• Energy Research

Abstract European and Italian standards establish high levels of energy performance of buildings that have to be designed considering their energy balance near zero. To achieve this goal, the reduction of energy demand, attainable by improving energy efficiency of the construction, and the use of renewable energy available both on site and off site are effective solutions to be applied. In particular, in buildings that use energy produced from renewable sources, due to their unstable and unpredictable nature, having the right strategy to compensate the variations is essential. A technical solution reevaluated as a consequence of passive design principles, is to provide an adequate thermal inertia in order to store energy when it is offered and to use it when the source is not available. In these cases, the ability of construction elements to retain heat becomes fundamental as they contribute to maintain internal comfort conditions. This paper aims to investigate how various types of heating and cooling systems, based on different modes of heat transfer, are able to interact differently with the thermal mass of the building, producing a different level of its activation. The investigation considers a case study used to carry out dynamic simulation by means of DesignBuilder which is a user interface of EnergyPlus. The model consists of a building with elementary geometry and a single thermal zone, delimited by walls with outside thermal insulation and a heat accumulation layer inside. The variation of the internal temperature by using different types of conditioning system is analyzed in order to individuate the technology that takes the greatest advantages from the thermal mass.

Abstract Following the increasing global request for natural gas, the regasification of Liquefied Natural Gas (LNG) is becoming a more widespread process. Liquefied natural gas is transported by gas tankers at a temperature of around 113K at atmospheric pressure. The successive process of regasification, necessary to inlet the gas in the pipeline network, makes it possible to use the LNG exergy for various applications, particularly for the production of electrical energy. In this work, the possibility of capturing the thermal energy released during regasification with an ammonia closed Rankine cycle and an LNG open Rankine cycle, associated to a steam closed Rankine cycle of waste incinerator, is investigated. The three consecutive cycles consent an increase in both the electrical production and thermodynamic efficiency, whilst carrying out regasification of the LNG with consequent environmental benefits. The set of three cycles constitutes a new plant configuration whose functioning does not constrain the processes of the regasification terminal.

Energy performance of buildings is a worldwide increasing investigated field, due to ever more stringent energy standards aimed at reducing the buildings’ impact on the environment. The purpose of this paper is to assess the impact that occupant behavior and climate change have on the heating and cooling needs of residential buildings. With this aim, data of a questionnaire survey delivered in Southern Italy were used to obtain daily use profiles of natural ventilation, heating, and cooling, both in winter and in summer. Three climatic scenarios were investigated: The current scenario (2020), and two future scenarios (2050 and 2080). The CCWorldWeatherGen tool was used to create the weather files of future climate scenarios, and DesignBuilder was applied to conduct dynamic energy simulations. Firstly, the results obtained for 2020 demonstrated how the occupants’ preferences related to the use of natural ventilation, heating, and cooling systems (daily schedules and temperature setpoints) impact on energy needs. Heating energy needs appeared more affected by the heating schedules, while cooling energy needs were mostly influenced by both natural ventilation and usage schedules. Secondly, due to the temperature rise, substantial decrements of the energy needs for heating and increments of cooling energy needs were observed in all the future scenarios where in addition, the impact of occupant behavior appeared amplified.

AbstractThis paper introduces a database of 34 field-measured building occupant behavior datasets collected from 15 countries and 39 institutions across 10 climatic zones covering various building types in both commercial and residential sectors. This is a comprehensive global database about building occupant behavior. The database includes occupancy patterns (i.e., presence and people count) and occupant behaviors (i.e., interactions with devices, equipment, and technical systems in buildings). Brick schema models were developed to represent sensor and room metadata information. The database is publicly available, and a website was created for the public to access, query, and download specific datasets or the whole database interactively. The database can help to advance the knowledge and understanding of realistic occupancy patterns and human-building interactions with building systems (e.g., light switching, set-point changes on thermostats, fans on/off, etc.) and envelopes (e.g., window opening/closing). With these more realistic inputs of occupants’ schedules and their interactions with buildings and systems, building designers, energy modelers, and consultants can improve the accuracy of building energy simulation and building load forecasting.

Abstract In the last four decades several methods have been used to model occupants' presence and actions (OPA) in buildings according to different purposes, available computational power, and technical solutions. This study reviews approaches, methods and key findings related to OPA modeling in buildings. An extensive database of related research documents is systematically constructed, and, using bibliometric analysis techniques, the scientific production and landscape are described. The initial literature screening identified more than 750 studies, out of which 278 publications were selected. They provide an overarching view of the development of OPA modeling methods. The research field has evolved from longitudinal collaborative efforts since the late 1970s and, so far, covers diverse building typologies mostly concentrated in a few climate zones. The modeling approaches in the selected literature are grouped into three categories (rule-based models, stochastic OPA modeling, and data-driven methods) for modeling occupancy-related target functions and a set of occupants’ actions (window, solar shading, electric lighting, thermostat adjustment, clothing adjustment and appliance use). The explanatory modeling is conventionally based on the model-based paradigm where occupant behavior is assumed to be stochastic, while the data-driven paradigm has found wide applications for the predictive modeling of OPA, applicable to control systems. The lack of established standard evaluation protocols was identified as a scientifically important yet rarely addressed research question. In addition, machine learning and deep learning are emerging in recent years as promising methods to address OPA modeling in real-world applications.

Thermal performance and stability over time are key parameters for the characterization and application of PCMs in the building sector. Generally, inorganic PCMs are dispersions of hydrated salts and additives in water that counteract phase segregation phenomena and subcooling. Traditional methods or in "house" methods can be used for evaluating thermal properties, while stability can be estimated over time by using optical techniques. By considering this double approach, in this work thermal and structural analyses of Glauber salt based composite PCMs are conducted by means of non-conventional equipment: T-history method (thermal analysis) and Turbiscan (stability analysis). Three samples with the same composition (Glauber salt with additives) were prepared by using different sonication times and their thermal performances were compared by testing both the thermal cycling and the thermal properties. The stability of the mixtures was verified by the identification of destabilization phenomena, the evaluation of the migration velocities of particles and the estimation of variation of particle size. This publication is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 657466 (INPATH-TES).