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Microcogeneration systems guarantee the reduction of primary energy consumption and greenhouse gas emissions in residential sector, by reducing fossil fuels demand and grid losses with respect to conventional energy conversion systems. Energy, environmental and economic benefits can be obtained sharing the cogenerated thermal and electric energy among different end-users to increase the operating hours of the microcogeneration plant with respect to the scenario in which energy demand of each end-user is satisfied by a single cogeneration system. This paper analyses a microcogeneration system used to satisfy electric, space heating and domestic hot water demands of two separate residential buildings located in Spain in a load sharing approach. It consists of a natural gas fuelled internal combustion engine with a thermal and electric power of 12.5 kW and 5.5 kW, respectively. An auxiliary boiler with a nominal thermal power of 24 kW, is also included. The domestic hot water and the heating requirements are managed by means of two different thermal energy storages. The proposed energy conversion systems were experimentally analysed in a test facility in Vitoria Gasteiz (Spain). The models representing the components and the buildings have been implemented in TRNSYS 17. The energy, environmental and economic performance of proposed system are compared with those achieved by a traditional system based on separated energy production. The results highlight that the load sharing between users with different load profiles leads to better environmental and thermo-economic results with respect to the conventional system. The microcogeneration plant works for about 3000 hours per year achieving a primary energy saving of 12.1% and a reduction of equivalent CO2 emissions equal to 27.8%. The payback period of the analysed solution is equal to 11.9 years unless economic support mechanisms are considered. The results of this study show that the introduction of a microcogeneration system in load sharing approach leads to energy, environmental and economic benefits even considering two separate residential buildings, occupied by users with different behaviour.

This work describes the project submitted to the University-Society-Business 2021 call for proposals whose aim is to integrate the knowledge and university practices in the field of energy in buildings into secondary school students. The aim is to define the energy strategies to be implemented to strengthen the relationship between secondary education and university studies, by means of a "pilot project" at a secondary school, as well as to promote Science, Technology, Engineering and Maths (STEM) scientific vocations in young people, with particular emphasis on the female gender. The project will carry out an energetic study at a school developed by university research staff and secondary school students. The aim is to motivate and confirm the qualities of people in STEM teaching, to arouse interest and closeness as well as to promote education in the subject of energy efficiency in buildings

This work analyses deeply and critically the behavior of a heat recovery device of the ventilation system, in a dwelling of the Basque Country, under the energy and the exergy point of view. The aim is to show the different results that come from both perspectives. Heating period was monitored and data of the velocities and temperatures of the extracted and renovation airflows have been registered. With the data recorded, the effectiveness, energy efficiency and exergy efficiency of the recovery system have been calculated. Later, energy savings, primary energy savings and economic savings have been evaluated. Besides, the minimum difference between the outdoor and the indoor temperatures, from which the operation of the recovery system achieves a primary energy saving, an economic saving or an exergy saving were calculated. In addition to the exhaustive monitoring, the concentration of carbon dioxide in each room of the dwelling has been measured. The results obtained show the convenience of using ventilation systems with heat recovery from an energy point of view (with an energy efficiency of 89%), but not so if an exergy analysis is performed (with an exergy efficiency of 4%). After all, Second Law perspective penalizes a lot the electricity consumption for heating purposes, requiring a temperature differences (between the indoor and outdoor temperatures) higher than 32 °C in order to obtain exergy savings (not so under the energy perspective, where a difference of 1.6 °C is enough for having savings). The indoor air quality analysis confirms the adequacy in terms of CO2 concentration. This work is pioneer in terms of deep exergy application for ventilation systems.

Concerning the building environment HVAC facilities, even if a great effort has been made in developing components and systems with high nominal efficiencies, less attention has been paid to the problem of system maintenance. The main objective of the thermoeconomic diagnosis is to detect possible anomalies and their location inside a component of the energy system. The second objective, and indeed the one to be achieved in this paper, is indicated as inverse problem. It is associated with the quantification of the effects of anomalies in terms of thermoeconomic quantities. Its rigorous application in building thermal installations has some difficulties relating to the strong interrelation between the different components and the fact that energy supply facilities are continuously changing with time. The way to deal with dynamic circumstances is thoroughly explored in this article. Likewise, this paper’s main goal is to demonstrate an application of two thermoeconomic diagnosis methodologies in the building sector, one based on the malfunction and dysfunction analysis and the other one based on the characteristic curves of the components. The results obtained allow us to point out the advantages and limitations of both methodologies as well as to combine them and then develop a more reliable diagnosis.

Application of Thermoeconomics in the diagnosis of building energy supply systems allows the localization and quantification of an abnormal operation, which can cause significant increase in energy consumption to obtain the same product. To do that, a comparison between the real operation of the energy system and the reference operation must be done. In this paper a DHW and heating plant based on a condensing boiler has been analysed. Diagnosis is applied through a mono-failure case using a methodology based on the fuel impact formula and the malfunction and dysfunction analysis. An innovative methodology will be presented in order to filter the induced effects that take place in a dynamic situation due to the control system. Although the real aim of diagnosis is to solve the inverse problem, in this work we have faced a direct problem, in which a parameter of one component of the plant has been modified and its effect over the other components and the whole plant is evaluated. The major outcome is that by the application of this methodology the effects produced by the faulty component can easily be quantified, both in performance and economic terms. Those effects are due to the component malfunction as well as the induced malfunctions and dysfunctions generated in the other components of the facility.