In the European Guidelines the assessment of measures is applied on the building as a whole, including its envelope and all technical building systems. Despite the text brevity, important concepts are highlighted in this document, as the specification that “Maintenance is the best conservation measure” and in this field “non-standard measures could be considered”.  
The procedure consists of six steps, collected in three main phases that should be carried out by a multidisciplinary team. It was followed step by step, from the first phase of data collection on cases, to the evaluation of the chosen measures.
STEP 1-2: Building Data Collection and Energy Performance Assessment
The first step is structured in nine points as a collection of information on the building, useful to address the planning process. The first three points collect general information on the building (historical, constructive, legal); the fourth point asks to highlight opportunities to reinstate lost or hidden character-defining elements (e.g. restoring/reinstate original window form), conservation priorities or constraints on behalf of the local heritage authorities, to understand the limitations of the intervention to define where, how much and how to intervene. The risk is to focus on the single building node rather than on a set of calibrated actions, which should constitute the purpose of the procedure.
In this phase the Guidelines require the energy performance assessment, that could be done by energy audit, a systematic inspection, or an analysis of energy use and energy consumption (asset rating) or calculating in-depth tailored energy performance (tailored rating). Case studies are examples of different procedures: case 1 and 2 data are those coming from the energy audits done by Sicily Region; case 3 hasn’t any energy profile because has no plants. For case 3, the attempt has been made to verify both a static simulation software (CENED+, freely provided by Lombardy region) and a dynamic software (EnergyPlus) to compare the two methods results in a singular condition. In a static simulation, although results are quickly produced, there are numerous problems, such as: lack of adequate databases, inability to define more complex parameters such as infiltration rate and internal gains and accuracy of weather data [33]. This meant that an approximate result was obtained in terms of global primary energy (540 kWh/m²). This kind of software is better for labelling energy in order to compare different performances in standard condition of use.
In contrast, the dynamic evaluation tool has allowed modelling each input parameter: detailed data were included both for describing climatic conditions, geometry and building properties. As output, building could be verified in terms of temperature and humidity, but also comparing energy requirement adopting a false plant as in the static model: the results is an half value (295 kWh/m²) respect to the previous one. It has been possible also to evaluate other parameters, useful for a complete evaluation of performance needs, such as: infiltration losses, air surface temperature, solar gains and daylight luminance to verify comfort needs. Although dynamic simulation involves more time compared to the static one, it yields more accurate data.
According to expressed considerations, a correct energy performance assessment is important to be able to make decisions in the following phases on retrofit options. The limit of both methods is in the correctness and accuracy of the input data that must be calibrated on measured data [34]. But, the output data must be also evaluated properly, according to the building needs and use. The Guidelines not necessarily directed towards one or the other method, however, one must be more explicit about the pros and cons of both.
STEP 3-4: Criteria, Objectives and Targets
The second phase of the procedure requires defining objectives and targets according to the priority criteria that address the project in the planning phase. Before this passage it is mandatory to define some criteria, upon which future action lines should be based: objectives (from the latin ob-jectum, ‘projected forward’) are specific and refer to individual cases and therefore variable, whilst some guiding criteria (from the greek κριτήριον, ‘rule’ or ‘principle’) could be of general validity, referring to the need of protection. Finally, the targets are measurable parameters, definable as "indicators" of the effectiveness of the objectives set for each case.
Here in Figure 2 the most common criteria, objectives and targets adopted in literature: