Effect of mutual radiative exchange between the surfaces of a street canyon on the building thermal energy demand

In this paper, a building energy simulation tool is exploited to study the impact of multiple radiative inter-reflections exchanges in an urban environment. The aim is to evaluate their influence on the thermal energy demand of buildings. A street canyon model validated in a previous work is used in TRNSYS to investigate the effects of the related urban radiative trapping. Due to multiple shortwave and longwave reflections, the actual radiation exchanged by the buildings facades is different if compared to a street canyon building, where only shadowing phenomena due to canyon geometry are considered. Buildings energy simulation commercial codes do not take in account inter-reflections inside urban canyons. The objective of this study is to evaluate how multiple shortwave and longwave reflections affect thermal energy demand (cooling and heating) of a street canyon building depending on its orientation, its transparent/opaque surfaces ratio and on the solar absorption factor of the envelope surfaces. Increases in cooling demand up to 50% and decreases in heating demand up to 20% are found

Retrofit Analysis of a Historical Building in an Architectural Constrained Area: A Case Study in Rome, Italy

A significant portion of Europe’s historical buildings have significant potential for energy efficiency. Social policy is typically opposed to energy retrofits because it is concerned about damaging historical or cultural sites. Contrarily, there are several approaches to energy efficiency that may be used with historic structures while also retaining the region’s architectural constraints. The findings of this study demonstrate that historical structures, which are typically not targets of energy efficiency technology because of architectural constraints on the building or in the neighbourhood, may also achieve a meaningful decrease in energy usage and GHG emissions. The significant energy-saving capability of this type of building is emphasized in the historical structure taken into consideration. The historical building object of the present study was built in the beginning of the 1900s and it was selected by the Ministry of Culture for energy efficiency improvements

Experimental investigation about the adoption of high reflectance materials on the envelope cladding on a scaled street canyon

In the last years innovative building envelope materials were studied in order to mitigate the urban heat island phenomenon in cities. Among them, cool materials represent a valid solution to achieve this goal. These materials are characterized by high solar reflectance and high thermal emittance. Another way to reduce the urban heat island effect is the adoption of retroreflective materials on the building facades, in order to reduce the amount of solar radiation entrapped within the urban fabric. The retroreflective materials have a particular surface conformation that allows to reflect the solar radiation back in the same direction of the incident radiation. In this case, the temperature of the surfaces inside an urban canyon should have lower values compared with the case with common construction materials. Consequently, also the air temperature inside the urban canyon has low values with significant advantages on outdoor thermal comfort and on building thermal energy demands. In this work the solar reflectance directional dependence was investigated with a Goniophotometer. Furthermore, experimental measurements of retroreflective materials effects on a scaled urban canyon were performed. It was found that the albedo of the RR material increases with the incident angle of the light beam from 38.2% to 42.3% with an angle of 8 degrees and 60 degrees respectively. An increase of the reflected radiation to the sky in the case of the use RR materials despite of a commercial Lambertian paint with same albedo at 8 degrees of incident light beam was evaluated. In particular, the measurement brings to assess a maximum average percentage canyon albedo difference of 2.03%. (C) 2021 Elsevier Ltd. All rights reserved

Buoyancy-Induced Convection in Water From a Pair of Horizontal Heated Cylinders Enclosed in a Square Cooled Cavity

Buoyancy-driven convention from a pair of horizontal heated cylinders, set side by side inside a square cooled cavity filled with water, is studied numerically. The system of the conservation equations of mass, momentum and energy expressed in dimensionless form is solved through a control-volume formulation of the finite-difference method. The pressure-velocity coupling is handled using the SIMPLE-C algorithm. Numerical simulations are executed for different values of the Rayleigh number based on the cylinder diameter, as well as the width of the cavity, the inter-cylinder spacing and the distance of the cylinders from the bottom wall of the cavity normalized by the cylinder diameter. Two heat and fluid flow configurations are generally found to establish inside the cavity, according as the cylinders are located at close distance or at such a distance that the effects of the lateral walls of the cavity become important, each of these configurations being distinguished by the existence of an optimum inter-cylinder spacing which maximizes the overall heat transfer rate. Moreover, when the inter-cylinder spacing is such that the cylinders are located sufficiently close to the cavity sides, a periodic flow arises

Transcriptomic and Proteomic Analysis of the Epicardial Adipose Tissue

The study of epicardial adipose tissue (EAT) has been limited by its accessibility due to its proximity to the heart. Moreover, many common animal models do not have EAT, leaving its functional role underestimated and poorly elucidated. Recent advances in medicine and science have allowed for better studies that provide a more comprehensive understanding of its physiological role. One way to dissect its function is the study of its gene expression. In this chapter, we summarize transcriptomic and proteomic analyses which show that EAT expresses a unique set of genes setting it apart from other adipose tissues in the body. This distinctive set of genes modulates a feedback mechanism that has direct interaction with the myocardium. The EAT shares its blood supply with the coronary arteries and innervation with the cardiac muscle, provides physical protection, and regulates energetic metabolites needed by the myocardium. Transcriptomic and proteomic studies show that it is a local source of adipokines with paracrine influence on the myocardium due to the intimate microcirculation shared by both tissues. These analyses also show that it has a role in the immune and endocrine systems affecting the rest of the body. Furthermore, regulation of EAT gene expression is not monolithic and can be affected by multiple factors such as sex, age, underling disease, medication, etc. Gene expression studies can therefore provide great insight into the function of EAT and its role in health and disease