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  • 1.
    Lindbergh, Lars
    et al.
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Business Administration.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Vesterberg, Jimmy
    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.
    Wilson, Timothy
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Business Administration.
    Reflections on sustainable Ålidhem: a case study in Swedish municipal public housing refurbishment2018In: Property Management, ISSN 0263-7472, E-ISSN 1758-731X, Vol. 36, no 2, p. 203-220Article in journal (Refereed)
    Abstract [en]

    Purpose: This work is initiated under the premise that reliable evaluation methods are necessary to ensure investments in energy conservation, and the purpose of this paper is to contribute to that literature. It describes some pilot changes and their impact in an actual field study oriented toward upgrading municipal public housing (MPH) units.

    Design/methodology/approach: The research for this paper was connected to an MPH refurbishment project situated in northern Sweden. The overall energy efficiency goal within the project was a 40-50 percent reduction in the supplied energy for central electricity, domestic hot water and space heating. In order to evaluate if these goals were feasible, a measurement system was installed in a pilot building and in a neighboring building used as a reference. The evaluation was conducted by comparing the post-retrofit performance of the pilot building with the performance of the reference building when it was kept in its initial state (a comparison possible because both buildings had initial similarities).

    Findings: Impacts could be quantified insofar as a reference (control) building in the same environment was sustained for comparison purposes. A 43 percent improvement was observed in energy utilization in the pilot building compared to its reference companion (99.8 vs 174.5 kWh/m2 per year). When the approach described herein was applied to new construction, the present goal of 65 kWh/m2 was approached as measured by Swedish standards.

    Practical implications: Results should be of interest to academics in the housing field, professionals involved in refurbishment and residents themselves, renting MPH flats.

    Originality/value: This study is unique in the following ways: first, it really was a field experiment with a control, thus it did not have any exogenous interference in interpreting results. To the best of our knowledge, this is the first study of its kind. The second interesting characteristic was that results were subsequently used in the refurbishment of other buildings in the complex and in the construction of others. The major value of the paper may be associated with its timing. It comes at a time when the Kyoto agreement has raised concerns about sustainability, but also at a time when many buildings are facing a need for refurbishment.

  • 2.
    Lindbergh, Lars
    et al.
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Business Administration.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Vesterberg, Jimmy
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Wilson, Timothy L.
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Business Administration.
    Project Ålidhem: a case study of a sustainable Swedish municipal public housing installation2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 121, p. 11-17Article in journal (Refereed)
    Abstract [en]

    A refurbishment project conducted within a municipal public housing complex is described and discussed through Project Ålidhem in northern Sweden. The overall energy efficiency goal within the project was a 40-50% reduction in the supplied energy for domestic hot water, building electricity and space heating. In the pilot study, a 43% improvement was observed. This paper focuses on the performance of four buildings constructed under a Delegation for Sustainable Cities program that specified an energy efficiency goal of 65 kWh/m2. This goal was approached, but not attained. Observations of utilization in four free-standing buildings were 68.3, 76.8, 87.2 and 87.6 kWh/m2 per year respectively, which are described and discussed herein.

  • 3.
    Mejtoft, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Vesterberg, Jimmy
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Integration av generiska kunskaper inom ingenjörsutbildning2017In: Universitetspedagogiska konferensen 2017, 2017Conference paper (Other academic)
  • 4.
    Mejtoft, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Vesterberg, Jimmy
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Integration of generic skills in engineering education: Increased student engagement using a CDIO approach2017In: The 13th International CDIO Conference: Proceedings – Full Papers / [ed] R. Brennan, K. Edström, R. Hugo, J. Roslöf, R. Songer & D. Spooner, Calgary AB, Canada: University of Calgary, 2017, p. 386-395Conference paper (Refereed)
    Abstract [en]

    To be able to successfully pursue a future career within engineering, students need to acquire not only disciplinary knowledge but also generic skills to become professionals. The CDIO model provides a foundation of generic skills that can be expected by the students’ future employers. This paper presents pros and cons when integrating generic skills in disciplinary projects and is based on surveys and interviews with students and teachers on two integrated courses, Project management and Interactivity in smart environments, on an integrated five-year Master of Science program at Umeå University.

    The results show that integrating two courses to give disciplinary meaning to projects make the students maintain their motivation during the course in Project management. In addition, the integration of the courses led to more time for the students for the actual project work. Lastly, both students and teachers also had the possibility to provide a better formal project structure on the disciplinary course. However, the results also show that the confusion among the students increased due to different requirements in each course. Thus, a high level of communication and a holistic view among the involved teachers is desirable to improve the overall success in course integration.

  • 5.
    Vesterberg, Jimmy
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A regression approach for assessment of building energy performance2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Reliable evaluation methods is needed to ensure that investments in energy conservation measures (ECMs) and the construction of new energy efficient buildings lives up to the promised and expected performance.

    This thesis presents and evaluates a regression method for estimation of influential building parameters: transmission losses above ground (including air leakage), ground heat loss, and overall heat loss coefficient.

    The analysis is conducted with separately metered electricity, heating and weather data using linear regression models based on the simplified steady-state power balance for a whole building.

    The evaluation consists of analyzing the robustness of the extracted parameters, their suitability to be used as input values to building energy simulations (BES) tools. In addition, differences between uncalibrated and calibrated BES models are analyzed when they are used to calculate energy savings. Finally the suitability of using a buildings overall heat loss coefficient as a performance verification tool is studied.

    The presented regression method exhibits high robustness and good agreement with theory. Knowledge of these parameters also proved beneficial in BES calibration procedures as well as in performance verifications. Thus, the presented method shows promising features for reliable energy performance assessments of buildings.

  • 6.
    Vesterberg, Jimmy
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Improved building energy simulations and verifications by regression2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    It is common with significant differences between calculated and actual energy use in the building sector. These calculations are often performed with whole building energy simulation (BES) programs. In this process the analyst must make several assumptions about the studied building and its users. These calculations are often verified with measured data through the EUI benchmark indicator which is calculated by normalizing the annual energy use (from the grid) with the floor area. Due to the highly aggregated nature of the EUI indicator it is problematic to use this indicator to deduce erroneous assumptions in the calculations. Consequently, the learning process is often troublesome.

    Against this background, the main aim of this thesis has been to develop methods that can provide feedback (key building performance parameters) from measured data which can be used to increase simulation accuracy and verify building performance. For the latter, regression models have been widely used in the past for verifying energy use. This thesis has the focus on the use of regression analysis for accurate parameter identification to be used to increase the agreement between BES predictions and actual outcome. For this, a BES calibration method based on input from regressed parameters has been developed which has shown promising features in terms of accurate predictions and user friendliness. The calibration method is based on input from regressed estimations of air-to-air-transmission losses, including air leakage (heat loss factor) and ground heat loss. Since it is known that bias models still can give accurate predictions, these parameters have been evaluated in terms of robustness and agreement with independent calculations. In addition, a method has been developed to suppress the bias introduced in the regression due to solar gain. Finally, the importance of calibrated simulations was investigated.

    The regressed parameters were found to be robust with yearly variations in the heat loss factor of less than 2%. The regressed estimates of ground heat loss were also in good agreement with independent calculations. The robustness of the heat loss factor based on data from periods of substantial solar gain was also found to be high, with an average absolute deviation of 4.0%. The benefit with calibrated models was mainly found to be increased accuracy in predictions and parameters in absolute terms. With increased access to measured data and the promising results in this thesis it is believed that the presented regression models will have their place in future energy quantification methods for accessing energy performance of buildings. 

  • 7.
    Vesterberg, Jimmy
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utilizing a regression approach for troubleshooting energy performance of Swedish buildings2016In: CLIMA 2016 - proceedings of the 12th REHVA World Congress, 2016, Vol. 8Conference paper (Refereed)
    Abstract [en]

    The follow-up of calculated and actual energy performance for new buildings is important to enable a learning process. Performance verification is however not a trivial task since the traditional energy use intensity indicator (EUI) can display large variations even for buildings with similar design and HVAC systems. Hence, there exists a risk for confusion between building owners and developers when predicted and actual outcome are compared using only this indicator. In this paper, simple methods, based on area normalization and regression analysis are investigated for interpretation of wide discrepancies in measured EUIs within four similar, newly built multifamily buildings in Umeå, Sweden. It was found that the discrepancies in specific annual energy demand were dependent on the area used for normalization but did not fully explain the variation in the EUIs. The utilization of linear regression for identification and comparison of the buildings heat-loss factor, (ventilation and transmission), and effective solar aperture provided further insights. The regression analysis indicated that the differences in EUIs were due to a combination of chosen area for normalization and solar gain and not the consequence of variations in actual U-values and HVAC systems. Due to the regression methods robustness against influence from the users, it was concluded that the method works well as a complement to the EUI indicator since it provides insights of the buildings thermal performance. This is often of interest to verify for the developer and the property owner since the thermal performance can be controlled in the construction process.

  • 8.
    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.
    Achieved Energy and Climate Goals in Project Ålidhem: An Evaluation of a Refurbishment of 21 Swedish multifamily Buildings2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 132, p. 51-56Article in journal (Refereed)
    Abstract [en]

    In Umeå, situated in the north part of Sweden, the largest refurbishment project undertaken by the public housing company in Umeå was completed in 2014. The project had ambitious goals to decrease the bought energy use for domestic hot water, building electricity and space heating, by 50 %. In order to achieve this, a variety of energy conservation measures were implemented in 21 multifamily buildings during the four-year project. This paper describes the used evaluation approaches and the achieved energy and climate goals. Finally, it offers some reflections that are hoped to be useful in similar projects. 

  • 9.
    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. 

  • 10.
    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. 

  • 11.
    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

  • 12.
    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.

  • 13.
    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 measurements2012Conference paper (Refereed)
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