Browsing by Author "Oliveira, M. José"
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- Influence of adaptive energy saving techniques on office buildings located in cities of the Iberian PeninsulaPublication . Bienvenido-Huertas, David; Sanchez-Garcia, Daniel; Rubio-Bellido, Carlos; Oliveira, M. JoséThe use of setpoint temperatures based on adaptive comfort algorithms is a method more and more used as an energy saving technique. Knowing the relationship between inhabitable rooms with their specific climate is crucial for users' climate adaptation, especially in a global warming context. This research analyses the influence of EN 15251:2007, EN 16798-1:2019, and ASHRAE 55-2017 standards on an office building located in 65 cities. The effects of climate change have been considered in the energy performance of current, 2050, and 2100 scenarios. Also, 780 dynamic simulations were performed so that a cluster analysis was carried out to determine the similarity relationships among the various zones. The results show that the model of the EN 16798-1:2019 standard was the option achieving a greater energy saving in current and future scenarios, and the use of energy was greatly reduced in those zones characterized by having a greater cooling energy consumption. Moreover, the differences of energy consumption between the adaptive models in the cities and years generated that the clusters presented differences among all cities, so such scenarios are required to be considered for future interventions. This research is the transition towards the goals proposed by the European Union for 2050.
- Mitigation of the negative effects of recycled aggregate water absorption in concrete technologyPublication . Eckert, Matthias; Oliveira, M. JoséThe widespread use of natural aggregates in construction activities, together with the global population increase, gave rise to a depletion of this natural resource and to progressive increase of its transport distances. On the other hand, the construction and demolition wastes (C&DW) resulting from the construction activities are often deposited in landfills and city outskirts, causing environmental and social problems, such as erosion, deforestation, water contamination and human conflicts. The reuse of C&DW in concrete preparation would be a good solution for both problems. Recycled aggregates show, however, high water absorption due to porosity. At saturation, water flows from the inside to the engaging cement paste matrix and at dryness the opposite process occurs. This water flow breaks the aggregate-cement paste bonds and increases the W/C ratio in the interfacial transition zone, this degrades the fresh and hardened concrete properties. In this work a staged mixing method based on the aggregate water absorption over time was developed. A staged mixing procedure was optimized to regulate the water flow and manufacture concrete, using recycled aggregates, with levels of workability, strength and shrinkage equivalent to those of conventional concrete. The physical, mechanical and geometrical properties of the aggregates were related to the properties of concrete in its fresh and hardened state. Three types of commercial recycled aggregates were evaluated. Two types of natural aggregates were also studied for comparison purposes. (C) 2016 Elsevier Ltd. All rights reserved.