Post-realization phase of an interior green wall: a case study

. One of the popular modern ways to bring greenery back into interiors are interior green walls, which are also known as vertical gardens. Along with the increase in awareness of green walls, their technical solutions are also increasing and their innovation is progressing rapidly. In recent years, green walls have rapidly moved from the simplest walls with the need for mechanical service to maintenance-free walls connected to the digital environment using various sensors. The contribution is focused on the inputs of monitoring in the post-implementation phase of the interior green wall located on the premises of the Technical University in Košice. The goal of the monitoring is to define the inputs for the transition to digitized maintenance of the green wall. The article analyses of the inputs of 3-month monitoring of a green wall with simple manual maintenance. At the end of the paper, the requirements for setting up a digital device ensuring suitable conditions for the sustainability of green construction are specified.


Introduction
Green walls, also known as vertical gardens [1,2], or vertical greenery [3] are important for several reasons.One of the benefits of green walls is that they improve air quality, as plants absorb carbon dioxide as well as other pollutants and release oxygen into the air.This reduces the amount of toxins inside and outside the building.
Green walls also have a positive effect on psychological health and well-being.Since plants have a calming effect, they can help reduce stress and improve mood and overall quality of life.A lot of research is devoted to the impact of green walls on improving the quality of the environment, which focuses on green walls from different points of view.For example, from the point of view of reducing the concentration of CO 2 in the space [4], from the point of view of reducing the cooling load in the building [5,6], from the sociological point of view of the perception of these elements by the users of the building [7,8].In the case of exterior green components, we also come across the impact on the urban structure in the publications.
Green walls represent a living system that needs to be taken care of during the entire life cycle, from the construction design, through implementation, the phase of use and the end of the service life.The main phase of the life cycle is the use phase, which in the long run represents the longest part.For the longest possible use of the green wall, it is necessary to maintain it as effectively as possible.Green wall technology offers different options for the level of maintenance, from manual systems to fully self-maintenance systems.Regardless of the system by which the green wall is procured, the element should be tracked, maintained, requirements optimized and addressed in a timely manner.
When transitioning from a manual maintenance method to a mechanical one, it is necessary to know how to collect data correctly and forward it to the equipment for evaluating the requirements of the green wall.This article, which is dedicated to a specific green wall in the interior, is focused on data collection during 12 weeks of operation after the start of the use phase.It also records errors arising during the adaptation of the wall in the postrealization phase.

Green wall construction
The green wall, located in the building of the Faculty of Architecture of the Technical University in Košice, is one of the outputs of the project "Improving the parameters of the internal environment by adapting a green wall to the classroom space", financed from the funds of a research grant for young scientists at TUKE in 2021.The first part of the project was aimed at determining the state of selected air quality parameters of the indoor environment in the addressed room (temperature in the room, relative humidity, radiation temperature, operational temperature, speed of air movement, concentration of solid particles PM2.5 and PM10, volatile organic substances, CO2 concentration, temperature and emotional well-being, noise intensity) before the installation of the green wall.After installing the green wall in the room, the same measurements should be taken in the future.After the measurements have been completed, both detected conditions should be evaluated and compared.The goal of the second part of the project was the actual production and application of a green wall prototype with a total size of 2.4m x 2.4m. to the assessed room no.227 at the TUKE Faculty of Civil Engineering, Vysokoškolská 4, Košice.
The construction of the green wall, together with the substrate and plants, was designed and implemented by the company Lusaro s. r. about.The wall is assembled from prefabricated plastic panels with flower pots for placing the substrate and greenery.The company also developed a proposal for artificial wall lighting, as the daylight in the room was not sufficient in terms of light requirements for the growth of planted plants.Figure 1 shows the design of the green wall in question.
Fig. 1 The construction of the solved green wall (source:Authors).
The construction system of the green wall prototype was designed from 16 pieces of prefabricated plastic wall panels with a design structure.Individual panels measuring 600x600 mm connect to each other (both horizontally and vertically).Each panel is anchored to the wall with a pair of anchors in the upper part of the panel.Plastic flower pots with a width of 600 mm are anchored to the wall separately using anchors and are arranged in 4 horizontal rows.The wall includes 12 plastic flower pots with a drainage system for water overflow into the lower rows and 4 flower pots in the lower row with a full bottom.Artificial lighting of the wall 2 pcs of lamps, attached to the ceiling at a distance of 2 m from each other, approx. 1 m from the green wall, is set for 8 hours a day and is controlled by a time switch.
For planting plants in interior green walls, fewer types of plants with different creeping and climbing properties are recommended, which would contribute to the integrity of the wall in the long term.For the prototype of the green wall, living plants suitable for the interior with the assumption of climbing were selected.The bottom row is made up of fern species, the remaining rows are made up of three types of plants, namely Golden Potosovec, Syngonuium peduncle and Asparagus Sprengerov.

Implementation of a green wall
The implementation of the green wall took place in November 2022.Before the installation of the wall, renovation work on the floor and walls was completed in the room, and preliminary preparations for future lighting were made.For financial reasons, a new door is not installed in the room at the moment.The implementation procedure is documented in Fig. 2 • Instalation of flower pots -The pre-prepared planted pots were anchored to the wall panel in this step.For the joint, anchors were used with anchoring at two points of the flower pot, which firmly connected them to the wall panel system.• Setting the lighting conditions and finishing works -The last step was the installation of artificial lighting with the setting of optimal lighting conditions for the growth of planted greenery.Finally, the floor of the room was cleaned and the wall construction and the horizontality of the entire system were checked.The total implementation time was 2 days, while the green wall construction was installed on the first day, the wall lighting was installed on the second day and the system was checked.

Maintenance and monitoring of the green wall
Since the green wall does not have a self-maintenance system installed, the greenery of the wall requires manual maintenance on a weekly basis.The main part of maintenance is watering the substrate with plants.The weekly care of the green wall also includes simple tasks, such as collecting dead plant parts and checking the lighting.
The post contains partial conclusions that emerged from the 12-week maintenance and mapping of the state of the green wall The goal of the monitoring is to map the selected parameters of the green wall as one of the inputs necessary for the analysis and subsequent design of the parameters of the digital solution for the self-maintenance system of the green wall.An equally important goal is to gain personal experience in the requirements and costs of maintaining a green structure.
During the maintenance of the green wall in its post-realization phase, a measuring device was installed and the following monitoring methodology was chosen: 1.At the beginning of the post-implementation phase, the expected amount of irrigation was set to 15-20 l applied manually once a week.The amount of water for one flower pot was approx.0.9-1.25 l per week.2. Monitoring was carried out at the time of watering/maintenance with a weekly frequency, the monitored parameters included: • maintenance time • amount of water used for irrigation • air temperature in the place of construction of the green wall (before and after watering) • relative humidity at the site of the green wall construction (before and after watering) • notes (maintenance performed, error and deficiencies found,...)

Photo documentation of the state of planted plants
An instrument for measuring the relative humidity of the air and a thermometer installed directly on the construction of the green wall (with sufficient distance from the axis of the living component) were used to monitor the parameters.In addition to the recording of monitored parameters, a photo of the prosperity of the live components was taken every week, detected errors and deficiencies were recorded and documented.
Partial results from the 12-week monitoring of the green wall are processed in an overview table, in Fig. 3.For detected errors, documented Fig. 4, measures for their elimination were continuously proposed and implemented.During the monitoring of the green wall, several errors and deficiencies were discovered that occurred during use in the post-implementation phase of the green wall, e.g. as a result of the overflow, there was a poor prosperity of the fern in the bottom row of pots, which appeared around the third week.Error 1 detected at week 6 was an overflow of the pot and overflowing the system, or error 2 at week 11 was the onset of an increased number of small insects.Photo documentation of the identified deficiencies is in Fig. 4. As a result of poorly set irrigation, the system overflowed during the first weeks (Fig. 4 a).The consequence of this spill was, in addition to the worse condition of the fern in the bottom row of flower pots, also the leakage of excess water from the bottom row of flower pots.With the bottom row secured with plugs, the plugs fell out (or overflowed).The set expected amount of water for irrigation had to be adjusted after 7 weeks to an irrigation amount of approx.5 l per week.Another error found was the poor adaptation of some types of plants.The prosperity of individual plant species did not proceed equally, some plant species required more frequent maintenance (collection of dead plant parts).The deteriorated condition of the plants, which can be seen in Fig. 4 b), was probably due to insufficient intensity of artificial lighting in the given part of the wall.Due to the larger dimensions of the wall, there was a different intensity of lighting in individual parts.While the plants thrived in the part with proper lighting, the plants thrived worse in the upper row of pots, where the range of lighting was lower.When fertilizing and spraying the plants, the underlying structure of the green wall got wet (Fig. 4 c).Even if its damage was not obvious at the time of monitoring, in the long term it could mean damage to the surface of the wall or some part of it.
During the monitoring of the green wall, an increased occurrence of small insects was detected (Fig. 4 d), not only in the immediate vicinity of the wall, but in the entire room.The insect death did not damage the structures or the vegetation, but it represented the need for additional work (harvesting, removal, cleaning) during the weekly maintenance.The problem was also that the exact source of the insect infestation of the room had not yet been identified.

Conclusion
The implementation of the green wall in the premises of the Technical University in Košice represented a short period from the point of view of its life cycle, the main phase is the onset of the post-implementation phase -the use phase.Since it is a living system with living plants, in order to maintain the efficiency of the system, it is important in the long term to focus on setting the correct maintenance of greenery and setting optimal conditions to support the sustainability of the green wall.The investigated green wall currently does not have a self-irrigation system, nor a connection to sensors for a self-maintenance system, so all maintenance must be performed manually.
As it turned out during the monitoring, manual maintenance of the green wall does not exclude the risk of bad maintenance settings.During the maintenance of the wall in the post-realization phase, several shortcomings were found: worse adaptation of some types of plants, higher incidence of small insects in the room, influence of irrigation on the surface of the underlying wall structure, overflow of the system due to poor setting of the irrigation of the green wall.These errors could be prevented by choosing a different level of maintenance, by adapting sensors for soil moisture, sensors for monitoring the quality of the environment in the room (humidity, temperature, air quality, ...), or even by introducing an irrigation system into the existing green wall.The green wall has the prerequisite of connection to digital monitoring and control of lighting and irrigation, which would help to better and more efficiently monitor the needs of the living system that is the green wall.Such a connection would not only make the maintenance of the wall more efficient, but it would also bring better adaptation and more stable conditions for living components.The ongoing monitoring of the green wall can be the basis for further research.The research could be focused on the transition of the manual maintenance system to a self-maintenance system, it could also be interesting to analyze the results of long-term data collection and monitor the impact of the type of maintenance on the green wall.In the future, it is expected that the conditions in the room will change (teaching in the room, completion of the room modernization project and associated new furniture, new filling structures, etc.), which may also cause a change in the requirements for the maintenance of the green wall so that it fulfills its ecological and aesthetic function .This work was supported by project under the VEGA 1/0336/22 Research on the effects of Lean Production/Lean Construction methods on increasing the efficiency of on-site and off-site construction technologies.

Fig. 2
Fig. 2 Procedure for the implementation of the green wall (source:Authors).

Fig. 3
Fig. 3 Analysis of the results from the 12-week monitoring of the green wall in the postimplementation phase (Source: Authors).

6 MATECFig. 4
Fig. 4 Deficiencies detected during the monitoring of the green wall in the post-implementation phase (Source : Authors).