Papers by Torhildur Fjola Kristjansdottir
This paper presents an analysis of how the design of a photovoltaic (PV) system influences the gr... more This paper presents an analysis of how the design of a photovoltaic (PV) system influences the greenhouse gas emissions balance in net zero emission buildings (nZEB). In a zero emission building, the emissions associated both with the energy required in the operation of the building (operational emissions), and the energy used to produce the building materials (embodied emissions), are offset by renewable energy generated on-site. The analysis is applied to a nZEB building concept for a single-family building, developed by the Norwegian Research Centre on Zero Emission Buildings. Previous analyses have shown that the installation of a PV system accounts for a significant share of the embodied emissions of a nZEB. The objective of this paper is to assess how the PV system design influences the embodied and avoided emissions as well as the energy yield. Three different PV technologies and four different module layouts for flat roofs are evaluated. In addition, the influence of two different grid emission factors is studied.
A major contributor to global greenhouse gas emissions is the production of concrete and steel fo... more A major contributor to global greenhouse gas emissions is the production of concrete and steel for the construction industry IPCC (2007). To combat global warming, innovative solutions are needed in the construction industry to reduce emissions from both energy and material use in buildings. In a previous study the first phase of a GHG emissions analysis for a Norwegian ZEB office concept was presented. The aim of which was to achieve a zero emission balance where operational and material emissions are accounted for ZEB OM. The results from the first phase showed that the load bearing system accounted for a large share of the embodied emissions. In addition, the ZEB OM ambition level was not met, thus emphasizing the need for further work on alternative solutions and material choices. This paper presents the results of a comparative study between this original office concept study and a predominantly wooden alternative loadbearing structure consisting of wood trusses, glue laminated beams and columns. The wooden alternative is comparable since it has been dimensioned to fulfil the same technical requirements for bearing capacity, sound and fire resistance. In addition, the system boundary was extended to include three alternative end-of-life scenarios. It was found that the wooden alternative structure almost halved the emissions compared to the original concrete and steel ZEB office concept model. This trend is the same in the cradle to gate and all three end-of life scenario’s. The analysis clearly shows that emissions from the production process outweigh any emissions from the material’s end-of-life treatment. This means that the material choice plays a major role in embodied emissions, as well as it being crucial to reduce the required construction material quantity.
SUMMARY Powerhouse Kjorbo is a refurbished commercial building in Sandvika, Norway which was comp... more SUMMARY Powerhouse Kjorbo is a refurbished commercial building in Sandvika, Norway which was completed in 2014. The goal of the project was to make an energy positive building by compensating the energy demand for the production of materials and components, the construction installation process, energy for operation and end-of-life treatment with onsite production of renewable energy. LCA-methodology was used to establish the primary energy balance and was used actively throughout the interdisciplinary and iterative design process to ensure decision making based on a lifecycle perspective. The results show a net positive primary energy balance over the lifecycle for Powerhouse Kjorbo. This shows a huge potential for developing the existing building stock to become, not only much more energy efficient, but also energy positive.
Solar Energy, Jun 1, 2016
This paper presents an analysis of how the design of a photovoltaic (PV) system influences the gr... more This paper presents an analysis of how the design of a photovoltaic (PV) system influences the greenhouse gas emission balance in a net zero emission building (nZEB). In a zero emission building, the emissions associated both with the energy required in the operation of the building (operational emissions) and the energy used to produce the building materials (embodied emissions) are offset by renewable energy generated on-site (avoided emissions). The analysis is applied to a nZEB concept for a single-family building, developed by the Norwegian Research Centre on Zero Emission Buildings. Previous analyses have shown that the installation of a PV system accounts for a significant share of the embodied emissions of a nZEB. The objective of this paper is to assess how the PV system design choices influence the embodied and avoided emissions, in order to determine how the environmental impact can be minimised. Four different PV technologies (Si-mono, poly-Si and CIS, and high-efficiency Si-mono) in four different system designs for flat roofs are evaluated using two different grid emission factors. The installations are compared by means of net avoided emissions, greenhouse gas payback time (GPBT), greenhouse gas return on investment (GROI), and finally the net emission balance of the building. The results show that the system with the largest area of high-efficiency Si-mono modules achieves the best lifetime emission balance, but that the greenhouse gas return on investment is highest for the optimally oriented CIS modules.
Materialet i denne publikasjonen er omfattet av åndsverklovens be stem mel ser. Uten saerskilt av... more Materialet i denne publikasjonen er omfattet av åndsverklovens be stem mel ser. Uten saerskilt avtale med SINTEF akademisk forlag er enhver eksemplarframstilling og tilgjengeliggjøring bare tillatt i den utstrekning det er hjemlet i lov eller tillatt gjennom avtale med Kopinor, interesseorgan for rettighetshavere til åndsverk. Utnyttelse i strid med lov eller avtale kan medføre erstatningsansvar og inndragning, og kan straffes med bøter eller fengsel.
ForskningsrapportSammenlikning av åtte isolasjonsmaterialer med hensyn til energibruk, klimagassu... more ForskningsrapportSammenlikning av åtte isolasjonsmaterialer med hensyn til energibruk, klimagassutslipp og -innhold og utslipp av helse- og miljøfarlige stoffer. Studien inkluderer utslipp fra råvarer, produksjon og transport til byggeplass i Norge. Rapporten kan brukes som beslutningsstøtte ved valg av isolasjonsmaterialer, og er nyttig for alle som er involvert i miljøvurdering av byggevarer – arkitekter, rådgivere, byggherrer og entreprenører, samt studenter og forskere. Analysen er basert på miljødeklarasjoner for isolasjonsmaterialer, og rapporten kan også brukes som en veiledning for sammenlikning av slike miljødeklarasjoner. Studien er finansiert av Husbanken
Energy and Buildings, 2018
In this study, the objective is to redesign a previous concept for a singlefamily Zero greenhouse... more In this study, the objective is to redesign a previous concept for a singlefamily Zero greenhouse gas Emission Building (ZEB). The concept is redesigned based on comparing greenhouse gas (GHG) emission loads and compensation from different design solutions applied in Norwegian singlefamily ZEB pilot buildings and selected sensitivity studies. The objective is to see if a previously developed ZEB model ( ) can be redesigned to achieve a life cycle energy and material emission balance (ZEB-OM), which previously was not achieved. Five different design parameters are evaluated: area efficiency, embodied emissions in the envelope, insulation thickness, heating systems and different roof forms with respect to the photovoltaic area. Embodied emissions reductions were possible in the ground foundation, from around 1 kg CO 2 /m 2 to 0.6 kg CO 2 /m 2 per year. Both models are able to compensate for all operational emissions. The new model is in addition able to compensate for 60% of embodied emissions, whereas the previous model only could compensate for 5%. The new model does not reach the life cycle energy and material balance. The paper presents and discusses different approaches for achieving the ZEB-OM balance. Further concept model optimization is needed.
Energy and Buildings, 2018
In the frame of the Norwegian Research Centre on Zero Emission Buildings, nine real-life zero emi... more In the frame of the Norwegian Research Centre on Zero Emission Buildings, nine real-life zero emission pilot building projects were initiated during the period of 2009 to 2017. Eight of the pilot building projects have been constructed and are currently in use, whilst one of them is still in the planning phase. All the pilot projects have been followed up by researchers during the design, construction, and operation phases, by e.g. analyses of construction documents, and post-occupancy surveys. The main lessons learnt from this work are presented in this paper. They include the importance of an integrated design process, having clear goals and associated assessment methods, following a strategy based on 'trias energetica', as well as choosing locally sourced materials with low embodied carbon and long service lives, and increasing the focus on the users.
Building Research & Information, 2017
This report deals with how to define what a Zero Emission Building (ZEB) is with explanation and ... more This report deals with how to define what a Zero Emission Building (ZEB) is with explanation and analysis of different parameters related to embodied emissions of CO2 equivalents. The report can be used as a guidance tool on how to assess embodied emissions, and also on what parameters should be evaluated in such an assessment. Different ambition levels for ZEBs may include life stages, operation, material, construction and end-oflife and can be documented according to EN 15978. Calculation procedures should include system boundaries, embodied emissions from materials, transport, the construction process and waste handling according to the ambition level. CO2 eq emissions factors, service life estimates and payback scenarios for CO2 emissions need to be considered. The report does not contain one single clearly defined method, but rather a state-of-the-art summary on the different issues and refers to other relevant national and international work in the field of ZEB definitions. Th...
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Papers by Torhildur Fjola Kristjansdottir