Suchergebnisse

Due to EU and worldwide high energy consumption of the buildings stock, it is important to take measures to reduce these needs and, consequently, reduce the EU energy dependency as well as the greenhouse gas emissions. To improve the behaviour of the buildings, concerning thermal comfort of the occupants and energy performance, it is necessary to reduce the thermal amplitudes, the winter heat losses, the summer heat gains and to store the energy from solar gains. The thermal insulation and the thermal inertia play an important role in this. The use of phase change materials (PCM) is a way of achieving thermal mass without increasing the weight of the buildings and simultaneously improving the thermal comfort conditions inside buildings, by increasing thermal energy storage. The good thermal characteristics of PCM can be used, in new and existing residential or office buildings, as a passive way of saving energy and reducing running costs for both heating and cooling seasons. Therefore it is possible to achieve an adequate behaviour of buildings reducing the energy needs, using solar gains, night cooling and off-peak electricity and, at the same time, increasing the comfort conditions inside the buildings, reducing temperature fluctuations and peak temperatures. In the Mediterranean Countries the selection of the type and amount of PCM to be used is a challenge due to the different characteristics needed to achieve an adequate behaviour of the buildings during winter and summer periods. In this study, the use of micro and macro-encapsulated PCM in buildings was studied to evaluate the annual behaviour and to identify the amount of PCM needed to ensure a suitable thermal and energy performance of the buildings. ; The work was partially funded by the European Union (COST Action COST ...

Publicado em "Sustainable housing 2016: proceedings of the International Conference on Sustainable Housing Planning, Management and Usability" ; The existing European building stock is responsible for 40% of total energy consumption and 36% of greenhouse gas emissions in Europe. In order to reduce these values, the European Union (UE) has been strengthening and updating the regulations which define the minimum energy requirements for buildings. Therefore, Member States started to increase their energy requirements for buildings, with the purpose to raise their efficiency, reduce their emissions and energy needs, making them more sustainable at the energy level. The renovation of the existing buildings, especially those designed before the first thermal codes is an essential step to achieving the EU proposed targets, due to their low energy performance. Thus, the energy renovation of existing buildings, combined with other sustainable design practices, is a priority to reduce EU's energy dependency and carbon emissions. On this context, this study aims at presenting the energy renovation of a Portuguese dwelling, built in the late 60, using a Building Information Modelling (BIM) approach during the design phase. BIM methodology was used to perform an energy analysis of a case study, in order to discuss the advantages of this approach at identifying the best energy renovation scenario. From this study, it was possible to verify that the main added value of the BIM is that it can streamline the designers' decision making by improving better integrating between different design areas, saving time and money during the design stages and therefore promoting the better efficiency of the building ...

Nowadays, in the European Union the construction rate of new buildings is very low and therefore achieving the EU targets at the energy consumption level of the building sector is only possible through nearly zero energy renovation of the existing building stock. Reducing energy consumption through passive measures is a priority but this is not enough to achieve the nearly Zero Energy Building (nZEB) level. Therefore, the active systems, namely those that allow harvesting the solar energy to partially replace the use of non-renewable energy, are one of the best solutions to consider. At this level, solar thermal and photovoltaic panels play an important role, mainly in countries with high levels of solar radiation, as in the Southern European countries. Nevertheless, there are still some barriers to overcome for the broader dissemination of the implementation of these systems. One of the most important is that building owners are not fully aware of the life-cycle benefits that systems have at the economic level. As in every new different design approach, the best way to arise awareness is through the analysis of case studies, highlighting the reduced life-cycle costs and potential environmental impacts and other long-term benefits resulting from the integration of these active solutions. Thus, this paper is aimed at assessing the contribution of the solar systems to achieve three levels of energy performance (Basic Renovation, nearly Zero Energy Buildings - nZEB and Zero Energy Buildings - ZEB) in the energy renovation of a multifamily building located in Portugal. From the results, it is possible to conclude that, on an annual basis, and for the Portuguese climate, it is possible to overcome, a large amount of the energy needs for acclimatization and domestic hot water preparation with the integration of these systems. The study also shows attractive cost and carbon payback times resulting from their use. ...

In the last decades, public and governmental awareness on thermal comfort and indoor air quality (IAQ) has been growing. In buildings the number of potential pollutants is significant, and even low concentration levels can cause health problems (increased incidence of asthma and allergies, for example) if combined effects are considered. Therefore, the assessment of thermal comfort conditions and IAQ is very important to ensure health, wellbeing and productivity. This paper presents the results of a thermal comfort conditions and IAQ assessment of two hospital buildings with natural ventilation. The goal of this study was to verify the thermal and IAQ conditions inside Portuguese hospital buildings. The air temperature, the black bulb temperature, air velocity, relative humidity and the concentration of suspended particles, carbon dioxide, carbon monoxide, ozone, formaldehyde and total volatile organic compounds were measured. A standard questionnaire was delivered to the occupants to also obtain a subjective assessment of the thermal comfort and IAQ conditions. The results showed that, in general, the occupants were uncomfortable and that the main IAQ problems were related to high concentrations of carbon dioxide, volatile organic compounds and ...

In the last decades, public and governmental awareness on thermal comfort and indoor air quality (IAQ) has been growing. In buildings the number of potential pollutants is significant, and even low concentration levels can cause health problems (increased incidence of asthma and allergies, for example) if combined effects are considered. Therefore, the assessment of IAQ is very important to ensure health, well-being and productivity. This paper presents the results of a thermal comfort conditions and IAQ assessment of two hospital buildings with natural ventilation. The air temperature, the black bulb temperature, air velocity, relative humidity and the concentration of suspended particles, carbon dioxide, carbon monoxide, ozone, formaldehyde and total volatile organic compounds were measured. A standard questionnaire was delivered to the occupants to also obtain a subjective assessment of the thermal comfort and IAQ conditions. The goal of this study was to verify the thermal and IAQ conditions inside Portuguese hospital buildings. The results showed that, in general, the occupants were uncomfortable and that the main IAQ problems were related to high concentrations of carbon dioxide, volatile organic compounds and formaldehyde. ...

The recast of the energy performance of buildings directive stipulates that by 2020 all new buildings should reach nearly zero energy levels (2019 for buildings owned or occupied by public authorities). Therefore technicians involved in the design, conception and approval of such buildings should be able to understand and apply nearly zero energy buildings (nZEB) concepts both towards new buildings and the refurbishment of existing ones. However the number of architects and engineers that are able to deal with new technologies and standards might not be adequate to the increasing market demand. Additionally, at European Union (EU) level there are differences in commitment to the EU targets and the construction of nZEB. In this context, arose the SouthZEB project, that is an Intelligent Energy Europe (IEE) funded project, that aims to fill this gap and address the need to develop training schemes to professionals involved in nZEB building process, transferring successful practices and knowledge from front runners to target Southern EU countries that are less advanced in this area. This paper presents the project aims and ...

The first global oil crisis, led the European Union to start the necessary procedures in order to control and reduce the energy consumption of buildings. In Europe the energy consumption of residential buildings increased since 1990 until 2003 1.3% per year and it is expected that, by 2050, the energy consumption of buildings will have increased by 40%. According to the EPBD-recast all member states should adopt the necessary measures so that buildings become highly efficient - nearly Zero Energy Buildings (nZEB's). Nevertheless, quantitative standards are not appointed, so each member state should establish the minimum requirements for energy performance in buildings attending to the local conditions. However before establishing these requirements it is necessary to evaluate the building stock and its energy efficiency. As most of the Portuguese residential buildings are old and degraded an opportunity arises for the energy rehabilitation of the building stock, implementing EPBD-recast principles, making it more energy efficient and comfortable. The aim of this study was to describe the current conditions of the building stock in order to identify whether there are suitable conditions for energy rehabilitation of buildings. The analysis performed showed that although there are a significant potential for building energy rehabilitation, there are also some constraints, namely the lack of credit and loans financing of ...

In average, man spends about 90% of the time inside enclosed spaces, in both residential and office buildings, exposed to consistently higher concentrations of air pollutants than outdoors, which has led to the increased rate of allergies and asthma incidences. In the last decade, public and governmental awareness on indoor air quality (IAQ) has been growing. Portugal implemented the National Building Energy and Indoor Air Quality Certification System in 2006 which imposes periodic IAQ audits for office buildings. However, in residential buildings, the only normative imposition related to IAQ is the obligation of a minimum air change rate of 0.6 h-1. The number of potential pollutants inside residential buildings is significant, and even low concentration levels can cause health problems if combined effects are considered. Additionally, the inhabitants' behaviour can have a significant impact on IAQ. Therefore, the assessment of IQA is very important. This paper presents the application of the IAQ audit methodology, defined by the Portuguese legislation for office buildings, to residential buildings. The concentration of suspended particles, carbon dioxide, carbon monoxide, ozone, formaldehyde and total volatile organic compounds were measured as well as the air change rate. A standard questionnaire was delivered to the inhabitants to also obtain a subjective assessment of the IAQ. The goal of this study was to verify the IAQ conditions inside the Portuguese residential buildings and to establish a comprehensive IAQ audit approach for residential buildings. The results gathered will also be used to identify the main problems of Portuguese residential building stock and to develop guidelines to improve IAQ in residential ...

In 2002 EU implemented the Energy Performance of Buildings Directive which led to the revision of the buildings thermal codes. The transposition of EBPD into the Portuguese legislation was made through three regulations: RCCTE for residential buildings, RSECE for office buildings and SCE that establishes the energy labelling system. The national code RCCTE sets two methodologies for assessing the energy performance of buildings: a simplified methodology and a more detailed one, depending if it is an existent or a new building. It has been observed that since the entrance into force of these codes, the project teams are using the RCCTE methodologies as tools to estimate the energy consumption of buildings. In this work it was tested the accuracy of this approach, performing two studies: one where the energy needs obtained with the RCCTE methodology were compared with the ones obtained with a dynamic simulation tool; and another where the same energy needs were compared with the ones obtained with a simplified RCCTE methodology foreseen for existing buildings. With the studies performed it was verified that the RCCTE methodology is accurate enough, except for the coldest regions, where another kind of tool should be applied. The simplified methodology showed inaccurate results and must be used with caution. However, with some corrections, important improvements can be ...

The driving force of the thermal regulations revision in the European Union (EU) was the European Energy Performance of Buildings Directive – EPBD (European Commission, 2003). The main objectives of the EPBD are the harmonization of all thermal regulations in the EU and the optimization of buildings energy performance, taking into account the climatic conditions, interior comfort conditions of the occupants and economic viability, for both new and existing buildings. In order to be efficient and effective, the thermal regulations must accurately estimate the energy performance of buildings and so, the building certification will allow comparisons of the results obtained in the different climates to be more meaningful. Having this fact in mind the Portuguese calculation methodology will be put side by side with a dynamic simulation for the energy performance estimation. This study was based on the heating and cooling needs estimation of single houses and dwellings, for the three major Portuguese thermal regions, using the simplified calculation models established in the Portuguese thermal regulation and the results obtained with a dynamic simulation tool. ; Department of Energy United States of ...

The driving force of the thermal regulations revision in the European Union (EU) was the European Directive for the Energy Performance of Buildings – EPBD (European Commission, 2003). The main objectives of the EPBD are the harmonization of all thermal regulations in the EU and the optimization of buildings energy performance, taking into account the climatic conditions, indoor comfort conditions and economic viability, for both new and existing buildings. In order to be efficient and effective, the thermal regulations must lead to an accurate estimation of the energy performance of buildings allowing the energy certification to become a useful tool to compare results obtained in different countries. Having this fact in mind, the results obtained with the Portuguese calculation methodology, together with the results obtained with the methodologies used in two other countries (UK and Belgium), will be put side by side and also compared with the results obtained with a dynamic simulation tool for the energy performance estimation - VisualDOE. This case study will be based on the heating and cooling needs estimation of some Test Cells built in the School of Engineering of the University of Minho. The simulated results obtained using the simplified calculation models established in the mentioned three countries thermal regulations and by ...

The recast of the Energy Performance of Buildings Directive settle that by 2020 all new buildings should reach nearly zero energy levels (2018 for buildings owned or occupied by public authorities). Therefore, technicians involved in the design, management and approval of buildings should be able to understand and apply nearly zero energy buildings (nZEB) concepts in both new buildings and refurbishment of existing ones. At European Union (EU) level there are differences in commitment to the EU targets and the construction of nZEB. Therefore, it is necessary to develop studies that demonstrate the advantages of the nZEB and ZEB design process that can increase the awareness of both building clients and other stakeholders regarding this issue. In this context, the aim of this paper is to assess the energy and environmental life-cycle performance of different renovation scenarios (Basic Renovation, nZEB and ZEB) for multifamily buildings in Portugal. This will be focused on the goals of the nZEB and ZEB design process and on the contribution of solar systems (both solar thermal collectors, STCs, and photovoltaic panels, PVs) to the achievement of those goals. The results presented in this paper show that, in the Portuguese climate and for a typical multi-family building, it is possible to overcome 100% of the energy needs for acclimatization and domestic hot water (DHW) preparation with the integration of solar systems. From the results, it is also possible to conclude that a significant amount of energy and carbon emissions are avoided for every renovation scenario during the considered lifetime (30 years) and that the nZEB and ZEB scenarios are cost-effective with attractive payback times. ; IEE Project SouthZEB (under the reference IEE/13/393) ; Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Projects UID/ECI/04047/2013 and ...