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  • 1.
    Akander, Jan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Department of Management and Engineering, Division of Energy Systems, Linköping University.
    Assessing the Myths on Energy Efficiency When Retrofitting Multifamily Buildings in a Northern Region2017Inngår i: Sustainable High Rise Buildings in Urban Zones: Advantages, Challenges, and Global Case Studies / [ed] Ali Sayigh, Cham: Springer Publishing Company, 2017, 1, s. 139-161Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    In the light of EU’s requirements to achieve a major cut in energy use by 2050, Sweden has the same target. The built environment must by 2020 reduce energy use by 20 and 50 % by 2050. The size of the future building stock will naturally increase and regardless of how energy efficient future buildings will be, the energy performance of the old stock must be improved in order to reach those goals. In major renovation projects involving multifamily buildings in large residential areas in the cities, 50 % reduction can be achieved. This is cost-effective and profitable even if the rent is increased.

    Gävleborg is a sparse region in the North, with few cities. Multifamily buildings are generally much smaller than in large cities and owners are reluctant to impose changes that increase rents due to the housing situation in the region. In consequence, the Regional Council and the University of Gävle set out to assess the potential and feasibility of reducing energy use and carbon dioxide emissions in this region’s multifamily buildings. Eleven real buildings were investigated, each having various ownership forms, different technical attributes and heating sources. Energy audits and measurements were conducted to assess the condition of each building. Performances of the buildings and proposed improvements were simulated with building energy simulation programs, whilst life cycle cost analyses were conducted to study viability. Carbon dioxide emission (CO2) reductions were estimated for each improvement.

    Based on the results, a concluding discussion is made on whether or not some myths on energy use and retrofitting are true. The following is concluded: It is possible to reach a 50 % reduction, but it is not economical with the costs involved and with today’s energy prices and moderate price increase over time.

    Retrofitting or improvements made in the building’s services systems (HVAC) are more economical than actions taken to improve performance of building by constructions. HVAC improvements give about 20 % reduction in energy use. However, mechanical ventilation systems with heat recuperation are not economical, though these may or may not substantially reduce use of thermal energy.

    Solar energy is, despite the latitude of the region, economically viable—especially PV solar energy. Photovoltaic panels (PVs) are becoming viable—the combination of PVs and district heating is beneficial since saving electricity is more important than thermal energy in district-heated areas.

  • 2.
    Akander, Jan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Morberg, Åsa
    Högskolan i Gävle, Akademin för utbildning och ekonomi, Avdelningen för utbildningsvetenskap, Utbildningsvetenskap.
    Sustainability of world heritage: who inherits the ownership of decorated farmhouses of Hälsingland?2017Inngår i: A Good Life for All: Essays on sustainability celebrating 60 years of making life better / [ed] Fagerström, Arne and Cunningham, Gary M., Mjölby: Atremi AB , 2017, 1, s. 139-161Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This chapter discusses sustainability of Sweden’s most recent World Heritage (WH) site, the Decorated Farmhouses of Hälsingland. A general overview presents what WH is, why it is special and why it should be preserved for future generations. The views of WH farm owners on managing a WH site and how they feel about the task have been assessed. WH must be preserved for future generations and it is necessary for the farms to interact sustainably with their local communities. Most WH farms are privately owned and have been within the same family for centuries. Will this continue in the future or are there problems with succession?

  • 3.
    Akander, Jan
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Stojanovic, Bojan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Hallberg, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Simulated Long-term Thermal Performance of a Building That Utilizes a Heat Pump System and Borehole2008Inngår i: Durability of Building Materials & Components 11: Globality and Locality in Durability / [ed] A. Nil Türkeri, Özkan Sengül, Istanbul, Turkey: Istanbul Technical University, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Over the last decades, installation and use of heat pumps has grown rapidly in Sweden, to the extent that these mainly or partly heat roughly 25 % of the heated floor space in single-family houses. A majority are ground coupled where the heat exchanger is a borehole of 60-220 m depth. As the heat pump system operates, heat extraction will in time reduce borehole temperatures, rendering lowered efficiency of the heat pump system thus directly affecting its economical and environmental aspects. Within the building sector, durability and life performance dynamics of energy systems is often not reflected upon. System performance and efficiency is assumed to be static over time, changing only due to different operation scenarios. This paper serves to quantify the long-term thermal performance degradation of a component, in this case the borehole, and how the degradation of this component affects performance-over-time of an entire system, in this case the heating system of the building. A dynamic thermal simulation model is used to assess the long-term thermal performance of the borehole. The building, which the heat pump serves, is assumed to be a typical Swedish house with normal energy consumption. Simulation results show that the depth of the borehole is of great importance to limit over-time temperature drops. The efficiency of the heat pump system is directly dependent of temperatures in the borehole. How the overall system performance is affected by component performance degradation, is highlighted.

  • 4.
    Björling, Mikael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Steen Englund, Jessika
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    On Measuring Air Infiltration Rates Using Tracer Gases in Buildings with Presence Controlled Mechanical Ventilation Systems2016Inngår i: Indoor Air 2016: The 14th International Conference of Indoor Air Quality and Climate, July 3-8 2016, Ghent, Belgium: Conference Proceedings / [ed] E. Van Kenhove, J. Laverge, P. De Vlieger, ISIAQ , 2016, artikkel-id 875Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The ventilation and air leakage of a school building was investigated. Information was collected from the parameters of the mechanical ventilation system and from measurements of the local mean age of air using the homogeneous emission method. While the average local mean ages of air can be accurately measured by passive integrative samplers, the estimation of the average room specific air change rate by taking the inverse of the measured average local mean age of air did not give correct results. The main problem is that integrative sampling represents a linear averaging process that is inappropriate to capture the average of nonlinearly related properties. This problem is accentuated when the ventilation rates for different periods differ a lot. A simple computational model was developed to discuss the system behavior. A partial solution to the measurement problem is to actively sample the different populations of air change rates separately.

  • 5.
    Björling, Mikael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Infiltration of Air into two World Heritage Farmhouses in Sweden during Winter Conditions2018Inngår i: Roomvent & Ventilation 2018: Excellent Indoor Climate and High Performing Ventilation / [ed] Risto Kosonen, Mervi Ahola, Jarkko Narvanne, Helsinki, Finland, 2018, s. 1079-1084Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As a part of an ongoing study, we report measurements of air infiltration during winter conditions into two Decorated Farmhouses of Hälsingland designated as UNESCO World Heritage Sites. In winter these two-storied farmhouses are rarely heated, except for special occasions. In this measurement one farmhouse  was  unheated,  whereas  one  room  was  heated  for  a  brief  period  in  the  other  one.  The observed local mean ages of air measured with tracer gas techniques generally increase with height, both  locally  within  each  room  and  between  floors.  The  average  temperature  and  humidity  also increases from the first to the second floor. The indoor temperature follows the outdoor temperature with a time lag. The differences in water content between inside and outside air correlate with changes of the indoor relative humidity. The correlation is stronger for humidity increase than for humidity decrease, possibly due to moisture absorption by interior text.

  • 6.
    Hallberg, Daniel
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Stojanovic, Bojan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för inomhusmiljö.
    Kedbäck, Mikael
    Life Cycle Management System: a planning tool supporting Long-term based design and maintenance planning2008Inngår i: Durability of Building Materials & Components 11: Globality and Locality in Durability / [ed] A. Nil Türkeri, Özkan Sengül, Istanbul: Istanbul Technical University , 2008, s. 1871-1878Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Construction projects include large amounts of information that has to be communicated to a number of actors, such as authorities, companies, clients and end users. Information exchange is complex, involving various players on different levels and phases of the construction process. For private clients, who generally have little experience and knowledge of this process, the on-going “Bygga Villa”-project has developed a web-portal, which offers them relevant information about the process and a number of services to facilitate realisation of their projects. One of the services provides a tool for supporting long-term strategy planning. The tool is based on the Life cycle Management System (LMS) that is a predictive and generic life cycle-based management system, aimed to support decision-making and planning of optimal design and maintenance of any construction works. The LMS-Bygga Villa tool estimates service life and maintenance intervals of different building parts and systems based on environmental-dependent degradation models. Simulated scenarios can give optimised solutions by applying life cycle cost analysis. This paper presents two case studies within LMS-Bygga Villa. The first case focuses on service life performance analysis of exterior parts of buildings. The second focuses on service life performance analysis of energy systems; here specifically a borehole assisted heat pump system used for heating a Swedish single-family residence.

  • 7.
    Hallberg, Daniel
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Stojanovic, Bojan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Långsiktig underhållsplanering av fjärrvärmenät: en förstudie av möjligheter till utveckling av LMS2007Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Samtidigt som fjärrvärme är ett effektivt sätt att leverera värme så leder en centraliserad värmeproduktion till att fler personer drabbas vid eventuella driftavbrott. Detta skapar ett behov av ökad leveranssäkerhet och kontroll av prestanda över hela fjärrvärmenätets livscykel. Genom en långsiktig planering av nätets utbyggnad och förvaltning erhålls effektivare resursanvändande och större säkerhetsmarginaler. Långsiktig planering bygger till stor del på analys av olika scenarier där såväl rådande förutsättningar som ”worst cases” kan beaktas utifrån olika aspekter (tekniska, ekonomiska, säkerhetsmässiga m.m.). Målet är att hitta optimerade åtgärder, vilket kräver systematisk hantering och bearbetning av en stor mängd information. Detta kan endast göras rationellt med hjälp av IT-verktyg. Life cycle Management System (LMS) är ett resultat av tre konsekutiva EU-finansierade forskningsprojekt där gruppen för byggnadsmaterialteknik – Högskolan i Gävle, har haft en ledande roll. Systemet innehåller utvecklade rutiner och metoder för hantering av information som ligger till grund för långsiktig planering och optimerad förvaltning av byggnadsverk. Systemmässigt är LMS uppbyggt av moduler som hanterar och analyserar data på olika sätt. Anledningen till systemets modulbaserade struktur är att det, helt eller i delar, kan anpassas mot de krav och önskemål som klienten ställer på systemet. På så sätt behöver klienten bara komplettera sitt befintliga system med de funktioner som önskas av LMS, samtidigt som denne undviker att ”kasta ut” det gamla systemet. Förstudien omfattar en litteraturstudie och analys av Gävle Energi AB:s (GEAB) drift- och underhållsdata. Förstudiens syfte är att identifiera och kartlägga de anpassnings- och utvecklingsbehov som föreligger en implementering av LMS som planeringsverktyg för GEAB:s fjärrvärmenät.

  • 8.
    Hallberg, Daniel
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - byggnadsmateriallära.
    Stojanovic, Bojan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - byggnadsmateriallära.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggnadsteknik.
    Status, needs and possibilities for service life prediction and estimation of district heating distribution networks2012Inngår i: Structure and Infrastructure Engineering, ISSN 1573-2479, E-ISSN 1744-8980, Vol. 8, nr 1, s. 41-54Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    An optimised and proactive maintenance strategy aims to maximise the economical profit, minimise environmental impacts and keep the risk of failure to a low level. Implementation of such strategy in the context of district heating requires efforts and abilities for predicting future performances and estimating service life of district heating components. A literature review on failures (damages and performance reductions) occurring on district heating pipes, reveals that failures in district heating pipes are mainly leaks due to corrosion or mechanical impacts and reduced thermal insulation performance: leaks being the more serious damage type. A feasible service life estimation method for this type of damage is the Factor Method. Since the application of this method within the context of DH pipes has not been found in other publications, this paper focuses on describing the method and discusses the possibilities on how to apply it in two specific cases with respect to leakage: service life estimation of repaired district heating pipe sections (i.e. maintenance of district heating network) and of district heating pipes in new or extended district heating networks. A particular attention is paid on which modifying factors to consider and how to quantify them.

  • 9.
    Hayati, Abolfazl
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Development of a Numerical Air Infiltration Model Based On Pressurization Test Applied On a Church2016Inngår i: ASHRAE and AIVC IAQ 2016 — Defining Indoor Air Quality: Policy, Standards and Best Practices, 2016, ASHRAE, 2016, s. 224-231, artikkel-id C030Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Pressurization (blower door) test is a well-established standardized method, performed in order to quantify the total leakage in a building envelope. However, blower door results are not adequate to use when air leakage through the building envelope during natural conditions (non-pressurized) is to be estimated. A common assumption made when estimating air leakage during natural conditions, is that air leakage paths are evenly distributed in the areas of the building envelope. This assumption gives quite poor calculation results since different leakage configurations are often situated unevenly in the envelope. In order to improve the correspondence between Blower door and air leakage model results, more information on the types and locations of the leakage paths are required as input to simulation models. 

    This paper investigates if additional information from visual inspection and IR-thermography observations at site can increase the precision when simulating air change rates due to air leakage in natural conditions.  A numerical model is developed in this study by allocating leakage in various parts of the building envelope. The leakage allocation is based on visual inspection and IR-thermography observations at the site during the blower door test.

    This procedure is tested in the case study of a large single zone church. Blower door, neutral pressure level measurement and leakage allocation results are used as input in the numerical model. Model results are compared with tracer gas measurements and result accuracy is compared with results from the Lawrence Berkeley Laboratory model (LBL) and the Alberta Air Infiltration Model (AIM-2) for the same church. 

  • 10.
    Hayati, Abolfazl
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Simulation of Ventilation Rates and Heat Losses during Airing in Large Single Zone Buildings in Cold Climates2019Inngår i: Cold Climate HVAC 2018: Sustainable Buildings in Cold Climates / [ed] Johansson, D., Bagge, H., Wahlström, Å., Springer, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Airing can be a solution to introduce extra ventilation in large single zone buildings, especially where there are large aggregations of people such as churches or atriums. In naturally ventilated domestic and ancient buildings, opening of a window or door can introduce extra fresh air and remove particles and other contaminants emitted from people and other sources such as lit candles in churches. However, the energy use might be an issue in cold climates, where airing might lead to waste of heated air, at the same time as indoor air temperatures can be uncomfortably low. In the present study, the energy loss and ventilation rate due to airing in a large single zone (church) building is investigated via IDA-ICE simulation on annual basis in cold weather conditions. The results can be used in order to prepare airing guidelines for large single zone buildings such as atriums, churches, industry halls and large sport halls. According to the results, one-hour of airing in the studied church building resulted in 40-50 % of exchanged room air and, if practiced once a week, an increase of around 1 % in heating energy.

  • 11.
    Khosravi Bakhtiari, Hossein
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik. Department of Construction, Gavlefastigheter Company, Gävle, Sweden.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Evaluation of Thermal Comfort in a Historic Building Refurbished to an Office Building with Modernized HVAC Systems2019Inngår i: Advances in Building Energy Research, ISSN 1751-2549, E-ISSN 1756-2201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Envelopes with low thermal performance are common characteristics in European historic buildings, causing higher energy demand and insufficient thermal comfort. This paper presents the results of a study on indoor environmental quality (IEQ), with special focus on thermal comfort, in the historic City Hall of Gävle, Sweden, now used as an office building. There are two modern heat recovery ventilation systems with displacement ventilation supply devices. The district heating network heats the building via pre-heat supply air and radiators. Summer cooling comes from electric heat pump ejecting heat into the exhaust ventilation air. A building management system (BMS) controls the heating, ventilation and air-conditioning (HVAC) equipment. The methodology included on-site measurements, BMS data logging and evaluating the occupants’ perception of a summer and a winter period indoor environment using a standardized questionnaire. In conclusion, indoor environmental quality in this historic building is unsatisfactory. Stuffy air, too high, too low and varying room temperatures, lighting problems and noise are constant issues. Although it is equipped with modern ventilation systems, there are still possibilities for improving thermal comfort by improved control strategies, since upgrading the building’s envelope is not allowed according to the Swedish Building Regulations in historic buildings with heritage value.

  • 12.
    Khosravi Bakhtiari, Hossein
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Department of Construction, Gavlefastigheter Company, Gävle, Sweden.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Thermal Comfort in Office Rooms in a Historic Building with Modernized HVAC Systems2018Inngår i: Proceedings of the 4th International Conference On Building Energy & Environment, COBEE 2018: RMIT University, Melbourne, Australia, Feb 5-9th 2018 / [ed] Kiao Inthavong,Chi Pok Cheung, Guan Yeoh, Jiyuan Tu, Melbourne: Conference On Building Energy & Environment , 2018, s. 683-688, artikkel-id 230Konferansepaper (Fagfellevurdert)
    Abstract [en]

    SUMMARY

    Envelopes with low thermal performance are common characteristics in European historic buildings, leading to higher energy demand and insufficient thermal comfort. This paper presents the results of a study on thermal comfort in the historic office building of City Hall in Gävle, Sweden. It is equipped with two modern heat recovery ventilation systems with displacement ventilation supply devices in offices. District heating network heats the building via pre-heat supply air and radiators. Summer cooling comes from electric heat pump, rejecting heat into the exhaust ventilation air. A building management system controls HVAC equipment. Methodology includes on-site measurements, data logging on management system and evaluating the occupants’ perception of a summer and a winter period indoor environment using a standardized questionnaire. In conclusion, thermal comfort in this historic building is poor although it is equipped with modern ventilation systems and there should be possibilities for improving comfort, by improved control strategies.

    Keywords — Historic Buildings, On-site Measurements, Standardized Questionnaire, Thermal Comfort

  • 13.
    Liu, Linn
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Comprehensive investigation on energy retrofits in eleven multi-family buildings in Sweden2014Inngår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 84, s. 704-715Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rapidly growing energy use in the building sector is considered a serious problem by both the European Union (EU) and Sweden. Reducing energy demand in the building sector is important for Sweden in order to reach national energy goals for reduced energy use and CO 2 emissions in the future. This project aims to find energy efficiency potential in multifamily buildings in the Gävleborg region, which is a cold climate region in Sweden. Measurements and simulations have been made on eleven multifamily buildings from the whole region. The results include different energy efficiency measure packages, profitability analysis of individual measures and packages, and primary energy use analysis. The paper also includes CO 2 emissions reduction analysis based on different methods. The project shows that the multifamily buildings in the Gävleborg region have good potential to reduce their energy use by more than 50%, which in turn will contribute to 43% primary energy reduction and 48% CO 2 emissions reduction. 

  • 14.
    Lundström, Lukas
    et al.
    Mälardalens högskola, Framtidens energi, Västerås, Sweden; Eskilstuna Kommunfastighet AB, Eskilstuna, Sweden.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Zambrano, Jesus
    Mälardalens högskola, Framtidens energi, Västerås, Sweden.
    Development of a space heating model suitable for the automated model generation of existing multifamily buildings: a case study in Nordic climate2019Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 3, artikkel-id 485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Building energy performance modeling is essential for energy planning, management, and efficiency. This paper presents a space heating model suitable for auto-generating baseline models of existing multifamily buildings. Required data and parameter input are kept within such a level of detail that baseline models can be auto-generated from, and calibrated by, publicly accessible data sources. The proposed modeling framework consists of a thermal network, a typical hydronic radiator heating system, a simulation procedure, and data handling procedures. The thermal network is a lumped and simplified version of the ISO 52016-1:2017 standard. The data handling consists of procedures to acquire and make use of satellite-based solar radiation data, meteorological reanalysis data (air temperature, ground temperature, wind, albedo, and thermal radiation), and pre-processing procedures of boundary conditions to account for impact from shading objects, window blinds, wind- and stack-driven air leakage, and variable exterior surface heat transfer coefficients. The proposed model was compared with simulations conducted with the detailed building energy simulation software IDA ICE. The results show that the proposed model is able to accurately reproduce hourly energy use for space heating, indoor temperature, and operative temperature patterns obtained from the IDA ICE simulations. Thus, the proposed model can be expected to be able to model space heating, provided by hydronic heating systems, of existing buildings to a similar degree of confidence as established simulation software. Compared to IDA ICE, the developed model required one-thousandth of computation time for a full-year simulation of building model consisting of a single thermal zone. The fast computation time enables the use of the developed model for computation time sensitive applications, such as Monte-Carlo-based calibration methods. 

  • 15.
    Steen Englund, Jessika
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Björling, Mikael
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Division of Energy Systems, Department of Management and Engineering, Linköping Unviersty, Linköping, Sweden.
    Assessment of Airflows in a School Building with Mechanical Ventilation Using Passive Tracer Gas Method2017Inngår i: Mediterranean Green Buildings & Renewable Energy: Selected Papers from the World Renewable Energy Network’s Med Green Forum / [ed] Sayigh, Ali, Springer, 2017, 1, s. 619-631Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The focus of this study is to assess the airflows in a school building built in 1963 in Gävle, Sweden, which is subject to energy conservation measures (ECMs) in a forthcoming renovation. Today, the school building is mainly ventilated by several mechanical ventilation systems, which are controlled by a constant air volume (CAV) strategy. Schedules and presence sensors impose a high operation mode during the day and a low operation mode at night, on weekends and on holidays. The homogeneous tracer gas emission method with passive sampling is used to measure the average local mean age of air (τ) during different operation modes. Temperature, relative humidity and CO2 concentration are simultaneously measured. The calculated relative uncertainty for the average local mean age of air in every measured point is approx. ±20 %. The results during low operation mode show an average value of τ of approx. 8.51 h [corresponding to 0.12 air changes per hour (ACH)], where τ in various zones ranges between 2.55 and 16.37 h (indicating 0.06–0.39 ACH), which is related to the unintentional airflow in the school. The results during mixed operation mode show an average value of τ of approx. 4.60 h (0.22 ACH), where τ in various zones ranges between 2.00 and 8.98 h (0.11–0.50 ACH), which is related to both unintentional and intentional airflows in the school. Corridors, basement and attic rooms and entrances have lower τ compared to classrooms, offices and other rooms. High maximums of the CO2 concentration in some rooms indicate an imbalance in the mechanical ventilation systems. During a regular school week of mixed operation, which includes both high and low operation modes, it is found that mainly the low operation modes show up in the results. The dynamics of the highly varying airflows in the building cannot be identified using the passive sampling technique.

  • 16.
    Stojanovic, Bojan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - byggnadsmateriallära.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggnadsteknik.
    Build-up and long-term performance test of a full-scale solar-assisted heat pump system for residential heating in Nordic climatic conditions2010Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 30, nr 2-3, s. 188-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the build-up and long-term performance test of a full-scale Solar-Assisted Heat Pump System (SAHPS) for residential heating in Nordic climatic conditions. This particular SAHPS was developed within the EU project ENDCHOUSING, by predominantly using components and techniques that are available on the market. The analysis primarily focuses on system performance, with emphasis on Heat Pump (HP) and total system Seasonal Performance Factor (SPF), based on long-term and full-scale operation. Analysis shows that despite unfavourable building conditions, for low energy use and utilisation of a SAHPS, the system was successfully in full operation (for about 2 years) fulfilling heating requirements. Data processing of the series representing the full year period of 2007(February)-2008(February), presented a HP and total SAHPS performance of. SPF(HP) = 2.85 and SPF(SAHPS) = 2.09. The authors argue that with an optimised SAHPS control and operation strategy, additional use of circulation pumps and energy (electricity) could be vastly reduced, hence attaining a SPF(SAHPS) value that is in parity with the SPF(HP). As the Nordic (Swedish) Endohousing SAHPS has not yet been properly optimised/designed and installed in an appropriate house, the SPFHP = 2.85 is considered satisfactory.

  • 17.
    Stojanovic, Bojan
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Long-Term Thermal Performance Modelling and Simulations of a Borehole2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the long-term thermal performance modelling and simulation of a single heat extraction borehole with a U-shaped pipe, by applying the Macro Element Modelling (MEM) method, developed by Schmidt (2004). The dynamic thermal performance of the ground around the borehole is analysed in the frequency domain. Thereafter, the ground properties are transformed into a network of discrete resistances and capacitances (RC’s) that together with the pipe, models the thermal performance of the borehole. The method allows the parameters of the RC-network components to be estimated and optimised for time domain simulations. The advantage of this modelling method is that it establishes a simplified yet accurate thermal borehole model, which requires less computing time and power compared to a traditional finite difference/element model. This makes it easier to perform several decades of long-term thermal performance simulations. In this paper the U-pipe was modelled by applying a star resistance network that calculates the weighted heat fluxes between the solid borehole and the U-pipe. The presented work shows that at small temperature increases and at relative large fluid velocities the U-pipe fluid temperature can be seen as rising linearly. This provides the borehole modelling with the possibility to model the entire borehole construction by using only one macro element. To compensate for any errors when using the linearly increasing fluid temperature for calculating the energy extraction from the borehole, the total U-pipe star resistance network is compensated. The U-pipe star network was also compared with a FEM (Finite Element Method) simulation, showing that the correspondence between the two models is good. The half 5-node network that was used by Schmidt (2004) for modelling the solid construction of the borehole was modified in this paper, with an additional resistance to ensure the stability of the network when simulation long-term heat extraction periods. The borehole RC-network was optimised for a time period of 100 years. The results from the long-term performance simulation made with the derived borehole model, were also compared to other presented borehole simulations. The model proved to have, at a first stage of comparison, a good correspondence with the other presented results.

  • 18.
    Stojanovic, Bojan
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för inomhusmiljö.
    Akander, Jan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Oglasade takintegrerade solfångare: Ett energitekniskt aktivt byggnadsskal2008Inngår i: Bygg & Teknik, ISSN 0281-658X, nr 4Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 19.
    Stojanovic, Bojan
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Use of a Peltier Element to Increase Time of Wetness of Unglazed Solar Collector Specimens in a Natural Field Exposure Test2008Inngår i: Durability of Building Materials & Components 11 (11DBMC), Istanbul, Turkey, 11-14 May 2008, 2008, s. 1169-1175Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In accelerated testing, material specimens are exposed to completely artificial environments, where exposure to individual degradation agents is enhanced. In contrast, field-testing exposes specimens to multiple degradation agents. When performing a semi-natural test, the influence of a selected degradation agent may be increased while the specimen is still situated in its natural environment. Moisture is such an agent. In an experimental set-up for evaluating long-term optical performance of an building integrated Unglazed Solar Collector, a sub-task was to increase Time of Wetness (TOW) for several collector specimens for two reasons: to “simulate” an active cooling of the component as is the case for solar collectors; and to assess the role of TOW on optical degradation of the solar collector. Specimen cooling and increase in TOW was achieved by utilisation of a Direct-Air Peltier Element. TOW was estimated through measurements with WETCORR sensors (monitoring surface temperatures and moisture) and climate parameters (temperature and relative humidity) at site. At this particular test site in Gävle, Sweden, TOW was more than doubled in comparison to non-cooled surfaces. The Peltier Element proved to be inexpensive and flexible for this purpose.

  • 20.
    Stojanovic, Bojan
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för inomhusmiljö.
    Akander, Jan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Eriksson, Bengt
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Natural and semi-natural field exposure testing and analysis, on optical degradation of a building integrated unglazed solar collector surface2008Inngår i: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 41, nr 6, s. 1057-1071Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Durability is of great importance when considering sustainable energy systems. In turn it lays emphasis on assessing performance over time of energy systems and components. This paper presents a study on optical degradation of a building-integrated Unglazed Solar Collector (USC) surface, by exposing USC specimens to a natural and semi-natural field exposure test. Particular interest is devoted to the semi-natural field exposure test method evaluation, and the degradation of optical properties. The study showed that about 11 months of field exposure testing did not cause any significant optical (total solar absorptance and IR emittance) or material (surface coating) degradation; although measurements revealed a decrease in specular reflectance as diffuse increased. It was likely due to surface pollution that predominantly consisted of quartz. The study also showed that it is possible to achieve a considerable increased moisture exposure on test surfaces (seminatural field exposure test), through a relatively simple cooling device (Direct-Air Peltier-Element) and rough control strategy.

  • 21.
    Stojanovic, Bojan
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Oostendrop, Peter
    TNO.
    Kronström, Urban
    IVT.
    Improvements in Heat Pumps for Endothermic Systems: ENDOHOUSING deliverable D7b2006Rapport (Annet vitenskapelig)
  • 22.
    Stojanovic, Bojan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - byggnadsmateriallära.
    Hallberg, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - byggnadsmateriallära.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggnadsteknik.
    A steady state thermal duct model derived by fin-theory approach and applied on an unglazed solar collector2010Inngår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 84, nr 10, s. 1838-1851Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the thermal modelling of an unglazed solar collector (USC) flat panel, with the aim of producing a detailed yet swift thermal steady-state model. The model is analytical, one-dimensional (ID) and derived by a fin-theory approach. It represents the thermal performance of an arbitrary duct with applied boundary conditions equal to those of a flat panel collector. The derived model is meant to be used for efficient optimisation and design of USC flat panels (or similar applications), as well as detailed thermal analysis of temperature fields and heat transfer distributions/variations at steady-state conditions; without requiring a large amount of computational power and time. Detailed surface temperatures are necessary features for durability studies of the surface coating, hence the effect of coating degradation on USC and system performance. The model accuracy and proficiency has been benchmarked against a detailed three-dimensional Finite Difference Model (3D FDM) and two simpler ID analytical models. Results from the benchmarking test show that the fin-theory model has excellent capabilities of calculating energy performances and fluid temperature profiles, as well as detailed material temperature fields and heat transfer distributions/variations (at steady-state conditions), while still being suitable for component analysis in junction to system simulations as the model is analytical. The accuracy of the model is high in comparison to the 3D FDM (the prime benchmark), as long as the fin-theory assumption prevails (no 'or negligible' temperature gradient in the fin perpendicularly to the fin length). Comparison with the other models also shows that when the USC duct material has a high thermal conductivity, the cross-sectional material temperature adopts an isothermal state (for the assessed USC duct geometry), which makes the ID isothermal model valid. When the USC duct material has a low thermal conductivity, the heat transfer course of events adopts a 1D heat flow that reassembles the conditions of the 1D simple model (for the assessed USC duct geometry); ID heat flow through the top and bottom fins/sheets as the duct wall reassembles a state of adiabatic condition.

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