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- Andersson, Staffan, 1952-, et al.
(författare)
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Building performance based on measured data
- 2011
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Ingår i: World Renewable Energy Congress – Sweden, 8–13 May, 2011, Linköping, Sweden. - Linköping : Linköping University Electronic Press. - 9789173930703 ; , s. 899-906
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Konferensbidrag (refereegranskat)abstract
- With increasing liability for builders, the need for evaluation methods that focuses on the building’s performance and thus excludes the impact from residents’ behavior increases. This is not only of interest for new buildings but also when retrofitting existing buildings in order to reduce energy end-use. The investigation in this paper is based on extensive measurements on two fairly representative type of buildings, a single family building in Ekerö, Stockholm built 2000 and two apartment buildings in Umeå (1964) in order to extract key energy performance parameters such as the building’s heat loss coefficient, heat transfer via the ground and heat gained from the sun and used electricity. With access to pre-processed daily data from a 2-month periods, located close to the winter solstice, a robust estimate of the heat loss coefficient was obtained based on a regression analysis. For the single family building the variation was within 1% and for the two heavier apartment buildings an average variation of 2%, with a maximum of 4%, between different analyzed periods close to the winter solstice. The gained heating from the used electricity in terms of a gain factor could not be unambiguously extracted and therefore could only a range for the heat transfer via ground be estimated. The estimated range for the transfer via ground for the two apartment buildings were in very good agreement with those calculated according to EN ISO 13 370 and corresponded to almost 10% of the heating demand at the design temperature. For the single family building with an insulated slab and parts of the walls below ground level, the calculations gave slightly higher transfer than what was obtained from the regression analysis. For the estimated gained solar radiation no comparison has been possible to make, but the estimated gain exhibited an expected correlation with the global solar radiation data that was available for the two apartment buildings.
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- Olofsson, Thomas, 1968-, et al.
(författare)
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Energy Performance for Buildings Evaluated with Multivariate Analysis
- 2005
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Ingår i: Proceedings of the of the Ninth IBPSA Conference and Exhibition, Building Simulation 2005. ; , s. 891-898
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Konferensbidrag (refereegranskat)abstract
- Numerous problems can occur for an investigatorof larger datasets, e.g. how to handledimensionality, many variables and fewobservations, few variables and many observations,correlations, missing data, noise and to extractinformation from all data simultaneously.Multivariate analysis (MVA) is an establishedmethod for dealing with such problems.In this work, we introduce a methodology based onMVA, which was developed to model the buildingenergy performance from the perspective of theproperty holder. Data from a Swedish database of500 buildings, which recently has been compiledand is under expansion, was used for theinvestigation. The available data consists ofbuilding specific information and consumptiondata, monitored on a monthly basis, reported by theproperty holder. Electrical consumption for lightingand appliances is paid by the tenants in Sweden,and is thus lacking in the database. This means thatthe data base just include the part of the total energyuse that is paid by the property holder. With theoverall goal to assess the energy use paid by theproperty holders, a methodology is suggested forestimating the electrical energy paid by the tenants.At this early stage of our work, we found that theused methodology gives a fairly robust model andthat the interpretation of the model is believed to beaccurate in terms of comparing the energy usebetween different buildings.
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| 5. |
- Olofsson, Thomas, 1968-, et al.
(författare)
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Multivariate Methods for Evaluating Building Energy Efficiency
- 2004
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Ingår i: Proceedings of the 2004 ACEEE Summer Study of Energy Efficiency in Buildings. - 0918249538 ; , s. 265-274
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Konferensbidrag (refereegranskat)abstract
- For an owner or operator of a building, benchmarking can be a useful guide for finding outhow energy efficient the building is and identifying what to improve. For successfulevaluation of the building energy efficiency, the categorization as well as the parameteridentification has decisive importance. That selection can be based on mathematical modelingsuch as linear regression accompanied with more or less user expert knowledge. Theselection, however, is not a simple task since analyses based on statistical data are sensitive tocorrelations between different measured parameters. For improving that analysis multivariatemethods such as Principal Component Analysis (PCA) can be a valuable support.We demonstrate here how PCA can be a useful tool for investigating aggregated statisticaldatasets. The investigation illustrates how a set of building performance parameters exhibitsdifferent relations depending on how the categorization is made, which is relevant to considerwhen benchmarking. The study is based on a national Swedish database of aggregated energyuse and building performance statistics.
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- Sjögren, Jan-Ulric, 1958-
(författare)
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Energy performance of multifamily buildings : building characteristic and user influence
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today many professional property holders use different types of software for monthly energy analyses. The data is however often limited to energy and water use, that is paid for by the property holder. In year 2001, financed by the Swedish Energy Agency, the first steps were taken to create a national web based data base, eNyckeln. A property holder may then enter consumption data together with about 50 other building specific parameters to this data base in order to enable benchmarking and energy performance evaluations. Due to EU-regulations and the increasing awareness of energy and environmental issues there is a large interest in evaluating the energy performance and also to identify effective energy retrofits. The used energy performance indicator is still only the annual energy use for heating per square meter of area to let, kWh/m2,year, despite the fact that monthly data often are available. The main problem with this indicator, which is the stipulated measure, is that it reflects a lot of user influence and that only a part of the total energy use is considered. The main focus of this thesis is to explore the possibilities, based on the national data base, to extract additional energy information about multi family buildings (MFB) using monthly data in combination with different assumed consumption pattern but also to identify potential for energy savings. For the latter a multivariate method was used to identify relations between the energy use and building specific parameters. The analysis gave clear indications that the available area, the area to let, is not appropriate for normalization purposes since the remaining heated area can be significant. Due to this fact, the analysis was mainly limited to qualitative conclusions. As measure of the buildings energy characteristic, the total heat loss coefficient, Ktot,(W/ºK) is determined and the robustness for the estimate of Ktot to different assumptions of user behaviour is investigated. The result shows that the value of Ktot is fairly insensitive to different indoor temperature, use of domestic hot water and household electricity. With the addition of m2 it can of course be used for benchmarking. Using the mentioned measure of the buildings energy characteristic for validating the energy performance has a clear advantage compared to the traditional kWh/m2, since the user behaviour is of minor importance. As a result of this an improved analysis of the energy performance will be obtained. A guarantee for new buildings energy performance based on this method is therefore a challenge for the building sector to develop.
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