• Energy Research

AbstractA large variety of transparent materials is available for uses in buildings façades and all glazing properties must be considered in their choice. Such a selection should be a careful process of evaluation and weighing of tradeoffs. The correct glazing specifications for façades can reduce energy consumption in buildings, because the heat exchange and passage of radiation into the building as light and heat occur through transparent surfaces. Therefore, glazing significantly contributes to the heat transfer between outdoor and indoor spaces, which act directly on daylighting and thermal comfort. This manuscript addresses a spectrophotometric characterization of glazings for the study of components for the design of a modular façade system based on the climate of Portugal. The study focused on results of spectrophotometric measurements of an optical behavior in different solar spectrum intervals (ultraviolet, visible and near infrared), specifically the transmittance of some types of simple glazings. The results show the percentage of transmission to spectrum intervals, which enabled the analysis (OK?) of the efficiency of the glazing regarding daylighting and correlation to the thermal performance. Indications for specifications and adequate uses based on transmission of transparent surfaces have been obtained and complemented the datasheets available from the manufactures.

Sustainable development can be achieved through several activities. The building and construction sector (B & C sector) is one of the major industries, and it can play a crucial role in the improvement of the most relevant environmental impacts. Nowadays, there are major concerns related to sustainability in construction. All types of buildings have different technical aspects; therefore, it is required to develop specific sustainability assessment tools. A school building has peculiarities connected to aspects of sustainability, as it is a building planned to offer adequate environments for the education of adolescents and children. This article shows the application of the SBTool methodology developed specifically for Portuguese high schools, SAHSBPT (Sustainable Assessment for High School Buildings) methodology, that is being elaborated by the first author in her PhD Thesis. This methodology allows architects, engineers and designers to improve sustainability in school buildings, in projects or in the rehabilitation of buildings. The objective of this research is to apply that evaluation tool in order to verify the efficiency of this methodology, as well as to recognize the level of sustainability of the Francisco de Holanda High School Building, in Guimarães, Portugal. The values found in the application of the Sustainable Assessment for High School Buildings in that high schools demonstrate a good result, as the overall value is A, 75% of the total result.

Abstract The building sector is responsible for consuming approximately 40% of the final energy in Europe. However, more than 50% of this consumption can be reduced through energy-efficient measures. Our society is facing not only a severe and unprecedented environmental crisis but also an economic crisis of similar magnitude. In light of this, EU has developed legislation promoting the use of the Cost-Optimal (CO) method in order to improve building energy efficiency, in which selection criteria is based on life cycle costs. Nevertheless, studies show that the implementation of energy-efficient solutions is far from ideal. Therefore, it is very important to analyse the reasons for this gap between theory and implementation as well as improve selection methods. This study aims to develop a methodology based on a cost-effectiveness analysis, which can be seen as an improvement to the CO method as it considers the investment willingness of stakeholders in the selection process of energy-efficient solutions. The method uses a simple graphical display in which the stakeholders’ investment willingness is identified as the slope of a reference line, allowing easy selection between building solutions. This method will lead to the selection of more desired – from stakeholders’ point of view – and more energy-efficient solutions than those selected through the CO method.

While facing increasingly strict regulations regarding energy efficiency, the construction sector should also adopt sustainable solutions in terms of new constructions and renovations of buildings. In particular, energy renovation of existing buildings has specific technical and economic constraints that are generally addressed through implementation of new materials and building integrated systems, whose environmental impact should be considered when assessing the most adequate solution. Within the context of the More-Connect Project, which aims to develop modular prefabricated solutions for energy renovation of buildings, several renovation scenarios for a pilot building in Portugal were assessed using a methodology to compare the cost-effectiveness of renovation measures. The article explores the use of lifecycle assessment to analyse the effect of considering embodied primary energy in cost-effectiveness calculations. The MORE-CONNECT project is funded by the European Commission within the framework of the Horizon 2020 program.

The cooperative housing sector is directed at low and medium income residents who cannot afford to buy their homes in the regular private market. Due to social housing legislation, it is possible to build cooperative housing below regular market costs and use tax benefits, therefore providing affordable dwellings to their owners. Traditional cooperative housing used to provide less comfort and higher running costs in indoor and domestic hot water heating than in standard construction. However, cooperative housing has started to change its method of traditional construction towards sustainable construction, in order to benefit from the savings on energy consumption and domestic water as well as to provide an improvement as far as the comfort of its residents is concerned. Therefore, in this article, the savings in electricity and natural gas in different building settlements, calculated for Madalena building—sustainable construction—and for Azenha de Cima building—traditional construction—will be presented, according to two different criteria of calculation: efficiency of dwellings at a pre-determined standard level of indoor comfort opposed to real consumptions made by residents. For each building under analysis, an energy audit and further monitoring were brought in, in order to issue an energy evaluation according to the Portuguese energy agency rules. Results showed an expected decrease of the operational costs of natural gas and electricity, obtained by the use of efficient building systems and equipment, as well as a decrease of the payback period for each situation.

With the ongoing significance of overheating calculations in the residential building sector, building codes such as the European Energy Performance of Building Directive (EPBD) are essential for harmonizing the indicators and performance thresholds. This paper investigates Europe's overheating calculation methods, indicators, and thresholds and evaluates their ability to address climate change and heat events. e study aims to identify the suitability of existing overheating calculation methods and propose recommendations for the EPBD. The study results provide a cross-sectional overview of twenty-six European countries. The most influential overheating calculation criteria are listed the best approaches are ranked. The paper provides a thorough comparative assessment and recommendations to align current calculations with climate-sensitive metrics. The results suggest a framework and key performance indicators that are comfort-based, multi-zonal, and time-integrated to calculate overheating and modify the EU's next building energy efficiency regulations. The results can help policymakers and building professionals to develop the next overheating calculation framework and approach for the future development of climate-proof and resilient residential buildings. - (undefined)

Europe’s commitment to reduce energy consumption and CO2 emissions by 2050 led to a proposal to amend the EPBD in December 2021. This proposal introduces the environmental footprint assessment for new buildings involving all phases of their life cycle. The life cycle approach, however, could provide valid suggestions and results even if applied to energy renovation interventions. In this study, the LCA methodology - according to the variant cradle-to-gate with options - is used to investigate the energy and emissions consumed and produced for the energy-oriented retrofit of both opaque and transparent building envelope of a residential building, in the Mediterranean area. The analysis shows that the solutions that allow maximum energy savings in the operational phase of the building differ from those characterized by minimal energy impact from a life cycle perspective. At the same time, however, the latter enable an acceptable operational energy saving and a higher total reduction of energy demands. In detail, the solution that allows maximum energy savings in the operational phase, equal to about 39.4%, has a weight of the embedded energy of 7.1%. The solution with the minimum weight of the incorporated energy, equal to about 5.5%, allows an operating energy saving of 39.1%.