesn’t require too many additional costs, for example, ABG or other housing companies, like us, speak about 3-4% more investment cost for Passiv Haus. We quickly get these costs back by saving energy over a couple of years. Our green facades, in addition, require relatively little effort. I mean, when I own a front yard I also do not let it run wild or expect absolutely zero maintenance. One of us cares more, the other one cares less, but some basic gardening once or twice a year is mot much. And as said, watering is working automatically.

Rhein-Main TV: So, despite Passiv House elements: shadowing, isolation and orientation regarding the whole building complex, as well as surrounding greenery, which needs a bit of care and maintenance – it still provides an appropriate price? Would you summarise it that way?

Weber: Yes. Physics doesn’t change immediately when you are in 100 meters in height. Admittedly, it is a little bit different. However, Passiv house has shown – that is the beauty of it – we can use this quality label and knowledge, which we are very thankful of. By the way, as we know Passiv House well doesn’t lead to rising costs with Single- or Double-family houses, which can’t be compensated over a couple of years – it also doesn’t differentiate concerning high-rises. Green-Towers just developed one construction solution to implement it.

As a technology firm this is the kind of innovation, I was talking about. Also, on the garden side, which uses mass production and a high standardisation, costs are very well controlled. Like with your front yard which is not completely cost-free – you have to make up your mind about whether you want one or not.

Rhein-Main TV: To bring it to a close: Are there various projects, which are running globally or are in progress? When it comes to Frankfurt and seeing this wonderful skyline: What is your vision for this city, for which you have been active for a long time and also participated in certain projects? How green can or should Frankfurt be and what do you have to contribute to this development?

Frankfurt is the ´capital of Passiv House´ and is also sometimes nick named a ´jungle´. I think the acceptance for projects like this is high and even curiosity and ambition in society is there. In my opinion, we should demand vertical gardens and green high-rises much more often. We do offer something that surely will be copied; and I say: Why not? There are also other experimental approaches like ´the Eden´ in the Europa-Quarter. Others think about it, too. More of it! No, symbol politics, which lands in some stories or academic reviews, but rather ask how can we move the city at large as well as positively affect tenants.

Rhein-Main TV, Frankfurt Main, August 2018