About the shortwave multiple reflections in an urban street canyon building related to three different European climates

Chiara Colucci,Luca Mauri,Andrea Vallati

doi:10.1051/matecconf/201824005004

Chiara Colucci, Luca Mauri + Show 1 more

Open Access

https://doi.org/10.1051/matecconf/201824005004

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Abstract

Energy exchanges between buildings is affected by urban fabric. As a matter of fact, heat exchange between adjacent buildings is due to convective and radiative heat flows. The main parameters which influence these heat exchange mechanisms are due to climate conditions such as air temperatures/humidity, wind speed/direction and solar irradiance. Most building energy simulations are done on an independent single building with typical meteorological year (TMY). These TMY meteorological data cannot represent the state of the urban microclimate and rather ignores the microclimate influence on buildings adjacent to street canyons. However, solar radiation shading and reflection of the environment within the street canyons are important factors affecting the energy consumption of buildings. In this work, a building energy simulation tool is used to study the impact of multiple shortwave inter-reflections in an urban environment. A street canyon model validated in a previous work was modeled in TRNSYS in order to simulate the effects of the urban radiative trapping. An urban canyon with aspect ratio H/W=1 was chosen, with South-North orientation, with transparent/opaque surfaces ratio Atr/Aop=0.5 and 4 values (0.2, 0.4, 0.6, 0.8) of reflectance factor of the envelope surfaces. The goal is to characterize how solar absorption influence the urban energy requirements. The analysis was conducted for 3 cities in different climatic zones: Rome, Palermo and Krakow.

Highlights

Energy saving is an important priority in developed countries where a substantial part of energy consumption is represented by buildings
A street canyon model validated in a previous work was modeled in TRNSYS in order to simulate the effects of the urban radiative trapping
The objective of this study is to evaluate how shortwave multiple reflections affect thermal energy demand of a street canyon building located in three different climatic zones: Rome, Palermo and Krakow

Summary

Introduction

Energy saving is an important priority in developed countries where a substantial part of energy consumption is represented by buildings. In the EU region, buildings account for about 40% of total energy consumption. For this reason, the "Building Energy Efficiency Directive" has been introduced [2] to prescribe requirements for either new and existing buildings. Building energy efficiency can be improved by implementing both active or passive energy efficient strategies. Can be classified as active strategies, whereas, improvements to building envelope elements can be classified under passive strategies [3,4,5,6,7]. Cities are heat and pollution anthropogenic sources, as demonstrated by several studies that have attributed to urbanization radical changes in the radiative, thermodynamic and aerodynamic characteristics of the surface compared to those of the surrounding rural areas [8,9].

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