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  • 51.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energy Models for single-family buildings2000Doctoral thesis, comprehensive summary (Other academic)
  • 52.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Allard, Ingrid
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A quantitative evaluation of airtightness measurement experiences2014In: NSB 2014 10th Nordic Symposium on Building Physics 15-19 June 2014 Lund, Sweden: FULL PAPERS / [ed] Jesper Arfvidsson, Lars-Erik Harderup, Anders Kumlin, Bitte Rosencrantz, 2014Conference paper (Refereed)
    Abstract [en]

    Evaluation of building air tightness based on field measurements is an important aspect in the process to provide good indoor environment and energy efficient buildings. The measurements are generally conducted by experts. To improve field methods for evaluation of building air tightness, experience of these experts can be useful. The scope of this paper is to problematize usefulness of methods for airtightness measurements, how and when methods are used and potential for future development. Surveyed Swedish and Finnish experts have valued the performance and usefulness of methods in the perspective of being used for singe family, multifamily, new, inhabited, under construction, renovation, leaky and air-tight buildings. They also valued the future potential, as well as their own level of experience and expertise, of the methods. Although the results of the survey were based on a small set of collected data, it indicated that the experts favored methods with their highest assessed experience and expertise, i.e. Blower door and Surface temperature measurements/Thermography. Potential of future development within quantitative and component methods was assessed to be positive in general and in particular for the favored methods.

  • 53.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Heidi
    Olofsson, Sverker
    Små steg har betydelse2015In: Västerbottenskuriren, p. 7-Article in journal (Other (popular science, discussion, etc.))
  • 54.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Heidi
    Olofsson, Sverker
    Viktiga små steg för bättre klimat2014In: Västerbottenskuriren, ISSN 1104-0246, p. 6-Article in journal (Other (popular science, discussion, etc.))
  • 55.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Analysis of the interaction between heating and domestic load in an occupied single family buildning1999In: Proceedings of the fifth symposium of building physics in the nordic countries / [ed] C.E. Hagentoft, P.I. Sandberg, 1999, p. 473-480Conference paper (Refereed)
  • 56.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Long term energy demand predictions for buildings based on short-term measured data2001In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 33, no 2, p. 85-91Article in journal (Refereed)
    Abstract [en]

    In order to obtain long-term predictions based on short-term data, a neural network model was developed. The model parameters are indoor and outdoor temperature difference and energy for heating and internal use. For purposes of training the neural network model a method for extending the measured data to represent an annual variation is proposed. The method has been applied on six single-family buildings.

    Based on access to data from 2 to 5 weeks, the deviation between predicted and measured diurnal energy demand on an annual basis was about 4% with a correlation of 90–95%, when access to the indoor and outdoor temperature difference was assumed. For models based on access to data from the warmest periods with a very small heating demand, the deviation was about 2–4 times larger.

  • 57.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Overall heat loss coefficient and domestic energy gain factor for single family buildings2002In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 37, no 11, p. 1019-1026Article in journal (Refereed)
    Abstract [en]

    In this work we introduce a method for estimating the variation of the overall heat loss coe"cient and the domestic energy gain factor. Based on a neural network model, these parameters were extracted from analyzing the model by indirect methods. The used model parameters were: the supplied heating demand, the domestic electrical demand and the indoor–outdoor temperature di5erence. A feed-forward back propagation neural network was used as modeling tool. The proposed method has been found accurate, based on an analysis of arti6cially generated data. Additionally, measured data of inhabited single family buildings were examined and the model was found to generate reliable results, in parity with results obtained by comparable methods and estimations.

  • 58.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utvärdering av Energiprestanda med byggnadens värmeförlustfaktor2008In: Bygg och Teknik, no 5, p. 47-50Article, review/survey (Other academic)
  • 59.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sjögren, Jan-ulric
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Building energy parameter investigations based on multivariate analysis2009In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 41, p. 71-80Article in journal (Refereed)
    Abstract [en]

    System identification can be used for evaluations of how measured energy use is influenced by theoperation, design and equipment of buildings and their users. However, it can be difficult to accessappropriate data for modelling purposes due to a small number of buildings, parameters not distributednormally, lumped information, etc. In this work, data of a subset of 112 comparable multifamily buildingslocated in the Stockholm area were derived from a larger Swedish building energy consumption survey.In that database, the accessible data are monthly consumption data together with a large number ofbuilding-specific classification parameters, e.g. building code, age of control system, type of owner,maintenance organization, area to let, etc.A multivariate PLS method (partial least squares to latent structures) was used to model differentenergy performance measures, such as the use of energy for heating, electricity used to operate thebuilding technical system, the building total heat loss coefficient and the use of domestic cold water. ThePLS model was investigated for both the total annual use and the annual use normalized to the availablefloor area. For most measures of performance, only qualitative estimates of the impact of differentclassification parameters could be drawn due to the goodness value of the model. However, for some ofthe investigated parameters, quantitative estimates could also be drawn. The obtained results are, inmost cases, in good agreement with what might be expected.To enable benchmarking of different energy use measures, the area to let is commonly used as anormalizer by real estatemanagers in Sweden. In this study, we find strong indications that the area to letis not suitable for this purpose.

  • 60.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sjögren, Jan-Ulric
    Multivariate Methods for Evaluating Building Energy Efficiency2004In: Proceedings of the 2004 ACEEE Summer Study of Energy Efficiency in Buildings, 2004, p. 265-274Conference paper (Refereed)
    Abstract [en]

    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.

  • 61.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A method for predicting the annual building heating demand based on limmited performance data1998In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 28, no 1, p. 101-108Article in journal (Refereed)
    Abstract [en]

    In this paper, we present an investigation of the possibility to use a neural network combined with a quasi-physical description in order to predict the annual supplied space heating demand (P) for a number of small single family buildings located in the North of Sweden. As a quasi-physical description for P, we used measured diurnal performance data from a similar building or simulated data from a steady state energy simulation software. We show that the required supplied space heating demand may be predicted with an average accuracy of 5%. The predictions were based on access to measured diurnal data of indoor and outdoor temperatures and the supplied heating demand from a limited time period, ranging from 10 to 35 days. The prediction accuracy was found to be almost independent of what time of the year the measurements were obtained from, except for periods when the supplied heating demand was very small. For models based on measurements from May and fo some buildings from April and September, the prediction was less accurate.

  • 62.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energy load predictions for buildings based on a total demand perspective1998In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 28, no 1, p. 109-116Article in journal (Refereed)
    Abstract [en]

    The outline of this work was to develop models for single family buildings, based on a total energy demand perspective, i.e., building-climate-inhabitants. The building-climate part was included by using a commercial dynamic energy simulation software. Whereas the influence from the inhabitants was implemented in terms of a predicted load for domestic equipment and hot water preparation, based on a reference building. The estimations were processed with neural network techniques. All models were based on access to measured diurnal data from a limited time period, ranging from 10 to 35 days. The annual energy predictions were found to be improved, compared to models based on only a building-climate perspective, when the domestic load was included. For periods with a small heating demand, i.e., May-September, the average accuracy was 7% and 4% for the heating and total energy load, respectively, whereas for the rest of the year the accuracy was on average 3% for both heating and total energy load.

  • 63.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Using CO2 concentrations to predict energy consumption in homes1998In: Proceedings of the 1998 ACEEE Summer study of energy efficiency in buildings, 1998, p. 211-222Conference paper (Refereed)
  • 64.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Bäckström, Ingemar
    Borg, Matts
    Ohlis, Nils
    Majabacka, Patrik
    Energihandledning för växthus: handbok för växthus2008Book (Other academic)
  • 65.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Johnsson, Eva
    Computations of earning capability from energy conservation measures2003In: First international conference on sustainable energy, planning and technology in relationship to the environment, 2003, p. 329-339Conference paper (Refereed)
  • 66.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Mahlia, TMI
    Modeling and simulation of the energy use in an occupied residential building in cold climate2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 91, no 1, p. 432-438Article in journal (Refereed)
    Abstract [en]

    In order to reduce the energy use in the building sector there is a demand for tools that can identify significant building energy performance parameters. In the work introduced in this paper presents a methodology, based on a simulation module and graphical figures, for interactive investigations of the building energy performance. The building energy use simulation program is called TEKLA and is using EN832 with an improved procedure in calculating the heat loss through the floor and the solar heat gain. The graphical figures are simple and are illustrating the savings based on retrofit measures and climate conditions. The accuracy of the TEKLA simulation was investigated on a typical single-family building in Sweden for a period of time in a space heating demand of relatively cold and mild climate. The model was found applicable for relative investigations. Further, the methodology was applied on a typical single family reference building. The climate data from three locations in Sweden were collected and a set of relevant measures were studied. The investigated examples illustrate how decisions in the early stages of the building design process can have decisive importance on the final building energy performance. (C) 2011 Elsevier Ltd. All rights reserved.

  • 67.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Majabacka, Andreas
    Novia, Svenska yrkeshögskolan Vasa.
    Engblom, Sten
    Novia, Svenska yrkeshögskolan Vasa.
    Evaluations of energy performance for greenhouses based on multivariate analysis methodology2006In: Proceedings of the IIIrd international symposium on models for plant growth, environmental control and farm management in protected cultivation (hortimodel 2006) / [ed] L.F.M. Marcelis, G. van Straten, C. Stanghellini, E. Heuvelink, 2006Conference paper (Refereed)
    Abstract [en]

    Improved energy efficiency is very important in order to increase the profitability for the greenhouse industry in northern Europe. For example in the Närpes region in Finland the average energy consumption has been estimated to 525 kWh/m² and year. From the energy use perspective, an operated greenhouse is a very complex system. For evaluating the energy efficiency of a greenhouse and for identification of what to improve, an owner or operator will need guidance. It is however difficult to identify the most energy efficient concept from monitored performance and consumption data. Correlations between the investigated parameters can render the analysis very difficult. To facilitate and improve the analysis, multivariate statistical methods can be a valuable support. We introduce here a multivariate methodology for analysing monitored performance data from greenhouses, with the objective to illustrate ways of improving the energy efficiency. The methodology was applied to a data set from an operated greenhouse in Närpes in Finland. The results illustrate how improvements of transmission and ventilation influence the supplied space heat demand. The methodology was found to be easy to use and the accuracy of the evaluation on the available data set and the parameters appeared to be reasonable.

  • 68.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Applied Physics and Electronics.
    Meier, Alan
    International Energy Agency / OECD, Paris, France.
    Lamberts, Roberto
    Department of Civil Engineering, Federal University of Santa Catarina, Brazil.
    Rating the Energy Performance of Buildings2004In: The International Journal of Low Energy and Sustainable Buildings, ISSN 1403-2147, Vol. 3Article in journal (Refereed)
    Abstract [en]

    In order to succeed in developing a more sustainable society, buildings will need to becontinuously improved. This paper discusses how to rate the energy performance of buildings.A brief review of recent approaches to energy rating is presented. It illustrates that there is no single correct orwrong concept, but one needs to be aware of the relative impact of the strategies. Different strategies of settingenergy efficiency standards are discussed and the advantages of the minimum life cycle cost are shown.Indicators for building energy rating based on simulations, aggregated statistics and expert knowledge arediscussed and illustrated in order to demonstrate strengths and weaknesses of each approach. In addition, theimportance of considering the level of amenities offered is presented.Attributes of a rating procedure based on three

  • 69. Olofsson, Thomas
    et al.
    Nair, Gireesh
    Azizi, Shoaib
    Enkät om renovering och energieffektivisering2018In: Energi & Miljö, no 1Article, book review (Other (popular science, discussion, etc.))
  • 70.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ohlsson, K. E. Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Measurement of the environmental temperature using the sol-air thermometer2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 132, p. 357-362Article in journal (Refereed)
    Abstract [en]

    Heat flow measurement with a heat flow meter is a standardized method (ISO 9869-1) to estimate thermal transmittance (U-value) of a building element. The heat flow meter is a thin plate mounted on top of the surface of the element, and measures the heat flux q through the plate. The measured q is the product of the difference in temperatures between exterior and interior environment, and the U-value. The heat transferred from the element is based on the radiant and the convective heat transfer.

    ISO 9869-1 specifies that the environment temperature Te “is a notional temperature" and it "cannot be measured directly” (section A.3.1). The air temperature Ta is proposed as a reasonable approximation for the indoor environment, while overcast conditions and absence of significant solar radiation are specified conditions for replacing Te with Ta for the exterior environment.

    The sol-air thermometer (SAT) measures the sol-air temperature Tsa, i.e. the equivalent temperature of the convective and the radiative environment. In the absence of solar radiation, Te = Tsa. SAT is a sensor consisting of a thin flat solid plate, of high thermal conductivity. The front side of the sensor is exposed to the environment, whose Tsa is to be measured, and the backside is thermally insulated. The temperature of the SAT-plate equals Tsa.

    In this work we propose introduction of the measured Te in the existing standard (ISO 9869-1). The method for measurement of Tsa, using the SAT, has been demonstrated experimentally for different periods, without solar radiation present and under stable climatic conditions.

  • 71.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sjögren, Jan-Ulric
    Hur kan energiprestanda anges för en byggnad2008In: Väg- och Vattenbyggaren, Vol. 5, p. 58-61Article, review/survey (Other academic)
  • 72.
    Olofsson, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sjögren, Jan-Ulric
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energy Performance for Buildings Evaluated with Multivariate Analysis2005In: Proceedings of the of the Ninth IBPSA Conference and Exhibition, Building Simulation 2005, 2005, p. 891-898Conference paper (Refereed)
    Abstract [en]

    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.

  • 73. Ramirez-Villegas, Ricardo
    et al.
    Eriksson, Ola
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Assessment of renovation measures for a dwelling area - Impacts on energy efficiency and building certification2016In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 97, p. 26-33Article in journal (Refereed)
    Abstract [en]

    The European Union has an ambitious plan to reduce energy use and emissions by the year 2030. The building and real estate sectors have a great potential to help reduce emissions by energy efficiency. However, different energy sources and environmental standards affect the decision making of these major renovations in the existing stock. This study investigates how different renovation strategies affect the energy rating of a selected Building Environmental Assessment Tool and analyses the consequences in terms of greenhouse gas emissions for the local district heating system. Both building energy simulations and energy systems cost optimization were used to determine the energy use and local emissions. The results of different renovation scenarios were used to evaluate the rating in the selected tool and the impact in the district heating local emissions. The used methodology illustrates how energy efficient renovation impacts on the district heating system's local emissions. However, a bias towards resource classification within the Swedish Building Environmental Tool, Miljobyggnad, needs to be addressed in order to assess the impact of local emissions.

  • 74. Shekarchian, M.
    et al.
    Moghavvemi, M.
    Rismanchi, B.
    Mahlia, T. M. I.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    The cost benefit analysis and potential emission reduction evaluation of applying wall insulation for buildings in Malaysia2012In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 16, no 7, p. 4708-4718Article, review/survey (Refereed)
    Abstract [en]

    Due to the rapidly increasing number of air-conditioned spaces in buildings, the electricity demand has significantly increased during the past decade in Malaysia. The present energy analysis attempts to predict the long term environmental impact of utilizing thermal insulation materials for exterior walls of Malaysian buildings. The optimum insulation thickness is mainly influenced by local electricity tariff rate, and the capital insulation outlays. In the present work, some of the commonly used insulators available in the Malaysian market were analyzed. The results show that 2.2 cm of fibreglass-urethane produces the largest cost savings, of around 1.863US$/m(2) and is the most economically feasible insulation material that reduces the annual CO2 emission production level by 16.4 kg/m(2). The main focus of the survey is to predict the potential emission production fluctuation for over the next 20 years. In this regard, three different scenarios were introduced, based on different electricity production policies. It was revealed that the increase in the contribution of renewable power plants on one hand, and phasing out of the conventional thermal coal plants on the other will substantially lead to a diminished CO2 emission in long term. (c) 2012 Elsevier Ltd. All rights reserved.

  • 75.
    Sjögren, Jan-Ulric
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    An approach to evaluate the energy performance of buildings based on incomplete monthly data2007In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 39, no 8, p. 945-953Article in journal (Refereed)
    Abstract [en]

    The energy performance of buildings has become increasingly important in the general strive to reduce the overall energy use, which ismanifested in the Energy Performance of Buildings Directive launched by the European Union. An important first step is of course to identify andaddress buildings that have an energy saving potential. In order to achieve this, robust methods for evaluation as well as reliable energy key figuresare needed.For a large majority of multifamily buildings in Sweden the available data of the energy use originates from the property holder. Unfortunately,the data is often limited to the energy that the property holder is responsible for. Thus, information from the tenants about their household electricityuse, indoor temperatures, number of residents, etc., is missing.In this paper an evaluation was conducted on monthly consumption data registered by the property holders for over 100 multifamily buildings/real estates in Sweden. The used approach, based on the energy signature method, was developed for evaluating the energy performance ofmultifamily buildings in terms of the overall heat loss coefficient, Ktot. To compensate for the missing data, different assumed consumption profileshave been used.The results shows that although the obtained value of Ktot for an individual building is rather sensitive to the assumed consumption profiles ofhousehold electricity, the sensitivity is reduced if the evaluation is made in relative and not absolute terms. Thus, the use of consumption profilescould be a successful way to circumvent the present lack of a detailed knowledge of a buildings total energy use. In addition, an evaluation inrelative terms instead of absolute values is also more correct, since available data in almost all cases does not support the determination of the truevalue of Ktot. The use of an average consumption profile instead of a detailed knowledge is of course not desirable, but for fairly large buildings suchan approach could be successful.

  • 76.
    Sjögren, Jan-Ulric
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sensitivity of the total heat loss coefficient determined by the energy signature approach to different time periods and gained energy2009In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 41, no 7, p. 801-808Article in journal (Refereed)
    Abstract [en]

     

    In order to identify buildings that have energy saving potential there is a need for further development of robust methods for evaluation of energy performance as well as reliable key energy indicators. To be able to evaluate a large database of buildings, the evaluation has to be founded on available data, since an in-depth analysis of each building would require large measurement efforts in terms of both parameters and time. In practice, data are usually available for consumed energy, water, and so on, namely consumption that the tenants or property holder has to pay for. In order to evaluate the energy saving potential and energy management, interesting key energy indicators are the total heat loss coefficient Ktot (W/K), the indoor temperature (Ti), and the utilisation of the available heat (solar radiation and electricity primarily used for purposes other than heating). The total heat loss coefficient, Ktot, is a measure of the heat lost through the building's envelope, whereas Ti and the gained energy reflect the user's behaviour and efficiency of the control system.

    In this study, a linear regression approach (energy signature) has been used to analyse data for 2003–2006 for nine fairly new multifamily buildings located in the Stockholm area, Sweden. The buildings are heated by district heating and the electricity used is for household equipment and the buildings’ technical systems. The data consist of monthly energy used for heating and outdoor temperature together with annual water use, and for some buildings data for household electricity are also available. For domestic hot water and electricity, monthly distributions have been assumed based on data from previous studies and energy companies. The impact on Ktot and Ti of the time period and assumed values for the utilised energy are investigated.

    The results show that the obtained value of Ktot is rather insensitive to the time period and utilised energy if the analysis is limited to October–March, the period of the year when the solar radiation in Sweden yields a minor contribution to heating. The results for the total heat loss coefficient were also compared to the calculations performed in the design stage; it was found that Ktot was on average 20% larger and that the contribution to heating from solar radiation was substantially lower than predicted. For the indoor temperature, however, the utilised energy had a large impact.

    With access to an estimate of Ktot and Ti, an improved evaluation of the energy performance may be achieved in the Swedish real estate market. At present the measure commonly used, despite the fact that monthly data is available, is the annual use of energy for space heating per square metre of area to let.

  • 77.
    Sjösten, Jerry
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Golriz, Mohammad
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Heating energy use simulations for residential buildings2003In: Eight IBPSA conference and exhibition, building simulation, 2003, p. 1221-1226Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a new simulation program, TEKLA, for estimating energy use of residential buildings according to the European standard, EN832. The simulation program is written in MATLAB 6.2. The focus is to estimate variations of significant parameters influencing the energy use of the building. TEKLA can be used in design of new and retrofitted energy-efficient buildings. The model predictions are in good agreement with monitored data from an occupied residential building located in Umeå in northern Sweden.

  • 78.
    Vesterberg, Jimmy
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Industrial Doctoral School, Umeå University, Umeå, Sweden.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A single-variate building energy signature approach for periods with substantial solar gain2016In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 122, p. 185-191Article in journal (Refereed)
    Abstract [en]

    The use of regression analysis for the identification of building performance parameters based on measurements is often difficult due to collinearity between the outdoor temperature and the global solar radiation (S). This study proposes a method to overcome this issue. The proposed method is based on using the seasonal symmetry of S to pair data from time-periods equidistant from the winter solstice. In addition, a method to utilize synthetic data to fine-tune the paired-data approach is presented. To evaluate the paired-data approach, two years data from a multifamily building in Umeå was used to estimate the heat loss factor (air-to-air transmission including air leakage). The results were compared with results obtained when S was very low (S ≈ 0). It was found that, the fine-tuned paired-data approach resulted in a modest deviation in the heat loss factor with an average absolute deviation of 4.0%. The small deviation indicates that the paired-data approach can extend the use of single-variate regression models for accurate identification of heat loss factors to situations where the solar gain is substantial. The paired-data approach was also used to calibrate a commercial energy building simulation tool. 

  • 79.
    Vesterberg, Jimmy
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Calibration of low-rise multifamily residential simulation models using regressed estimations of transmission losses2016In: Journal of Building Performance Simulation, Taylor & Francis, ISSN 1940-1493, E-ISSN 1940-1507, Vol. 9, no 3, p. 304-315Article in journal (Refereed)
    Abstract [en]

    In this study, we evaluated a proposed calibration approach for whole-building energy simulation models. This approach was based on a regression analysis of measured data collected during a time period when the global solar radiation was the lowest. The proposed approach was compared with a more conventional calibration approach with different degrees of complexity, starting from design stage assumptions, through audits, and lastly by refining the model with detailed measurements and numerical calculations. The evaluation was performed using measured data from two multifamily buildings located in Umeå, Sweden, and the IDA ICE 4.61 simulation software. The best agreement between simulated and measured data was obtained with the proposed calibration approach. The monthly normalized mean bias error and the coefficient of variation was less than 5.0% and 6.0% respectively. For the conventional calibration approach, detailed measurements and time-consuming numerical calculations were required to reach similar results. 

  • 80.
    Vesterberg, Jimmy
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Robustness of a regression approach, aimed for calibration of whole building energy simulation tools2014In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 81, p. 430-434Article in journal (Refereed)
    Abstract [en]

    An approach, able to easily and effectively integrate field measured data in whole Building Energy Simulation (BES) models is crucial to increase simulation accuracy for existing buildings. In this paper the robustness of a linear regression method for extracting transmission losses above ground (including air leakage) and ground heat loss parameters are analyzed. The regression method is evaluated on two documented and monitored multifamily buildings with mechanical supply and exhaust ventilation systems, with and without heat recovery.   

    The obtained results are found to be robust, with variations less than 2% in the extracted estimates of transmission losses above ground (including air leakage) and with a high goodness of fit (R2>0.96) against measured data from two years. In addition, the estimations of the buildings ground heat loss were in good agreement with calculations in accordance with EN ISO 13370:2007. The high quality output from the used regression method serves as good prerequisites for the method to be used in conjunction with BES models to aid the analyst in a BES calibration process

  • 81.
    Vesterberg, Jimmy
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    The influence from input data provided by the user on calculated energy savings2014In: 10th Nordic Symposium on Building Physics, Lund, Sweden,15-19 June, 2014, 2014, p. 1301-1308Conference paper (Refereed)
    Abstract [en]

    It is generally accepted that the most correct decisions are made when the used support system provides the most accurate description of the starting point as possible. That is, in this case, a detailed initial description of a building, planned to be refurbished and evaluated with the building energy simulation software IDA ICE (v 4.5).In order to assess this statement, we have used two different models to predict energy savings due to different planned energy conservation measures (ECMs):

     - A basic model based on inputs from currently available standards and as-built drawings.

     - A calibrated model based on an analysis of measurements from two months, together with measured air handling unit parameters, hourly electricity usage and indoor temperatures.

    The relative prediction differences between the models are investigated as well as compared with the actual outcome in a neighboring building where the analyzed ECMs have been implemented. The result indicates that a calibrated model should be used, in order to accurately determine the post-retrofit energy demand. However, if only investigation of ECMs which aims to decrease a buildings transmission loss is of interest, the findings suggest that BES calibration is of minor importance.

  • 82.
    Vesterberg, Jimmy
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Evaluation of energy conservation measures in a multifamily building, using on site measurements2012In: Proceeding of the Technoport Conference, Trondheim, 2012Conference paper (Refereed)
  • 83.
    Westerlund, Kim
    et al.
    Yrkeshögskolan Novia, Finland.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energy Self-Sufficient Areas, a case study on the Vaasa Housing Fair2008In: Proceedings of the Renewable Efficient Energy Nordic Conference, Vaasa Finland, July 9-11 20, 2008Conference paper (Refereed)
    Abstract [en]

    EU has targeted 20% renewable energy use by 2020 which has put great pressure on themember states to change energy production, and to use the energy in the most efficient way.New concepts are needed and state-of-the art solutions need to be much more wildly applied.One concept is energy self-sufficient initiatives. There are a number of such initiatives inEurope. One of the most recent ones has been established in Finland at Vaasa Housing Fairopening at July 11, 2008 demonstrating first time innovations and new developments andcombinations.Used technology at the Housing Fair in Vaasa, Finland 2008 is:• A fuel cell power plant running on biogas• Combination with a micro turbine also running on biogas• Utilising sea heat from piping submerged under the sea bottom with a novel technique• A low temperature district heat network directly providing low temperature heat andcooling to the houses• Passive building utilising state-of-the art solutions applicable for large productionvolumesThe housing fair consists of 42 single-family and small houses and 3 apartment houses. Inthis paper we will introduce the used energy supply technology. Based on official informationfrom a pilot study of design conditions conducted by the Geological Survey of Finland andthe technology suggested for the fair, the self sufficiency has been estimated. We concludethat there are reasonable conditions for self sufficiency in both heat and power for at least90% of the average year.Preliminary calculations show an energy self sufficiency of 120% for electricity and160% for heat. The calculations are using specific consumption values based on experienceas declared in this paper.The system is target for measurements, follow-up will be performed and the benefits and possibledrawbacks evaluated in further research.

  • 84. Wäckelgård, Ewa
    et al.
    Dahlquist, Erik
    Karlsson, Björn
    Mosgfegh, Bahram
    Myhren, Jon Are
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Resource efficient energy systems for built environment2014Conference paper (Refereed)
  • 85.
    Yang, Bin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A questionnaire survey on sleeping environment conditioned by different cooling modes in multistory residential buildings of Singapore2017In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 26, no 1, p. 21-31Article in journal (Refereed)
    Abstract [en]

    A good sleep environment is essential to maintain a person's health and daily working performance. How to create comfortable and healthy sleep environments with less energy use is worth exploring. Findings, based on one questionnaire survey on sleep environments conditioned by different cooling modes have been reported. The study investigated the use of different cooling devices in relation to the effect on sleep. Human responses to thermal environments and air quality created by different cooling modes were also studied. Totally 229 completed questionnaires were statistically analysed. The results show that most of the respondents prefer to use air conditioner 3–6 months in a year with relatively low temperature settings especially for respondents living below fifth floor. It is better to choose relatively high temperature settings to reduce air conditioning intensity especially for elders and outdoor workers, which can not only avoid cold thermal discomfort but also reduce electric energy use. For elders, outdoor workers and persons living in higher floor levels, there was an increase usage of electrical fans or natural ventilation. Thermal comfort can be maintained by raised air movement and the perceived air quality could improve obviously by introducing outdoor air, which would create a good sleep environment to ensure sleep quality.

  • 86.
    Yang, Bin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A questionnaire survey on sleeping environment under different cooling modes in multi-story residential buildings of Singapore2015Conference paper (Refereed)
    Abstract [en]

    Good sleeping environment is important to guarantee person’s health and performance. How to create comfortable and healthy sleeping environment with less energy use is worth exploring. Findings, based on one questionnaire survey on sleeping environment conditioned by different cooling modes (split system air conditioning unit, different kinds of electrical fans or purely natural ventilation), were reported. The study aimed to investigate human factors such as bedding and sleepwear use, using habits of different cooling devices, and human responses to thermal environment and air quality created by different cooling modes. 290 effective questionnaires were collected between June 2013 and May 2014, which were statistically analyzed. The results showed that most of the respondents prefer to use air conditioner for certain number of hours with relatively low temperature settings especially for respondents living below 5th floor. For respondents living above 10th floor, the number of hours using electrical fan or purely natural ventilation increase and their perceived air quality improve obviously. Respondents, who work outdoors during daytime, use less time for air conditioner with relatively high temperature setting. Elder respondents above 55 seldom use air conditioner.

  • 87.
    Yang, Bin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Outdoor thermal bioclimatic environments and human behavior pattern under subarctic climate of north Sweden: a pilot study in Umeå2016In: 14th International Conference on Indoor Air Quality and Climate (INDOOR AIR 2016), International Society of Indoor Air Quality and Climate (ISIAQ) , 2016, Vol. 6, p. 3745-Conference paper (Refereed)
  • 88.
    Yang, Bin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nair, Gireesh
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kabanshi, Alan
    Outdoor thermal comfort under subarctic climate of north Sweden: a pilot study in Umeå2017In: Sustainable cities and society, ISSN 2210-6707, Vol. 28, p. 387-397Article in journal (Refereed)
    Abstract [en]

    Outdoor microclimate is important to determine the quality of outdoor spaces. Swedish people cherish summer period and prefer more outdoor activities in summer because of long winter with harsh outdoor environments. People in urban areas use parks for recreation and outdoor activities frequently in summer. Under subarctic climate, limited studies have been performed to explore the effect of microclimate environments on usage of outdoor spaces such as parks. The study explored the relationship of microclimate environments, park use and human behavioral patterns in urban area of Umeå, Sweden, which is under subarctic climate. Observations of naturally occurring behavior were recorded. Structured interviews, based on specially designed questionnaires, were performed during July to August in 2015. Measurements of objective parameters for microclimate environments, including air dry bulb temperature, relative humidity, wind speed, solar radiation and globe temperature, were performed. Human subjective responses from the questionnaire survey were compared with objectively measured results. 49% of local persons still prefer higher solar radiation even under "slightly warm" Thermal Sensation Vote (TSV), which reflects their high expectation to solar radiation. Local persons in Umeå, who expose themselves to a wider climate, are more adapted to subarctic climate than non-local persons. Practical implications: The pilot study demonstrated that wind attenuation together with strong sunshine can improve Thermal Sensation Vote (TSV), which could be realized by specially designed hump terrain for attenuating wind without shading effects. The results will be used for optimizing design of urban outdoor environments such as parks under subarctic or arctic climate.

  • 89.
    Yang, Bin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, China.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Wang, Faming
    Lu, Weizhuo
    Thermal comfort in primary school classrooms: A case study under subarctic climate area of Sweden2018In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 135, p. 237-245Article in journal (Refereed)
    Abstract [en]

    Limited studies were focused on primary school buildings especially under subarctic climate. Thermal comfort of children was assumed to be similar as that of adults, which may cause inaccuracy. To fill data blank and enrich global database, a field study was performed from late fall 2016 to early spring 2017 covering whole heating period in north part of Sweden. Indoor CO2 concentration was continuously monitored to evaluate indoor ventilation. Thermal comfort related parameters were continuously measured and predicted mean vote (PMV) was calculated. Subjective questionnaire surveys were performed every week except holidays. Subjective thermal sensation value (TSV) was always higher than objective PMV, which reflected thermal adaptation. The thermal adaptation became not obvious in middle and late winter because of long term exposure to heating environments. Heating system should be intensified gradually in early heating period, operated based on actual outdoor climate instead of experience in middle and late heating periods, extended under part load operation in early spring if necessary. The new 13-point TSV scale was pointed out by other researchers and tested inthis study, which can explore tiny TSV deviations from thermally neutral status and reflect more accurate thermal sensations.

  • 90. Yu, Zhun
    et al.
    Li, Jun
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Zhang, Guoqiang
    Temporarily occupied space with metabolic-rate-initiated thermal overshoots: A case study in railway stations in transition seasons2017In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 122, p. 184-193Article in journal (Refereed)
    Abstract [en]

    Temporarily occupied space (TOS) is defined as an air-conditioned space in which most of occupants stay for less than a certain period (e.g., 40 min), such as post offices, supermarkets, bookstores, and banks. The definition mainly emphasizes two aspects: obvious temperature step up/down and short-term exposure periods. Typical TOSs with predominantly temperature-initiated thermal overshoots have been explored in previous studies. Indeed, apart from temperature-initiated thermal overshoots, thermal overshoots can also be initiated by other parameters, such as metabolic rates. In this view, the definition of thermal overshoots was generalized and a case study was conducted at high-speed railway station in China under conditions of transition seasons. The phenomenon of metabolic-rate-initiated thermal overshoots instead of temperature-initiated thermal overshoots was observed and explored, based on objective measurements and subjective questionnaire surveys. The results could optimize the design and operation of air conditioning and mechanical ventilation (ACMV) systems in such TOSs as embodied by railway stations. In addition, the probit analysis method for analyzing neutral temperature ranges instead of neutral temperature points was also discussed.

  • 91. Yu, Zhun
    et al.
    Li, Jun
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Zhang, Guoqiang
    Temporarily occupied spacewith metabolic-rate-initiated thermal overshoots: a case study in railwaystations in transition seasons2017In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 122, p. 184-193Article in journal (Refereed)
    Abstract [en]

    Temporarily occupied space (TOS) is defined as an air-conditioned space in which most of occupants stay for less than a certain period (e.g., 40 min), such as post offices, supermarkets, bookstores, and banks. The definition mainly emphasizes two aspects: obvious temperature step up/down and short-term exposure periods. Typical TOSs with predominantly temperature-initiated thermal overshoots have been explored in previous studies. Indeed, apart from temperature-initiated thermal overshoots, thermal overshoots can also be initiated by other parameters, such as metabolic rates. In this view, the definition of thermal overshoots was generalized and a case study was conducted at high-speed railway station in China under conditions of transition seasons. The phenomenon of metabolic-rate-initiated thermal overshoots instead of temperature-initiated thermal overshoots was observed and explored, based on objective measurements and subjective questionnaire surveys. The results could optimize the design and operation of air conditioning and mechanical ventilation (ACMV) systems in such TOSs as embodied by railway stations. In addition, the probit analysis method for analyzing neutral temperature ranges instead of neutral temperature points was also discussed.

  • 92. Yu, Zhun
    et al.
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Zhu, Neng
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Zhang, Guoqiang
    Utility of cooling overshoot for energy efficient thermal comfort in temporarily occupied space2016In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 109, p. 199-207Article in journal (Refereed)
    Abstract [en]

    Temporarily occupied space (TOS) is defined as an air-conditioned space in which most of occupants stay for less than a certain period (e.g., 40 min) such as post offices, supermarkets, bookstores and banks. After moving from a hot and humid outdoor environment to TOS in summer, thermal alliesthesia takes effect, which refers to 'thermal pleasure sensation and overshoot generated by the restoration of thermal stress toward a neutral interior condition'. Because of the overshoot, occupants' acceptable temperature ranges in TOS are possibly elevated while they still feel thermally comfortable. To study the temperature ranges, a human subjective response study was performed in one climatic chamber used to simulate TOS in Tianjin. Real outdoor environments, instead of chamber simulated outdoor environments, were used for exploring this thermal transient process. Sixteen healthy university students, 8 males and 8 females, were exposed to an outdoor environment for 20 min before they stayed in the chamber for 40 min. Their votes on thermal sensation, comfort and preference were recorded for evaluation at different time points. The results show that the recommended design standard effective temperature (SET) range of TOS is between 24.5 degrees C and 26.5 degrees C. Meanwhile, thermal comfort for staffs who have long term exposure to TOS could be maintained by personal comfort systems such as desk fans or personalized ventilation.

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