Study on the Leaves Densities as Parameter for Effectiveness of Energy Transfer on the Green Facade

Abstract

This research involves the study of two models of green facades and a model of bare wall. A house miniature was used as thermal lab. The aim of the project is evaluating the performance of energy transfer based on the various leaves densities on the green facade. Heat calculation was used to calculate heat transfer on the wall surface. There are two kinds of leaves densities, 50% and 90%. The data measurement show that the green facade has a significant cooling effect and more visible for the facade with higher leaves densities. Respectively, from experiment I to experiment III, the average of heat fluxes are 22.35 W/m2, 8.76 W/m2, and 0.60 W/m2 where in experiment III, the negative heat flux occurred during day time due to interior surface temperature is higher than exterior surface temperature. Lastly, higher leaves densities possibility can create a better cooling effect but also has the risk of creating higher relative humidity, especially for the interior air layer.

Observation to Building Thermal Characteristic of Green Façade Model Based on Various Leaves Covered Area

“…Widiastuti et al [15] also found that the lowest difference up to 0.30 • C between exterior and interior surfaces temperature occurred on the green façade with higher leaves densities. Using the Newton cooling law calculation, the authors also found that during day time, heat flux on the green façades with higher leaves densities was negative.…”

“…As mentioned in the introduction, to study the effect of the greenery layer on building thermal characteristics, three kinds of green façades were installed with different leaves covered areas in Semarang City, around Architecture Department at Diponegoro University. They included a non planted wall (experiment I), green façade with 50% leaves covered area (experiment II), and green façade with 90% leaves covered area (experiment III) [15]. At that moment, the building model placed behind other buildings and surrounded by large trees can be seen in Figure 1.…”

“…As previously already mentioned, in this study, three field measurements with different leaves covered area were done on the building model, which was like a house miniature with a scale of 1:4 compared to an original building [15,19,20]. Details of the dimensions of the building model can be seen in Figure 2.…”

“…Holm [13] also found that the foliage of the green layer made walls covered by climbing plants have different heat transfer mechanisms compared to bare walls, where outer layers of leaves act as filters, while the inner layers worked as insulation. When the covering ratio of the green layer increased, the insulation characteristic (thermal resistance) of the building envelope also increased [14][15][16].…”

“…Lack of experiments referring to the total energy savings related to these parameter make it possible to develop this research. This is part of a research series where leaves densities (percentage of leaves covered area) was used as the main parameter for observation [15]. The present study aimed to observe the thermal characteristics of the model with green façade under various kinds of leaves covered areas.…”