Development of a metallic structure shading system that integrates green roofs, recovery of rainwater and the production of photovoltaic energy
This project focuses on the development of an innovative and sustainable green roof shading structure for car parks with energy production and rainwater harvesting features. The solution is a hybrid system that integrates green roof modules, PV panels with sun tracking and a rainwater harvesting. The project, with 24 months duration, started in September 2016 and involved Constálica (lead promotor), Itecons and ANQIP (R&D entities).
PROJECT ACTIVITIES AND EXPECTED RESULTS
The main activities set out to be carried out during the project are:
MAIN RESULTS ACHIEVED
Preliminary studies and system design: The target market with the greatest potential for acceptance of the solution was identified and the demands and requirements to be met by the system were defined.
Solution development and specification: A one axis system with a horizontal axis (N-S) was defined (enabling E-W sun tracking between -30° and 30°). A tracking control algorithm based on astronomical equations was implemented, allowing the maximization of solar radiation collection and taking into account the action of the wind. All control, energy generation and storage, and security components were specified.
Efficiency improvement with solar tracking: In comparison with a fixed inclination solution, a 9% energy production increase was estimated A 25% increase was estimated in comparison with a horizontal panels solution.
Life Cycle Analysis (LCA): A comparative assessment concluded that the system leads to a significant reduction in environmental impacts (55 to 77% when compared to a conventional shading system and 5 to 21% when compared to a fixed system) in most environmental categories due to the production of solar energy in the use stage.
Increased biodiversity: It was found that the use of a mixture of herbaceous vegetation with sedum and grasses is suitable for exposure in full sun and half shade (panel area) and that it offers a wide variety of species.
Reduction of rainwater runoff: For the modular green roof solution, a percentage of water retention between 20% and 40% was obtained.
Filtering rainwater: Drainage tests were performed using pollutants typically found in pavements. It revealed a high capacity for retaining heavy metals (between 70 and 96%) as well as oils and fats (approximately 30%).
Lightweight and modular solution: For the roof module, a tray measuring 500 mm x 500 mm was selected. This corresponds to a modular solution weighing between 14 kg and 17.5 kg, which allows for easy handling and assembly.
Increased sound absorption coefficient: A weighted sound absorption coefficient (αW) greater than 0.75 was obtained from an experimental campaign carried out in a reverberant chamber.
Reduction of heat flux to the environment: The influence of the green roof on the surrounding temperature and energy production of the PV panels was evaluated.
LIST OF COMMUNICATIONS
1. Serra C, Simões N., Matos S., Miranda N., Pimentel-Rodrigues C. Silva-Afonso A., Shading System Integrating Green Roofs, Solar PV Trackers and Rainwater Harvesting, 3rd Energy for Sustainability International Conference – EfS2017, 8-10 de february 2017, Funchal, Portugal.
2. Silva R., Serra C., Brett M., Kanoun-Boulé M., Simões N., Tadeu A., Matos S., Miranda N., Conception and Design of a Sustainable Green Roof for Car Parks with Solar Tracking Photovoltaic System, 9th International Renewable Energy Congress – IREC2018, 20-22 march 2018, Hammmet, Tunisia.
3. Ferreira A. D., Fino R., Thiis T., Lopes A.M.G., Sousa A.C.M., On the modelling of wind erosion threshold of piles in tandem, 7th International Symposium on Computational Wind Engineering – CWE 2018, 18-22 June 2018, Seoul, Republic of Korea.
4. Simões N., Serra C., Simões I., Flat roof surface temperature assessment using IRT, 14th Quantitative InfraRed Thermography Conference - QIRT 2018, 26 - 29 June de 2018, Berlin, Germany.
LIST OF PUBLICATIONS
1. Pimentel-Rodrigues C., Silva-Afonso A. (2017), Determination of Runoff Coefficients with a View to Integration of Green Roofs with Rainwater Harvesting Systems, International Journal of Environmental Science, Volume 2, pp. 366-372.
2. Silva R., Serra C., Brett M., Kanoun-Boulé M., Simões N., Tadeu A., Matos S., Miranda N. R. (2018), Conception and design of a sustainable green roof for car parks with integrated solar tracking photovoltaic system, 2018 9th International Renewable Energy Congress (IREC), Hammamet, DOI: 10.1109/IREC.2018.8362460
3. Ferreira A. D., Fino R., Thiis T., Lopes A.M.G., Sousa A.C.M., (2018) On the modelling of wind erosion threshold of piles in tandem, 7th International Symposium on Computational Wind Engineering Proceedings, Seoul.
4. Simões N., Serra C., Simões I. (2018), Flat roof surface temperature assessment using IRT, 14th Quantitative InfraRed Thermography Conference Proceedings, Berlin, DOI: 10.21611/qirt.2018.032.