• Energy Research

Abstract New policies on energy efficiency in buildings aim to improve our environment. EU requirements on reduced energy demand to achieve Nearly Zero Energy Buildings are of equal importance to pollution and raw-material consumption. Addressing these parameters, building life-cycle analyses are needed, not only to reduce energy consumption, but also to encourage the use of renewable materials. Other priorities are building maintenance and construction material management at the end of the useful life of the building. The use of wooden facades is not very common in Spain. In this study, its energy efficiency is assessed against Spanish Government Regulations, through the Building Technical Code. Hence, this analysis of wooden facades examines their influence on the thermal behavior of the whole building, considering both material properties and structural design, focused on the exterior cladding or protective layer. These structures imply an optimized assembly design together with the application of a protective treatment, depending on its natural durability. “Radiata pine” was selected as one of the most common pine species in the Basque Country, suitable for cladding and grown in sustainable forestry programs. Several commercial simulation tools were used, such as: Therm, Wufi, and DesignBuilder aiming to a full thermal characterization of these particular enclosures, whereas the results obtained were finally validated through an experimental facility.

Abstract Double-skin perforated sheet facades, are enclosures composed of a perforated metallic sheet, air chamber and glass, is showing an increasing tendency in modern building design. In a previous research, their thermal behavior was addressed, taking into account several physical parameters such as, perforation rates, colors and materials, as well as the influence of wind penetration through a Matlab® model, validated through a fully experimental test campaign, monitoring metallic sheets during 1 year, for different configurations, within a range of 0–35% (perforation rates), black-white (colors) and galvanized steel-aluminum (materials). Here, following this research, first of all, the behavior of such configurations is also fully addressed, through a complete Energyplus® model (design builder), which was validated through the abovementioned Matlab® model and experimental outputs. The relevant contribution shows a new parametric energy assessment taking into account additional variables such as the air-gap and location (according to the different climate zones defined for Spain). Finally, the influence of different enclosures on the cooling, heating and lighting loads (energy consumptions) of the building as a whole was obtained, demonstrating the suitability of the previously optimized configurations in terms of relative energy savings. This leads to set up a new methodology aiming to the optimization of design sustainability based on minimum energy consumption.

Abstract New materials with external shading systems are mainly implemented on building facades to improve energy efficiency, but also to add a distinctive appearance. The double-skin perforated sheet-metal facade, an enclosure composed of sheet metal, air chambers and glass, is an example of this tendency in modern building design. The aim of this research is to study the thermal behavior of the facade taking into account several physical parameters such as, perforation rates, colors and materials, as well as the influence of wind penetration. The study also quantifies the improvements in terms of energy savings that different configurations of these parameters can bring to the building as a whole. First of all, a theoretical model was built in Matlab® based on an energy balance of these types of enclosure. The experimental process for validation purposes consisted of monitoring metallic sheets within a range of 0–35% (perforation rates), black-white (colors) and galvanized steel-aluminum (materials) in a large-scale test campaign. Excellent agreement was achieved between the outputs from the above-mentioned numerical model and the test campaign, sufficient for its validation. The behavior of different configurations will be described in a further paper, addressing their influence on cooling, heating and lighting loads in the building, with an Energyplus® model, which will be also validated with our theoretical model. Finally, additional parameters such as air-space width and location in the various climate zones defined for Spain will be carefully studied, for the optimization of design sustainability.

The commitments by the governments for the net zero emissions for the coming decades will be a huge challenge for the renewable sector all over the planet. Wind energy will play a significant role in this transition and scale-up, in both offshore and onshore, is a crucial step to move forward. The quick development of the new onshore wind turbine models in the race for the most powerful machine, the gradual increase in the hub height, and the unitary power of the new onshore wind turbines are producing modifications in different components of the turbines. This work presents a review of the onshore wind turbines foundations, especially about the different foundation design concepts available in the onshore business, the analysis of some of them and the trends.

A new structural typology of a hybrid purlin, made of type C cold steel and rectangular laminated wood (SWP), is presented in this paper. As a result, improvements on the most commonly used steel purlins are achieved, by substituting some of the steel sections for wooden sections. Although the wooden section is weaker and has a lower elastic modulus than the steel, the overall dimensions of the SWP are no larger than the type C steel purlin. In comparison with the steel ones, SWP purlins achieve a far better performance in terms of sustainability and are of lower weight, so less material will be needed for the main structure of the building. The behavior of each material in its position and the improvements in terms of sustainability and lower weight are analyzed as a function of span length, slope, and design load. To do so, the influence of both tensile stress and deformation design criteria in each section and the influence of those criteria on the choice of material and the lengths of each section are all examined. Finally, a design guide for the SWPs is presented that applies the proposed technical specifications.

The thermal behavior of three different walls, made with and without by-products, is assessed by means of the Finite Element Method, aiming to evaluate its performance in terms of the sustainable construction of the blocks. Results were compared to those obtained from an experimental campaign, aiming at validation of the model. The by-products used for the blocks were “lime sludge” and “sawdust”, whose performance was compared against the traditional blocks made of concrete as a reference, aiming to demonstrate its sustainability, showing decreases of the thermal transmittance up to 10.5%. Additionally, following the same methodology, the thermal behavior of these above-mentioned blocks but now with added internal insulation made of “recycled cellulose” was assessed, showing higher decreases up to 25.5%, increasing sustainability by addressing an additional reduction in waste, so the right combination of using by-products and the insulating filler in their cavities has been revealed as a promising way of optimizing the walls, offering a relevant improvement in energy savings. Finally, when comparing the U-values of the blocks made of concrete without insulation versus those made of by-products, with insulation, improvements up to 33.3% were reached. The adaptation of the procedure through a moisture correction factor was also incorporated.

The increasing energy consumption levels of buildings within Europe call for controlled consumption and improvements to energy savings and efficiency and effective energy efficiency regulations. However, many aging and energy-inefficient buildings require energetic retrofitting that can employ various façades solutions and insulation materials. The selection of the most sustainable options in each situation therefore requires a decision-making methodology that can be used to prioritize available retrofit solutions based on economic, functional, environmental and social criteria. In this paper, both the methodology and the economic basis of the retrofitting process are presented. The methodology was validated in a case study, and a sensitivity analysis also demonstrated its validity, robustness and stability

Double-skin perforated sheet façades, enclosures consisting of perforated screens, air chambers and glass/wall sheets, are features of modern building design that are winning greater acceptance. A detailed analysis of their suitability across Europe is first performed here. A reference building both with and without the protective double-skin perforated sheet envelope is subjected to a comparative test of solar energy gains with regard to the environment. Additionally, the results of a preliminary survey are presented on the visual perceptions of different patterns of perforated metal sheets. Then the behaviour of these configurations is addressed, through a complete “Energyplus® model” (design builder). A test campaign on a reference perforated screen mounted on a service building of reference was fully monitored over one year, supported by thermographic data recorded for additional validation purposes during the same period. The new parametric energy assessment takes additional variables into account, such as orientation and location of the façade, demonstrating that the real performance for such enclosures greatly depends on them. Accordingly, the influence of different combinations of perforated screens on cooling, heating and lighting loads demonstrates the suitability of a previously optimized configuration in terms of relative energy savings. The authors are deeply grateful to the Basque Government, through projects IT781-13 and IT1314-19