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- The assessment of measures is the most important section to be examined: absent in the Italian document, the risk assessment plays a central role in the European one, but deserves some calibration: it doesn’t allow to define a subset of final alternatives, but it is a matrix that collects all retrofit choices data for the multidisciplinary team to discuss - with the effect, however, of losing the different choices’ fallout and a global vision of actions.
- The improvement assessment should consider no single measures, but the whole of actions, considering their effects on the microclimatic change and compliance with building and users. requirements. A systemic approach is necessary to be adopted to avoid rebound effects and unintended consequences, thinking about improvements as long-term opportunities for preserving the building [36].
3. Draft of the Methodology Structure
From the considerations above, it is necessary to develop an holistic and multi-criteria methodology, for the evaluation and planning of retrofit measures, which could be integrated in the existing Guidelines. It is expected that the new procedure could be able to highlight possible implications and interactions of measure packages, to suggest relations without strict directing the decision-making.
The new guidance tool should adopt a whole building approach with regard to potential risks for the constructions. The structure has to be as an interactive system as a flowchart with multiple choices, organised both for guiding professionals to plan retrofit actions - starting from the analysis of stakeholders’ and building conservation needs - (bottom-up approach), and for simply organizing the assessment of selected improvement options, evaluating their impact and interrelation (top-down approach) – (see the general structure in Figure 6).
- In the bottom-up approach, the planning process starts with the introduction on building data (climate zone and building typology) and the selection of retrofit criteria - first step; then, objectives and targets are suggested by the platform, according to the building category and use (as mentioned during the Guidelines analysis, objectives are specific and refer to individual cases and therefore variable; so, as exemplification, for a museum one objective could be the collection preservation, whilst for an office users’ behavior) – second step. Then – third step - retrofit options are recommended and explained with pros and cons and interrelations among other measures. The structure of this part should be similar to the Retrofit Wheel made by STBA in the UK [24]: in this tool 50 measures’ advantages, concerns about their performance and possible interactions between them are depicted in a ‘wheel’ matrix system to promote and deliver a more sustainable traditional built environment. Each option is seen as interrelated in a whole system of choices.
- The top-down approach, on the contrary, the assessment process starts with a selection of retrofit options to be evaluated and the definition of criteria and building typology and use – first step. In the platform, measures advantages and disadvantages are proposed according to single objectives and targets – second step. Three areas are recognized on which the consequences of actions must be verified: heritage, energy and users. For each measure, possible interrelated measures are evaluated.