Abstract
Contrarily to what happens in northern European countries, buildings in the Mediterranean region are prone to overheating. Consequently, it is important to better understand the role that the thermal transmittance of the building envelope elements has on air-conditioning consumptions. This paper analyzes the effect of different U-values on building design in the Mediterranean area. 192000 residential buildings were randomly generated for sixteen distinct locations and the energy consumption was assessed for each. It was found that in northern Mediterranean locations, as U-values decreased, energy consumption also decreased. However, in warmer climates, low thermal transmittances tended to significantly increase energy consumption. Hence, the lower the latitude, the higher the U-values should be, in order to prevent increasing the cooling demands. Additionally, geometry-based indexes were correlated with the building’s energy performance. For high U-values, it was found that bigger buildings worsen the energy performance and larger windows tended to improve it. For low U-values, bigger north-facing windows were beneficial. There is an adequate interval of values for which the geometry has a lower impact, which is wider and higher for lower latitudes, thus meaning that not only does the building performance improve but architects are also freer to explore alternative designs.
Highlights
Energy consumption in the building sector continues to increase worldwide
The locations are sorted descending by latitude from top to bottom rows and the horizontal axis corresponds to each U -value group, ranging from 0.2 W · m−2 · K−1 to 5.0 W · m−2 · K−1, in steps of 0.2 W · m−2 · K−1, for transparent elements, and from 0.05 W · m−2 · K−1 to 1.25 W · m−2 · K−1, in steps of 0.05 W · m−2 · K−1, for opaque elements
The results of this study show some relation between the construction elements thermal transmittance and the buildings energy consumption and geometry
Summary
Buildings account for one-third of today’s final energy consumption, with households accounting for about three-quarters [1] This adds to the fossil fuels depletion and to the climate change, making the reduction of energy consumption in the building sector of crucial importance. This sector is considered one of the most cost-effective areas to reduce energy use [2]. In this context, some authors have already pointed out that the traditional thermal transmittance of building envelope elements may not be the most appropriate [2,3,4,5,6]. Inadequate U -values for opaque and transparent elements may lead to higher heating and/or cooling demands, worsening the buildings’ performance
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