Foundation-Free Vertical Greening: The Green Tower in Fulda

Project facts: Foundation-Free vertical greening

A shortage of green space in city centers

Many city centers have little room left for new greenery: sidewalks are sealed, facades are already occupied, and there is simply no space for additional street trees. At the same time, demand is growing for greening that captures particulate matter, supports biodiversity, and enhances heavily sealed areas, precisely where conventional solutions reach their limits. One example of foundation-free vertical greening has stood in Fulda’s Bahnhofstraße since May 29, 2026: the ALPAKA Green Tower. The free-standing tower, about 20 ft tall, is fully covered in greenery using Mobilane’s MobiPanel system.

The challenge: greening without space for trees or facade systems

The request originally came from the city of Fulda itself. In the Bahnhofstraße, neither additional street trees nor wall-mounted greening systems were feasible, as the street space is continuously sealed and the adjoining facades are already occupied by storefronts. The city was looking for a solution that could simply be placed in the street space without a foundation, without connecting to a facade, and without any permanent structural intervention and that could just as easily be relocated if needed. With this requirement, the city approached ALPAKA Innovation, in nearby Petersberg-Böckels. For the planting itself, ALPAKA opted for a system already proven on the market rather than developing its own greening solution.

Foundation-free vertical greening as the solution

The ALPAKA Green Tower combines a free-standing steel and timber structure with Mobilane’s MobiPanel system as the planted surface. GEFÄSSERIE carried out the greening, while ALPAKA developed the tower itself.

• • • Free-standing and foundation-free: approx. 19.7 ft high, approx. 5.6 ft in diameter, approx. 6.6 ft base structure
    • Modular MobiPanel cassette system: around 215 sq ft of planting area on just approx. 21.5 sq ft of footprint (roughly 90% space saving compared with ground-level planting)
    • Integrated, automatic irrigation via a 306-gallon water tank (around four weeks of autonomy in average weather conditions)
    • Fully relocatable and reusable, with no residual trace left behind, suitable for permanent locations as well as temporary events
    • Total filled weight (including the 306-gallon tank): around 13,200 lbs

Demonstrated impact: findings from the Hochschule Fulda study

The Laboratory for Mechatronics at Hochschule Fulda, led by Lara Ostermeyer, conducted a study examining the Green Tower’s contribution to capturing particulate matter and its effect on air temperature, CO2, and O2 in its surroundings. The study was based partly on a model calculation for the Bahnhofstraße: for the adjoining street sections, totaling around 820 ft, 24 Green Towers were assumed at intervals of roughly 82 ft in two rows.

Particulate matter capture (PM10) by the Green Tower

With a planting area of 215 sq ft per tower and an estimated leaf area index of 4 m² per m² (total leaf area: about 861 sq ft), a single Green Tower can, according to the calculation, capture up to 22.6 oz of particulate matter (PM10: particulate matter with a diameter of less than 0.0004 in) before the leaves are “reset” by rainfall (20% washed off in light rain, 35% in moderate rain, 50% in heavy rain). As it rains in Fulda on average every 2.4 days, considerably more often than the calculated 6 to 13 days needed between rainfall events to reach that capacity, this uptake capacity is available almost continuously. Based on traffic data for the adjoining street sections (together around 25,000 vehicles and 894 buses on school days), the study calculated daily traffic-related PM10 emissions of around 20.5 oz (including tire and brake wear). With the assumed 24 Green Towers, this figure could, according to the model calculation, be largely offset. For total PM10 emissions in the street space, however, of which traffic accounts for around 10%, or roughly 12.8 lbs per day, 24 towers are not sufficient.

Effect on air temperature

For the immediate air temperature, the study calculated the effect analytically only within a radius of around 1.1 in around the 1.5 m-diameter tower, and confirmed this with flow simulations (OpenFOAM) for a street model with multiple towers: temperature differences there were in the range of a few hundredths of a degree. The strongest cooling effect occurred under conditions of high temperature, low humidity, and high wind speed.

CO2 uptake and oxygen production of the Green Tower

According to the calculation, a Green Tower absorbs around 64.4 lbs of CO2 per year and produces approximately 11.8 lbs of O2. Compared with average annual per-capita CO2 emissions in Germany (about 17,600 lbs) and a person’s annual O2 consumption (about 616 lbs), each of these represents only a small share. Source for all figures in this section: Lara Ostermeyer, “Einfluss des ALPAKA Green Towers auf die Umgebung, insbesondere auf Temperatur und Feinstaubbelastung” (“The influence of the ALPAKA Green Tower on its surroundings, particularly on temperature and particulate matter pollution”), Laboratory for Mechatronics, Hochschule Fulda, 2026. [Link to the study in German here]

Foundation-free vertical greening: the Green Tower in figures

1. Up to 90% less space required

On around 21.5 sq ft of footprint, the Green Tower accommodates approximately 215 sq ft of MobiPanel planting: a space saving that is difficult to achieve by any other means in a densely built city center such as Fulda’s.

2. A calculated contribution to particulate matter capture

According to the model calculation by Hochschule Fulda, a single Green Tower can capture up to 22.6 oz of PM10; a network of 24 towers could largely offset the Bahnhofstraße’s daily traffic-related PM10 emissions of around 20.5 oz.

3. Installed entirely without a foundation or facade connection

The tower stands free in the street space, requires no structural anchoring, and can be relocated without leaving any trace: ideal for city centers and temporary events.

4. Low maintenance thanks to automatic irrigation

An integrated 306-gallon water tank automatically supplies the MobiPanel planting for around four weeks in average weather conditions before it needs refilling.

5. New habitat in the heart of the city

The continuously planted surface creates additional habitat for insects and visibly enhances a heavily sealed public space.

Summary at a glance

• • • • Mobilane’s MobiPanel as the planted surface of the ALPAKA Green Tower in Fulda
      • Around 215 sq ft of greenery on just 21.5 sq ft of footprint (approx. 90% space saving)
      • Up to 22.6 oz of PM10 capture per tower, according to the model calculation by Hochschule Fulda
      • No foundation, no facade connection (free-standing and fully relocatable without residual trace)
      • Automatic irrigation via a 306-gallon tank, around four weeks of autonomy

Project partner for foundation-free vertical greening: GEFÄSSERIE and ALPAKA

GEFÄSSERIE – Die Wandbegrüner GmbH is a German company which draws on almost 40 years of experience in horticulture, around 10 of them specializing in facade and wall greening. Over this time, it has established itself as an expert in holistic greening concepts, from consultation and planning through to installation and maintenance. GEFÄSSERIE delivers facade greening for office buildings, hotels, and public institutions, tailoring each solution to the architecture and location. It also designs interiors with plant walls and room dividers to improve indoor climate and wellbeing. As a long-standing Mobilane partner, the company draws on a proven, site-appropriate plant range. GEFÄSSERIE additionally offers a comprehensive maintenance service for outdoor and indoor greening throughout Germany, with certified facade-greening consultants on its team. This makes the company a reliable partner for demanding greening projects, as demonstrated once again in the installation of ALPAKA’s Green Tower.

Technical documentation

Planners and architects can find the BIM model, AutoCAD drawing, and factsheet for the MobiPanel system on Mobilane’s download page.

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