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Abstract Even under the powerful thrust of 20–20–20 measures, solar thermal systems are experiencing a slow-down in their development in most EU countries. One reason is their traditional confinement to sanitary hot water (SHW) production; another one is the growing competition with photovoltaic (PV) systems. In order to widen the use of solar thermal collectors, they should also be able to contribute to space heating and cooling and become Multi-Purpose Solar Thermal Systems (MPSTS). This paper addresses the issue of optimal sizing of MPSTS. The criterion adopted is based on maximization of Net Present Value and has been applied to some cities in Italy and in Pakistan with diverse climate conditions. Results show that optimal thermal collector areas per peak cooling demand ( A c / P c ) can be conveniently expressed as a function of Peak Heating to Cooling Ratio ( P h / P c ). Optimum A c / P c varies between 3 and 5 m 2 /kW c and decreases with increasing P h / P c . The paper also analyses and compares a MPSTS with a multi-purpose PV-based heat pump system using a traditional one (boiler and compression chiller) as reference. Results show that steadily decreasing prices have made PV systems more favorable, even without consideration of public subsidies.

This study investigates human-building interaction in office spaces across multiple countries including Brazil, Italy, Poland, Switzerland, the United States, and Taiwan. We analyze social-psychological, contextual, and demographic factors to explain cross-country differences in adaptive thermal actions (i.e. cooling and heating behaviors) and conformity to the norms of sharing indoor environmental control features, an indicator of energy consumption. Specifically, personal adjustments such as putting on extra clothes are generally preferred over technological solutions such as adjusting thermostats in reaction to thermal discomfort. Social-psychological factors including attitudes, perceived behavioral control, injunctive norms, and perceived impact of indoor environmental quality on work productivity influence occupants’ intention to conform to the norms of sharing environmental control features. Lastly, accessibility to environmental control features, office type, gender, and age are also important factors. These findings demonstrate the roles of social-psychological and certain contextual factors in occupants’ interactions with building design as well as their behavior of sharing environmental control features, both of which significantly influence building energy consumption, and thus, broader decarbonization.

Abstract The production and use of biogas and biomethane by anaerobic digestion is part of the critically needed energy transition, and it is achieving a growing interest in Europe. The planning and design of biogas/biomethane solutions necessitates the support of modelling tools for the calculation and evaluation of mass, energy and emission flows originated by different process and technological configurations. In the present study, a model for the preliminary evaluation of biogas and biomethane systems is presented. The model (named MCBioCH4) focuses on triple targets: i) obtaining information about the productivity of biogas/biomethane plants regarding achievable gas flow rates; ii) determining the plant energy expenditures and subsequently the economically exploitable energy flow shares; and iii) assessing the entire environmental impact of the system. The design of MCBioCH4 was specifically addressed to dual objectives: i) provide support to the preliminary assessment and comparison of different potential plant configurations and technological solutions, and ii) assist users in the complete definition of mass, energy and environmental flows, through the implementation of default datasets and assisted data input. The model is a standalone application fully equipped with graphical user interfaces. A set of default parameters was implemented in MCBioCH4, based on a detailed literature review. Alternatively, customized input parameters may be introduced by the user. If biogas scenarios are selected, the model simulates a combustion in a cogeneration unit. If biomethane scenarios are selected, the user is allowed to define the type and features of the upgrading technology. Two different options are implemented for biomethane: injection to the natural gas distribution grid, or use as a transportation fuel. The emission of carbon dioxide equivalent associated to each phase of the process is estimated by the model, based on a cradle-to-grave approach. Default emission factors are available, but these can be customized by the user. MCBioCH4 was tested on a case study in Italy. It provides a valuable support to project developers and administrations in defining the most economically and environmentally sustainable plant configurations.

Abstract Mold growth in buildings represents a widespread issue. It is, indeed, not only an aesthetic problem, but above all, a serious concern for the indoor air quality, which is directly related to the occupants’ health. Most of the existing residential buildings are poorly insulated and heavily affected by the presence of thermal bridges, that constitute the first area colonized by mold. In this paper the mitigation of the thermal bridges impact by applying a fine layer of insulating rendering coat in the interior side was analyzed. The numerical analyses were focused on a typical thermal bridge occurring on the Italian building stock between a vertical wall and a concrete slab and were carried out through dynamic 2D Heat and Moisture Transfer simulations. Moreover, the results related to the surface temperatures and relative humidity were used for the calculation of the mold index by means of the VTT growth model. Results are encouraging showing that the presence of the fine insulation rendering coat could moderately reduce the effect of the thermal bridges but can have a significant effect on the mold growth risk reduction.

Abstract Model predictive control (MPC) has achieved considerable success in the process industries, with its ability to deal with linear and nonlinear models, while observing system constraints and considering future behaviour. Given these characteristics, against the backdrop of the energy maximising control problem for Wave Energy Converters (WECs), with physical constraints on system variables and a non-causal optimal control solution it is, perhaps, natural to consider the application of MPC to the WEC problem. However, the WEC energy maximisation problem requires a significant modification of the traditional MPC objective function, resulting in a potentially non-convex optimisation problem. A variety of MPC formulations for WECs have been proposed, with variations in the WEC model, discretisation method, objective function and optimisation algorithm employed. This paper attempts to provide a critical comparison of the various WEC MPC algorithms, while also presenting WEC MPC algorithms within the broader context of other WEC “optimal” control schemes.

A double-null configuration is being considered for the EU-DEMO, due to its potential benefits for power exhaust arising from the use of two active divertors and magnetically disconnected low- and high-field sides. Using systematic parameter scans in fluid simulations, we have investigated the divertor power exhaust in the EU-DEMO in a connected double-null configuration, and compared the edge plasma properties to those obtained in a single-null configuration under detached conditions anticipated for reactor operation. Neglecting drift effects and kinetic behaviour of the neutrals, no clear benefits of the double-null configuration could yet be identified for the radiation pattern and power mitigation on open field lines. Future work should address the aforementioned physics as well as the effect of the additional X-point on core radiation.

A novel transport model is developed for a space conditioned by a cooled liquid desiccant dehumidification membrane ceiling (LDMC-C) and displacement ventilation DV in which the space is divided into three zones: an occupied cool with fresh air zone; an upper recirculation zone; and a ceiling adjacent boundary layer zone where the air is drawn at the exhaust grill. The adjacent air boundary layer at the ceiling membrane predicted the latent and sensible heat transfer to the desiccant solution. The boundary model was validated experimentally in a climatic chamber. The developed model predicted of the LDMC-C/DV system operational parameters such as the supply flow rate and temperature and the liquid desiccant concentration, flow rate, and inlet temperature that meet thermal comfort and air quality requirements. Extensive simulations were performed on a typical office load of 75 W/m2 to generate design charts of the system for three DV supply air temperatures of 18, 20, and 22 °C to identify the appropriate DV flow rate and inlet desiccant (CaCl2) solution temperature that provide comfort and air quality and ensures that condensation is unlikely to occur. The LDMC sensible and latent load removal from the space load is directly read off the charts.