6,478 research outputs found

    Enhancement of the UK Standard Assessment Procedure (SAP) solar water heating prediction algorithm using parametric dynamical thermal simulations

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    SAP is the UK Government’s method for calculation of a dwelling’s energy efficiency and carbon dioxide emissions. This paper presents a method of informing the SAP procedure regarding evaluation of the advantage given to SAP ratings by installation of typical domestic Solar Domestic Hot Water (SDHW) systems. Comparable SDHW systems were simulated using the dynamic thermal simulation package TRNSYS and results were translated into empirical relations in a form that could be input into the SAP calculation procedure. Findings were compared against the current SAP algorithm and differences explained. Results suggest that calculation variances can exist between the SAP methodology and detailed dynamic thermal simulation methods. This is especially true for higher performance systems that can deviate greatly from default efficiency parameters. This might be due to SAP algorithms being historically based on older systems that have lower efficiencies. An enhancement to the existing SAP algorithm is suggested

    Comparison of the simplified methods of the ISO 13790 standard and detailed modelling programs in a regulatory context

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    The CEN Standards that support the European Energy Performance of Buildings Directive requirement for calculation of the energy consumption of buildings allow various methods to be used for the same calculation. The impact of using the different methods within the updated ISO 13790 Standard for space heating and cooling energy calculations was examined with a parametric analysis of a common building specification. The impact was assessed by considering the energy band which would be assigned for the building based on the calculation results. The Standard describes three different methods that can be used for the calculations: a monthly quasi-steady state method, a simplified hourly method and detailed simulation. For most cases studied, differences in the building rating given by the various methods were a maximum of one band. More significant differences were noticed in some cases. Parameter values in the monthly method were determined which would lead to improved matching

    Impact of using different models in practice - a case study with the simplified methods of ISO 13790 standard and detailed modelling programs

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    The updated ISO 13790 Standard is part of the new set of CEN Standards that supports the European Energy Performance of Buildings Directive (EPBD) requirement for a general framework for calculation of the energy consumption of buildings. The Standard sets out procedures for space heating and cooling energy calculations, allowing the use of three different methods: a simplified monthly quasi-steady state method, a simple-hourly method and detailed simulation. This paper examines the implications of allowing different methods to be used for assessing the energy usage. The research method used was to undertake a comparison of the various methods applied to a common building specification, with parametric analyses of variations in this specification. The paper discusses differences in results for heating and cooling requirements between the simplified methods and when a detailed simulation program (ESP-r) is used with constrained (according to the Standard) inputs and with a number of unconstrained inputs. The case where two different detailed simulation programs (ESP-r and EnergyPlus) are used in practice for the same building is also included and conclusions are drawn regarding the practical use of different detailed modelling programs against the simplified methods, as well as against each other

    Adaptive Comfort Degree-Days: an index to compare adaptive comfort standards and estimate changes in energy consumption for future UK climates

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    This paper introduces the concept of the Adaptive Comfort Degree-Day, a temperature difference/time composite metric, as a means of comparing energy savings from Adaptive Comfort Model standards by quantifying the extent to which the temperature limits of the thermal comfort zone of the Predicted Mean Vote Model can be broadened. The Adaptive Comfort Degree-Day has been applied to a series of climates projected for different locations (Edinburgh, Manchester and London) under different emissions scenarios in the United Kingdom for the 2020s, 2030s, 2050s and 2080s. The rate at which energy savings can be achieved by the European adaptive standard EN15251 (Category II) was compared with the ASHRAE 55 adaptive standard (80% acceptability) during the cooling season. Results indicate that the wider applicability of the European standard means that it can realise levels of energy savings which its counterpart ASHRAE adaptive standard would not achieve for decades

    Evaluation of building envelope energy performance through extensive simulation and parametrical analysis

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    More than 30% of the final energy uses in the European Union are due to the building energy consumptions. In order to reduce their energy impact and improve their efficiency, the design activity has been given a large importance, both for new buildings or refurbishment projects. Moreover, besides these goals, during the last years the indoor comfort conditions have assumed a more and more relevant significance for professionals in the building design. That required the development of properly detailed instruments of analysis, such as building energy simulation tools (BES). Generally, the more complex a tool, the higher the number of required inputs but not all of them are always available in the early design stages. For this reason, BES codes have been used also to elaborate simpler models. This research analyses the possibilities given by an extensive use of the BES for the evaluation of the building envelope energy performance and some of the different issues related to BES. The first topic discussed is related to the external boundary conditions in BES, in particular the definition of a representative weather file for the description of the external environment and of the modelling of the heat transfer through the ground. The second topic analyses the problems of the validation of the results provided by BES tools and the relative accuracy introduced by the choice of a specific code. The comparison between BES software is carried out both considering the outputs of a whole thermal zone, such as heating and cooling energy needs and peak loads and the time of their occurrences, and the response of a single component (i.e., opaque walls and glazings). Finally, the coherence between the energy needs elaborated by means of BES tools and those by the quasi-steady state model presented in the technical Standard EN ISO 13790:2008 is studied and some correction factors are proposed for this simplified method

    Modelling of double ventilated facades according to CEN Standard 13790 method and detailed simulation

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    The European Energy Performance of Buildings Directive (EPBD) encourages the use of technologies in buildings that can potentially improve their energy performance. Double ventilated façades can often have a positive contribution to this objective and their effect has to be quantified during the calculation of the overall energy performance of the buildings. The updated EN ISO 13790 Standard is part of the new set of CEN Standards that have to be delivered to support the EPBD requirement for a general framework for the methodology of calculation of the total energy performance of buildings. It contains a method to calculate the contribution of the double ventilated façades to the annual heating and cooling requirements of buildings. At the same time (validated) detailed simulation tools, which are also allowed in this Standard, offer an alternative way to quantify the effect of the double ventilated façades on the buildings' energy performance. This paper examines a case study where the ESP-r simulation program and the method described in the Standard were used for a common building specification to investigate the impacts from a double ventilated façade on the energy performance of the building. It discusses the potential differences that might appear when a detailed simulation tool (ESP-r) is used with constrained (according to the Standard) inputs and also unconstrained inputs, compared to the outputs obtained from the method described in the Standard. Some parametric studies are included to show whether the same trends are obtained using both the method in the Standard and the detailed simulation approach

    Validation of SEAS, a Quasi-Steady-State Tool for Building Energy Audits

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    SEAS is an energy auditing software that can simulate residential, office, school, and hospital buildings, providing energy requirements for heating, domestic hot water production, ventilation, lighting, and other electrical uses. In order to validate this quasi-steady-state tool, we simulated in SEAS several reference cases (based on EN 15265 benchmark room) and a residential dwelling. We also used the dynamic simulation software TRNSYS and compared the results of the two software in terms of seasonal energy requirements for space heating and energy fluxes through the elements of the building envelope. Most of SEAS results are in good agreement with EN 15265 and with TRNSYS. Nonetheless, we pointed out that SEAS lacks in accuracy when it simulates high thermal inertia buildings with intermittent heating: for these particular cases, new correlations for dynamic parameters and reduction factors should be developed

    Investigation of Dynamic and Steady State Calculation Methodologies for Determination of Building Energy Performance in the Context of the EPBD

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    The aim of this thesis was to investigate the ability of a dynamic and a quasi-steady state calculation methodology to capture the heating and cooling aspects of a buildings energy performance in the context of the requirements of the EU Energy Performance of Buildings Directive (EPBD). Chapters 1 and 2 provide a general background review and description of the implementation of the directive’s requirements in Ireland. Chapter 3 established the usefulness and relevance of building energy benchmarks, traditional approaches to building energy performance calculation methodologies. Chapter 4 established the ability of a sample of simplified and dynamic calculation tools to deal with the requirements set out in the directive and the extent the requirements are dealt with. This investigation observed that the underlying calculations and assumptions vary across different calculation tools; resulting in a variety of energy performance solutions. Chapter 5 investigated the ability of a dynamic methodology (IES) and simplified quasi-steady state methodology (SBEM/ prEN 13790) to capture the effects of variation of key parameters of a building design in order to generate an improvement in energy performance. The investigation analysed the sensitivity of both methodologies to the variation of design parameters and their effect in terms of the annual energy performance calculation. In addition, the calculation algorithms of both IES and SBEM were summarised and analysed to account for the difference in results obtained. This investigation established that a dynamic methodology rewards design improvements with greater magnitude than a quasi-steady state methodology
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