Office buildings built before the entry into force of the first thermal regulation in 1991 constitute a relevant group for analysing the energy performance of the Portuguese building sector. A dynamic energy simulation was used to assess the energy performance of an existing office building located in the town of Bragança, Portugal. Four energy efficiency measures were selected and a financial evaluation through the internal rate of return (IRR) method was undertaken to choose the best retrofit option for improving the building’s energy performance. An investment package consisting of the roof insulation and a new equipment for the domestic hot water system presented an IRR higher than the discount rate used in the analysis, and, thus, a positive financial return. The results of the study also suggest that the EU’s comparative methodology framework is not particularly suitable for assessing building retrofit investment at the private investor’s perspective and further refinement in the cost-effective approach to renovations is needed to help stimulate building’s energy renovation market. Suggestions for further studies conducted for office buildings in the different climate zones in Portugal are also proposed.

Vibrations in rock masses can be a significant hazard, leading to human discomfort and structural damage. Recent cases of subway or tunnel excavation near existing dams in Portugal have raised again the importance of this topic. Traditional statistical tools have been used to study wave propagation in rock, but fall short when rock fracturing or faulting radically changes the way vibration propagates. Numerical models such as finite-element or finite-difference models also have some insufficiencies, namely in the way discontinuities are represented. We propose the utilization of bonded particle models based on the Particle Discrete Element Method. Synthetic rock samples are generated and their static elastic properties are calibrated by manipulating microproperties (assembly organization and normal and shear contact stiffness). The static and dynamic properties of the rock cores are tested and the complete elastic response of the model is evaluated and discussed.

The Sun is the largest source of energy available and many studies for the development of technologies capable of harnessing this energy are constantly being conducted. Among the technologies developed are photovoltaic solar panels that have many applications and among them are the autonomous solar lighting columns that have been growing in popularity especially in urban and industrial environments. These columns are installed in open regions and have their structure exposed to the mechanical actions imposed by the wind, so they need to be correctly designed to support them. There are aerodynamic variables that must be determined for the design of these columns, especially the drag coefficient, a property linked to the geometry  of a body, which represents its interaction with a flowing fluid. Due to the complexity of determining these variables, experimental methods are constantly used to obtain these values. Classically, wind tunnel simulations are used for this purpose, but they can be expensive and difficult to perform. Fluid dynamic computational analysis has been widely applied to replace physical analysis. In this work, the drag coefficient of an autonomous solar lighting column is determined by wind tunnel simulations and computational analysis. With the obtained results, a comparison is made to verify  the fidelity of the data obtained by computational means when compared to those obtained through the wind tunnel simulations. Keywords: Drag coefficient, Wind tunnel simulations, Computational Fluid Dynamic analysis, Autonomous solar lighting columns

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Sustainability and efficiency in buildings are concepts that have been recently growing and developing. Its application in several buildings has become mandatory in many countries around the world. One of the major challenges faced by sustainable buildings is the achievement of satisfactory levels in efficiency terms, without negatively impacting the economics. The residential construction sector has great potential for energy savings and is also where building strategies need to be carefully planned,  as they seek to meet the needs of residents not only in the present, but also over time. Residential design must be done thoroughly and must include the analysis of all climate variables involved. In order to verify a residential building envelope behaviour regarding energy and thermal efficiency, this paper intended to evaluate through software Design Builder®, walls and roofs with a rock wool layer, placed in a Light Steel Frame (LSF) house. Keywords: Insulating materials, Light steel frame, Heat gains, Heat losses