A proposal was posted to the German-speaking Lemmy community “dach” suggesting large trellises be built spanning over streets, with wild grape and other climbing vines trained across them to create shade and evaporative cooling as a way to beat the heat. The idea is that it takes up less space and works faster than planting trees. While commenters pointed to examples like moss-based shade sails and the vine-covered benches already in use in the city of Goslar, concerns piled up too — climbable walls are easier targets for burglars, wooden trellises raise fire risks, and vines can damage building facades.
My take: why not use large trellis structures for urban heat protection?
Whenever urban greening comes up as a climate response, people always say “there’s not enough space” or “trees take too long to grow.” So why not build big trellises spanning right over the roads and train wild grape (a type of wild vine) across them? Wild grape transpires water about as actively as a tree does, so it should give similar cooling, forms a dense leaf canopy that blocks sunlight, and is said to be hardy and easy to grow. Of course the plants need watering, but it doesn’t have to be tap water.
This works too, but shade sails strung over the street would be nice as well.
[Image: Shade sails strung over a street in Seville, Spain, 1918]
https://solar.lowtechmagazine.com/2025/06/dressing-and-undressing-the-home/](https://feddit.org/pictrs/image/6303af1e-98f8-454a-bff6-cc490f27b69b.png
8Anonymous2026-09-02 04:47
Re: #2 I recently read about a company that developed special shade sails that grow moss on them. They need watering, but apparently they cool way better than regular shade sails.
26Anonymous2026-09-02 00:02
Re: #2 If the shade sail itself heats up, doesn't that just trap the warmed air underneath it? Is that actually a smart design?
4Anonymous2026-09-02 04:35
Re: #26 Wait… are you saying it's hotter under a parasol than in direct sunlight, so shade is pointless? The whole point of making shade is to stop it from getting that hot in the first place.
18Anonymous2026-09-02 18:18
Re: #4 Unlike the setup in the top image of this post, a parasol doesn't have walls on either side trapping the air and keeping it from escaping sideways.
7Anonymous2026-09-01 20:20
Re: #3 Worth adding: in cities, a "climbable" house is also a house that's easier for burglars to break into. It's a real shame that this even has to be a concern.
20Anonymous2026-09-02 05:10
Re: #7 Then just take precautions for that. But honestly, it's kind of pathetic that we live in a world where that's a real concern at all.
10Anonymous2026-09-02 00:00
Re: #11 "Just install it and keep it properly maintained," sure! But don't moss walls need some kind of irrigation system to get through hot summer days? (Genuinely asking, I don't actually know.)
11Anonymous2026-09-01 21:06
Small-scale versions already exist using moss and vines — Goslar, for instance. All that's left is to actually roll it out more widely.
14Anonymous2026-09-02 05:06
Re: #10 Yep, they do need one. That's why moss walls are the most labor-intensive option — you have to plan the irrigation system (usually fed by a rainwater tank) in from the start when the building goes up. Vines are much less hassle. There's a detailed breakdown in the link I posted in another comment.
22Anonymous2026-09-02 07:09
Re: #10 Yep, it does. Goslar's vine-covered benches have a built-in irrigation system too. What I like is that rainwater collected from the shade sails feeds straight into that irrigation system. Also, I'd guess vines hold up longer than moss. (Link: Goslar city's official blog)
12Anonymous2026-09-02 04:51
Honestly, I think this is a really good idea overall. There are still open questions — fire safety (what happens if it burns, since it's a wooden structure) and the effect on road visibility (would patchy shade throw drivers off?) — but it's definitely worth trying out at least once.
25Anonymous2026-09-02 05:08
Re: #12 Sure, it's usually wood, but it doesn't have to be. You could use other materials too.
13Anonymous2026-09-02 05:12
Re: #3 Apparently "your facade is gonna love this (sarcasm). Plants like wild grape cause serious damage to walls — they work their way into every gap and pry joints apart." Guess that makes you more of an expert than the actual professionals who do this for a living. (Link: Facebook video)
15Anonymous2026-09-02 05:17
Re: #17 There's always some risk of hitting pipes or cables — the ground's been a tangled mess of buried stuff forever anyway. But honestly, personally I think having a city with tolerable temperatures matters more than the occasional risk of hitting a pipe.
16Anonymous2026-09-02 06:37
Re: #6 That's exactly how I felt too. It turns into a cozy spot that makes you want to strike up a conversation with people.
21Anonymous2026-09-02 11:48
Re: #9 Even with regular inspection and maintenance, how can you say it would end up like that?
23Anonymous2026-09-02 18:20
Re: #14 👍 Haven't had the time to check the link yet. I'll take a look later. 🙂
24Anonymous2026-09-02 06:42
Re: #14 I see a lot of broken moss walls and moss planters around. Doesn't moss just not have that much durability to begin with?
Background and Key Points of This Discussion
Underlying this discussion is the growing interest in “facade greening” (Fassadenbegrünung) across German-speaking countries. Rather than relying on air conditioning to cope with summer heat, the idea of using plants for heat-blocking and evaporative cooling is being studied even at the municipal level, with cities like Goslar already installing benches and trellises using moss and vines. Where opinions split in the thread was over whether vines actually damage building facades — the original poster was met with pushback along the lines of “even the experts disagree on that one.” There’s also a point worth highlighting: the observation that climbable structures can be a security weak point shows how greening and crime prevention can end up in tension, a trade-off that’s easy to overlook. And while moss walls cool more effectively, they need dedicated irrigation systems that add cost, which is why lower-maintenance vines came out as the easier option to actually adopt.
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