In Flanders long lasting massive brick constructions are cha

In Flanders long-lasting massive brick constructions are characteristic, especially within the housing market. Such houses own concrete floors installed in situ with raw materials or with prefabricated elements. The walls outside and inside are mostly brickwork. Outside walls are layered: inside wall, thermal insulation, a narrow cavity, and as façade some fancy brickwork. Fig. 1 shows at the top the reference house of this study. The bottom is a detail of the outer wall of the house. The insulation PUR plates are placed in cross-over for tightening the seams; the black colour outside brick is the finishing. Currently new built massive brick houses are expected to remain part of the built environment for decades to centuries. Such buildings undergo systematic renovations in cycles of about thirty years (Liebregts and Persoon, 2009). For meeting evolving technical requirements, for maintaining market value (Eichholtz et al., 2009), (NBWO (Nederlands Bureau Waardebepaling Onroerende Zaken) [Dutch Agency Valuation of Immovable Property], 2008), for gratifying comfort demands, for minimizing aminopeptidase inhibitor use and associated costs, and for meeting social expectations and environmental regulations, house owners may like to improve energy performance during the midst of the house\'s first life cycle. Also refurbishments within usual renovation cycles must implement minimum energy performance requirements, according to article 7 of the 2010-EPBD (EU, 2010) “building components with a significant impact on the energy properties of the building envelope need retrofit or replacement”. The outside view of the nowadays brick houses in Flanders reflect the architectural taste of the owners. The long-lasting hull also covers functions like thermal insulation, water parry, security, etc. (see Fig. 1) Observed energy performance levels however do not anticipate future evolutions. This may create significant energy and sustainability challenges already within the first 30 years of the building\'s lifespan. Second, studies on house upgrading and recommending retrofit and efficiency measures, mostly deal with outlived houses (Verbeeck and Hens, 2005; LEHR (Low Energy Housing Retrofit), 2010; Verbruggen, 2008). The lessons from such projects are not simply transposable to contemporary newly built houses as the considerations mentioned in the previous point reveal. The descriptive approach of this article is complemented by an exploratory experiment (case study) and by an analysis of the results (Yin, 2009). The exploratory experiment is stylized and based on an existing representative house in Flanders. This choice has two important advantages. First, we use available realistic data (building costs, context); second, it is feasible to compare a variety of transformations on architectural, financial, and energy use aspects. For representing real building practices, consecutive upgrading steps from lower to higher energy performance levels, are considered. The hypothesis of the analysis builds on the theoretical approach of time-sequential decision-analysis by Verbruggen et al. (2011) and Verbruggen (2012), criticizing the standard scholarly practice of applying expected value methods. At the design phase the Energy Performance Endowment (EPE) of a house is decided. Different attributes and items affect the EPE of a house. These attributes and items can be classified as ‘precluded’ (strong irrevocability), ‘rigid’ (medium irrevocability) and ‘adaptable/addable’ (weak irrevocability). Several important EPE features belong to the strong irrevocability or preclusion class. Therefore appropriate decision analysis of attributes and items of a building\'s EPE leads to “Choose or Lose” (provide now to avoid preclusion) situations, opposite to the common “Wait and Learn” (defer the irrevocable investment and keep the option to decide later). The irrevocability characteristics of energy efficiency investments stimulate immediate very efficient buildings rather than standard obeying buildings. Applied here the hypothesis is: The characteristics of recently built houses according to the massive brick building method leads to “Choose now” the best energy performance endowment in order to avoid preclusion of efficiency solutions in the future.