Vertical gardens : Manufacturing materials proposal

Vertical gardens emerged with the aim of increasing green areas in large urban centres, thus reducing the negative impacts of this dense urbanization. In general, vertical gardens are able to improve air quality, reduce heat islands, increase biodiversity, among other advantages presented in this work. This study proposes the use of two materials for making panels for vertical gardens. The panels were based on the model developed by the French botanist Patrick Blanc, using “green felt” and “grey cacharel” with each panel measuring 50 x 80 cm and with 24 pockets. These were installed in a residence in the municipality of Ilha Solteira, São Paulo state, Brazil; having with vegetal species Trandescantia zebrina. During January 19 to February 2, 2020, the temperatures of the panels, the wall and the region behind the panels were measured. An average thermal damping of up to 8.71°C was observed; it was concluded that the panels developed were effective for the construction of vertical gardens.


Introduction
Regarding urban population growth in recent years, there have been changes in city scenario. The increase in constructions and buildings led to decrease in green areas in urban centres, causing worsening air quality, increased average temperatures and noise, formation of heat islands, increased soil impermeability, changes in the ecosystem (Ekren, 2017).
Green areas are extremely important in people's lives inside cities, with psychological influence and visual impact being one of the main points. The vegetation present in the cities beneficially affects population health in several aspects: "The greener there is in a region, the lower the risk of mortality from non-accidental causes, especially cancer and respiratory diseases" (Saldiva, 2017).
Thus, vertical gardens are emerging as an alternative to reduce the negative impacts of urbanization in large cities.
These are elements used in the internal or external walls of buildings, being covered by vegetation through specialized techniques.
The use of green gardens in buildings generates an improvement in temperature, air quality, reduction of heat islands, reduction of noise, influence of biodiversity, buildings aesthetics, reduction of energy costs and helps in rains water retention (Costa, 2011).
One of the exponents in the area was the French botanist Patrick Blanc, who started to install vertical gardens in the 1980s by himself and patented technology in several countries around the world (Blanc, 2008;Costa, 2011).
In Brazil, one of the main precursors of the idea of reconciling man with nature in the urban environment was Burle Marx, who, with his works performed between 1930 and 1980, transformed the concept of landscape and urban space in main brazilian cities (Lopéz & Narváez, 2015), as an example the garden of Safra Bank, in São Paulo-SP/Brazil, when it used metal columns filled with coconut fibre, where epiphyte plants develop (Petty, 2008).
The method of vertical gardens construction with blankets is the most used today. This method, commonly used by Patrick Blanc, consists of three parts: a metal plate (usually aluminium), a PVC layer and a felt layer. The aluminium plate is hung on the wall, providing efficient thermal and acoustic insulation. The PVC layer is fixed to the aluminium plate, offering rigidity to the entire structure in addition to making it waterproof. Finally, the felt layer is installed over the PVC layer where the plants will be inserted. The high capillarity of the felt allows a homogeneous water distribution, facilitating the irrigation that is done by the top of the panel (Blanc, 2008).
Vertical gardens, in general, support a great diversity of plant species and, therefore, require more intense maintenance, especially in the replacement of nutrients from the substrate or water, behaving like hydroponic systems; this method of technology allows development in tall buildings or very large surfaces. (Sharp et al. 2008;Manso & Castro-Gomes, 2015).
Thus, regarding the number of materials presented the objective of this work was to evaluate two materials for use in vertical gardens.

Methodology
The work was developed from September 14 th , 2019 to February 2 nd , 2020 in a residence located at coordinates 20°26'16.1"S, 51°20'58.4"W, in the municipality of Ilha Solteira, São Paulo state, Brazil, with panels fixed on a wall on the outside of the residence facing south, being a vertical masonry.
The panels had dimension of 50 x 80 cm, with 24 pockets, which varied from 10-12 cm in width by 15-20 cm in height and volume between 450 and 600 grams (these variations in dimensions are problems related to those who made them).
For panels assembly it was used green plastic canvas, "cacharel" fabric (gray fabric) and felt (green fabric) (Figures 1 and 2).
The material for confection was purchased directly from a representative in the municipality of São José do Rio Preto and Ribeirão Preto, both in São Paulo state.  4 decoration due to its compact aspect (small size) and its leaves of purple and green colours. This plant has good adaptation to full sun and half shade and has a perennial life cycle (Patro, 2013).
Containers of both materials were made, 8 cm high and 7 cm in diameter, which were filled with commercial substrate and measured the mass of three empty containers, filled with dry commercial substrate and subsequently wet (at the moment and 24 hours later).
In samples of 10 cm x 10 cm from both fabrics (three replications of each one), dry and wet weight were measured, at the time and after 2, 4 and 8 hours. The dry and wet weight (at the time and 1 hour later) of the panel with the plant and its moist substrate was measured.
The temperature was measured daily, for 15 days, during the period from 01/19/2020 and 02/02/2020; the temperatures of the environment, the wall on which the panels were installed, the panels and the region behind the panels were measured with a digital infrared thermometer for surfaces. Plants were irrigated at 10 AM and temperatures were measured once a day at 1 PM.
On 02/04/2020, the green and gray panel plants (two replications of each one) were removed and weighed (g), and also 1 plant with the appropriate panel filling; thus it was possible to estimate the filling of the panel and its visual aspect.

Results and Discussion
The wall temperature is always higher than the environment temperature; this is due to the fact that the wall is made of structural masonry, thus presenting two important properties related to heat storage: thermal conductivity and heat capacity.
Thermal conductivity is related to the material's capacity to conduct heat to its interior, and heat capacity refers to the material's capacity to store heat in its volume. Masonry has high thermal conductivity, as well as high heat capacity, justifying the wall always presenting higher temperatures than the environment (Gartland, 2008).
Tables 3 and 4 present data on the thermal damping that occurs in the panels and in the region behind them, in relation to the wall, for the green and gray panels, respectively.  It may be observed that there was an average thermal damping of 6.16 and 6.19 °C between the wall temperatures in relation to the green and gray panels, and the areas behind these 8.71 and 8.59 °C, respectively. This is explained by Labaki et al. (2011), who says that vegetation acts differently from other ways, as its function is to block solar incidence. The energy balance of vegetation cover is composed of thermal exchanges by radiation and convection, evapotranspiration of soil and plants, in addition to thermal conduction and heat storage in the soil layers (Gagliano et al., 2015), which explains the results shown in Tables 3 and 4. For Chen et al. (2013), the vertical garden is an instrument capable of removing heat from the wall and the air cushion formed by the space between the panel and the wall, so the smaller the cavity, the greater the thermal efficiency, as the ventilation and the exchange of heat by convection, as seen in the present work.
Research, Society andDevelopment, v. 10, n. 7, e41510716709, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i7.16709 8 According to Silva et al. (2011), vegetation acts through passive cooling based on two mechanisms: the shading cast by plants, which decreases the conversion of radiant energy into sensible heat and which through this decreases the surface temperatures of objects that by they have been shaded; and the evapotranspiration of leaves surface and the substrate that results in this system cooling of this assembly and of the air passing through its surface, due to the exchange of latent heat.
This explains the fact that the panels with vegetation have an average temperature lower than the wall that has no vegetation at all. Wong et al. (2009) performed research in order to analyse the thermal efficiency of different types of green walls founding reduction in wall surface temperature up to 11.58 °C; Matheus et al. (2016) studied the influence of vertical gardens in a building in spring-summer period and observed a 15-30°C reduction in external surface temperature of wall; on the other hand, Lima Júnior (2018) analysed the influence of vertical gardens on opaque walls and observed that there was difference of 5.9 °C between the average temperatures of the external surfaces with and without the vertical gardens prototypes; thus, comparing the results obtained by the aforementioned authors with those of this work, it may be noticed that the temperature reduction presented coherent values and the variations may have occurred due to the local climate in each experiment, the material used to make the panels, as well as the plant species used.
The two materials used to make the panels (green felt and cacharrel) had similar performance, as may be seen in Tables 1, 3 and 4 and Figure 4.
As for the visual aspect, a plant with the proper filling of the panel weighed 38.9 g ( Figure 5). The evaluation of total weight of plants in each panel is shown in Table 5, and the expected value would be 933.6 g, considering the weight of the one with ideal filling (38.9 g x 24 pockets). This non-development of plants, as well as the lack of complete filling of the panels, was due to a failure in the confection, as the pockets ranged from 10-12 cm in width by 15-20 cm in height and volume between 450 and 600 g.  Table 6 shows the value of 0.4 m 2 (from the panel) and m 2 for comparison. were added, the amount of R$ 31.92 would be added to each panel, relating to 24 units (Table 6).
On the market it is possible to find several panels similar to the one developed in this work with prices ranging from R$ 280.00 (1×1m -1 m 2 ; 72 pockets) to R$ 360.00 (0.7×2.3m -1.61 m 2 ; 56 pockets / R$223.60/m²); these values were found on the Mercado Livre and Loja Flash websites, sold by several sellers. According to Kehdi (2019), the final price of a vertical garden may vary greatly depending on the type of structure, vegetation and irrigation system, ranging from R$ 800.00 to R$ 1,700.00/m 2 .
Thus, it may be reported that the value of the panels in this work is consistent with the price of those sold in the market, even presenting lower values in relation to those of the researched products; it may also be concluded that the prices of both panels made were very similar, as well as all the other aspects analysed in this work.

Conclusion
Both materials used in the manufacture of vertical garden panels proved to be viable for this purpose. In addition, the panels developed obtained satisfactory results in relation to thermal damping.