• Energy Research

Standard ISO 10077-2 gives the procedure to calculate thermal transmittances of window frames in 2D numerical simulations. It also introduces some examples of frame geometrical models with all necessary input data and the solutions so as to perform validation of the applied numerical tools. In the present paper, the models prepared with a commercial finite volume software of a PVC window frame were first positively validated with the results given in the Standard. An experimental test was then implemented to confirm the simulated data, with satisfactory agreement. The numerical code was used on one of the frames provided by the Standard to perform a sensitivity analysis of all the components and boundary conditions playing a role on the definition of the frame thermal transmittance, such as surface heat transfer coefficients, values of the solid thermal conductivity, emissivity and insulation properties of air gaps. Results demonstrate that the air gap properties represent the most influential parameters for the definition of the PVC window frames thermal transmittance, followed by the surface heat transfer coefficients and the PVC thermal conductivity. The rubber and the steel properties show a negligible effect on the whole frame performance. This procedure could constitute a design tool to guide the efforts of window manufacturers for the achievement of high performance products.

Green building concept plays a fundamental role in reducing the use of resources and the impacts on human health and environment, during the whole building life cycle. Therefore, a method to measure the building sustainability rate is crucial for comparing various alternatives in terms of use of different materials, energy resources, production processes to reduce energy consumption and environmental impacts. Many protocols have been proposed to perform buildings’ sustainability evaluation; however, different operators applying these certification tools might need to make hypotheses, even different from each other, to complete the whole procedure. Hence, this work aims to evaluate whether and how the hypotheses formulated by each operator can influence the final certification level. To this end, a Round Robin Test among international partners was performed using different versions of LEED sustainability protocol to the same building with the same boundary conditions, comparing and analyzing the results provided by the participants. The final aim was to identify which issues have more influence on the final performance rate, giving to the users a deeper knowledge of the aspects included in these procedures. The results showed the potential of these building environmental certification systems, capable of offering a transversal level of environmental sustainability.

Abstract The envelope thermal behaviour in dynamic conditions is becoming essential to assess the whole year energy performance of buildings. International Standards describe in detail the theoretical approach, but few examples of experimental analyses and procedures exist to determine the performance of materials and components in unsteady-state conditions. The work is aimed at filling this vacancy, describing a modification of hot box devices, which are generally designed for stationary measurements, but they could be successfully used also for time-dependent investigations. Two different methods are proposed: a hot box system where one-day period sinusoidal solicitations in terms of temperature and heat flow are imposed, and another type of boundary condition, with a faster impulsive thermal driving force. The former showed a good agreement with the expected theoretical results; the latter proved also suitable but suffered a lower accuracy, being characterised in turn by a significant reduction of the measurement time. It is also showed that hot boxes allow also more detailed investigations, such as infrared thermography imaging, to better analyse the thermal performance of the tested samples.

Abstract Passive systems are acknowledged to highly optimize the thermal and energy performance of buildings. A detailed literature review shows that solar shading technologies play a key role in improving indoor thermal and lighting behavior according to outdoor environmental condition. Moreover, the possibility to control their dynamic operations by means of automatic systems is showing promising findings. In this view, the present paper aims at analyzing the thermal and lighting performance of a full scale test room with varying the layout of an external venetian blind system. In particular, the test-room was continuously monitored in two different periods with the purpose of evaluating the effects of several shading system configurations compared to an automatic one, controlled by outdoor selected parameters (air temperature and illuminance). The experimental apparatus consists of a full scale prototype building designed considering Italian typical residential buildings in terms of envelope materials and geometry (transparent and opaque envelope area). The shading layout was periodically modified with the final objective of quantifying the effect of such modifications in terms of indoor thermal and lighting performance. The results show that the different configurations of the venetian blind hugely affect indoor thermal and lighting performance. In particular, the dynamic behavior of the automated venetian blind is able to produce the highest benefits.

24 figures, 7 tables.-- © 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/ Energy harvesting from renewable sources can play a vital role to decarbonize the environment, limit global warming and mitigate the growing energy demand. The objective of this work consists of decarbonizing a University Campus and neighboring communities by producing electricity from solar photovoltaic systems integrated with an energy storage system and local grid station. A new mathematical model is developed to maximize the system power generation and balance the load demand. The simulation and optimization software System Advisor Model (SAM) is used to develop and test model results. The software is used to analyze and optimize the solar energy generation, the energy demand, and the economic performance: capital cost, overall investment, net present value, and the Levelized Cost of Energy of the project. A novel approach decentralized load centers is adopted to share power with adjacent communities. At the aim of improving the system flexibility, reliability, and climate resilience, the established model is grid-connected. The CO2 emissions reduction is also determined to evaluate the environmental impact of the interventions. Peer reviewed

17 figures, 12 tables.-- © 2023. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/ Clean energy technologies are playing a vital role in energy transition, realization of Net-Zero emission goals, and satisfying increasing energy demands. The objective of this work is to investigate the potentials of renewable energy sources and propose a state-of-the-art new grid connected energy system model, which increases the penetration of renewable energies in the medium-size Municipality of Perugia, Central Italy. The presented energy system model integrates and optimises renewable energy sources mainly consisting of hydro, solar, and biomass, by implementing new dispatch strategies and advanced mathematical model. The developed model maximises the power generation of each source based on the least Net Present Cost and the lowest Levelized Cost of Energy and balances the fluctuating load demand by using combined dispatch strategies. Furthermore, demand-side load management strategies are implemented for efficient energy management. An economic and environmental analysis has been performed to evaluate the impact of the proposed system. The results show that a significant amount of clean energy (33.2 GWh/year) is produced at the lowest Levelized Cost of Energy of 0.067 €/kWh. Moreover, up to 78% of the energy demand of the selected community is covered by renewable energies, which evades 13,452 tons of CO2 emission yearly. Peer reviewed

Abstract The intervention on the existing building envelope thermal insulation is the main and effective solution in order to achieve a significant reduction of the building stock energy needs. The infrared technique is the methodology of the energy diagnosis aimed to identify qualitatively the principal causes of energy losses: the presence of thermal bridges. Those weak parts of the building envelope in terms of heat transfer result not easy to treat with an energy efficiency intervention, while they are gaining importance in the buildings total energy dispersion, as the level of insulation of opaque and transparent materials is continuously increasing. It is generally possible to evaluate the energy dispersions through these zones with a deep knowledge of the materials and the geometry using a numerical method. Besides, authors proposed in the past a methodology to assess the flux passing through thermal bridges with an infrared image correctly framed. The analysis of surface temperatures of the undisturbed wall and of the zone with thermal bridge, allows to define the Incidence Factor of the thermal Bridge (Itb). This parameter is strongly affected by the thermographic image accuracy, therefore, this paper deals with the development and validation of an innovative mathematical algorithm to enhance the image resolution and the consequent accuracy of the energy losses assessment. An experimental campaign in a controlled environment (hot box apparatus) has been conducted on three typologies of thermal bridge, firstly performing the thermographic survey and then applying the enhancement algorithm to the infrared images in order to compare the Itb and the linear thermal transmittance ψ values. Results showed that the proposed methodology could bring to an accuracy improvement up to 2% of the total buildings envelope energy losses evaluated by quantitative infrared thermography. Moreover, the proposed algorithm allows the implementation of a further process applicable to the images, in order to extract the physical boundaries of the hidden materials causing the thermal bridge, so revealing itself as a useful tool to identify exactly the suitable points of intervention for the thermal bridge correction. The application of the imaging process on the quantitative infrared thermography is an innovative approach that makes more accurate the evaluation of the actual heat loss of highly insulating buildings and reaching a higher detail on the detection and treating of thermal bridges.