A Methodology to Link the Internal Heat Gains from Lighting to the Global Consumption for the Energy Certification of Buildings in Italy

Abstract

This paper critically discusses the procedure prescribed by the Italian Technical Standards to account for the internal gains in the calculation of the energy performance indices for a building. This procedure is based on a tabular value set depending on the building usage only (e.g., 6 W/m2 for office buildings), independently of the site and of the controls for blinds and lighting systems. Instead, the paper proposes a new procedure, which relies on the lighting energy numerical indicator (LENI) according to the European Standard EN 15193:2007. Basically, the procedure consists of the following steps: 1) internal gains from lighting are calculated accounting for the integration between electric appliances and daylighting; 2) these gains are summed to the internal gains from occupants and appliances; 3) the global gains are used as input data to calculate the energy performance indices for an office building (for space heating, space cooling, and lighting consumption) following the Italian Technical Standards. The office building which was used as case-study is the Department of Energy of the Politecnico di Torino. This was assumed to be located both in Turin (northern Italy) and in Palermo (southern Italy). In the study, the use of a manual on/off switch and of a photodimming sensor was also compared. For each configuration, the single and the global energy performance indices were calculated comparing two approaches to calculate the internal gains (Italian standard vs. new proposed procedure): a shift of one energy class for the building energy label was observed depending on the approach, which was used.

Keywords

• Internal gains from lighting
• Energy demand for lighting
• Lighting energy numerical indicator
• Building energy performance indices EP