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| 2. |
- Örn, Tomas, 1976-
(författare)
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Energy efficiency in heritage buildings : Conservation approaches and their impact on energy efficiency measures
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The impeding climate change challenge urges for a reduction of energy use in the built environment. Buildings account for nearly 40% of the total energy use and about 35% of the greenhouse gas emissions in Europe. EU member states are required to improve the energy efficiency of the existing building stock, for example by sharpening building regulations and developing enforcement schemes. Since energy efficiency retrofits can affect irreplaceable values in heritage buildings, heritage buildings are often excluded from mandatory demands aiming at reducing the energy use in buildings. However, saving energy have gradually become embraced by the conservation community and heritage buildings with are seen as part of the solution.This licentiate thesis discusses the methods to identify heritage significance in a building and how the underlying theory determines different scenarios in a energy retrofitting process. The choice of conservation theory and conservation approach will affect the success the energy retrofitting process and determine how much the energy use that can be reduced. This thesis therefore suggests a framework to understand the different interpretation of the impacts that one could exert either by having an Objectivistic or Relative conservation value approach.. Based on this framework, a decision-support tool is developed to further detail the impacts of such approaches for different energy measures.Other results show that a majority of reviewed research publications focused on the operational energy in a building and only a few were concerned with energy use over the entire life- cycle of a building. These analyses are used to evaluate where most energy savings can be made, and often pinpoint weak spots in the building’s envelope or technical system. If it was mentioned at all, the influence of cultural and historical factors on energy efficiency measures as applied to heritage buildings tended to be assessed only briefly. Indeed, the majority does not describe conservation principles or even mention the methodology used – if any – for assessing or defining heritage values. Instead, researchers often show an explicit (sometimes an implicit) understanding of conservation as essentially something that is not destructive of original construction material and hence the authenticity of a building.This licentiate thesis is a compilation thesis, consisting of one separate sub-study, one literature review and an extended cover essay. The study is oriented towards a Swedish and European context, especially when it comes to climate conditions and discussions on building regulations and the theory and practice of architectural conservation. It addresses the growing research field of energy efficiency in heritage buildings and the thesis aims to contribute to an increased understanding on how the process of assessment and evaluation of heritage significance in buildings affects the making of heritage buildings more energy efficient. The main research question is: How do different approaches for assessing and evaluating heritage significance in buildings affect possible technical energy saving measures in heritage buildings?
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| 3. |
- Bhattacharjee, Shimantika, et al.
(författare)
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Energy and indoor thermal performance analysis of a glazed façade high-rise building under various Nordic climatic conditions
- 2023
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Ingår i: Energy Reports. - : Elsevier. - 2352-4847. ; 10, s. 3039-3053
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Tidskriftsartikel (refereegranskat)abstract
- Research has shown that glazed buildings can have higher energy use and are more prone to overheating than other types of buildings. However, few studies have explored the performance of glazed buildings in cold climates. This article aims to evaluate the energy and indoor thermal performance of a high-rise residential building with glazed façades and balconies under Nordic climatic conditions, through a parametric study. Dynamic, whole-year simulations are used to evaluate the impact of four design parameters (with and without glazed balconies, type of balcony glazing, window to wall ratio, and building location within the Nordic region) on the energy and indoor thermal performance of the building. The results show that the building without glazed balconies outperformed that with glazed balconies. Changing from single- to double-pane glazing also helped to reduce energy use and overheating, as did lowering the window-to-wall ratio. Overheating of apartments was found to occur during the summer in five of the six locations simulated, which suggests that solar control strategies might be needed for glazed buildings even in a Nordic climate. This study highlights the importance of further research on glazed residential buildings, which are becoming more common in contexts subject to such climates.
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| 4. |
- Bhattacharjee, Shimantika
(författare)
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Energy efficiency strategies for residential buildings in a subarctic climate: Impacts on energy use and indoor thermal climate
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adopting energy efficiency strategies in residential buildings are beneficial as these not only improve the energy performance but also improves the indoor thermal climate and minimizes the greenhouse gas emissions. There exist numerous studies on energy efficiency strategies and their influence on indoor thermal climate in residential buildings in cold climates. However, there is a lack of documented and systematic studies that explicitly investigated the selection of appropriate energy efficiency strategies and their impact on the indoor thermal climate in residential buildings in a subarctic climate. Moreover, the impact of such energy efficiency strategies on the life cycle energy use of buildings has not been given appropriate attention in the existing literature. Due to the extreme climate conditions in a subarctic climate – severe cold and dark winter with heavy snow and mild short summer – buildings require a considerable amount of heating energy to maintain a comfortable temperature indoors. Therefore, it is important to adopt energy efficiency strategies that can help obtain operational and life cycle energy savings along with a better indoor thermal climate.The aim of this study is to evaluate the impact of different energy efficiency strategies on energy use and thermal indoor climate of three selected case study residential buildings in a subarctic climate. Three research questions were formulated: (1) What is the impact of evaluated energy‐efficiency strategies on the operational energy use?, (2) What is the impact of evaluated energy‐efficiency strategies on the life‐cycle energy use?, and (3) What is the impact of evaluated energy‐efficiency strategies on the thermal indoor climate? To address research questions 1 and 3, implemented energy‐efficiency strategies in two low‐energy buildings were evaluated using measured energy data and dynamic building energy and indoor climate simulations. To address research question 2, different combinations of energy efficiency strategies were explored using a multiobjective optimization method to identify optimal retrofitting solutions in terms of life cycle energy savings for a 1980s building.Results show that besides an airtight and highly insulated building envelope, a well‐functioning heating system is important to achieve low operational energy use. Findings highlight that the role of occupants is vital both in regard to the proper functioning of the heating system and to reduce the need for active heating in an airtight and highly insulated building. The occupants are also important in terms of maintaining a comfortable indoor thermal climate, especially during summer since manual airing and shading can help moderate temperatures indoors. Furthermore, findings show that applying glazed balconies is not necessarily a favorable strategy in terms of operational energy use and indoor thermal climate for a building in a subarctic climate. In comparison, using double instead of single pane balcony glazing and lowering the window to wall ratio improved the operational energy and indoor thermal climate performance. A combination of energy efficiency strategies including the addition of insulation on walls and roofs, there placement of windows from double pane to triple pane ones and the installation of heat recovery ventilation were found optimal to achieve considerable savings in both operational and life cycle energy use. In many cases, the fundamental aim of adopting energy efficiency strategies is to reduce operational energy use, while impacts on life cycle energy use and indoor thermal climate are less prioritized. The findings illustrate the importance of considering impacts on operational energy use, life cycle energy use and indoor thermal climate simultaneously to select energy efficiency strategies that ensure a better and more sustainable built environment.
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| 5. |
- Bhattacharjee, Shimantika, et al.
(författare)
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Performance evaluation of a passive house in sub-arctic climate
- 2018
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Ingår i: 9th International Cold Climate Conference, Kiruna, Sweden. March 12-15, 2018. - Cham : Springer International Publishing.
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Konferensbidrag (refereegranskat)abstract
- As the operational energy use in buildings contributes highly to the total energy used and greenhouse gases emitted in the cold climate regions of Europe, buildings which are more energy-efficient and less carbon-intensive during operation are key to meet sustainability objectives in these regions. Yet, research shows that the practice of passive or low-energy buildings in the sub-arctic climate of northern Sweden is comparatively less than in the southern region. Moreover, previous studies did not explicitly examine the performance of low energy buildings in sub-arctic climate in relation to established building energy efficiency standards. Consequently, knowledge regarding the energy performance of low-energy buildings in such climate is limited. Therefore, the aim is to evaluate the performance, in terms of indoor temperature and energy use for heating, domestic hot water and electricity of a new-built passive house titled “Sjunde Huset” in the sub-arctic town of Kiruna. It is Sweden’s northernmost house designed to fulfil the Swedish passive-house criteria of a maximum heat loss factor of 17 W/m2 and a maximum annual energy use of 63 kWh/m2. The implemented passive design strategies include a highly insulated, compact and airtight building envelope with a vestibule, mechanical ventilation with heat recovery and renewable energy production through photovoltaic solar cells. The house is connected to district heating and is equipped with energy-efficient appliances to allow low occupant energy use. Ongoing performance evaluation is based on building simulation and measurements of energy and temperature in different zones of the building. Energy performance deviations between occupied and non-occupied zones are explored through internal heat gain evaluations. The indoor temperature is also evaluated to assess the temperature variations throughout the year. The ongoing research further evaluate a comparative simulated and measured energy analysis of heating, hot water and electricity based on both the international passive house standard and the Swedish passive house criteria “Feby 12”.
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| 6. |
- De Windt, Laurent, et al.
(författare)
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MSWI bottom ash used as basement at two pilot-scale roads : comparison of leachate chemistry and reactive transport modeling
- 2011
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 31:2, s. 267-280
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Tidskriftsartikel (refereegranskat)abstract
- The recycling of municipal solid waste incineration bottom ash as aggregates for road basement requires assessing the long-term evolution of leachate chemistry. The Dåva (Sweden) and Hérouville (France) pilot-scale roads were monitored during 6 and 10 years, respectively. Calculated saturation indices were combined to batch test modeling to set a simplified geochemical model of the bottom ash materials. A common reactive transport model was then applied to both sites. At Hérouville, pH and the concentration of most elements quickly drop during the first two years to reach a set of minimum values over 10 years. The decrease is less pronounced at Dåva. The evolutions of pH and major element concentrations are fairly well related to the following pH-buffering sequence: portlandite, C-S-H phases or pseudo-wollastonite and, finally, calcite in equilibrium with atmospheric CO2. Al(OH)3, barite, ettringite and monohydrocalcite may also control leachate chemistry. Cu release is correctly modeled by DOM complexation and tenorite equilibrium. Temperature has no significant effect on the modeling of leachate chemistry in the range 5-30 °C, except at high pH. Effects at road edges and roadside slopes are important for the release of the less reactive elements and, possibly, for carbonation processes.
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| 7. |
- De Windt, L., et al.
(författare)
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Reactive transport modeling of leachate evolution of MSWI bottom ash used as road basement : Hérouville (France) and Dåva (Sweden) sites
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The recycling of municipal solid waste of incineration (MSWI) bottom ash as aggregates for road basement requires a better characterization of the evolution of leachate chemistry over a timescale of many decades. In this paper, a common reactive transport model is applied to the Hérouville (France) and Dåva (Sweden) pilot roads whose leachate emissions have been sampled during 10 and 6 years, respectively. The model considers simultaneously the hydrodynamic processes (rain water infiltration, advective and diffusive transport), pH-buffering and solubility-controlled processes by secondary minerals, ageing by atmospheric carbonation, and the leachate chemistry (major elements and trace metals such as Al, Cu, Pb). The evolution of pH is fairly well simulated with the following pH-buffering sequence: portlandite, calcium silicate hydrate (CSH), ettringite and, finally, calcite. The quantity of CO2 dissolved in the percolating rain water is generally not sufficient to explain the pH evolution and carbonation processes, requiring atmospheric gaseous inputs. The relation between pH evolution and element release is discussed for both sites. Calculated Pb release is overestimated when based on solubility-controlled mechanisms only. Edge effects are shown to be important at both sites with an emphasis of carbonation and release of non reactive elements. Temperature has no significant effect on the calculated leachate chemistry in the range of 5 - 30° C, except at high pH.
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| 8. |
- Engström, Susanne, et al.
(författare)
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From the Pilot Project to the Mainstream Practice : Learning Explored in Planning and Design of a Low-Energy Quarter
- 2015
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Ingår i: Procedia Economics and Finance. - 2212-5671. ; 21, s. 288-296
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Tidskriftsartikel (refereegranskat)abstract
- Pilot projects are common platforms for developing/testing construction methods or solutions for e.g. low-energy house-building. Whereas studies report on their technical/engineering outcomes, little is known from a learning perspective. In our study of pilot-project learning, the planning for and assessment of learning from a “low-energy quarter” pilot was explored. In step one, the initiators and the local authority participantswere addressed. The findings of the interviews indicatedthe changed understandings during the pilot of e.g. the planning and design criteria for sustainable building. Although stressed at the pilot outset, it seems that the learning among the stakeholders was not so well documented or systematically evaluated and shared so that the mainstream practice could have been informed or changed
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