Effects of Building Scale Parameters on Pressure Equalization Capacity of Roof Paver Systems

Roof pavers are commonly installed with a cavity beneath the paver that develops an internal suction pressure. These cavity pressures reduce the net pressure felt by a roof paver subject to uplift. Paver-scale parameter effects are well-understood, in this study, the effects of changing building-scale parameters such as height, aspect ratio, afterbody length, small and large scale roof obstructions, and paver to roof size ratio on cavity pressures are investigated. To do so pressure measurements were taken at the University of Western Ontario’s Boundary Layer Wind Tunnel Laboratory on a modular flat roof building model at four different heights with four different plan aspect ratios per height. It was found that size and shape of the separation vortices affect the pressure equalization capacity of the system. It was also found that the ratio of paver size to roof size greatly impacts the magnitude of peak pressures observed

Løsninger på utfordringer knyttet til snø for økt utbredelse av solcelleanlegg

Photovoltaic (PV) systems are becoming more competitive due to a cost reduction of the technology and increased electricity prices. As the technology extends to cold climates with lower irradiance, a knowledge gap in how PV systems are affected by the environment arises, which can limit PV system deployment. This thesis focuses on the impact of snow, which is perhaps the most distinguished environmental impact compared to the high irradiance climates where PV systems traditionally have been deployed. An interdisciplinary perspective is used to investigate different snow challenges connected to the deployment of PV in cold climates, and how they can be resolved. One of the challenges explored in the thesis is the development of snowdrifts in ground mounted PV plants. This challenge is relevant for PV systems installed in exposed snowdrift climates. To document the challenge itself, field measurements of snowdrift development in a small-scale PV plant in a polar climate were performed. The study concludes that PV plants designed with established principles commonly used at lower latitudes are susceptible to snowdrift accumulation. To achieve a snowdrift resilient plant, the design of the plant itself can be adapted. This strategy is further investigated in a numerical study using Computational Fluid Dynamics and energy yield simulations to quantify the impact of changing the design parameters on the snowdrift accumulation conditions and the energy yield. It is found that all the design parameters can be adjusted to improve the snowdrift conditions, with variable effect on the yield. Based on these results, adaptions to local climate conditions can be made to increase the snowdrift resiliency of the PV plant while minimizing an adverse impact on the yield, enabling the use of ground mounted PV plants in exposed snowdrift climates. Another of the investigated snow challenges is the use of active snow mitigation with PV systems on existing building roofs. Such systems reduce heavy snow loads so that roofs which lack structural capacity can be utilised for PV power production. In the thesis, PV snow mitigation systems are analysed in two separate studies focusing on the influence of active snow mitigation with PV systems on (i) the structural safety of building roofs, and (ii) the energy consumption and production compared to ordinary PV systems. The results provide a foundation for estimating which structures and climates PV snow mitigation systems are suitable. The research address former knowledge gaps for the use of PV snow mitigation systems and can contribute to increased utilisation of roof area for PV power production in the built environment. Snow contributes to an uncertainty in the yield of PV systems as it is difficult to predict snow shedding from the PV modules. There are several models for estimating yield losses in PV systems based on empirical data of snow shedding, but due to being developed based on single systems, the applicability to different configurations in different snow climates are limited. With the intent of achieving a model with wider applicability, an existing snow loss model is improved by considering the influence of snow depth on the snow shedding. By applying the model to seven different PV systems in different snow climates, the error in estimation of snow loss is reduced by 23 percentage points compared to the original model. The model contributes to reducing the uncertainty in PV yield estimations without the need for system specific empirical data of snow shedding. The overall contribution of the work is to resolve specific snow challenges which limit the deployment of PV systems in cold climates. Additional snow challenges have been identified during the work with the thesis, and recommendations for paths for future work are suggested. With ongoing research on this topic, the limitations for PV deployment in cold climates can be resolved and PV systems can contribute to increased renewable energy production in cold climates.Reduserte produksjonskostnader og økte strømpriser øker konkurransedyktigheten til solcelleanlegg. Solcelleanlegg har vært mest utbredt i, og delvis blitt utviklet for, varme klima med mye stråling, men når solcelleanlegg sprer seg til kaldere klima begrenses bruken av teknologien av manglende kunnskap om klimapåkjenninger. En av de største forandringene i klimapåkjenninger i kalde klima kontra varme klima er påvirkningen fra snø. Denne avhandlingen omhandler hvordan snø begrenser bruk av solcelleanlegg og hvordan slike utfordringer kan løses. En av utfordringene som undersøkes er snøfonndannelse i bakkemonterte solcelleanlegg. For å undersøke hvor utsatt solcelleanlegg er for snøfonndannelse er det gjennomført feltforsøk på et bakkemontert solkraftverk i et polart klima. Studien viser at solcelleanlegg som er designet ut ifra samme prinsipper som på lavere breddegrader gir en utforming som er svært utsatt for snøfonndannelse. En måte å redusere risikoen for snøfonndannelse på er å tilpasse designet av anlegget. For å undersøke denne tilpasningsstrategien er det gjennomført en numerisk studie som anvender fluidmekanikk- og energiytelsessimuleringer til å kvantifisere hvilken påvirkning det gir å endre utformingen av solkraftverket. Resultatene viser at alle de undersøkte designparameterne i solcelleanlegg kan tilpasses for å redusere risikoen for snøfonndannelse, men at de forskjellige designparameterne gir forskjellig påvirkning på energiytelsen. Resultatene fra disse studiene gir et grunnlag for å tilpasse utformingen av solkraftverk til klima med betydelig snødriv samtidig som ytelsen ivaretas. En annen utfordring som undersøkes er hvordan solcelleanlegg med snøsmeltefunksjon kan benyttes på eksisterende takkonstruksjoner som ikke tåler den totale vekten av snølasten og solcelleanlegget. I avhandlingen undersøkes det hvordan slike solcelleanlegg påvirker konstruksjonssikkerheten til bygg ved å benytte statistiske metoder. Resultatene tydeliggjør påvirkningen styringen og designet av slike anlegg har på konstruksjonssikkerheten til bygg, samt hvordan forskjellige kapasitets- og lastforutsetninger påvirker utbyttet av slike anlegg. I tillegg til påvirkningen på konstruksjonssikkerhet undersøkes energibehovet og hvilken potensiell produksjonsøkning det medfører å aktivt redusere snølasten på tak i en studie som benytter en kombinasjon av numeriske verktøy. Resultatene viser hvilke type klimatiske forhold som gir lavest energibruk og høyest økning i produksjon. En sammenstilling av resultatene fra de to studiene danner et grunnlag for å vurdere hvilke konstruksjoner og klima som egner seg for å benytte solcelleanlegg med snøsmeltefunksjon. Forskningen reduserer kunnskapshull for bruken av solcelleanlegg på tak med begrenset bæreevne og kan bidra til økt utnyttelse av eksisterende takflater til solstrømproduksjon. Den siste undersøkte utfordringen omhandler modellering av påvirkningen snø har på solcelleanleggs ytelse. En begrensing med mange eksisterende modeller for ytelsestap fra snø er at de er utviklet med empiriske data fra ett type snøklima og ikke nødvendigvis gir gode resultater når de anvendes i andre klimaforhold. Dette forsøkes å forbedres ved å videreutvikle en eksisterende snøtapsmodell til å ta hensyn til snødybde i avsklidningen av snø fra solcellepanelene. Sammenlignet med den opprinnelige snøtapsmodellen reduseres nøyaktigheten til modellen med 23 prosentpoeng når den anvendes til syv forskjellige solcelleanlegg. Modellen kan bidra til å redusere usikkerheten til ytelsen av solcelleanlegg i forskjellige type snøklima. Det overordnede bidraget til avhandlingen er å løse utfordringer snø gir for bruk av solcelleanlegg. Gjennom arbeidet har det blitt oppdaget ytterligere utfordringer. På bakgrunn av dette foreslås det hva som er aktuelt å fokusere på i fremtidig forskning på solcelleanlegg i klima med snø. Videre forskning på temaet kan føre til at bruken av solcelleanlegg i mindre grad hindres av snø og til å redusere klimautslipp i kalde klima

Developing a methodology for appraising building integrated low or zero carbon technologies

Strathclyde theses - ask staff. Thesis no. : T13113The advent of environmentally driven building regulations, rising energy costs, and heightened client awareness of energy related issues has increased the demand for assessing the potential of Low or Zero Carbon (LZC) energy supply systems. There are many software tools that have been developed to assist the designer in carrying out performance appraisals ranging from simple device models for feasibility assessments through to integrated simulation tools for detailed analyses of building integrated technologies. However, it is seldom the case that any one software tool can undertake a complete appraisal for building integrated LZC technologies. Usually a range of tools is required for different technology options at different design stages. Therefore there is a clear need for an effective assessment methodology for the use of software in LZC technology analysis. The objective of this project was to develop this methodology and apply the software (termed a "toolkit") to a 'real design' problem. The results from the analysis are discussed and clarity for presenting these results to non-technical stakeholders, within the design process, has been emphasised.The advent of environmentally driven building regulations, rising energy costs, and heightened client awareness of energy related issues has increased the demand for assessing the potential of Low or Zero Carbon (LZC) energy supply systems. There are many software tools that have been developed to assist the designer in carrying out performance appraisals ranging from simple device models for feasibility assessments through to integrated simulation tools for detailed analyses of building integrated technologies. However, it is seldom the case that any one software tool can undertake a complete appraisal for building integrated LZC technologies. Usually a range of tools is required for different technology options at different design stages. Therefore there is a clear need for an effective assessment methodology for the use of software in LZC technology analysis. The objective of this project was to develop this methodology and apply the software (termed a "toolkit") to a 'real design' problem. The results from the analysis are discussed and clarity for presenting these results to non-technical stakeholders, within the design process, has been emphasised

Effect of roof-mounted solar panels on the wind energy exploitation on high-rise buildings.

The analysis of the wind flow around buildings is of great interest in the field of renewable energies. This work presents an investigation of the effects of roof-mounted solar panels on the wind flow on building roofs, from the point of view of the wind energy exploitation. CFD simulations of the wind flow around an isolated building are performed with OpenFOAM. The simulations are compared with two wind tunnel experiments for validation: an isolated building and an array of solar panels. The wind flow on an empty roof is compared with roof-mounted solar panels cases. The solar panels are tested with tilt angles of 10° and 30°, the most adequate inclination for solar panels in the Mediterranean region. The analysis is carried out both quantitatively and qualitatively. The full-scale building results are compared with a reduced-scale model and scaling issues are reported. The most adequate wind turbine for each roof region is suggested

Deployment characterization of a floatable tidal energy converter on a tidal channel, Ria Formosa, Portugal

This paper presents the results of a pilot experiment with an existing tidal energy converter (TEC), Evopod 1 kW floatable prototype, in a real test case scenario (Faro Channel, Ria Formosa, Portugal). A baseline marine geophysical, hydrodynamic and ecological study based on the experience collected on the test site is presented. The collected data was used to validate a hydro-morphodynamic model, allowing the selection of the installation area based on both operational and environmental constraints. Operational results related to the description of power generation capacity, energy capture area and proportion of energy flux are presented and discussed, including the failures occurring during the experimental setup. The data is now available to the scientific community and to TEC industry developers, enhancing the operational knowledge of TEC technology concerning efficiency, environmental effects, and interactions (i.e. device/environment). The results can be used by developers on the licensing process, on overcoming the commercial deployment barriers, on offering extra assurance and confidence to investors, who traditionally have seen environmental concerns as a barrier, and on providing the foundations whereupon similar deployment areas can be considered around the world for marine tidal energy extraction.Acknowledgements The paper is a contribution to the SCORE project, funded by the Portuguese Foundation for Science and Technology (FCT e PTDC/ AAG-TEC/1710/2014). Andre Pacheco was supported by the Portu- guese Foundation for Science and Technology under the Portuguese Researchers' Programme 2014 entitled “Exploring new concepts for extracting energy from tides” (IF/00286/2014/CP1234). Eduardo GGorbena has received funding for the OpTiCA project from the ~ Marie Skłodowska-Curie Actions of the European Union's H2020- MSCA-IF-EF-RI-2016/under REA grant agreement n [748747]. The authors would like to thank to the Portuguese Maritime Authorities and Sofareia SA for their help on the deployment.info:eu-repo/semantics/publishedVersio