The Influence of Openings on Energy Demand of Buildings: Analysis of their characteristic parameters using LIDER software (Spain)

Abstract

Openings on buildings facades perform several functions, namely, illumination, ventilation, vision, and communication with outside conditions. Furthermore, when energy efficiency is to be considered, the opening plays a major part in the energetic balance of a building. This article studies the opening as a specialized low technology system which regulates the external climatic conditions having an impact on the building energy demand. First, it was analysed the main parameters that characterize the opening as an element of solar reception in order to indentify the influence of each of them with regard to energy demand. By means of LIDER software calculation method the opening is studied as a solar gain element. LIDER is a recognized free computer programme of Spanish Building Regulation (Codigo Tecnico de la Edificacion, CTE). The contribution of 14 specific parameters of the opening to energy demand is evaluated, specifically, orientation, window-to-wall ratio, frame percentage, degree of absorption, glazing g-value, frame U-value, glazing U-value, overhangs, returns, louver blinds, awnings, air permeability, infiltration and air change rate. With this approach, it was obtained the relative relevance of the 14 parameters under study with regards to energy performance of a simulated space considering the conditions set in the analysis. The alteration in those parameters allows for variations in energy demand estimated at the range 10-60% in heating, and between 2-150% in cooling. The outcomes are more important in qualitative than in quantitative terms due to the limitations of the method and to the working hypotheses of the onset conditions.