Analysis of solar direct irradiance models under clear-skies: Evaluation of the improvements for locally adapted models

Direct solar irradiance has to be determined for the design of many energy applications such as photovoltaic systems and concentration systems, and the generation of solar potential maps for energy use. Knowledge of the accurate values of radiation components in a local area will allow optimal sizing of solar energy conversion systems. The estimated values of direct solar irradiance from models are still necessary at those sites where no measurements are available. In this work, different models used for the estimation of the direct component of solar irradiance are analyzed. First, an evaluation of the performance of eight existing original models was performed from which three were selected. Second, the selected models were calibrated to adapt them to our studied geographical area, which is the important aspect of this work, and an assessment of performance improvements for locally adapted models is reported. Experimental data consisted of hourly horizontal global, direct, and diffuse solar irradiance values, provided by the National Meteorological Agency in Spain (AEMET) for Madrid. Long-term data series, corresponding to a total period of time of 32 years (1980–2011), have been used in this study. Only clear sky models were treated at present. The three selected models were adapted to the specific location of Madrid, and root mean square error (RMSE) and mean-biased error were determined. By comparing the performance in the direct horizontal irradiance estimation from existing original and the corresponding locally adapted models, it is found that the values of RMSE decreased from 9.9% to 5.7% for the Louche model, from 7.8% to 7.4% for the Robledo-Soler model, and finally from 8.8% to 6.7% for the European Solar Radiation Atlas model. Thus, significant improvements can be reached when parametric models are locally adapted. In our case, it is up to approximately 4% for the Louche model. It is expected that calibrated algorithms presented in this work will be applicable to regions of similar climatic characteristics.Spanish Government (grant ENE2011-27511) and the Department of Culture and Education of the Regional Government of Castilla y León, Spain (grant BU358A12-2

Energy-saving potential of large housing stocks of listed buildings, case study: l'Eixample of Valencia

[EN] A significant part of the European residential building stock is architectural heritage and is protected by law in different grades. Although these dwellings seldom fulfil the current eco-efficiency requirements, listed buildings are exempt from energy regulations requirements. This paper reviews the constructional characteristics common to 588 multi-storey listed buildings (circa 6000 dwellings) located in l'Eixample district in Valencia (Spain). The poor thermal performance of these buildings proven by this study reveal a significant potential for saving energy and reducing CO2 emissions, particularly when considering the current requirements fixed by the current Spanish building code. Retrofitting measures intended to improve the thermal behaviour of these buildings, while being respectful to their listed nature, are proposed and assessed in terms of energy demand, air pollution and economy.Perez-Garcia, A.; Guardiola, AP.; Gómez-Martínez, F.; Guardiola Villora, AP. (2018). Energy-saving potential of large housing stocks of listed buildings, case study: l'Eixample of Valencia. Sustainable Cities and Society. 42:59-81. https://doi.org/10.1016/j.scs.2018.06.018S59814

Methodology to improve water and energy use by proper irrigationscheduling in pressurised networks

With the aim of reducing energy consumption and improving water use in pressurised irrigation systems, the methodology to minimise energy consumption by grouping intakes of pressurised irrigation networks into sectors, as developed by Jimenez Bello et al. (2010a), was modified to enable irrigation intakes to operate during the scheduled period for each intake instead of operating during restricted irrigation periods of the same length. Moreover, a method was developed to detect the maximum number of intakes that can operate without extra energy if the source has sufficient head to feed at least some of the intakes. These methods were applied to a Mediterranean irrigation system, where the total cropped area was mainly citrus orchards. In this case study, water was allocated to two groups of intakes, one fed by gravity and the other by pumps. A saving of 36.3 % was achieved by increasing the total volume supplied by gravity, decreasing the injection pump head, and improving the pump performance. Therefore, all the intakes only operated during the irrigation periods at the minimum required pressure.This research was supported by funds from Climate-KIC AGADAPT and from EU 7th Framework Programme FIGARO projects. The authors wish to acknowledge the support provided by Picassent Sector XI staff. The revision of this paper was funded by "The Universitat Politecnica de Valencia, Spain".Jiménez Bello, MA.; Royuela Tomás, Á.; Manzano Juarez, J.; García Prats, A.; Martínez Alzamora, F. (2015). Methodology to improve water and energy use by proper irrigationscheduling in pressurised networks. Agricultural Water Management. 149:91-101. doi:10.1016/j.agwat.2014.10.026S9110114

Rebalancing urban mobility: a tale of four cities

The key of mobility in urban planning is not in dispute. Integrated strategies that take into account the interrelations among land use, transport supply and demand and the different transportation modes are more necessary than ever. In Europe, regulatory tools such as local mobility plans or traffic plans have been enforced for a long time, evolving into so-called sustainable urban transport plans (SUTP) ? that is, plans thatmerge urban planning,mobility governance, social awareness and environmental safeguards to develop a vision based on sustainability and equity. Indeed, SUTP are aimed at solving typical problems in current land use, such as urban sprawl, which make clear the need for a paradigm shift from transport (or mobility) planning to land use (or city) planning, thereby producing urban mobility plans that are fully aligned with integrated urban development plans. This paper describes how SUTP are articulated across Europe according to four case studies: Peterborough (UK), Chambe¿ry (France), Ferrara (Italy) and Pinto (Spain), to highlight variations and commonalities, both among the four national legal frameworks and the actual planning processes at the local level. Objectives, measures and indicators used in the monitoring and evaluation phases have been analysed and the results assessed. The main conclusion of the paper is that, as seen in these real-life examples, the lack of integration between spatial planning and transport strategies results in the unsustainability of urban areas and, therefore, in a significant loss of competitiveness

Adaptation of pressurized irrigation networks to new strategies ofirrigation management: Energy implications of low discharge andpulsed irrigation

This paper analyzes the consequences of adopting new on-farm irrigation management strategies (lowdischarge rates, long irrigation times and high frequencies) in an existing on-demand and sectorizedpressurized irrigation system in eastern Spain. The sectorized behavior of the network was analyzedusing two criteria: (i) the operating sectors obtained in a first stage by arranging the hydrants dependingon their altitude respecting the pumping station and (ii) the operating sectors obtained by means ofan optimization process. The Simulated Annealing combinatorial metaheuristic optimization techniquewas employed to find the best solution. Random on-demand patterns were generated using a Montecarlosimulation. The hydraulic requirements of the network were analyzed in every scenario by the Epanet2.0 engine. The effect on energy consumption, power requirements and energy costs was assessed takinginto account the electricity tariff billing structure. It was found that reductions in emitter discharge (qe)and Energy consumption (E)-Energy Cost (EC) savings are not inherently related to each other. Certainamounts of E and EC could be saved when the number of sectors and operating time parameters wereproperly selected. Pulsed irrigation in the current scenario showed an energy saving potential of 10.67,6.43 and 6.99% for power capacity, E and EC, respectively.The study has been partially funded by the IMPADAPT project (CGL2013-48424-C2-1-R) with Spanish MINECO (Ministerio de Economia y Competitividad) and Feder funds.Garcia-Prats, A.; Guillem Picó, S. (2016). Adaptation of pressurized irrigation networks to new strategies ofirrigation management: Energy implications of low discharge andpulsed irrigation. Agricultural Water Management. 169:52-60. https://doi.org/10.1016/j.agwat.2016.02.023S526016

An AHP (Analytic Hierarchy Process)/ANP (Analytic Network Process)-based multi- criteria decision approach for the selection of solar-thermal power plant investment projects

In this paper the AHP (Analytic Hierarchy Process) and the ANP (Analytic Network Process) are applied to help the managing board of an important Spanish solar power investment company to decide whether to invest in a particular solar-thermal power plant project and, if so, to determine the order of priority of the projects in the company's portfolio. Project management goes through a long process, from obtaining the required construction permits and authorizations, negotiating with different stakeholders, complying with complex legal regulations, to solving the technical problems associated with plant construction and distribution of the energy generated. The whole process involves high engineering costs. The decision approach proposed in this paper consists of three phases. In the first two phases, the managing board must decide whether to accept or reject a project according to a set of criteria previously identified by the technical team. The third phase consists of establishing a priority order among the projects that have proven to be economically profitable based on project risk levels and execution time delays. This work analyzes the criteria that should be taken into account to accept or reject proposals for investment, as well as the risks used to prioritize some projects over others.The translation of this paper has been funded by the Universitat Politecnica de Valencia.Aragonés Beltrán, P.; Chaparro González, FV.; Pastor Ferrando, JP.; Pla Rubio, A. (2014). An AHP (Analytic Hierarchy Process)/ANP (Analytic Network Process)-based multi- criteria decision approach for the selection of solar-thermal power plant investment projects. Energy. 66:222-238. doi:10.1016/j.energy.2013.12.016S2222386