1,720,974 research outputs found
Thermal inertia and energy efficiency - Parametric simulation assessment on a calibrated case study
Get PDFThe reduction of energy consumption for heating and cooling services in the existing building stock is a key challenge for global sustainability today and buildings' envelopes retrofit is one the main issues. Most of the existing buildings' envelopes have low levels of insulation, high thermal losses due to thermal bridges and cracks, absence of appropriate solar control, etc.Further, in building refurbishment, the importance of a system level approach is often undervalued in favour of simplistic "off the shelf" efficient solutions, focused on the reduction of thermal transmittance and on the enhancement of solar control capabilities. In many cases, the importance of the dynamic thermal properties is often neglected or underestimated and the effective thermal capacity is not properly considered as one of the design parameters.The research presented aims to critically assess the influence of the dynamic thermal properties of the building fabric (roof, walls and floors) on sensible heating and cooling energy demand for a case study. The case study chosen is an existing office building which has been retrofitted in recent years and whose energy model has been calibrated according to the data collected in the monitoring process.The research illustrates the variations of the sensible thermal energy demand of the building in different retrofit scenarios, and relates them to the variations of the dynamic thermal properties of the construction components.A parametric simulation study has been performed, encompassing the use of calculation tools and performance metrics at the different scales of the building (envelope-zone-overall building) considering the realistic operating conditions assumed for the initial calibrated model and different climate conditions, typical of the Italian territory and, more in general, of the Southern European and Mediterranean area
Local energy efficiency programs: A monitoring methodology for heating systems
No full textIn recent years, as a result of an important agreement with the Italian Ministry of the Environment, Lombardy Region has promoted and supported numerous measures for energy efficiency and renewableenergy sources integration within its territory. Subsequently, monitoring campaigns have been launched to evaluate the global outcomes of the different calls and programs. Among other types of interventions, the promotion of the replacement of diesel boilers with high efficiency natural gas boilers represents an effective way to reduce primary energydemand and emissions and, more in general, to support the definitive transition from oil derived fuels toless polluting fuels like natural gas.The research presents the results of the monitoring campaign performed on about 1500 heating system's retrofit interventions subsidized by Lombardy Region within its Framework Program Agreementin the field of Environment and Energy. Local energy efficiency programs are particularly important today and have to be designed, managed and monitored to clearly identify the real energy, economic and environmental benefits that they produce. The research presented aims to provide a methodology and useful insights for the implementation of such programs along with their monitoring and analysis processes. In particular, the research illustrates the use of indicators to enable a comparison according to multiple criteria and different perspectives, in particular the societal one and the end-user's one
Calibration and uncertainty analysis for computer models – A meta-model based approach for integrated building energy simulation
No full textIn energy and environment field models are constructed, in general, based on well-defined physical phenomena and properties. Calibration and uncertainty analysis hold a particular interest because models
represent a simplification of reality and, therefore, it is necessary to quantify to what degree they are imperfect before employing them in design, prediction and decision making processes. Integrated building
energy models attempt to describe the effect of various internal and external actions (weather, occupancy, appliances, etc.) through physical relations (both algebraic and differential) and they are being
widely used to design and operate high performance buildings, which are an essential component of a global energy strategy to reduce carbon emission and fossil sources depletion. An approach oriented to
systems and able to integrate effectively field measured data and computer simulations for calibration in the modeling process has the potential to revolutionize the way buildings are designed and operated, and to stimulate also the development of new technologies and solutions in the field. The research presented in this paper aims to represent an initial step towards this integrated approach
Building Automation and Control Systems and performance optimization: A framework for analysis
No full textThe pressing global environmental issues are fostering a rapid change in the energy and sustainability policies
for the built environment. New paradigms are emerging, such as “Nearly Zero Energy Building” (nZEB), and
resource efficiency is progressively becoming a crucial topic in the building sector, implying an appropriate
consideration of performance over the whole life cycle. However, empirical evidences show how, very often, the
gap between the predicted (design phase) and measured (operation phase) performance is very large, due to
errors committed during all the phases of building life cycle. This performance gap determines a problem of
credibility in the building industry and, more in general, in sustainability oriented practices. Therefore, design
and operation practices should evolve in order to be able to cope with performance uncertainty determined, for
example, by evolution of climate conditions, variability of behavioural patterns and performance degradation of
technological components.
For these reasons, a framework for the analysis of the potential of Building Automation and Control Systems
for performance optimization is proposed. This framework aims to highlight, in particular, the possibility of
establishing an effective methodological continuity among building performance simulation, control and data
analytics, not immediately recognizable in current practices. Further, it aims to envision the possibility of
creating a unified methodological approach, which could guarantee multiple feed-backs from measured data,
useful for the evolution, first of all, of design and operation practices but also, more in general, of the whole
value chain of the building sector
Cost optimal analysis of heat pump technology adoption in residential reference buildings
No full textIn European Union (EU) buildings consume approximately the 40% of total primary energy. Heat pump (HP) systems have proven to be an efficient and economically viable alternative to conventional systems to provide heating and cooling services in buildings. An effective penetration of this technology in the built environment is critical to achieve the ambitious goals set by the recent EU Directives on energy efficiency and energy performance of buildings. Although this technology is very versatile, its optimal design and management are related to specific climate, operational and economic conditions. The research presented aims to evaluate the performance of technical solutions for heating and cooling in residential buildings, using a "reference building" methodology. The comparison involves performance indicators such as primary energy consumption, CO2 emission and net present cost.The potential improvements with respect to conventional baseline solutions are assessed and the performance gap between air-source and water-source HP systems is shown referring to realistic operational and climate conditions within the Italian territory. The research suggests the possibility of reducing this performance gap by concentrating future research effort on design and control optimization
A simplified model for the estimation of energy production of PV systems
No full textThe potential of solar energy is far higher than any other renewable source, although several limits exist. In detail the fundamental factors that must be analyzed by investors and policy makers are the cost-effectiveness and the production of PV power plants, respectively, for the decision of investment schemes and energy policy strategies. Tools suitable to be used even by non-specialists, are therefore becoming increasingly important. Many research and development effort have been devoted to this goal in recent years. In this study, a simplified model for PV annual production estimation that can provide results with a level of accuracy comparable with the more sophisticated simulation tools from which it derives is fundamental data. The main advantage of the presented model is that it can be used by virtually anyone, without requiring a specific field expertise. The inherent limits of the model are related to its empirical base, but the methodology presented can be effectively reproduced in the future with a different spectrum of data in order to assess, for example, the effect of technological evolution on the overall performance of PV power generation or establishing performance benchmarks for a much larger variety kinds of PV plants and technologies
Performance monitoring and modeling of an uncovered photovoltaic-thermal (PVT) water collector
No full textPVT technology presents many attractive features for a wide application in the building sector since it is able to produce electricity and thermal energy at the same time with better overall performances and reduced surfaces in comparison with the two separated solar technologies. However the effectiveness of the PVT modules is most evident when they are integrated in complex systems, capable of fully exploiting their multi-functionality (e.g. heat pump coupling, multi-storage interconnection, etc.). For that reason, the research work presents a mathematical model for energy simulation of PVT systems, which takes in account all factors and parameters involved in the energy performance of an uncovered hybrid collector; the model can be easily implemented in any performance calculation tool in order to carry out technical-economic assessment of PVT systems.The experimental calibration and validation of the proposed model was performed in outdoor conditions on a commercial PVT product, at the Test Facility of the Politecnico di Milano University, and finally the model was ran supposing the application in three different locations. The validation of the developed simulation model shows a good agreement with monitored data also if a mismatch occurred due to an assembling defect of the tested commercial PVT component
Parametric energy performance analysis and monitoring of buildings—HEART project platform case study
No full textBuilding performance analysis changed the way in which buildings are designed and operated. The evaluation of different design and operation options is becoming more resource intensive than ever before. Although building dynamic simulation tools are potentially a suitable way for assessing energy performance of buildings accurately, they require adequate training and a careful evaluation of model input data. In Europe, the majority of buildings were constructed before 1990 and are in urgent need for a significant energy efficiency improvement, through deep renovation. In this respect, advanced renovation solutions are available, but costly and lengthy renovation processes and technical complexities hinder the achievement of a large scale impact. Energy refurbishment of buildings is an open challenge and essentially requires the adoption of a valid methodological approach to link design and operational performance analysis transparently, in order to address the potential gap between simulated and measured results. The HEART project, funded in the EU Horizon 2020 program, aims to address the increasing need for deep retrofit interventions and to develop systemic strategies leading to high performance and cost effective solutions. The research for the cloud platform used in the project is based on two fundamental tools: parametric simulation to produce a large spectrum of possible building energy performance outcomes (considering realistically the impact of the user behaviour and variable operating conditions from the very beginning), and model calibration employing simple, robust and scalable techniques. In this paper we present the preliminary development and testing of the computational processes that will be implemented in the cloud platform, employing the first pilot case study of HEART Project in Italy, currently under refurbishment.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
