Energy and Buildings 43 (2011) 476–484 Contents lists available at ScienceDirect Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild New indices to assess building energy efficiency at the use stage Guillermo Escrivá-Escrivá ∗ , Carlos Álvarez-Bel, Elisa Pe ˜ nalvo-López Institute for Energy Engineering, Universidad Politécnica de Valencia, Camino de Vera, s/n, edificio 8E, escalera F, 2 a planta, 46022 Valencia, Spain article info Article history: Received 5 August 2010 Received in revised form 24 September 2010 Accepted 5 October 2010 Keywords: Building classification Energy audit Energy efficiency Use stage abstract Numerous computer programs are available to calculate the energy efficiency of buildings. Many are based on the use of a reference building to determine the degree of efficiency. However, this methodology presents a major constraint when assessing a building after construction and during the use stage. To assess the energy efficiency of buildings, this paper proposes new indices based on energy consumption during different periods; as well as other parameters of the buildings such as construction area, number of users, and air-conditioned volume. Results are presented as an application for various buildings on the campus of the Universidad Politécnica de Valencia. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Energy consumption has recently become a major issue because of growing concern about CO 2 and other greenhouse gas emissions and concern about scarce fossil fuels [1]. Energy behaviour characterisation and quantification are the first step towards the identification of actions to improve energy use. Energy required, technology deployed, and facility use are basic information for evaluating the efficiency and performance of energy consuming facilities. Non-industrial buildings are one of the biggest consumers of energy and account for 30–40% of the total primary energy con- sumed in developed countries, and this consumption is increasing in line with human activity [2]. The energy behaviour of these types of buildings has received a great deal of attention in Europe, and has been the subject of a specific European Directive (2002/91/CE) [3]. This directive states that the building energy demand depends on building construc- tion quality, climatology, and the efficiency of the energy systems deployed in the building. Reference energy consumptions are used for evaluation purposes. The application of this norm has revealed some drawbacks [4] that have resulted in problems when evaluating existing buildings, especially at the use stage. These problems have arisen because the use of the facility and associated maintenance procedures were not properly considered. ∗ Corresponding author. Tel.: +34 963 879 240; fax: +34 963 877 272. E-mail address: guieses@die.upv.es (G. Escrivá-Escrivá). Some of these country specific regulations (Spain, Italy, and Greece) focus the energy behaviour of the building only in terms of specific global consumptions or CO 2 emissions, disregarding other important aspects [4,5]. The implementation of this regulation has not been correctly performed in many European countries because of these drawbacks. This is the case in Spain, where the analysis required by the Spanish regulation is only oriented to CO 2 evalua- tion, disregarding some other important energy parameters. There are two official programs for performing energy certification for building analysis: Calener VYP (for residential or small commercial buildings), and Calener GT (for medium and large tertiary build- ings). Comparison against reference (not optimal) levels is made using validated software programs that are usually cumbersome and applied during the design phase [4]. However, analysis of energy consumption at the use stage is very important. It is obvious that the construction characteristics of the buildings strongly affect consumption during the life cycle of the building. Furthermore, the way in which the facilities are used during the use stage is also very important when determining the efficiency of the building. The objective of this paper is to provide new indices for perform- ing energy characterisation and classification of buildings as part of a complete and accurate method that does not require exten- sive information. The manner in which the building is managed, as well as the characteristics of construction are taken into account when computing energy qualification. The efficiency of a building strongly depends on the way it is used and managed. Accordingly, a methodology based on new energy indices is pro- posed. This methodology will enable the identification of inefficient and unsuitable building use. The paper is organised as follows. Section 2 describes the methodology. Section 3 describes the building information 0378-7788/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.enbuild.2010.10.012