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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.
    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.

  • 2.
    Nair, Gireesh
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Azizi, Shoaib
    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 management perspective on energy efficient renovations in Swedish multi-family buildings2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 132, p. 994-999Article in journal (Refereed)
    Abstract [en]

    Sweden has around 2.5 million dwellings in multi-family buildings, which constitute about 55% of the total dwelling units. The multi-family building ownership in Sweden can be categorized into municipal, private and co-operative ownership. Approximately 40% of apartments in multi-family buildings belong to municipal housing companies, while the rest is equally shared by private companies and co-operative housing associations. These organizations have different priorities, limitations and concerns related to energy renovations. Accordingly, in this sector the decisions to invest in energy efficiency improvement depends to a large extent on the type of ownership.

    In this study we analyzed the perspectives of different types of building ownership on energy efficient renovation. The analysis is based on detailed interviews of 4 senior managers representing the multi-family buildings under different ownership categories. Along with this we also interviewed a municipality energy adviser. All the interviewees are based in in North Sweden. The drivers to facilitate the rate of adoption of energy renovation in such buildings are discussed.

  • 3.
    Ohlsson, K.E. Anders
    et al.
    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.
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sol-air thermometer measurement of heat transfer coefficient at building outdoor surface2018In: 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.

  • 4.
    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.

  • 5.
    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. 

  • 6.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Evaluation of a Single Family Low Energy Building in Cold Climate2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 132, p. 9-14Article in journal (Refereed)
    Abstract [en]

    Verification of energy performance and indoor climate by detailed field measurements in buildings is of great importance and promotes an assurance in the process of constructing low energy buildings and enables to utilize the full potential of energy efficiency measures.

    In the present work a single family building with a heated living space area of 175 m2 has been monitored. The heating system has a wood pellet stove for space heating (SH) and domestic hot water (DHW) and on the roof there are solar collectors in a southerly direction contributing to SH and DHW. SH is distributed by the ventilation system and an under floor heating system which is connected to a heat storage water tank. The incoming outdoor air is pre-heated in an earth-to-air heat exchanger and the building has a measured specific energy usage of 54 kWh/m2year which is far lower than today’s regulation at 130 kWh/m2year in the actual climate zone. The low energy use in the building are due to thick thermal insulation (average Um = 0.18 W/°C m2), an air tight envelope (q50 = 0.165 l/sm2), heat recovery of exhaust air (average 74 % efficiency) and free heat from the ground pre-heating of supply air which is above 2°C even for outdoor temperatures down to -27°C. An essential factor was the low rate of air changes during the heating season about 40 % of the regulated requirement. Measurements of indoor air quality like carbon dioxide occasionally indicated insufficient ventilation.

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