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The spread of intelligent buildings and advanced HVAC systems controls emphasizes the necessity of evaluating the impact of malfunctions caused by errors in the design, installation, or maintenance of these systems. In this work, the effect of the most diffused faults in ventilation systems is studied for an air handling unit installed in a Danish residential apartment. For this purpose, a dynamic model was built in Modelica, representing the building and the ventilation system. Different faults with varying intensities were implemented in the model. The impacts were evaluated by comparing the results of the obtained “with-fault” models with the “fault-free” model used as a benchmark. The comparison involved thermal and electrical energy use, thermal comfort and indoor air quality. Results showed that, for the studied system, the increase in thermal energy use was significant for the offset of the sensor controlling the bypass (up to + 27%), the bypass damper leakage and stuck (up to + 90%) and ducts’ thermal losses (up to + 48%). In the latter case, an increase in thermal discomfort was observed (+7% of hours with operative temperature below 18.5 °C).

Thermal energy storage systems are valuable assets to enable high penetration of renewable energy sources into district heating and cooling (DHC) systems. One of the main benefits of using thermal storage is that it can contribute to matching energy supply and energy demand when they do not coincide in time. Aquifer thermal energy storage (ATES) is an attractive technology to provide sustainable heating and cooling to buildings through DHC systems. In ATES systems, storage and recovery of thermal energy is achieved by extraction and injection of groundwater using wells. To calculate the energy performance of ATES, most of the studies use detailed simulation models developed using computational fluid dynamics software. However, such programs have limited capability of simulating the integration of ATES into building and district energy systems. The aim of this research study is to develop a simplified ATES model, which is suitable for coupling with building and district energy simulation programs. The model has been developed using a finite-difference approach in the MATLAB computing platform to solve the transient heat and mass transfer equations in porous media in two dimensions. The aquifer around the wells is modelled as two independent radially symmetric discs with an inner radius and an outer radius. The model has been validated by comparing predicted warm/cold well temperatures with measurements data from literature. Since the model is developed in MATLAB, it can be coupled with building energy software (such as TRNSYS, Modelica, EnergyPlus) via co-simulation., CLIMA 2022 conference, 2022: CLIMA 2022 The 14th REHVA HVAC World Congress

Data Centers are currently undergoing a great period of change. Developments in business and personal data transfer together with new technologies such as virtualisation and cloud computing are transforming Data centers into dynamic environments with greater power demands unexpectedly. The cooling requirements of the Data Center infrastructure form a large part of the overall power requirements and it is therefore critical to ensure correct optimisation to achieve the desired energy efficiency levels. In Planning data centers for the future, it is imperative that the design matches the infrastructure with greater scalability and integration enabling Data Centrers to evolve to cope with less power demands and lower running costs. This work brings together the main layouts of high efficiency IT cooling systems, highlighting their operation and efficiency in the case of an IT room with a thermal load of 1 MW and three different climatic scenarios. The efficiency of the systems is evaluated through a calculation routine in which all the components of each cooling system are modelled and the regulation logics of the software of these units are implemented. The climatic scenarios for 3 different locations (Palermo, Milan, and Frankfurt) are represented according to the hourly distribution of temperatures and humidity in order to evaluate the seasonal performance of each cooling system. The results give an overview of the consumption referred to each IT cooling technology in relation to the application climate. The calculation routine developed allows to choose the most suitable technology for the climate and the installation considered, also leaving the possibility of a subsequent optimization of the unit design based on the most appropriate technology., CLIMA 2022 conference, 2022: CLIMA 2022 The 14th REHVA HVAC World Congress

Thermal energy storage systems are valuable assets to enable high penetration of renewable energy sources into district heating and cooling (DHC) systems. One of the main benefits of using thermal storage is that it can contribute to matching energy supply and energy demand when they do not coincide in time.Aquifer thermal energy storage (ATES) is an attractive technology to provide sustainable heating and cooling to buildings through DHC systems. In ATES systems, storage and recovery of thermal energy is achieved by extraction and injection of groundwater using wells. To calculate the energy performance of ATES, most of the studies use detailed simulation models developed using computational fluid dynamics software. However, such programs have limited capability of simulating the integration of ATES into building and district energy systems.The aim of this research study is to develop a simplified ATES model, which is suitable for coupling with building and district energy simulation programs. The model has been developed using a finite-difference approach in the MATLAB computing platform to solve the transient heat and mass transfer equations in porous media in two dimensions. The aquifer around the wells is modelled as two independent radially symmetric discs with an inner radius and an outer radius. The model has been validated by comparing predicted warm/cold well temperatures with measurements data from literature. Since the model is developed in MATLAB, it can be coupled with building energy software (such as TRNSYS, Modelica, EnergyPlus) via co-simulation.

The energy use for ventilating buildings involves high economic and primary energy consumption costs. Nevertheless, ventilation is essential, especially in public places, to ensure acceptable Indoor Air Quality (IAQ) levels and reduce the risk of airborne virus infection. The latter aspect has recently increased because of the ongoing COVID-19 pandemic. In this paper, a model that couples a zonal ventilation model with infection risk calculation is integrated with an energy consumption model to analyse the energy consumption and infection risk from COVID-19 at different ventilation flow rates for three case studies: an office room, a high school and a university classroom. The main results show that the increase in ventilation flow rate involves reducing risk, but it increases energy consumption. Moreover, the mask-wearing resulted in having a relevant effect, whereas the effect of the relative position difference inside the room was not detected with the proposed discretisation., CLIMA 2022 conference, 2022: CLIMA 2022 The 14th REHVA HVAC World Congress

In this work, the climatic chamber CORE-CARE is presented. The laboratory was built at the Industrial Engineering Department of the University of Padova, in order to further investigate issues related to indoor environmental quality, the comfort perceived by people in confined spaces and thermal performance of radiant systems. CORE-CARE is equipped with radiant panels in each surface, which can be controlled separately. The room presents two real windows on the East side, equipped with shading systems. Furthermore, the mechanic controlled ventilation system installed in the room can act as integration of sensible or latent heat both in heating and in cooling conditions. The climatic chamber is provided with a data acquisition system, consisting of 38 sensors, that allow the evaluation of the surface temperatures in different positions, the air temperature at different heights, the mean radiant temperature, relative humidity and CO2 concentration. The CORE-CARE chamber is thermally characterized using a detailed model developed at the Industrial Engineering Department of the University of Padova and the simulations results are compared with test measurements. Moreover, the impact of radiant asymmetry is investigated.

The “Most Easy, Efficient and Low Cost Geothermal Systems for Retrofitting Civil and Historical Buildings” (GEO4CIVHIC) project aims to accelerate the deployment of shallow geothermal systems for heating and cooling purposes when retrofitting existing and historical buildings. Analyzing the implementation process of borehole heat exchangers (BHEs), allows the understanding of how to promote the long-term sustainability of shallow geothermal energy systems. The thermal interference between BHE systems represents a problem, especially due to the increasing deployment of this technology and its spread in densely built-up areas. The main goal of this paper is to propose a conceptual model and to apply this to different case studies. The methodology includes phases to adopt an integrated approach for preventing long term thermal interference in neighbouring borehole heat exchangers, by providing management strategies and technical suggestions for design and operation. The method developed follows the following steps: 1) literature review to determine what are the main drivers for thermal interference between shallow geothermal systems, in the context of the GEO4CIVHIC project case study sites; 2) to create a conceptual model to limit thermal interference at both design and operational phases; 3) to apply the developed method to real and virtual case studies in countries with different regulatory frameworks and to test its main strengths and weaknesses. The application of this conceptual model to specific case studies provides evidence of critical planning and operational characteristics of GSHP systems and allows the identification of measures to mitigate impacts of thermal interference to be identified.

Nowadays, the search for new solutions to the pandemic situation caused by the spread of SARS-CoV-2 is one of the most important issues worldwide. The difficulties encountered in finding an effective cure for the infection and the ongoing vaccination campaign place a priority on minimising the transmission of this disease. This paper deals exclusively with the airborne route of transmission for COVID-19, proposing a model for the evaluation of infection risk. It starts from the well-known Wells-Riley model and its successive modifications and tries to couple it with a zonal model which analyses the air movement in an indoor environment. The objective of this model is evaluating whether the infection risk depends considerably on the position of the infected subject and the susceptible person in the room and how different ventilation concepts affect these aspects. The model was applied to an office room with a mixing ventilation system. The results obtained concern the sub-division of the considered volume in four cells, each one perfectly mixed. The evaluation of infection risk in different positions was carried out and an analysis on the parameters affecting this value was performed.