•A novel PCM h-T function is implemented for PCM melting temperature optimization.•Optimization is applied to find the optimum PCM melting in different climates.•High energy savings are achieved in ...buildings with PCM-enhanced gypsum technology.•In cooling dominant climates PCM melting at 26°C achieves higher energy savings.•In heating dominant climates PCM melting at 20°C achieves higher energy savings.
Globally, a considerable amount of energy is consumed by the building sector. The building envelope can highly influence the energy consumption in buildings. In this regard, innovative technologies such as thermal energy storage (TES) can help to boost the energy efficiency and to reduce the CO2 emissions in this sector. The use of phase change materials (PCM), due to its high heat capacity, has been the centre of attention of many researchers. A considerable number of papers have been published on the application of PCM as passive system in building envelopes. Researches have shown that choosing the PCM melting temperature in different climate conditions is a key factor to improve the energy performance in buildings. In the present paper, a simulation-based optimization methodology will be presented by coupling EnergyPlus and GenOpt with an innovative enthalpy-temperature (h-T) function to define the optimum PCM peak melting temperature to enhance the cooling, heating, and the annual total heating and cooling energy performance of a residential building in various climate conditions based on Köppen-Geiger classification. Results show that in a cooling dominant climate the best PCM melting temperature to reduce the annual energy consumption is close to the maximum of 26°C (melting range of 24–28°C), whereas in heating dominant climates PCM with lower melting temperature of 20°C (melting range of 18–22°C) yields higher annual energy benefits. Moreover, it was found that the proper selection of PCM melting temperature in each climate zone can lead to notable energy savings for cooling energy consumption, heating energy consumption, and total annual energy consumption.
•Leaf area index to measure the shadow potential of a green façade.•Indirect method to measure LAI is suitable for green facades.•GF provide comparable shadow factor for all orientations than ...artificial barriers.•For a LAI of 3.5–4, 34% of energy savings was measured.•Energy savings provided by GF are wall orientation dependent.
To “green” building envelopes is currently one of the most promising ways to provide energy savings in buildings and to contribute to the urban heat island effect mitigation. The shadow effect supplied by plants is the most significant parameter for this purpose. One way to characterize the potential shadow effect of greenery is to calculate the facade foliar density by means of the leaf area index (LAI). As LAI is commonly used in horizontal crops, their use in vertical greenery systems (VGS) has generated dispersion and uncertainty in previous studies both in terms of methodologies and results obtained. In addition, a lack of data relating to the influence of the facade orientation in the final contribution of vertical greenery to the energy savings has been observed in previous studies.
This study aims at establishing a common and easy way to measure LAI and to lick it to the energy savings provided by VGS. Moreover, the energy savings achieved as well as the influence of facade orientation on the final thermal behaviour of two different VGS, a double-skin green facade and a green wall, was studied.
From the results, it can be stated that the most simple and quick procedure to measure LAI in order to characterize the foliar density of VGS is the indirect method based on the amount of light transmitted through the green screen. From the experimental tests interesting energy savings were obtained (up to 34% for Boston Ivy pant specie with a LAI of 3.5–4, during summer period under Mediterranean continental climate). Moreover, the dependence on facade orientation was confirmed with representative contribution over the whole energy savings from East and West orientation.
•Understanding of the current education supply worldwide is analyzed.•Shortage is more acute in developing countries.•There is a mismatch between education system offer and industry demand.•There is ...a mismatch in the suitability of the curricula.•Students and educators are moving towards online training.
One of the barriers to achieve the expected renewable energy market development is the shortage of qualified human resources. Global data on education and training on renewable energies was analyzed in order to gain an understanding of the current education supply worldwide. Findings are: (i) the shortage is more acute in developing countries; (ii) there is a mismatch between education system offer and industry demand; (iii) there is also a mismatch in the suitability of the curricula; (iv) students and educators are moving towards online training for collaborating and learning. While it remains a challenge to increase, improve, and facilitate access to renewable energy education and training, the high interest of females in renewable energy education represents an opportunity to counter the scarcity of professionals in the sector.
Buildings contribute to climate change by consuming a considerable amount of energy to provide thermal comfort for occupants. Cooling energy demands are expected to increase substantially in the ...world. On this basis, technologies and techniques providing high energy efficiency in buildings such as passive cooling are highly appreciated. Passive cooling by means of phase change materials (PCM) offers high potential to decrease the cooling energy demand and to improve the indoor comfort condition. However, in order to be appropriately characterized and implemented into the building envelope, the PCM use should be numerically analyzed. Whole-building energy simulation tools can enhance the capability of the engineers and designers to analyze the thermal behavior of PCM-enhanced buildings. In this paper, an extensive review has been made, with regard to whole-building energy simulation for passive cooling, addressing the possibilities of applying different PCM-enhanced components into the building envelope and also the feasibility of PCM passive cooling system under different climate conditions. The application of PCM has not always been as energy beneficial as expected, and actually its effectiveness is highly dependent on the climatic condition, on the PCM melting temperature and on the occupants behavior. Therefore, energy simulation of passive PCM systems is found to be a single-objective or multi-objective optimization problem which requires appropriate mathematical models for energy and comfort assessment which should be further investigated. Moreover, further research is required to analyze the influence of natural night ventilation on the cooling performance of PCM.
•Embodied energy and embodied carbon as a tool for climate change mitigation.•A keyword analysis regarding EE and EC was carried out.•Bibliometric analysis and literature maps were developed.•1003 ...documents were found in the Scopus database for the 1981–2019 period.•Current building material research claims for EE and EC standardization.
Climate change mitigation is a recurrent consciousness topic among society and policymakers. Actions are being adopted to face this crucial environmental challenge, with a rising concern with a big impact on the building sector. Construction materials have a high carbon footprint as well as an energy-intensive activity. To measure the environmental damage and effects, life cycle assessment (LCA) is the methodology most widespread. However, the LCA methodology itself and the assumptions done to carry it out leads to a generalized burden to compare the case studies outcomes. LCA method and for instance geographical location are incompatibilities also revealed in embodied energy and embodied carbon assessments. Urgent actions are needed to clarify the confusions arisen in the research, considering a detailed study on the embodied energy and embodied carbon values. From a material level point of view, this paper aims to illustrate the chronological overview of embodied energy and embodied carbon through keywords analysis. Moreover, to support and corroborate the analysis, an organized summary of the literature data is presented, reporting the range of embodied energy and embodied carbon values up to now. This systematic analysis evidences the lack of standardization and disagreement regarding the assessment of coefficients, database source, and boundary system used in the methodology assessment.
This review summarizes and organizes the literature on life cycle assessment (LCA), life cycle energy analysis (LCEA) and life cycle cost analysis (LCCA) studies carried out for environmental ...evaluation of buildings and building related industry and sector (including construction products, construction systems, buildings, and civil engineering constructions). The review shows that most LCA and LCEA are carried out in what is shown as “exemplary buildings”, that is, buildings that have been designed and constructed as low energy buildings, but there are very few studies on “traditional buildings”, that is, buildings such as those mostly found in our cities. Similarly, most studies are carried out in urban areas, while rural areas are not well represented in the literature. Finally, studies are not equally distributed around the world.
•Potential of industrial waste heat for heating and cooling applications is studied.•An economic analysis with maximum feasible investment cost as output.•Different consumer types are defined: ...“Enthusiast”, “Real estate” and “Industry”.•Absorption chillers are profitable when applied for at least 2500h per year.•Electric heat pumps are profitable for more than 4000h/a, absorption heat pumps with 3000h/a.
In this paper, the potential of industrial waste heat for heating and cooling applications is investigated. Therefore, heat transformation technologies are presented and their technical and economic potential are discussed. First, different industrial processes and their operating temperatures are presented as possible waste heat sources as well as low temperature processes, which can be supplied with waste heat. Then, a general economic analysis is performed for three different cases of waste heat use: an absorption chiller producing cold and heat production with a compression and an absorption heat pump. The maximum acceptable investment cost for each technology is estimated and compared with the current investment cost depending on the operating hours of the system. For this, three different consumer types, Enthusiast, Real Estate and Industry, are defined to represent different expectations in interest rate, payback period and the resulting annuity factor. Instead of judging if a technology is profitable or not, it is calculated how much the system is allowed to cost in order to be competitive for certain operating hours. Combined with present day cost of the technology, this serves as a rough judgment of the market deployment process. Finally, a sensitivity analysis of the initial assumptions for the economic analysis is performed, revealing a strong influence of the annuity factor. For the present day technology cost, absorption chillers were found to be profitable for two of the three consumer types when operated for at least 2500h per year. Electric heat pumps are profitable for all consumer types when exceeding 4000operating hours per year while absorption heat pumps start at 3000h of operation per year to be profitable for all consumer types.
This review paper organizes and summarizes the literature on Vertical Greenery Systems (VGS) when used as passive tool for energy savings in buildings. First, with the information obtained in the ...reviewed literature some key aspects to consider when working with VGS are clarified, such as the classification systems, the climate influence, the plant species used and the different operating mechanisms. Then, the main conclusions of this literature, sorted by construction system (Green Walls or Green Façades) and climatic situation, are summarized. In general, it can be concluded that VGS provide great potential in reducing energy consumption in buildings, especially in the cooling periods. However, a lack of data on operation during the heating period as well as during the whole year has been found. On the other hand, results show that the investigations of VGS are not equally distributed around the world, being basically concentrated in Europe and Asia. Moreover, the review concludes that some aspects must be studied in depth, such as which species are the most suitable for each climate, influence on energy savings of the façade orientation, foliage thickness, presence of air layers, and finally, substrate layer composition and thickness in the case of green walls.
To be able to extend the operation of a solar power plant (CSP) up to 15h, thermal energy storage (TES) is necessary. But TES also provides more versatility to the plant and makes its reliance during ...operation hours more dependable. On the other hand, due to the different CSP configurations, a broad spectrum of storage technologies, materials and methods is needed. Sensible and latent heat storage are known technologies in CSP, but thermochemical storage (TCS) is still very much at laboratory level. Nevertheless, TCS has de advantage of nearly no losses during storage and very good volumetric energy density. This review summarizes and compares the different TCS that are today being investigated. Those systems are based in three redox reactions, sulfur-based cycles, metal oxide reduction–oxidation cycles, and perovskite-type hydrogen production, and metal oxide non-redox cycles due to their similarity. This review shows that all these cycles are promising, but none of them seems to have all the characteristics necessary to become the only one storage system for CSP. The main conclusion of the review is that the calcium carbonate is the cycle with most experimentation behind it to infer that it could be viable and should thus be attempted at a research plant scale once a reactivation cycle can be designed; and the manganese oxide cycle, while less developed, is fundamental enough to be a suitable application for desert climates over the rest of the water-frugal or even water-avoiding cycles.
•Fanger thermal comfort model is used in PCM-incorporated buildings.•Energy performance of buildings with different HVAC schedules has been studied.•Cooling and heating performance has been improved ...in all cases with PCM except for office profile in winter.•Short payback periods, below three years, have been achieved.
In buildings, HVAC systems consume a high amount of energy to provide thermal comfort for occupants. A methodology is presented in this paper to control thermostat operation of the buildings considering the effects of indoor and outdoor boundary conditions and phase change material (PCM) characteristics. EnergyPlus v8.1 building energy simulation software was used to analyze the energy performance of the PCM incorporated building models and to implement Fanger model to control HVAC thermostat operation according to BS EN 15251:2007 thermal comfort categories. Three types of building HVAC schedule, PCM with different melting points and layer thicknesses were studied for Madrid climate zone. Moreover, the impact of occupants clothing on the energy consumption was investigated. Furthermore, payback analysis was conducted to find out the economic benefits of PCM integration into the building envelopes. Application of PCM improved the cooling and heating energy performances except for the office model in winter (heating period). Additionally, higher energy savings and lower payback periods were observed when PCM with higher melting point was applied to the buildings. Eventually, energy savings in PCM incorporated models were found to improve further when occupants changed their clothing behavior in winter.
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