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Soiling of PV modules is an issue causing non-negligible losses on PV power plants, between 3 and 4% of the total energy production. Cleaning is the most common way to mitigate soiling. The impact of the cleaning activity can be significant, both in terms of cost and resources consumption. For these reasons, it is important to monitor and predict soiling profiles and establish an optimal cleaning schedule. Especially in locations where raining is irregular or where desert winds carry a high concentration of particles, it is also important to know how precipitation and dust events affect the soiling ratio. This paper presents a new model based on environmental conditions that helps the decision-making process of the cleaning schedule. The model was validated by the analysis of five large grid-connected PV plants in Spain over two years of operation, with a total power of 200 MW. The comparison between the model and soiling sensors at the five locations was included. Excellent results were achieved, the mean difference between sensors and model being 0.71%. [ABSTRACT FROM AUTHOR]

Aligned with the goals of achieving higher sustainability in water systems, the minimization of energy costs is a top priority for the operators and owners of such systems. Early research contributions on the rate of energy dissipation due to head losses, defined as energy slope J , demonstrated that this parameter can be optimized so that such cost minimization is achieved. However, an important factor that was not considered in previous research is that water demand might be variable during the lifetime of water systems. Whether due to daily variation patterns, seasonal changes, or long-term water demand growth, variations on the flow rate complicates the determination of the optimized energy slope Jopt that will minimize energy costs. This work addresses this knowledge gap, performing an evaluation of how demand variation impacts Jopt and how deviations from the optimum energy slope affect costs for varying water demands. In addition, this work also provided insights into pipe cost installation terms and pipe cost exponents using real-world data of existing water systems in Spain. Such exponents are very important in the computation of optimum energy slopes. It is hoped that this research will provide practical guidance to designers and operators of water systems regarding the minimization of energy costs, leading to greater sustainability of such systems. [ABSTRACT FROM AUTHOR]

Buildings account 40% of the EU's total energy consumption. Therefore, they represent a key potential source of energy savings to fight, among others, against climate change. Furthermore, around 54% of the buildings in Spain date back before 1980, when no thermal regulation was available. The refurbishment of a façade of an old building is usually the most effective way to improve its energy efficiency, by adding layers to the external envelope in order to reduce its thermal transmittance. This paper deals with the problem of minimizing costs for the thermal refurbishment of a façade with thickness and thermal transmittance bounds and with an intervention both on the opaque part (wall) and the transparent part (windows). Among thousands, even millions of combinations of materials and thicknesses for the different layers to be added to the opaque part, types of frame, and combinations of glasses and air chambers for the transparent part, the aim is to choose the one that minimizes the cost without violating any restriction imposed to the thermal refurbishment, in particular the current energy efficiency regulations in the zone. To optimally solve this problem, it will be modelled as an Integer Linear Programming problem with binary variables. The case study will be Building 1B of the School for Building Engineering of the Polytechnic University of Valencia, Spain. It was built in the late 1960s and has had a very inefficient energy consumption record. The optimal solution will be found among more than 6 million feasible solutions. [ABSTRACT FROM AUTHOR]

Indoor swimming pools are high energy demand facilities. Current knowledge about their energy demand does not offer reliable information for a correct design of their thermal installations. A deeper knowledge about actual energy needs of these installations is then necessary to improve their energy efficiency. The objective of this work is to define and validate a new and specific model for the characterisation of an indoor swimming pool and its dynamic energy behaviour with sufficient accuracy. To do that, a module including the calculation of the evaporation and other heat losses is proposed and integrated as a new component defined in TRNSYS for a dynamic simulation of the problem. In order to validate the model, a two-phase procedure has been implemented. Firstly, a full-monitoring system has been put in place at a public indoor swimming pool in the municipality of Archena, Spain, where records have been contrasted with the model results. Secondly, energy data from four other swimming pools have been also used to confirm the good behaviour of the model. The work carried out validates the model and demonstrates the usefulness of dynamic modelling tools to solve complex thermal situations like the case of energy demand in indoor swimming pools. The proposed model results in an accurate method to estimate heating demand, giving a mean error of − 1.77%. The new dynamic simulation model has also served to do a sensitivity analysis of the energy demand in relation with the main control parameters of the facility, recommending set points for a more efficient work of these facilities. [ABSTRACT FROM AUTHOR]

In recent years, pump-as-turbines (PATs) have been highlighted for their potential benefits as an application of micro-hydropower (MHP) in water distribution networks. However, PATs come with disadvantages of relatively low peak efficiencies, which can be reduced further with large flow fluctuations. MHP and PATs in particular applied in irrigation networks is a relatively new area of research focus for these devices, and one that poses significant opportunities for energy saving as well as significant challenges due to variations in flow rate. This paper discusses the validation of a statistical methodology to estimate the flow and head variability in a network, and to select PATs whose best efficiency point (BEP) returns the lowest payback period. A comparison between the predicted and actual occurrence probabilities for different flow rates was carried out at nine potential points for MHP installation identified within a real network in Southwestern Spain. For the flow occurrence probability, the coefficient of determination (R2) of 0.804. A total of 281.0 MWh were obtained from the flow prediction and PAT selection methodology, in contrast to 230.5 MWh using the actual measured data. An overall difference of 0.2% was obtained when both PATs were simulated under actual conditions. • The validation of a methodology for flow prediction and pump as turbine selection was carried out. • An average coefficient of determination of 0.804 was obtained for flow occurrence probability. • Difference of 22% on the energy recovery potential with predicted and actual conditions. • Difference of 0.2% was found when predicted pump as turbines were tested under real conditions. • In comparison to alternative approaches, this methodology represents a 7.4 and 38% improvement in accuracy. [ABSTRACT FROM AUTHOR]

This paper presents the technical, environmental, and economic evaluation of integrating various combinations of renewable energy sources-based systems in the expansion of a district heating and cooling network of a Technology Park near Barcelona in Spain. At present, a combined heat and power plant running on fossil fuels serves the heating, cooling, and electricity demand of the Park. However, this energy demand is expected to increase substantially in the coming years. EnergyPRO software was used to model the energy demand growth till 2030. Validation of the software application was done by making a base model using real plant data from the year 2014. The software was then used to project the energy supply based on three 15-year scenarios, having different combinations of renewable energy technologies, from 2016 until 2030. Primary energy consumption, CO2 emissions, and the net present value obtained in each scenario were used to decide the best combinations of renewable energy sources. The results of the study showed that presently, biomass boilers combined with absorption chillers and supported with solar thermal cooling are the most competitive technologies in comparison to ground source heat pumps for large DHC networks. This is mainly because of the lower primary energy consumption (624,380 MWh/year in 2030 vs. 665,367 MWh/year), higher net present value (NPV) (222 million € vs. 178 million €), and lower CO2 emissions (107,753 tons/year in 2030 vs. 111,166 tons/year) obtained as a result of the simulations. [ABSTRACT FROM AUTHOR]

This paper explores whether the changes in energy intensity in Spain have led to improvements in the energy consumption levels or to a backfire effect offsetting the expected decrease. Jevon's paradox or backfire effect happens when a rebound higher than 100% causes energy efficiency improvement to raise energy consumption. To test Jevon's paradox or the backfire effect caused by energy efficiency actions, a Logarithmic Mean Divisia Index I (LMDI-I) is used for the Spanish economy. The period under consideration ranges from 2000 to 2015, when three national action plans were implemented. The main methodological novelty of this paper consists on to block the economic activity effect in a second decomposition round to better explore the effect of energy efficiency on energy consumption. As a whole, our results do not support Jevon's paradox for the sectors analyzed. However, they do warn about a possible backfire effect in the industry, transport and service sectors. Major findings follow these same findings when the activity effect is blocked. • Backfire effect caused by energy intensity is explored. • Focus is on the Spanish case from 2000 to 2015. • Main methodological novelty is to block the economic activity in a LMDI approach. • Results do not support Jevon's paradox for the sectors analyzed. [ABSTRACT FROM AUTHOR]

The energy retrofitting of residential stock is not always straightforward where heritage protected housing is concerned. In southern Europe, many examples built under the Modern Movement codes are now obsolete in terms of energy efficiency. The aim of this paper is to assess the potential for improvement of comfort conditions and energy efficiency in Mediterranean heritage residential buildings, through the incorporation of passive strategies in keeping with preserving heritage values. Long-term monitoring and field tests in representative flats of the case-study building were carried out and, focusing on a single example, adaptive comfort equations were used to assess results. The passive strategies considered are the thermal isolation of the air cavities of walls, changing window frames, optimizing window glazing, and setting up regular mechanical ventilation rates for indoor air changes. Although simulation results generally predict a better energy performance after testing retrofit strategies, the potential decrease in energy demand is more noticeable than the potential improvement in comfort conditions. • The improvement of comfort and energy efficiency in a heritage building is assessed. • Long-term monitoring and field tests were carried out in representative flats. • Passive strategies in keeping with preserving heritage values were examined. • Adaptive comfort equations were used to assess results focusing on one flat. • Energy efficiency improvements are more noticeable than those of comfort conditions. [ABSTRACT FROM AUTHOR]

The low energy efficiency of the European building stock is both a social and environmental issue. However, plans and studies on energy retrofitting interventions do not usually evaluate the impact of these measures on households' energy affordability. This paper analyses and compares the effect of alternative retrofitting strategies on thermal energy services' affordability in Spanish vulnerable households. This analysis was carried out by applying the Required Thermal Energy Expenditure model proposed in previous studies to several 2030 residential building stock scenarios, setting 2020 as a baseline. Therefore, this work proposes a methodological approach to assess the impact of the considered energy efficiency interventions on energy poverty in winter (WEP) and summer (SEP) and carries out both a 'social cost' and a cost-benefit analysis. The dwelling's thermal-enclosure retrofitting stands out as a very WEP-reduction and social-cost effective measure. Instead, replacing old thermal systems with more efficient ones would have a higher impact on SEP. Combining both kinds of retrofitting measures could reduce heating and cooling required expenditures by, respectively, 49% and 59%, and decrease the WEP and SEP share, correspondingly, by 35% and 63%. These results might inform policymakers to enhance the targeting and design of energy efficiency programs. [ABSTRACT FROM AUTHOR]

• Advanced climate-resilient energy retrofit technology reduces the use of non-renewable energy in the building sector. • Renewable District Heating as an optimal technology in deep energy renovation strategies. • Sustainable cities and buildings are feasible by Centralised District Heating system powered by biomass. • Key Performance Indicators (KPIs), to achieve nZEB performances established in the European legislations. This paper presents the implementation of a biomass-fuelled District Heating System (DHS), as a part of a deep energy renovation exercise to achieve a climate-resilient campus with minimum carbon dioxide emissions. The case study is carried out for the University of Valladolid, an average-sized university in Spain, with a continental weather climate. Prior to renovation, the different building blocks had a wide-ranging level of fossil fuel consumption for space heating and domestic hot water ranging between 60 and 430 kWh/m2·year. The application of this centralised heating system allows to achieve the minimum threshold for near zero-energy buildings (nZEB) of 100–120 kWh/m2, in accordance with the Spanish Standards. These values correspond to the maximum European indicators for offices in continental weather conditions. Results of this comprehensive study show that 15 out of the 19 buildings reached the nZEB target, due to the proposed strategy. The overall carbon dioxide emissions have dropped by 92.69% as compared to the original fossil-fuel powered boiler, thus bringing carbon dioxide emissions down to 1.57 kgCO 2 /m2·y. Therefore, it is shown that deep energy renovation strategies through renewable energy DHS have the potential of achieving nZEB for universities in continental weather conditions. [ABSTRACT FROM AUTHOR]

• The Stanford Energy System Innovations plan is adapted to a university in Valencia. • Waste heat recovery from a large data centre is used to heat campus buildings. • A polyvalent heat pump that can simultaneously provide cooling and heating is used. • Thermal energy and emission savings of more than 64% in three campus buildings. • The findings help to promote similar studies in Mediterranean universities. In this research work, the Stanford Energy System Innovations action plan is adapted to the decarbonization of the Universitat Politècnica de València, of the Mediterranean coast of Spain. Special focus is dedicated to waste heat recovery from a data centre located on campus with an almost constant cooling demand throughout the year, amounting to a yearly 1,661,020 kWh. To recover the waste heat generated by the data centre, a method for assessing thermal performance of the system is presented, which is implemented by selecting a 300 kW polyvalent heat pump (capable of easily switching from water-to-water to air-to-water working modes). It can simultaneously provide cooling and heating to a set of strategically identified buildings on the campus: the university data centre and three buildings located nearby that currently use the university's central natural gas boilers for heating. A thermal storage system is designed to balance the cooling and heating needs. The results lead to potential thermal energy savings of more than 254,106 kWh/year, and a consequent reduction in CO 2 emissions of at least 64,035 kg/year, supporting the decarbonization of the Vera campus. The outcomes of the study can help to design similar research projects applied to large data centres in Mediterranean cities. [ABSTRACT FROM AUTHOR]

This paper presents a study of the thermal performance of a single-family house located in a coastal city in northern Spain that was built according to Spanish standards during the 1990s. The study estimates an annual energy demand of around 95 kWh/m 2 and a thermal power rating of the heating system of around 16 kW. The potential energy savings that would be obtained by implementing different retrofitting measures frequently used nowadays are also quantified: installing a ventilation system with heat recovery, improving the insulation of opaque construction elements, replacing the existing windows with high-thermal performance windows, and reducing air infiltration rates. These integrated actions on the house would reduce the annual energy demand below the requirements of both the Technical Building Code (24.24 kWh/m 2 year for this case of study), which is the regulation currently in force in Spain, and the well-known Passivhaus standard (15 kWh/m 2 year), which is one of the most widespread building standards in Europe. Compliance with these requirements means that the annual energy demand and the size of the heating system would respectively be potentially reduced by 81% and 57% of the present values. [ABSTRACT FROM AUTHOR]

The definition of the term gastronomy encompasses both the knowledge of food and its handling, preparation and consumption. Beyond a sense of cultural identity and tradition, gastronomy also represents a pole of tourist attraction. This is the case of Galicia, a region in north-western Spain. Within this framework, local dishes, which include distinctive elements of the Atlantic diet, have gained popularity. This research delves into the sustainability of 60 Galician recipes by performing a hierarchical cluster analysis to study their carbon footprint, the energy return on investment ratio and cost. The life cycle assessment methodology was followed to account for the carbon footprint and the energy return on investment ratio of the recipes. The scope was bounded to the cradle-to-fork phases through the life cycle: production of the ingredients, transport, and meal preparation. The functional unit selected was one serving of a Galician meal. The results suggest that the recipes could be classified into three main groups according to the presence of a greater or lesser amount of animal-based products. Cluster 1 comprises 10 meat recipes. Cluster 2 encompasses 31 recipes rich in fish with some vegetables and moderate consumption of red meat and dairy products. Cluster 3 includes 22 vegetable-based recipes. The higher the portion of animal products in the recipes (mainly red meat), the higher the costs and carbon footprint and the lower the energy return on investment ratio. Conversely, plant-based recipes tend to reduce greenhouse gases emissions and increase cost competitiveness and energy efficiency indicators. Based on this study, the food service could promote eco-labelling that support and certify restaurant menus. This research could also provide transformative climate education for sustainable food for consumers, giving advice to improve food-based dietary guidelines in Spain. • Analysis of the carbon footprint, energy consumption and cost of Atlantic recipes. • Recipes can be classified into three hierarchical dietary clusters. • Cluster 1 comprises meat recipes with low energy return on investment ratio and high carbon footprint and economic cost. • Cluster 2 comprises recipes rich in fish with vegetables and moderate meat. • Cluster 3 includes low-cost and low-carbon vegetable-based recipes. [ABSTRACT FROM AUTHOR]

In this paper, a case study of performing a reliable statistical procedure to evaluate the quality of HVAC systems in buildings using data retrieved from an ad hoc big data web energy platform is presented. The proposed methodology based on statistical quality control (SQC) is used to analyze the real state of thermal comfort and energy efficiency of the offices of the company FRIDAMA (Spain) in a reliable way. Non-conformities or alarms, and the actual assignable causes of these out of control states are detected. The capability to meet specification requirements is also analyzed. Tools and packages implemented in the open-source R software are employed to apply the different procedures. First, this study proposes to fit ARIMA time series models to CTQ variables. Then, the application of Shewhart and EWMA control charts to the time series residuals is proposed to control and monitor thermal comfort and energy consumption in buildings. Once thermal comfort and consumption variability are estimated, the implementation of capability indexes for autocorrelated variables is proposed to calculate the degree to which standards specifications are met. According with case study results, the proposed methodology has detected real anomalies in HVAC installation, helping to detect assignable causes and to make appropriate decisions. One of the goals is to perform and describe step by step this statistical procedure in order to be replicated by practitioners in a better way. [ABSTRACT FROM AUTHOR]

The Spanish residential building stock built between 1940 and 1980 period presents a high energy saving potential as it represents a significant percentage of the total housing stock and it was built without any regulation regarding energy efficiency. Accordingly, the first aim of this paper was to quantify the energy saving potential and the related reduction in CO 2 emissions of the housing stock in those years. The work focuses on the Mediterranean climate of the Comunitat Valenciana Region, therefore the energy efficiency strategies proposed are passive and deal with the envelope of buildings. On the basis of the results obtained, several scenarios with intervention periods of 10, 20 and 30 years were calculated. The conclusion was that with the current rate of annual building renovation, it will be nearly impossible to reach the goals established by the EPBD. Only a deep transformation of the building fabric within this sector could help in achieving them. Finally, it should be noted that the proposed methodology can be applied to other areas with different climates, particularly in Spain. [ABSTRACT FROM AUTHOR]

• A DCE is conducted to assess households' willingness to insulate their homes. • Determinants for the adoption of façade thermal insulation are identified. • The investment cost required in the existing building stock is below the obtained WTP. • The required subsidy level is lower than the grants set by existing aid programs. • Increased tax rebate has greater incentive effect than soft financing. This paper assesses Spanish households' willingness to thermally insulate their homes and the drivers that influence such a decision-making process. Stated preference data were collected through a discrete choice experiment (DCE). The final sample of 191 respondents and 1,145 observations was analysed by the use of a mixed logit model, weighing the factors that encourage homeowners to carry out façade energy renovations or not. The model enables the quantitative estimation of renovation adoption rates depending on the households' characteristics and public support instruments in place. The results show that homeowners are extremely interested in increasing the thermal insulation of their homes. The actual investment cost required in the existing building stock is lower than the obtained willingness-to-pay. Furthermore, it was found a relevant effect of a variety of household features on renovation choice (income, age, heating system, etc.), which should be contemplated in the energy efficiency policy design. Additionally, a case analysis is performed which comprises 3 household categories. The results reveal that the required subsidy level is different in each case, sometimes even unnecessary, although all of them lower than the grants set by existing aid programs. Thus, to reduce the free-riding effect, a closer perspective would enable targeted support mechanisms towards each household category. Moreover, the policy performance can be improved by combining subsidies with other measures such as low-interest loans or increased tax rebates, which could contribute to improving the cost effectiveness of the public expense associated with direct grants. Overall, an increased tax rebate is preferred to soft financing, although the influence of the latter increases in low-income households. [ABSTRACT FROM AUTHOR]

Designing a low energy building requires to evaluate a large number of parameters: design combinations, element thermal characteristics, HVAC systems efficiencies, etc. All of them determine the space heating and space cooling energy demands, energy consumptions, and life cycle cost over the lifetime of the building. This paper presents the achievements of SEDICAE research project consisting on a new methodology based on a tabu search and a simplified method to calculate energy consumptions. The methodology is designed to estimate the annual energy demand, life-cycle cost and energy rating. A second process is included to select the HVAC system is developed for the building designed with this methodology. In general, builders should look for low energy, but investment in building design is a limiting factor. This paper show the relationship between energy efficiency index and investment in optimized residential building. Furthermore, the best energy rate is obtained applying the HVAC systems in the integrated optimization method for residential buildings. This methodology reduces investment, reduce the energy demand and selects the best construction materials, allowing to study the cost in different economic scenarios. In this paper, a building design case study is studied in 2028 scenarios in 12 climatic zone in Spain. [ABSTRACT FROM AUTHOR]

Owing to its strategic nature, the Spanish energy policy is primarily the responsibility of the central state. In spite of this, the Spanish legal code does in fact also confer certain powers to territorial governments in Spain, the Autonomous Communities. The objective of this work is specifically to investigate the differences between the energy performance of Spanish regions, which may be a consequence of specific features of their productive structures and resource endowments, in addition to the specific decisions adopted by each of them within the scope for action that they have in this area. With this aim in mind, we intend to calculate the inefficiency levels of Spanish regions as regards their use of various energy sources during the period 2003–2008, by estimating an environmental directional distance function. The results obtained confirm the existence of significant differences in the behaviour and evolution of regional energy efficiency and point to the need to pay more attention to energy planning in this territorial sphere. [ABSTRACT FROM AUTHOR]

The total energy demand of data centres has experienced an important increase in the last years. This is why data centres industry and researchers are working on implementing energy efficiency measures in data centre portfolio. The cooling system of these unique infrastructures can account for 40% of the total energy consumption. Therefore, air management plays an important role to reduce operating costs and to increase overall cooling system efficiency. In order to improve and optimize the energy consumption and thermal management in data centres, appropriate metrics are imperative to evaluate their efficiency and performance. The present paper examines the air management of a real data centre by the use of the most promising air metrics. Noticeable air recirculation and hot spots were observed in the facility. Dynamic modelling was used to evaluate the benefit of air inefficiency mitigation. The combination of air management improvement with increasing the supply air temperature and reducing the air flow rate would allow important energy reduction in the cooling system. [ABSTRACT FROM AUTHOR]

Approval of the European Directive 2002/91/EU was followed by its reformulation in Directive 2010/31/EU, with reference to the Energy Performance of Buildings (EPBD). The partial transposition of this norm in Spain took place through Royal Decree 235/2013, which describes the Basic Procedure for the Energy Performance Certification of Buildings and acknowledges four different documents to certify the energy simulation of buildings: (i) CALENER VYP as the general method, and (ii) CE3, CEX and CERMA, as simplified methods. This study analyzes and compares these documents through the qualified opinions of a panel of 105 multidisciplinary professionals of the sector that determined the strengths and weaknesses. To this end a survey was drawn up, including aspects as diverse as: the background and professional characteristics of the experts, the types of residences studied, the characteristics of the documents, the means of processing documents, and the final results in terms of reports and energy certifications. Data analysis shows that most technicians prefer using programs with a simple interface—namely, the CEX. Although all the documents recognized are equally valid for energy certification, when certain types of residence are involved, there may be as much as a 26% difference in the determination of CO 2 emissions. This translates into a higher or lower level in the final energy certification obtained for a building. [ABSTRACT FROM AUTHOR]

Minimizing energy consumption in buildings is one of the priorities of the European Union energy strategy. The European legislation has defined a legal framework to determine the energy qualification of a building that is used by each of the member states to define its own energy qualification procedure. This paper presents a methodology to evaluate the effect of climate conditions in the energy qualification procedure. It evaluates the effectiveness of the qualification in representing the yearly energy demand and \CO2 emissions. Moreover, it determines the effects of improvements in different parameters of the procedure (e.g., the construction materials of the enclosure, thermal installations, etc.) in order to improve qualifications. It has been applied to the Spanish legislation using a series of simulations of a typical domestic building, with climatic data from different zones of the Spanish territory. The most significant results are the similarity in the energy certification values obtained in all scenarios and the lack of concordance between the energy rating scale, energy consumption, and \CO2 emissions. [ABSTRACT FROM PUBLISHER]

Centre pivots are one of the most widespread irrigation systems in the world. The aim was to develop a tool to optimise the design and management of the water distribution and centre pivot systems seeking to minimise water application cost per unit area ( C T ), including investment ( C a ), operation ( C e ), and maintenance costs. With this aim, two options were considered: to feed the centre pivot 1) directly from an aquifer or 2) using a regulation reservoir. A software tool DEPIRE (design of centre pivot with regulating reservoir), was developed and implemented in MATLAB 2012b (The MathWorks Inc., Natick, MA, USA). It determines optimal flows, pipe diameters, pumps power and the volume of the regulation reservoir for any crop water requirement, different electricity rates and water availability in the tube well. With this tool, the effect of the irrigated area ( S ), dynamic water level (DWL) in the aquifer and the pumping flow rate on the C T was evaluated for a maize crop in Spain. The study area representing the minor C T was 70 ha for direct pumping from the borehole and 100 ha when using an intermediate reservoir. Incorporating a regulation reservoir generates lower C T than direct feed from the borehole for S > 100 ha for any DWL. C T increased linearly with the DWL due to a significant increase in C e which primarily affects the cost of water extraction from the aquifer, with a smaller effect on the application cost of the irrigation system. [ABSTRACT FROM AUTHOR]

Residential end-uses represent a significant share of final energy consumption and material stocks. However, approaching sustainability of the residential sector merely as an environmental technical problem is insufficient. Home is the center of daily life providing essential functions to people. Household metabolism is not a matter of the sum of individual behaviors, typologies of buildings, or energy uses stripped out of context, but the system that emerges from the historical combination of these elements and the functions it performs. The residential sector comprises both families (units of organized individuals) and dwellings (within municipalities/urban forms). To analyze these dynamics, we draw upon practice theory and Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) illustrating with data from Sweden and Spain in 2015. The objective is to establish an interdisciplinary framework for analyzing the sustainability of the residential sector. We also present a list of possible measures and their trade-offs in diverse dimensions: energy carrier consumption and greenhouse gas emissions, materials, floor area, human activity, social organization and institutions, finance and desirability. Even though the inclusion of all variables in a single model is not feasible, the holistic understanding of household metabolism can help build coherent anticipation scenarios by selecting plausible hypotheses. Ultimately, this allows making profound transformations to sustainability. • Sustainability of the residential sector must be approached in an interdisciplinary way. • We provide an exhaustive review of measures and their trade-offs. • Energy, materials, emissions, social organization and desirability play a role. • The boundary of the residential sector moves when functions are addressed in services. • Social practices and household units affect performance and layout of dwellings. [ABSTRACT FROM AUTHOR]

Buildings are one of the most important energy consumers worldwide and heating requirements are usually achieved using fossil fuels. This situation poses a risk to achieving the objectives for emissions reduction in existing buildings and electrification, based on heat pumps. It is one of the most feasible solutions to achieve emissions reduction objectives. Current research analyzes the potential for decarbonization of heat pumps and uses the Spanish scenario as a novel case study, where 8.5% of carbon dioxide emissions into the atmosphere came from the residential sector, with 66% of the energy consumption associated with cooling and heating. Using EnergyPlan the potential of decarbonization using heat pumps or heating systems in existing buildings and installing this technology in new buildings is analyzed. Results show a reduction of 8.43% in total emissions and prove that the proposed methodology can be extended worldwide as a solution to reduce emissions and improve energy efficiency in existent heating systems in buildings. Moreover, the integration of electrical climatization systems allows increasing the renewable electricity share in the grid or electrical vehicles integration, among others. [Display omitted] • Heating in existing buildings using Natural Gas difficult decarbonization. • Building heating systems decarbonization poses a risk to achieve 2050 objectives. • EnergyPLAN to study potential of heat pumps for heating decarbonization in Spain. • Results show 8.43% greenhouse gases reduction and include an implementation roadmap. • The methodology and solution can be applied worldwide in existent and new buildings. [ABSTRACT FROM AUTHOR]

Street lighting has a big impact on the energy consumption of Spanish municipalities. To decrease this consumption, the Spanish government has developed two different regulations to improve energy savings and efficiency, and consequently, reduce greenhouse-effect gas emissions. However, after these efforts, they have not obtained the expected results. To improve the effectiveness of these regulations and therefore to optimize energy consumption, a study has been done to analyze the different devices which influence energy consumption with the intention of better understanding their behavior and performance. The devices analyzed were lamps, ballasts, street lamp globes, control systems and dimmable lighting systems. To improve their performance, they have been analyzed from three points of view: changes in technology, use patterns and standards. Thanks to this study, some aspects have been found that could be taken into account if we really wanted to use energy efficiently. [ABSTRACT FROM AUTHOR]

In this paper, the energy benefits of switchable insulation systems (SIS) are assessed when applied as shades for windows as well as dynamic insulation for exterior walls of residential buildings located in European countries including Belgium and Spain. A series of analyses is performed for detached houses and apartments representing common Belgian residential buildings to determine the energy performance of SIS when deployed to windows and exterior walls and operated using simplified rule-based controls. The analysis results indicate that SIS-integrated windows can achieve significant energy savings for both dwelling types in Belgium, including the elimination of any mechanical cooling and a reduction of up to 44% of heating energy end-use. Moreover, the results show that SIS can offer even more energy efficiency and thermal comfort benefits when deployed to both windows and exterior walls for residential buildings. These energy efficiency benefits are higher, especially for reducing heating needs, for the milder climates of Belgium and Spain. However, it should be noted that the energy performance of SIS could be affected substantially by windows' orientation and occupants' behavior. [ABSTRACT FROM AUTHOR]

The energy performance of a building located in La Roca del Vallès, close to Barcelona in Spain designed under the near Zero Energy Building (nZEB) and Net Zero Energy Building (NZEB) criteria was investigated. The aim was to introduce entropy generation rate as a magnitude to describe energy efficiency in buildings. This was achieved by studying the energy and entropy balances using a commercial energy performance simulation software for different scenarios proposing different efficiency conditions. The annual energy and entropy flow balances cancel. Entropy generation was due to heat losses through the envelope, sun irradiance, appliances, lighting and occupation of the building. The building designed following nZEB criteria was compared with the same building with poorer energy performance. The first one generated 45,834 kJ K−1 while the second one generated 79,985 kJ K−1. This is an important result because with a single magnitude, entropy generation, we combine the impact of all energy transformations taking place in the building. Sun irradiance is found to be the most important entropy generation source: a building with sun irradiance can generate nearly 3.4 times more entropy than a shadowed building. Finally, we evaluated the generated entropy ratio between the transferred entropy to the environment in terms of Gouy-Stodola theorem and the cumulated entropy that contributes to building degradation. Although cumulated degradation entropy is well below the threshold of building collapse, practical degradation effects in the building were shown. Entropy balance of a building from energy transformations in the building. [Display omitted] • Evaluation of energy and entropy balance of buildings in terms of Gouy-Stodola theorem. • Introduction of entropy generation as a magnitude to describe energy efficiency in buildings. • Relationship between entropy generation and building degradation. [ABSTRACT FROM AUTHOR]

• The study fills a gap in literature by breaking down the energy rebound effect. • The Spanish economy is taken as a case study. • The Direct Rebound Effect explains around 10% of the total effect. • Indirect Rebound Effect values range between 1.2% and 1.8%. • Economy-wide Rebound Effect values range from −4.51% to 128.45%, with no clear trend. The rebound effect caused by energy efficiency improvements demands greater attention from energy policymakers as it represents an important obstacle to energy consumption reduction measures. Despite the emerging literature about the rebound effect, no studies to date have managed to break down it. To do so, this study introduces the disruptive innovation of replacing the Logarithmic Mean Divisia Index method used in previous literature with Structural Decomposition Analysis. Based on Input-Output tables, a re-spending model allows us to assess the Indirect Rebound Effect for 14 productive sectors. Finally, Structural Decomposition Analysis enables us to determine the Economy-Wide Rebound Effect caused by energy efficiency improvements. As far as we are aware, no other study to date has done so. Spain is used as a case study for the 2000–2014 period. Major findings indicate that total rebound effect varies from nearly to 10% to around 50%. The part of rebound explained by Direct rebound effect is around 10%. Indirect rebound effect shows values between 1.2% and 1.8%. Finally, Economic wide rebound effect varies from −4.51% to around 40% but without showing a clear trend for the period considered. The novelty of this study is that it attempts to break the overall rebound effect down to the direct, indirect, and economic wide rebound effect by combining the Cobb-Douglas production function and decomposition techniques. [ABSTRACT FROM AUTHOR]

We estimate the energy consumption of toll highway transport on a number of Spanish roads. Regression parameters are balanced according to coefficients from an empirical analysis based on survey data by vehicle type. The mean energy consumption and subsequent CO 2 emissions on the toll highway sections are estimated as 1895 MJ/h/lane-km and 0.15 tCO 2 eq./h/lane-km, values that increase to 2644 and 0.22 when energy and carbon emissions of transport infrastructure are considered based on the life cycle energy consumption for toll highway construction and use. If the energy intensity of infrastructure construction is allocated to the users according to traffic, it is much higher for motorcycles than for cars, and is significantly lower for articulated trucks than for vans. [ABSTRACT FROM AUTHOR]

Abstract: Pressurized irrigation networks require large amounts of energy for their operation which are linked to significant greenhouse gas (GHG) emissions. In recent years, several management strategies have been developed to reduce energy consumption in the agricultural sector. One strategy is the reduction of the water supplied for irrigation but implies a reduction in crop yields and farmer's profits. In this work, a new methodology is developed for sustainable management of irrigation networks considering environmental and economic criteria. The multiobjective non-dominated Sorting Genetic Algorithm (NSGA II) has been selected to obtain the optimum irrigation pattern that would reduce GHG emissions and increase profits. This methodology has been applied to Bembézar Margen Derecha (BMD) irrigation district (Spain). Irrigation patterns that reduce GHG emissions or increase actual profits are obtained. The best irritation pattern reduces the current GHG emissions in 8.56% with increases the actual profits in 14.56%. Thus, these results confirm that simultaneous improvements in environmental and economic factors are possible. [Copyright &y& Elsevier]

The energy-saving strategies and operational costs of stand-alone, hybrid, and dual stream full-scale membrane bioreactors (MBRs) with capacities ranging from 1100 to 35,000 m3 day−1 have been assessed for seven municipal facilities located in Northeast Spain. Although hydraulic load was found to be the main determinant factor for the energy consumption rates, several optimisation strategies have shown to be effective in terms of energy reduction as well as fouling phenomenon minimization or preservation. Specifically, modifications of the biological process (installation of control systems for biological aeration) and of the filtration process (reduction of the flux or mixed liquor suspended solids concentration and installation of control systems for membrane air scouring) were applied in two stand-alone MBRs. After implementing these strategies, the yearly specific energy demand (SED) in flat-sheet (FS) and hollow-fibre (HF) stand-alone MBRs was reduced from 1.12 to 0.71 and from 1.54 to 1.12 kW h−1 m−3, respectively, regardless of their similar yearly averaged hydraulic loads. The strategies applied in the hybrid MBR, namely, buffering the influent flow and optimisation of both biological aeration and membrane air-scouring, reduced the SED values by 14%. These results illustrate that it is possible to apply energy-saving strategies to significantly reduce MBR operational costs, highlighting the need to optimise MBR facilities to reconsider them as an energy-competitive option. [Copyright &y& Elsevier]

Spain is heavily dependent on foreign energy. As such the main objectives of Spanish energy policy should be focused on guaranteeing a long-term energy supply and the provision of mechanisms to allow the fixing and awareness of energy prices in a reasonably reliable manner. This article is the first of two in which the author examines the energy policies prevalent in this country and establishes the action to be carried out to guarantee long-term energy supply. [ABSTRACT FROM AUTHOR]

Abstract: The first objective of this paper is to map the adoption of technologies for the reduction of energy and resource consumption in production and the second is to test the relationship between the implementation of those technologies and the performance of manufacturing firms. The aim is to contribute to the identification of the characteristics of the manufacturing firms that use this kind of innovative technology in order to help policy makers promote energy and resource efficiency in a suitable manner. Our research is based on the Spanish and Slovenian subsamples of a wider European Manufacturing Survey. Our suggested models explain how significant energy efficiency is, and how much of the variability in economic performance and environmental performance it can explain. The results show that the use of energy and material saving technologies does not have a clear and significant relationship with economic performance. On the other hand a significant positive relationship is found between energy and material saving technologies and environmental performance. [Copyright &y& Elsevier]

• A systematic literature-approach to classify retrofitting is proposed. • An overview of Spain's previous guidelines on residential retrofits is presented. • A review of financial and subsidies mechanisms in Spain to renovate buildings is introduced. • A literature-based matrix on retrofitting actions is presented. • A classification of energy efficiency strategies for retrofitting is proposed. The building sector is responsible for more than 40% of final energy consumption in Europe; consequently, retrofitting existing buildings can significantly contribute to mitigate greenhouse emissions. Nevertheless, although the European Union has introduced relevant policy instruments, up to now the annual retrofit rates are considerably low with an average of 0.2% at European level. Understanding the past would support the success of the new strategies, such as the recent ones launched through the New Green Deal, which reinforces the importance of renovating existing buildings stock, as the main aim of the renovation wave. As a starting point for assessing the main challenges to allocate the Recovery funds, this paper provides a review of Spain's relevant literature to clearly define the characterization of the existing building stock, which actions have been typically considered under the scope of retrofits, and which strategies have been implemented until now, considering both, private and public initiatives and public financial schemes. The present work has a strong focus on energy-related strategies, although other interrelated actions are mentioned, such as accessibility measures and interior refurbishment of dwellings. Differences and similarities within these approaches are presented through the analysis of 27 relevant references of retrofitting actions and 52 references of financial mechanisms. As in Spain 93% of multifamily buildings were constructed prior to the national transposition of the first Energy Performance Building Directive (EPBD), and therefore are in need of deep energy renovations, the retrofitting of multifamily buildings topic has been widely addressed, even though often in a disjointed manner. The study suggests that although historically there have been several recommended strategies, few are conceived as integral actions, only 15% of the intervention packages refer passive and active energy-related measures and renewable energy incorporation. Furthermore, considering the antiquity of the building stock and the advantage of addressing the topic through clusters, only 63% of the resources directly refer these actions to specific clusters among the six distinctive periods, although in most cases focusing their recommendations on buildings constructed before 1980 where the worst energy performance buildings are concentrated. Concerning public financial and funding instruments, the research illustrates that there has been a substantial increment of programs over the last years promoting energy-related measures, renewable energy and other complementary aspects such as accessibility and interior renovations, mainly for older clusters. Nevertheless, the funds constitute only 8% of the necessary declared investments, which along with the dispersion between the different procedures and the complexity of the processes, have significantly reduced the global impact of these actions without generating robust and oriented market dynamics. Despite the several resources found, both financial instruments and guidelines tend to describe in more detail strategies related to heating demand and consumption and not delve into other relevant actions for warmer climates, fact associated both to the dynamics coming from other countries, and to a vision of the past in which people do not consume refrigeration. This clear focus on heating loads rather than cooling could present limitations for warmer regions in the near climate-change future. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to map the adoption of technologies for energy reduction and resources consumption in production. The aim is also to contribute to the identification and understanding of the characteristics of the manufacturing firms that use these kinds of energy and material saving technologies. Our research is based on data from the largest European manufacturing survey to date and it includes data from Spain and Slovenia. The results show that the use of specific energy saving technologies and material saving technologies in manufacturing firms is still modest. Dividing manufacturing firms based on technology intensity sectors and based on their relative energy efficiency we have concluded that firms in high technology industries focus less on energy efficiency than low technology firms. Some other specific relationships between the use of energy efficient technologies and adopters' characteristics (e.g. use of environmental management systems) are presented in this paper. [ABSTRACT FROM AUTHOR]

Abstract: Nowadays, our dependence on electricity is strong because power consumption has increased considerably in the last years. For that reason, an efficient use of electricity is necessary, especially in public buildings. In order to manage the power consumption, it is vital to measure and monitor the electrical systems. Monitoring can provide advanced visualization and data analysis tools which can help us to achieve energy savings and peak power optimization. In this work, we present a power monitoring system developed for the campus buildings at the University of León (ULE) in Spain. This system is based on a three-layer structure. In the server layer, data are acquired from meters installed in the campus buildings. In the middle layer, data are stored and processed. In the client layer, monitoring interfaces, accessible remotely through the Internet, provide both traditional and advanced monitoring tools, based on statistical and data mining techniques. These techniques exploit data in order to find electrical patterns, detect faults and deviations, predict future power consumption, optimize peak power, etc. The data acquired by the monitoring system during 2010 are analyzed. The results from the visualization and data analysis tools, implemented in the monitoring system, are presented. The application of the proposed tools led to economic savings of around 15% and deeper knowledge about the electrical system. [Copyright &y& Elsevier]

Abstract: A method for determining the total heat loss coefficient, the effective heat capacity and the net solar gain of a building is presented. The method uses a linear regressions approach based on daily energy consumption combined with readily available meteorological data. The effective heat capacity of the building is evaluated by correlating the energy consumption and outdoor temperature changes from the previous day. The net solar gain of the building is assessed by analysing the data separated into groups by amount of daily solar irradiation. Corrected total heat loss coefficient is determined by explicitly including in the building''s energy balance the accumulated heat and the solar gain. The method has been applied to the analysis of nine public buildings in Spain. An improvement of the estimated heat loss coefficient due to the corrections is observed. The effective heat capacity normalised by the building area is shown to be a useful indicator of the building operation, detecting continuous or intermittent heating. The estimated parameters in this study can enable specific benchmarking, detecting opportunities for energy savings and evaluating their potential. With the increasing implementation of smart metering technologies, the method is promising for application to the analysis of large building stocks. [Copyright &y& Elsevier]

This work evaluates the potential for the reduction of energy demand in residential buildings by acting on the exterior envelope, both in newly constructed buildings and in the retrofitting of existing stock. It focuses on analysing social housing buildings in Mediterranean areas and on quantifying the scope of that reduction in the application of different envelope design strategies, with the purpose of prioritizing their application based on their energy efficiency. The analyses and quantifications were made by means of the generation of energy models with the TRNSYS tool for simple or combined solutions, identifying possible potentials for reduction of the energy demand from 20% to 25%, basically by acting on the windows. The case study was a newly built social housing building of a closed block type located in Seville (Spain). Its constructive techniques and the insulation level of its envelope are standardized for current buildings widespread across Mediterranean Europe [ABSTRACT FROM AUTHOR]

Abstract: Energy consumption in buildings accounts for a significant percentage of total world energy utilization. Great efforts have been made in order to reduce fossil energy consumption and mitigate its depletion by means of energy efficiency directives. The national transposition of such directives generates regional regulations that might be counterproductive if it is not clear which one is more restrictive. The main goal of this paper is to evaluate the potential of energetic savings of the dwellings in Catalonia and its economic impact, according to different scenarios of efficiency that have been defined according to current regulations at state and autonomic level. To achieve this objective, thirteen typologies of dwellings have been defined in order to categorize the stock of buildings in Catalonia. Simulations with LIDER software have been carried out in order to obtain the heating and cooling demand for each typology of dwelling in different climatic zones and orientations. The economic impact of each scenario has been stated as well. We show that the best normative scenario is not the regional but the national one, and only when full limitations imposed by the state regulations are fulfilled. Following the latter 6.4% reduction in CO2 emissions would be achieved, whereas following the former gives us only 2.8% reduction for year 2015. These results have been obtained considering a base case scenario without any energetic measures implemented for the same time line. [Copyright &y& Elsevier]

The present work is aimed at evaluating the results obtained during the first year of operation of a public building with high energy rating in Extremadura (a southwest Region of Spain), which it puts into practice techniques on saving and energy efficiency in buildings and renewable energy integration. The building has been built taking into account the climatic conditions of the city of Mérida (Spain), applying concepts of passive solar collection and thermal insulation, shading of windows and roofs, using natural lighting and technologies based on the integration of renewable energy. The results shows that it is possible to weatherize public buildings in cities of extreme weather by implementing measures that minimize energy consumption and using renewable energy sources (solar and biomass), demonstrating the economic viability, energy and environment of that buildings. It is a public buildings to use administrative and non- experimental with energy rated "A", operating since 2010 in Spain, which serves as an example to society of the efficacy of energy efficiency techniques. It´s larger than 5,000 m2, its particular envelope based on a production facility using biomass combined heat engine cycle with a single effect absorption, the ventilation free-cooling system and the integration solar thermal and photovoltaic, make it an international benchmark. [ABSTRACT FROM AUTHOR]

Abstract: Due to the increasing energy consumption of air conditioning in buildings and the need to decrease the fossil CO2 emissions to the environment, the interest of using renewable energy sources shows up stronger than ever. We present a general study whose aim is to propose a method to evaluate an upper bound in the potential of solar cooling by using some simplified models. As an example it has been applied to the very diverse climates of Spain. In the paper it has been assumed a direct solar coupling between the solar collector field and a single effect absorption cooling machine, without any intermediate solar storage tank. An equation is obtained that shows the dependence of the generator/solar-collectors equilibrium temperature on basic design parameters of the system (absorption machine-solar collectors). The paper analyzes the effect of these on the total amount of cooling produced along a typical mean year and the peak cooling power. The paper also includes a discussion on how to estimate the values and what is their physical meaning of the parameters which define the behavior of real absorption machines. Finally tables are included for the 12climates of Spain that can be used as an example of how to make a quick pre-sizing of such direct coupled system. The classification of the Spanish climates is based on general data (average monthly total horizontal solar radiation, average monthly dry temperature, etc.) and the results could be generalized for climates with the same severity. Moreover if hourly weather data is available for any place (like tmy2, bin, epw, etc. files), the procedure can be applied without further changes. [Copyright &y& Elsevier]

Abstract: Thermal energy storage (TES) is nowadays presented as one of the most feasible solutions in achieving energy savings and environmentally correct behaviors. Its potential applications have led to R&D activities and to the development of various technology types. However, so far there is no available data on a national scale in Spain and on a continental level in Europe, to corroborate the associated energetic and environmental benefits derived from TES. This is why, based on a previous potential calculation initiative model performed in Germany, this work intends to provide a first overview of the Spanish TES potential as well as an European overview. Load reductions, energy savings, and CO2 emissions reductions are tackled for the buildings and industrial sector. Results depend on the amount of implementation and show that, in the case of Europe for instance, yearly CO2 emissions may get to be cut down up to around 6% in reference to 1990 emission levels. [Copyright &y& Elsevier]

Abstract: Wastewater treatment plants (WWTPs) are energy-intensive facilities. Thus, reducing their carbon footprint is particularly important, both economically and environmentally. Knowing the real operating energy efficiency of WWTPs is the starting point for any energy-saving initiative. In this article, we applied a non-radial Data Envelopment Analysis (DEA) methodology to calculate energy efficiency indices for sampling of WWTPs located in Spain. In a second stage analysis, we examined the operating variables contributing to differences in energy efficiency among plants. It is verified that energy efficiencies of the analyzed WWTPs were quite low, with only 10% of them being efficient. We found that plant size, quantity of organic matter removed, and type of bioreactor aeration were significant variables in explaining energy efficiency differences. In contrast, age of the plant was not a determining factor in energy consumption. Lastly, we quantified the potential savings, both in economic terms and in terms of CO2 emissions, that could be expected from an improvement in energy efficiency of WWTPs. [Copyright &y& Elsevier]

Abstract: Numerous computer programs are available to calculate the energy efficiency of buildings. Many are based on the use of a reference building to determine the degree of efficiency. However, this methodology presents a major constraint when assessing a building after construction and during the use stage. To assess the energy efficiency of buildings, this paper proposes new indices based on energy consumption during different periods; as well as other parameters of the buildings such as construction area, number of users, and air-conditioned volume. Results are presented as an application for various buildings on the campus of the Universidad Politécnica de Valencia. [ABSTRACT FROM AUTHOR]

Abstract: In transmission and distribution systems, the high number of installed transformers, a loss source in networks, suggests a good potential for energy savings. This paper presents how the Spanish Distribution regulation policy, Royal Decree 222/2008, affects the overall energy efficiency in distribution transformers. The objective of a utility is the maximization of the benefit, and in case of failures, to install a chosen transformer in order to maximize the profit. Here, a novel method to optimize energy efficiency, considering the constraints set by the Spanish Distribution regulation policy, is presented; its aim is to achieve the objectives of the utility when installing new transformers. The overall energy efficiency increase is a clear result that can help in meeting the requirements of European environmental plans, such as the ‘20–20–20’ action plan. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to identify those sectors that contribute most to electricity consumption in Spain, using a methodology based on input–output tables, and to derive some recommendations aimed at increasing energy efficiency in those sectors. This input–output approach is complemented with a sector-focused study in which the availability of electricity-efficient technologies per sector and the barriers to their uptake are identified. This hybrid approach is deemed useful to derive policy implications. We thus propose several instruments to remove those barriers. [Copyright &y& Elsevier]

Abstract: The article presents the implementation of management measures that have reduced the gas consumption for space heating of a university building in Spain by 40%. The measures affect the use of the building, e.g., the use of its spaces, and the scheduling of its occupancy. They also affect the management of the heating system: a protocol for turning the system on and shutting it off has been developed. The work is part of a framework for action by the Technical University of Catalonia covering more areas and for a longer period of time, in which policies have been designed for managing buildings and a number of studies have been developed on the energy consumption of the university''s buildings. The article highlights the work methodology proposed to achieve the energy savings calculated theoretically in a previous study. The implementation of these measures in the case, from November 2006 until May 2007, has reduced consumption from 113.2kWh/m2 to 68.7kWh/m2 a year; thus, the hypothesis has been validated. In addition, it was possible to examine methodological details more closely. Finally, the relationship between the people involved in the process (the building owners, managers and energy users) is a determining factor. [Copyright &y& Elsevier]

Abstract: The current situation of worldwide concern over the emission of greenhouse gases and its effect on the climate demands an evaluation, from the perspective of energy efficiency and more specifically of non-renewable energy sources, of tendencies for change in the management of agricultural systems which have arisen in recent years. This article uses energy balances to evaluate the contribution of organic olive growing to the increase in the energy efficiency of Mediterranean agriculture, distinguished according to type of watering regime and intensiveness of cultivation. The results show, on one side, the lower energy efficiency of irrigated land as opposed to dryland (i.e. non-irrigated) regardless of their style of management and, on the other, the greater non-renewable energy efficiency of organic olive growing in comparison with the conventional production. Nevertheless, organic management could still improve its energy efficiency if it further adjusts and internalizes the flows of nutrients needed in order to achieve greater sustainability. [Copyright &y& Elsevier]

Industrial waste heat recovery shows significant potential for increasing energy efficiency in industry. However, to design strategies that exploit this potential, it is necessary to have data about the quantity and characteristics of industrial waste heat flows. This information is not always readily available and many companies do not even have a systematic record of these energy flows. Hence, bottom-up methodologies to estimate that recovery potential by means of key transfer figures are useful tools within this field. In the present article, four different methods are applied to determine the industrial waste heat recovery potential in the Autonomous Community of the Basque Country (northern Spain), an energy-intensive industrial region with large energy dependency from the outside. Besides, the analysis of the economic viability of the industrial waste heat recovery is essential, because it determines the final adoption of energy efficiency measures. For that aim, the authors develop an easy-to-apply bottom-up methodology to carry out an assessment for the economic potential of the estimated industrial waste heat at different temperature levels. This method is applied to 129 companies, whose potentials are characterized and discussed. The obtained results show that, for waste heat streams above 400 °C, more than 90% of the studied companies present payback periods below five years. For those industries with waste heat temperatures below 200 °C, the ratio decreases to around 40%, still a noticeable value. The estimations show a significant opportunity to implement solutions to recover this wasted energy, especially in the iron and steel sector and the petrochemical industry. The development of public policies that encourage these measurements would be also beneficial. • Evaluates the techno-economic potential of industrial waste heat recovery. • Lack of assessments of IWH recovery potential at local, regional or national scales. • 13%–16% of the primary energy consumption might be recovered. • For streams above 500 °C, almost all the companies present viable recovery potentials. • Iron and steel and petrochemical sectors present positive economic perspectives. [ABSTRACT FROM AUTHOR]

• Listed dwellings of southern Spain were monitored in winter to evaluate IEQ and EP. • Lengthy high rates of IRH were observed. • High levels of CO 2 concentration were recorded in bedrooms at night. • Thermal comfort is only achieved through a constant use of the heating systems. • Heat losses are entirely building-driven. Although European heritage buildings are excluded from energy efficiency targets, it would be beneficial to include the largest group, that of listed housing, in energy retrofit plans, in order to encourage its occupation and contributing to the sustainable maintenance of historic cities. This requires reliable experimental studies, which have been rare so far, in order to establish energy rehabilitation plans that do not jeopardize the conservation of their values. This paper aims to contribute to addressing this gap. It evaluates the energy performance and indoor environmental quality of dwellings within listed buildings of the conservation area of Seville, Spain, in the Mediterranean climate zone, under actual winter use and occupation conditions. An experimental campaign was conducted, generating energy models and measuring rates of indoor air temperature to validate them. The findings highlight important health and environmental issues: despite the mild winters of southern Spain, intensive use of the heating system is needed to maintain thermal comfort indoors, increasing polluting emissions; CO 2 concentration in bedrooms is usually excessive overnight and, regularly, indoor relative humidity remains too high; heat losses depend entirely on the physical condition of the constructive elements (walls, roofs, air leakage and glazing) which occupants cannot easily improve. [ABSTRACT FROM AUTHOR]