Embodied greenhouse gas emissions from PV systems in Norwegian residential Zero Emission Pilot Buildings

Greenhouse gas (GHG) emissions from the combustion of fossil energy need to be reduced to combat global climate change. For zero energy and Zero Emission Buildings (ZEB), photovoltaic solar energy systems are often installed. When the goal is to build a life cycle Zero Emission Building, all emissions come under scrutiny. Emissions from photovoltaic (PV) energy systems in Zero Emission Buildings have been shown to have a relative large share of material emissions. In this paper, we compare GHG emissions per kW h of electricity and greenhouse gas emission payback times (GPBT) for three residential PV systems in Zero Emission Pilot Buildings in Norway. All the buildings have roof mounted PV systems with different design solutions. The objective is to analyse the emission loads and GPBT of these three systems to facilitate for more informed choices of energy systems for Zero Emission Buildings. The results show that the total embodied emissions allocated per square meter of module area are around 150–350 kg CO2 eq/m2 for the three different systems. Emissions from the mounting systems vary from 10 to 25 kg CO2 eq/m2 depending on the material types and quantities used. When modules replace other roofing materials, such as roof tiles, mounting emissions were reduced by approximately 60%. GHG emissions per kW h electricity produced were in the range of 30–120 g CO2 eq/kW h for the different systems. The system with the lowest emissions was the largest system, which had a simple mounting structure and modules with reused cells. It was found that the GPBT was strongly dependent on the scenario used for electricity grid emissions. By applying a dynamic emission payback scenario with an optimistic reduction of emissions from the European electricity grid, the GPBT was 3–8 years for the different systems. When comparing the emissions with current Norwegian hydropower emissions, of around 20 g CO2 eq/kW h, it was found that all of the PV system’s emissions were higher. When compared to a mainly fossil fuel based grid, all the PV system’s emissions are low. This study highlights the importance of reliable emission documentation for PV modules and their mounting structures on the market.Acknowledgements. The authors gratefully acknowledge the support from the Research Council of Norway, several partners through the Research Centre on Zero Emission Buildings (ZEB) and the research project Building Integrated Photovoltaics for Norway (BIPV Norway). Special thanks to Harald Amundsen, Project Manager at Brødrene Dahl in Norway who provided details on the Multikomfort PV system. Also thanks to Roald Rasmussen at Skanska in Norway for providing details on the Skarpnes PV system.acceptedVersio

Lessons learnt from embodied GHG emission calculations in zero emission buildings (ZEBs) from the Norwegian ZEB research centre

The objective of this work is to present, evaluate and discuss the calculation methodology and embodied greenhouse gas (GHG) emission results from zero emission building (ZEB) case studies from the Norwegian ZEB research centre, to extract design drivers and lessons learnt. In all, two virtual models, and five ZEB pilot buildings are assessed; consisting of three residential, two office and two school buildings. The embodied GHG emission results show that the building envelope (ca. 65%) and production and replacement of materials (ca. 55-87%) are the main contributors to total emissions across the Norwegian ZEB case studies. Although difficult to draw definitive conclusions, this work builds upon the current body of knowledge on embodied GHG emissions in Norwegian ZEBs, and provides some practical indications for embodied GHG emission calculations and reduction strategies in future Norwegian ZEB and zero emission neighbourhood (ZEN) projects.Lessons learnt from embodied GHG emission calculations in zero emission buildings (ZEBs) from the Norwegian ZEB research centreacceptedVersio

ZEB pilot house Larvik. As Built Report

This report describes the ZEB pilot house Larvik, which was constructed during the autumn 2014. The ZEB pilot house is a two-storey single-family residential building situated near Larvik, Norway. The building was designed by Snøhetta, Brødrene Dahl, and Optimera for demonstration purposes, to showcase and test energy solutions for energy-efficient and plus-energy buildings. The report describes the building design and major design choices, the building services, the energy supply system and estimated energy need and delivered energy, the operational energy performance, the greenhouse gas (GHG) emissions from materials, as well as the ZEB balance. Further, the report presents information about the indoor climate performance, the design and construction processes, and information about costs. The ambition level of the building was ZEB-OM, which means that all GHG emissions related to all operational energy use (O) plus embodied emissions from the materials and technical installations (M) are to be compensated for by on-site renewable energy generation. In addition, the building should supply enough energy for an electric car. An interdisciplinary project team has been involved in the design and construction process. Research was made to reduce the emissions from construction materials, as well as to investigate their ability to contribute to a good indoor climate. A number of active and passive energy measures are demonstrated in the residence. Lessons learned from the project can be helpful for other building projects with ambitious goals. The energy generation system is based on roof mounted photovoltaic modules for electricity and a combination of different heat sources for thermal energy: a ground-source-to-water heat pump, an airto- water heat pump in the exhaust of the ventilation shaft, a solar collector system, and two different grey water heat recovery systems. The calculations show a net energy need for the building of 17,348 kWh per year, or 86.1 kWh/m2 of heated floor area. The demand for delivered energy is reduced due to the different heat sources for thermal energy. The remaining demand for delivered energy was calculated to 7,142 kWh electricity per year, or 35.4 kWh/m2. The calculated production from the photovoltaic system is in total 19,200 kWh per year. The GHG emissions are calculated to be 2,650 kgCO2 eq per year over a 60-year lifetime, or approximately 13.2 kgCO2 eq/m2 per year. It is estimated that 36 % of emissions come from operational energy use (B6), while 52 % of emissions come from building materials and replacements (A1-3+B4). 12 % of emissions are connected to the use of the electric car. The calculated emission balance gives a close margin on the ZEB-OM ambition for the ZEB-pilot house Larvik, but not when including 12,000 km with the electric car. Reducing the use of the electric car to 7,600 km gives a balance in the calculated emissions, given the described conditions. The approach is sensitive to methodology for material emission accounting and the choice of electricity emission factors for the import and export of electricity.This report has been written within the Research Centre on Zero Emission Buildings (ZEB). The authors gratefully acknowledge the support from the Research Council of Norway, BNL – Federation of construction industries, Brødrene Dahl, ByBo, DiBK – Norwegian Building Authority, Caverion Norge AS, DuPont, Entra, Forsvarsbygg, Glava, Husbanken, Isola, Multiconsult, NorDan, Norsk Teknologi, Protan, SAPA Building Systems, Skanska, Snøhetta, Statsbygg, Sør-Trøndelag Fylkeskommune, and Weber.publishedVersio

A zero emission concept analysis of an office building

The main aim of the work has been to do modeling and calculations of the energy use, embodied emission and the total CO2-emissions for a typical Norwegian office building. The goal is to find the most important parameters in the design of a zero emission office building, according to the current ZEB definition. The preliminary conclusions from this study are: 1. For a typical medium raise office building (4 storey) it is rather easy to achieve a ZEB-O (Operation) level, which in this case can be labeled a zero energy office building (energy produced on-site with PV equals total electricity demand). 2. Taking into account also the embodied emissions from materials and installations it seems very difficult to achieve the ZEB-OM (Operation and Material) level. The calculation is based on using areas with "acceptable" solar yield, namely the roof and the south (long) façade. 3. Even if the calculation of embodied emission (EE) has considerable uncertainties, preliminary results indicate that EE is considerable higher than the emission related to operational energy use. However, this is based on traditional design and material use of a Norwegian office building. A more optimized building with regard to low carbon materials, could change the balance between operational- and embodied emissions. 4. To achieve a ZEB-OM level a combination of further reduced energy demand, high performance thermal supply systems, reduced embodied emissions and increased PV-production seems to be the solution

Energi- og klimagassanalyse av isolasjonsmaterialer

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

A zero emission concept analysis of an office building

The main aim of the work has been to do modeling and calculations of the energy use, embodied emission and the total CO2-emissions for a typical Norwegian office building. The goal is to find the most important parameters in the design of a zero emission office building, according to the current ZEB definition. The preliminary conclusions from this study are: 1. For a typical medium raise office building (4 storey) it is rather easy to achieve a ZEB-O (Operation) level, which in this case can be labeled a zero energy office building (energy produced on-site with PV equals total electricity demand). 2. Taking into account also the embodied emissions from materials and installations it seems very difficult to achieve the ZEB-OM (Operation and Material) level. The calculation is based on using areas with "acceptable" solar yield, namely the roof and the south (long) façade. 3. Even if the calculation of embodied emission (EE) has considerable uncertainties, preliminary results indicate that EE is considerable higher than the emission related to operational energy use. However, this is based on traditional design and material use of a Norwegian office building. A more optimized building with regard to low carbon materials, could change the balance between operational- and embodied emissions. 4. To achieve a ZEB-OM level a combination of further reduced energy demand, high performance thermal supply systems, reduced embodied emissions and increased PV-production seems to be the solution.publishedVersio

Comparative emission analysis of low-energy and zero-emission buildings

<p>Different designs and concepts of low-energy and zero-emission buildings (ZEBs) are being introduced into the Norwegian market. This study analyses and compares the life cycle emissions of CO₂ equivalents (CO₂e) from eight different single-family houses in the Oslo climate. Included are four ZEBs: one active house, two passive houses, and a reference house (Norwegian building code of 2010). Monthly differences in CO₂e emissions are calculated for the seasonally sensitive Norwegian context for electricity generation and consumption. This is used to supplant the previous applied symmetric weighting approach for CO₂e/kWh factors for import and export of electricity for the ZEB cases. All the ZEBs have lower use-stage emissions compared with the other buildings or the reference case. Embodied impacts are found to be 60–75% for the analysed ZEB cases, confirming the importance of embodied impacts in Norwegian ZEBs. The lowest total emissions were from the smallest ZEB, emphasizing area efficiency. The highest emissions were from the reference case. By abandoning the symmetric approach, a new perspective was developed for assessing the performance of ZEBs within the Norwegian context. One of four ZEB cases managed to balance out its annual energy-related emissions.</p