In healthy buildings, it is considered essential to quantify air quality. One of the most fashionable indicators is radon gas. To determine the presence of this element, which is harmful to health, in the environment, the composition of the soil is studied. The presence of radon gas within a building depends both on the terrain in which it is located and on the composition of the materials of which it is composed, and not as was previously believed, only by the composition of the soil (whether granitic or not). Many countries are currently studying this phenomenon, including Spain where the building regulations regarding the accumulation of radon gas, do not list in their technical codes, the maximum dose that can a building can hold so that it is not harmful to people and the measures to correct excessive accumulation. Therefore, once the possible existence of radon in any underground building has been verified, regardless of the characteristics of the soil, the importance of defining and unifying the regulations on different levels of radon in all architectural constructions is evident. Medical and health science agencies, including the World Health Organization, consider that radon gas is a very harmful element for people. This element, in its gaseous state, is radioactive and it is present in almost soils in which buildings are implanted. Granitic type soils present higher levels of radon gas. Non-granitic soils have traditionally been considered to have very low radon levels. However, this paper demonstrates the relevant presence of radon in non-granitic soils, specifically in clayey soils, by providing the results of research carried out in the underground air raid shelter at Balmis Square in Alicante (Spain). The results of the measurements of radon accumulation in the Plaza Balmis shelter are five times higher than those obtained in a similar ungrounded building. This research addresses the constructive typology of an under-ground building and the radon presence in its interior obtained using rigorous measurement techniques.

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.

Current market conditions characterized by technological changes, increasing regulatory requirements and low funding make current construction management models obsolete. This tendency affects not only the private housing market but also public administration projects, which have large time and budget deviations across the board. As a result, new approaches are needed to improve the efficiency of the construction process, removing extra costs and delivering projects on time. The most representative trends in the construction industry that enable such improvements are both Building Information Modelling paradigm (BIM) and Lean Construction philosophy with one of its associated tools in the field of construction management—the Last Planner System. However, a review of the literature shows the scarcity of works on the synergy of both paradigms taking into account the extensive literature on Lean and BIM individually. This is further accused if we look beyond the theoretical literature reviews. Therefore, this paper is focused on the benefits derived from the synergy of both disciplines and the impacts on project efficiency through a case study of a public construction project at the university of Alicante in order to provide empirical evidence of the benefits and improvements of using BIM at the Look Ahead meetings and of the Last Planner System. Finally, the results of the case study allow us to make a comparison with the data related to cost deviations of other public projects with different uses, built areas, and complexity which were managed with traditional methods of construction.

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The construction industry needs contemporary approaches in order to improve the performance of the construction process, in terms of both time and cost. Currently, the most significant trends applied for this purpose are building information modelling paradigm (BIM) and Lean construction philosophy. Following the rise of both paradigms, many studies have been conducted to explore the benefits of its application in isolation. As a consequence, the aim of this paper is to bring to knowledge a state-of-the-art overview of literature about BIM and Lean construction synergies. Firstly, a general overview of each paradigm is presented. Secondly, the synergies between both principles and their theoretical and practical applications are also covered. Finally, conclusions and recommendations for future researches are presented.