Application of net zero extended exergy buildings concept for sustainable buildings analysis

[EN] Different Zero-Energy Building (ZEB)-related definitions considering its four main dimensions, such as zero energy, zero carbon, zero exergy and zero cost, have been proposed by different investigators. Among these, exergy-based definitions are relatively low in numbers. In this regard, the main objective of this present study is to propose net zero extended exergy buildings as a new concept, which combines extended exergy and net zero exergy building concepts and is a measure of the exergetic footprint. This concept setups a balance between extended exergy accounting of electricity from the grid and electricity generated in building. The proposed methodology is applied to a building available in the literature for heating and cooling seasons. Results show that 450Wp peak power and 44.181 kWh electrical energy must be obtained for meeting the electricity demand of the building. Another novel result is that the extended exergy accounting of the electricity generated by PV panels is bigger than the extended exergy of the electricity taken from the gird meaning that exergetic footprint of the electricity generated by PV panels is bigger. However, this result must be interpreted for the whole life time of the system.S

Effect of louver shading devices on building energy requirements

External louvers are increasingly used to provide solar protection for building glazed surfaces. In this work, a general study of the effect of louver shading devices applied to different façades of a building is carried out, for different locations (latitudes). Building energy requirements for a building in the cooling and heating seasons is quantified for different window and louver areas, under climatic conditions of Mexico (Mexico), Cairo (Egypt), Lisbon (Portugal), Madrid (Spain) and London (UK). Also, operative and indoor temperatures were calculated through simulations using TRNSYS software, whereas the model for the shading geometry study was solved with EES software. Both horizontal and vertical louver layouts were considered. The results show that the integration of louver shading devices in the building leads to indoor comfortable thermal conditions and may lead to significant energy savings, by comparison to a building without shading devices.Solar louvers Building simulation Energy requirements EES TRNSYS

Optimization of CSP Plants with Thermal Energy Storage for Electricity Price Stability in Spot Markets

This research presents a novel optimization strategy for concentrating solar power (CSP) plants with thermal energy storage (TES) systems that aims to stabilize and reduce electricity prices in spot markets. In the current international scenario of initiatives with regulatory changes aiming to reduce climate change effects and therefore CO2 emissions, many countries are reducing the fossil fuel share in their respective electrical systems and increasing electrical renewable energy systems. These carbon free generation systems have inherent problems such as their intermittence which, combined with the lack of high-scale energy storage systems, cause a stability risk in electrical grid systems and require conventional fuel systems to match demand and production. In this research, we analyze spot price markets using a marginal price system that relies on natural gas and is quite sensitive to an increase in fuel prices, causing a direct increase in the final energy cost in systems with a high renewable energy share, and we study how optimally sized CSP plants with TES can be used as manageable solar energy systems and contribute to both price and grid stability. For the Spanish market, we analyze the ongoing market situation and generation mix and we present an optimization scheme using the System Advisor Model (SAM) software that aims to maximize energy availability throughout the day and contribute to peak generation. The results show that the optimization strategy increases the profitability of CSP plants but also ensures a contribution to spot price stability and reduction. A sensibility analysis is presented, and a case study is analyzed in southern Spain. The results show the importance of optimized CSP plants in an energy transition and a strategy is proposed that can be extended to other locations worldwide