Characterization of green roof components: Measurements of thermal and hydrological properties

• Published in: Building and environment 2012-10, Vol.56, p.78-85
• Main Authors: Ouldboukhitine, Salah-Eddine, Belarbi, Rafik, Djedjig, Rabah
• Format: Article
• Language: English
• Subjects: Applied sciences; Buildings; Buildings. Public works; Characterization; Civil Engineering; Construction durable; Engineering Sciences; Evapotranspiration; Exact sciences and technology; External envelopes; Green roofs; Porosimetry; Roof; Sorption isotherms; Thermal conductivity
• ISSN: 0360-1323; 1873-684X
• DOI: 10.1016/j.buildenv.2012.02.024

In this study, three of the main physical properties of green roofs were experimentally investigated to determine some of the key green roof modeling parameters. First, the thermo-physical properties of green roofs were characterized by correlating the thermal conductivity of the substrate with the water content for different substrates and maximum water capacities. Next, the moisture storage was characterized using the dynamic vapor sorption technique to determine both the sorption and desorption isotherms for three different temperatures as well as the moisture buffer capacity. Third, the micro-structural properties of green roof substrate were characterized using mercury intrusion porosimetry to measure the porosity range of the substrate and to compare this porosity range with different concrete porosities. In addition to these characterizations, the evapotranspiration term, which is very important in the water balance, was measured. The few studies found in literature provide the expression of the evapotranspiration term for a watered grass and vegetated areas on a large scale. In this study, this term is expressed for the experimentally studied green roof complex (substrate + vegetation). The ultimate objective of these experiments is to estimate the parameters used as input data in the developed green roof model to evaluate the energy performance of a building. ► Green roofs improve the energy performance of buildings. ► Thermo-physical, moisture storage and micro-structural characterizations of soil properties were performed. ► The identification of key material properties of green roof components was conducted. ► The evapotranspiration term was expressed for the complex (substrate + vegetation) used in the studied experimental platform. ► The coupled heat and mass transfer model was used to predict the energy performance of a green roof.