795 research outputs found
Acoustic evaluation of beam and pot slabs with lightweight regularization layers: a case study
The objective of this work is to evaluate the acoustic performance of beam and pot slabs with
regularization layers made of lightweight concrete.
The study consists on the analysis of the acoustic behaviour of three types of solutions, through the execution of "in situ" measurements for the determination of the airborne sound insulation index and of the impact sound insulation index.
The studied elements have the same support element (concrete slab), but regularization layers made of different materials.
The regularization layers studied were: concrete with granulated expanded polystyrene, concrete with expanded clay aggregates and cellular concrete.
The acoustic performance of the three slabs is evaluated and compared with the performance of conventional solutions in way of evaluating their potentialities
Life cycle assessment of solar thermal systems
The better understanding of cost-benefit, economic and environmental performances of solar thermal systems (STSs) is crucial for designers to be able to take a conscious and weighted decision about the installation of these systems. Therefore the goal of this research was to create a methodology for designers to support decision-making in the selection of the most adequate STS for a project and as result to contribute to a more sustainable built environment. This methodology allows the calculation of the potential environmental impacts, such as the global warming potential, acidification, eutrophication, ozone depletion, embodied energy, amongst others, together with the life-cycle costs resulting from the implementation of STSs in buildings. The system boundary includes the production of the various parts of the solar thermal system, such as the solar collector and the hot water tank, the assembly process, the maintenance stage, the auxiliary energy consumption and the end of life of this system. In the economic analysis, both initial and maintenance costs are considered together with the cost of the auxiliary energy. At the end, it is possible to quantify carbon, energy and cost payback periods. One practical application of the methodology will be carried out in the end of this work, aiming the comparison between four different STSs to be applied in a case study. The case study showed that both the energy and environmental payback times of a STS are less than 3 years and the life cycle cost payback period vary from 7 to 13 years
Improving buildings refurbishment through operative conditions evaluation
As EU existing buildings stock account for 40% of the total energy consumption, it is important to take measures to reduce these needs and, consequently, reduce the EU external energy dependency as well as reducing the greenhouse gas emissions, in accordance with what is prescribed in the EU Directive 2002/91/EU on Energy Efficiency in Buildings (EPBD) and reinforced with the "EPBD-recast". The implementation of energy efficiency measures in the existing building stock is necessary to meet the 2020 targets. Thus, energy refurbishment of existing buildings is essential to achieve these goals. However, during the buildings refurbishment, energy issues should not be the only concerns since the indoor air quality is also as important. When planning a building refurbishment it is then necessary to take into account the energy efficiency exigencies and also the indoor air quality. To do so, the main problems of the existing buildings should be identified, in order to do the right choices regarding the refurbishment project. This work presents a study carried out in a large office building to identify the main pathologies, related to the energy efficiency and also to the indoor air quality. The study encompasses an “in-situ” evaluation of the operating conditions, indoor air quality and air change rate. The main objective of this study was to support the development of a refurbishment project of the building that can optimize the energy efficiency, but also the relevant parameters to the Indoor Air Quality. The results showed that the building has a poor envelope thermal resistance, inadequate shading systems and also several problems regarding high concentration of some pollutants like CO2 or VOC
Portuguese EPBD based regulation put side by side with energy simulation tools
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 achieved
Definition of the energy performance requirements in rehabilitation projects
Building rehabilitation is essential to achieve the targets defined by the EPBD-recast regarding energy efficiency, reduction of carbon emissions and use of on-site renewable energy sources.
To propose an effective building rehabilitation it is necessary to study the best combination of available options in terms of construction solutions, technical building systems (hot water, ventilation, heating, cooling and lighting), their cost, but also their impact on the thermal and acoustic comfort and indoor air quality of the building. Also, the definition of the cost-optimal level is essential, which is the minimum lifecycle cost (including investment costs, maintenance and operating costs, energy costs, earnings from energy produced and disposal costs) of each individual measure.
In this work the multi-criteria decision analysis method ELECTRE III will be applied to balance all these aspects, during the design phase of a refurbishment project, in order to assist the design team on the selection of construction solutions and technical building systems.
A simple case study is presented to demonstrate the feasibility of this approach in what concerns the definition of the energy performance requirements (e.g. thickness of insulation and efficiency of the heating system/air-conditioning system etc.), of a rehabilitation project. In this example several retrofit alternatives were studied, their implementation could lead to the reduction of the energy needs of the building from 13% to 83%. With this approach it was also possible to identify the alternative with the best global performance considering the investment costs, energy needs, indoor air quality, thermal comfort, and CO2 emissions
Contribution of the solar systems to the nZEB and ZEB design concept in Portugal: energy, economics and environmental life-cycle analysis
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 UID/FIS/04650/201
Portuguese building stock indoor environmental quality “in-situ” assessment
Since the implementation of the Energy Performance of Building Directive, EPBD, in general, and
the entrance into force of the respective Portuguese codes, in particular, buildings are requested to
have better energy performances. However, during the buildings performance evaluation, energy
issues should not be the only concerns since the indoor environmental quality is also as important.
Thus, in this paper it is presented an “in-situ” evaluation of the Portuguese building stock regarding
several parameters related to indoor environmental quality (IEQ), envelope thermal quality and
operating conditions, natural illumination levels, thermal and acoustic comfort and indoor air quality.
During the measurement campaign were evaluated several buildings that encompass different types
of construction solutions, climatic zones and construction periods. One of the major objectives of this
study was to support the development of building solutions that can optimize all the relevant
parameters to the IEQ. Another important objective is the dissemination of the results through public
entities, such as construction companies and design teams in order to influence the buildings projects
to include other parameters than energy during the design process. Even though the measuring
campaign is still in progress, there are already some preliminary results that show that, in average,
the Portuguese buildings have a poor envelope thermal resistance, untreated thermal bridges,
unsuitable natural illumination levels, several problems regarding high concentration of some
pollutants like CO2 or VOC and also problems with acoustic discomfort due to an inadequate sound
insulation
Tissue Composition of Carcass and Fatty Acids Profile of Lambs Meat Finished in Pasture and Feedlot of the Southern Region of Brazil
Volume de água precipitado para subsidiar avaliações da capacidade de suporte de edificações com tetos verdes mitigadores de ilhas de calo na cidade de Belém, Pará.
Oferta pluvial associada a respostas dendrométricas em vegetação secundária manejada em unidade familiar no Nordeste paraense.
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