Laboratory measurements

Evaporation flow rates

When plants are exposed to light they are able to take up carbon dioxide from the ambient air and produce carbohydrates under the use of light energy. The carbon dioxide uptake is accompanied by the loss of water, which is taken up by the root system. Water evaporation leads to a cooling of the leaf surface and produces a microclimate around the plants. The goal of the numerical model developed in the project is to determinate how this microclimate affects the energy balance of the builiding facade. To do so, the water flow rates evaporated by different species under different circumstances have been measured in order to use this

Temp 20 *C 30 "C

—growth chamber glasshouse —±—outdoor

Figure 4: Green layers orthogonal to the facade. Outdoor aspect at the left (by Nature) and indoor aspect at the right (by Arquitectura Produccions).

Figure 5: Evaporation flow rate. At the left, the same species grown in different conditions have different reactions to the same conditions. At the right, reaction of different species to the same conditions.

Figure 6: Global transmissivity and reflectivity Figure 7: Example of Montecarlo ray trac — of Parthenocissus Quenquifolia leafs in sum-ing simulation: Energy absorbed by earch mer and fall. Parthenocissus Quenquifolia leaf after multi­

ple reflexions in a canopy

data for the numerical model. Illustrative results of the experiments are presented in Fig. 5.

The evaporation flow rates depend not only on the plant specie and on the ambient con­ditions, but also on the ambient where the plant has grown. Thus, it will be convenient to repeat some of these measures in actual facades.

Optical properties of the leaves

Figure 8: Experimental set up to obtain data for the numerical models.

The optical properties of the plant leaves (transmissity and reflectivity) have been mea­sured in order to obtain data for the numerical model. Illustrative measures of Parthenocis­sus quenquifolia are presented in Fig. 6.