The concept of a Digital Building Logbook (DBL) was first introduced with the European strategy ‘Renovation Wave’. It is considered as one of two fundamental parts of which the Building Renovation Passport is composed: the DBL and a Renovation Roadmap. As the implementation of the DBL is a European priority, this paper reviews the existing literature and analyses the most developed European Digital Building Logbook models. The analysis includes iBRoad, ALDREN, X-tendo, and the Study on the Development of a European Union Framework for Buildings’ Digital Logbook, from the perspective of seven key aspects: References used as a starting point for the model definition; Identification of the relevant stakeholders in the DBL; Identified potential user needs; Proposed structure of indicators; Data sources; Potential functionalities; and Operation and use. The results show that important advancement has been made, although there is still no consensus about crucial subjects, such as the indicators to be collected or how to collect and use them. This is probably due to the fact that the final functionalities (objective and scope) that the logbook should provide are not fully clear.

According to the European Commission, the Digital Building Logbook (DBL) is a repository of all of the relevant data of a building. It was first introduced at the European scale in the Renovation Wave strategy and was first defined in the proposal for the recast of the energy performance of buildings Directive in December 2021. The European DBL has not been implemented yet, since a common model does not yet exist. Even though great efforts are being made to establish it, some relevant issues need to be addressed first. One of them is the identification of data sources that will feed the DBL. Existing digital data sources have already been explored in some countries and they have been found to be insufficient. In this paper, new digital data sources suitable for the logbook are identified, and their contribution in terms of indicators and interoperability is analysed. The analysis shows that these sources have great potential to contribute to the DBL, because they bring the possibility to collect a great amount of real data on buildings. However, the main barrier for these tools to be incorporated into the DBL is that their linkage still requires further research.

Opaque enclosures of buildings play an essential role in the level of comfort experienced indoors and annual energy demand. The impact of solar radiation and thermal inertia of the materials that make up the multi-layer enclosures substantially modify thermal transmittance behaviour of the enclosures. This dynamic form of heat transfer, additionally affected by indoor HVAC systems, has a substantial effect on the parameters that define comfort. It also has an impact on energy demand within a daily cycle as well as throughout a one-year use cycle. This study describes the destructive monitoring of an existing block of flats located in Alicante. Once the enclosure was opened, sensors of temperature (PT100), air velocity, and relative humidity were located in the different layers of the enclosure, as well as in the interior and exterior surfaces. A pyranometer was also installed to measure solar radiation levels. A temperature data correction algorithm was drawn up to address irregularities produced in the enclosure. The algorithm was applied using a Raspberry Pi processor in the data collection system. The comparative results of temperature gradients versus non-destructive monitoring systems are presented, providing measures of the transmittance value, surface temperatures and indoor and outdoor air temperatures. This remote sensing system can be used in future studies to quantify and compare the energy savings of different enclosure construction solutions.

Few houses have been built in the Spanish Mediterranean in accordance with the Passivhaus (PH) standard. This standard is adapted to the continental climates of Central Europe and thorough studies are necessary to apply this standard in Spain, especially in the summer. High relative air humidity levels in coastal areas and solar radiation levels of west-facing façades require adapted architectural designs, as well as greater control of air renewal and dehumidification. A priori, energy consumptions undergo big variations. In this study, the construction of a single-family house in the Spanish Levante was analysed. All enclosure layers were monitored using sensors of surface temperature, solar radiation, indoor and outdoor air temperature, relative humidity, and air speed. The thermal behaviour of the façade enclosure and air infiltration through the enclosure were examined using the blower door test and impacts on annual energy demand were quantified. Using simulation tools, improvements are proposed, and the results are compared with examples of PH housing in other geographical areas. The annual energy demand of PH housing was 69.19% below the usual value for buildings in the Mediterranean region. Very thick thermal insulation and low values of airtightness could be applied to the envelope, which would work very well in the winter. These technique solutions could provide optimal comfort conditions with a well-designed air conditioning system in summer and low energy consumption.

Two renovation strategies were considered and compared in this paper for the energy renovation of social housing in condo buildings built in 1945–1969, situated in residential estates that have been declared urban areas of interest. One of the strategies, named here the image conservation approach, consists of renovating the building with very efficient solutions, except for the brick-facing walls, which will only have insulation in the existing cavities. The other strategy, the image coordination approach, consists of renovating the whole building with efficient solutions, including external insulation for existing brick-facing walls, and drawing up coordination plans for each of the residential estates in order to guarantee a coordinated new image of the residential estates. By means of three case studies in the city of Zaragoza and four scenarios of improvement, the two strategies are compared regarding the regulation compliance, the energy use, the emissions reduction, the thermal comfort, and the cost-effectiveness of the measures. The results show that the image coordination approach is the best strategy in regard to the studied aspects, achieving a 69%–79% reduction of CO₂ emissions and a 75%–97% reduction of heating use, as well as being the only one capable of transforming these buildings into nearly zero energy buildings (nZEBs).