Browsing by Author "Freitas, Sara de"
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- Green roofs vegetation as a biotechnological solution to improve buildings thermal performance in urban areasPublication . Monteiro, Cristina M.; Freitas, Sara de; Ramos, Nuno M. M.; Castro, Paula M. L.
- Potentialities of infrared thermography application to green roofs aromatic plants surface temperature evaluationPublication . Monteiro, Cristina M.; Calheiros, Cristina; Palha, Paulo; Freitas, Sara de; Ramos, Nuno M.M.; Castro, Paula M. L.Introduction: In the last decades, urban environment climate has faced some gradual changes due to the replacement of vegetation by impervious areas. As a consequence, several environmental problems have appeared in urban centres. Rooftops are a significant part of the hard surfaces in urban areas changing the heat balance and thus increasing the heat island effect. Vegetation can have a positive effect in the microclimate and macroclimate lowering urban air temperature in the buildings surroundings due to evapotranspiration and shading. Therefore, green roof technology may help to overcome this well-known problem. In the present study, two green roof platforms with different substrates have been implemented with aromatic plant species. Infrared thermography studies have been performed to assess the effect of different aromatic plants on temperature mitigation. However, several limitations of this technique must be considered, namely, emissivity and exterior conditions. These limitations can be overcome with dynamic measurements, for different periods, which will be a future development of this work. Conclusions: The use of vegetation on roofs appears as a potential alternative technology that contributes to the mitigation of the urban heat island effect. The green roof structure as building component influences the microclimate in urban areas, especially due to the vegetation contribution. This contribution was positively evaluated with infrared thermography measurements for different green roof plant species in spite of the inherent technology limitations. The present research study will contribute to the application of infrared thermography as a technique to assess the surface temperature on green roofs vegetation at a smaller scale and to the urban environment at a larger scale.
- Substrate influence on aromatic plant growth in extensive green roofs in a Mediterranean climatePublication . Monteiro, Cristina M.; Calheiros, Cristina S. C.; Martins, João P.; Costa, Francisco M.; Palha, Paulo; Freitas, Sara de; Ramos, Nuno M. M.; Castro, Paula M. L.Green roofs have been described as technical solutions to overcome urban environmental problems, such as decrease of vegetation and stormwater management. In the present study, two pilot 20 m2 extensive green roofs were implemented in an urban Mediterranean region, at a 1st storey on a warehouse building structure, in order to test the adequacy of different substrates for supporting aromatic plants (Lavandula dentata, Helichrysum italicum, Satureja montana, Thymus caespititius and Thymus pseudolanuginosus). Experimental substrates included expanded clay and granulated cork as main components, supplemented with organic matter and crushed egg shell. A commercial substrate that obeys to FLL guidelines was also tested. Plant growth was assessed and compared within each platform. All experimental substrates proved to be adequate for vegetation growth, with the combination of 70% expanded clay, 15% organic matter and 15% crushed egg shell showing the best results regarding plant establishment and growth over time. Water runoff quality parameters - turbidity, pH, conductivity, NH4+, NO3−, PO43− - met standard values required for water reuse for non-potable purposes, such as toilet flushing or irrigation. Preliminary qualitative thermographic measurements comparing surface temperature of different plant species and the substrate showed that temperature of vegetation surface was lower than substrate, reinforcing green roofs benefits of lowering air temperature in their surroundings. The present research shows that aromatic vegetation combined with clay substrates are suitable for green roofs located in countries of the Mediterranean region.