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The building industry is responsible for 35% of final energy use and 38% of CO2 emissions at a global level. The European Union aims to reduce CO2 emissions in the building industry by up to 90% by the year 2050. Therefore, it is important to consider the environmental impacts buildings have. The purpose of this thesis was to investigate the environmental impacts and costs of a single-family house in Sweden. In the study, the life cycle assessment (LCA) and the life cycle cost (LCC) methods have been used by following the “cradle to grave” life cycle perspective. 

This study shows a significant reduction of global warming potential (GWP), primary energy (PE) use and costs when the lifespan of the house is shifted from 50 to 100 years. The findings illustrate a total decrease in LCA outcome, of GWP to 27% and PE to 18%. Considering the total LCC outcome, when the discount rate increases from 3% to 5% and then 7%, the total costs decrease significantly (60%, 85% to 95%). The embodied carbon, PE use and costs from the production stage/construction stage are significantly reduced, while the maintenance/replacement stage displays the opposite trend. Operational energy use, water consumption and end-of-life, however, remain largely unchanged. Furthermore, the findings emphasize the importance of using wood-based building materials due to its lower carbon-intensive manufacturing process compared to non-wood choices.  

The results of the LCA and LCC were systematically studied and are presented visually. Low carbon and cost-effective materials and installations have to be identified in the early stage of a building design so that the appropriate investment choices can be made that will reduce a building’s total environmental and economic impact in the long run. Findings from this thesis provide a greater understanding of the environmental and economic impacts that are relevant for decision-makers when building single-family houses.

The building sector is responsible for 34% of final energy consumption and contributes to 37% of global CO₂ emissions. In alignment with sustainability goals, the European Union has set a target to reduce CO₂ emissions in the building sector by up to 90% by 2050. Consequently, there is a great need to examine the climate impact of buildings and adopt a comprehensive perspective using a whole life carbon assessment. The aim of the thesis was to examine greenhouse gas (GHG) emissions and costs throughout all life cycle stages, applying a whole life carbon assessment and life cycle cost analysis for a single-family building situated in a Nordic climate. Additionally, both positive (released) and negative GHG emissions were explored and documented, encompassing operational and embodied impacts. In the thesis, the life cycle assessment and the life cycle cost methods have been applied by following the “cradle-to-grave” life cycle perspective. The study includes an analysis of the reference building design and comparisons with improved building design. 

The thesis findings highlight a substantial decrease in released GHG emissions with 23% reduction for the analyzed improved building design showing 5.2 kg CO₂e/m²/y₅₀ compared to the reference building design showing 6.7 kg CO₂e/m²/y₅₀. Moreover, incorporating biogenic carbon and the D module into the cradle-to-grave approach shows the lowest total GHG emissions, manifesting as negative values, -0.7 kg CO₂e/m²/y₅₀ for the improved building design. Embodied impact accounts for 79% and 72% of the total impact, while operational impact accounts for 21% and 28% for the reference and improved building designs. When analyzing all building materials, it is shown that an increased share of wooden building materials in the improved building design results in decreased released (positive) GHG emissions and increased negative GHG emissions. The results underscore the significance of using wood-based building materials due to their manufacturing process having lower GHG emissions compared to non-wood solutions. Considering the reference building design, when analyzing the building energy systems, it should be noted that the embodied GHG emissions from the production phase of solar PV panels are considerably higher when compared to emissions from the ventilation system and heat pump. To decrease the embodied GHG emissions during the production phase of solar PV panels, the manufacturing process should be done in countries with a larger share of renewable energy sources in the electricity grid. Moreover, recognizing building materials with low GHG emissions that are economically profitable during the early phases of building design and construction is essential for reducing long-term environmental and economic consequences. Additionally, considering the utilization of reusable building products over new ones could be seen as a winning strategy for mitigating the climate impact in the building sector and decreasing the use of natural resources and waste. 

Considering the economic impact, it can be noted that the construction costs are greater than operational costs and end-of-life costs comparing all life cycle stages. Approximately 50% of the construction costs are labor costs, followed by investment costs for building materials, installations, and pre-construction costs. Analyzing the building products’ costs, it is important to note that selecting cross-laminated timber (CLT) for a foundation could lead to higher investment costs compared to concrete slabs. 

In conclusion, the result of the thesis encompasses a whole life carbon assessment in buildings. It underscores the importance of revealing all carbon flows associated with single-family buildings. Finally, the thesis outlines the advantages of utilizing wood-based materials and reusable building products for building owners, contractors, designers, architects, consultants, and other decision-makers. It emphasizes the importance of considering both the environmental and economic aspects of buildings to attain a comprehensive understanding.

The aim of this study was to investigate how the carbon accounting of a wooden single-family house is affected by (1) decreasing the carbon footprint by changes in building design, (2) differentiating biogenic carbon from fossil carbon and (3) including external benefits beyond the state-of-the-art system boundaries. The motivation of exploring different system boundaries, improved building design and investigating benefits aside of system boundaries rely on the fact of having the “full” picture of GHG emissions of building products. Changes in building design were analyzed by life cycle assessment (LCA) focusing on greenhouse gas (GHG) emissions, while the costs were assessed by using lice cycle cost (LCC). The findings showed that by including positive and negative emissions from the production phase for an improved building design within scenario 4 ‘Cradle to Gate + Biogenic Carbon + D module’ has the lowest embodied GHG emissions when compared to other approaches with −3.5 kg CO2e/m2/y50. Considering the impacts of the whole building, the lowest GHG emissions are within the scenario 8 ‘Cradle to Grave + Biogenic Carbon + D module‘ for the improved building design with −0.7 kg CO2e/m2/y50. The results suggest that a change to sustainable alternatives for building components that makes the whole building to be constructed by wood, could lead to significant reduction of GHG emissions compared to conventional material choices. Economically, testing sustainable solutions, the highlighted results are the construction costs that are almost double higher for CLT elements for the foundation compared to concrete. © 2023

Previous research has shown a lack of studies with comparisons between primary (virgin) and secondary (re-used) building materials, and their embodied emissions. The creation of different scenarios comparing the environmental impact of virgin vs. re-used materials is also motivated by the scarcity of raw materials in the world and the emergency of mitigating greenhouse gas (GHG) emissions from buildings. The aim of this study was to investigate scenarios, including new vs. re-used building products, applying the LCA method for a wooden single-family building. The findings showed a 23% reduction potential for total released (positive) CO₂e when comparing the Reference scenario with Scenario I, using re-used wooden-based materials. Further, Scenario II, using all re-used building materials except for installations, showed a 59% CO₂e reduction potential compared to the Reference scenario. Finally, Scenario III, which assumes all re-used building products, showed a 92% decreased global warming potential (GWP) impact compared to the Reference scenario. However, when including biogenic carbon and benefits (A5 and D module), the Reference scenario, based on newly produced wooden building materials, has the largest negative GHG emissions. It can be concluded that the re-use of building products leads to significant carbon savings compared to using new building products.

To understand the reasons behind the large environmental impact from buildings the whole life cycle needs to be considered. Therefore, this study evaluates the carbon dioxide emissions in all stages of a single-family house in Sweden from the production of building materials, followed by construction and user stages until the end-of-life of the building in a life cycle assessment (LCA). The methodology applied is attributional life cycle assessment (LCA) based on ‘One Click LCA’ tool and a calculated life span of 100 years. Global warming potential (GWP) and primary energy (PE) are calculated by using specific data from the case study, furthermore the data regarding building materials are based on Environmental Product Declarations (EPDs). The results show that the selection of wood-based materials has a significantly lower impact on the carbon dioxide emissions in comparison with non-wood based materials. The total emissions for this single-family house in Sweden are 6 kg CO 2 e/m 2 /year. The production stage of building materials, including building systems and installations represent 30% of the total carbon dioxide equivalent emissions, while the maintenance and replacement part represents 37%. However, energy use during the in-use stage of the house recorded lower environmental impact (21%) due to the Swedish electricity mix that is mostly based on energy sources with low carbon dioxide emissions. The water consumption, construction and the end-of-life stages have shown minor contribution to the buildings total greenhouse gas (GHG) emissions (12%). The primary energy indicator shows the largest share in the operational phase of the house.

The Nordic countries have shown great interest in using Life Cycle Assessment (LCA) in the building sector compared to the past years. Sweden has set up an objective to be carbon neutral (no greenhouse gas emissions to the atmosphere) by 2045. This paper presents a case study of a single-family house “Dalarnas Villa” in the region Dalarna, Sweden within a 100-year perspective. The assessment is implemented using a new software based on hard data agreed by Environmental Product Declarations (EPDs). It focuses on building materials, transport distances of the materials, and replacement of essential construction materials. The LCA in this study demonstrates the environmental impact related to building materials from production and construction phase including transport, replacement and deconstruction phase. The study does not cover energy use and water consumption. The results show that the building slab made by concrete is the part of the construction most contributing to CO2e, while the wood frame and cellulose insulation have low environmental impact. Replacement of materials takes nearly half of total environmental impact over 100 years. Having a large share of wood-based products, make greenhouse gas emissions remains low.

The objective of this paper was to explore long-term costs for a single-family house in Sweden during its entire lifetime. In order to estimate the total costs, considering construction, replacement, operation, and end-of-life costs over the long term, the life cycle cost (LCC) method was applied. Different cost solutions were analysed including various economic parameters in a sensitivity analysis. Economic parameters used in the analysis include various nominal discount rates (7%, 5% and 3%), an inflation rate of 2%, and energy escalation rates (2-6%). The study includes two lifespans (100 and 50 years). The discounting scheme was used in the calculations. Additionally, carbon-dioxide equivalent (CO2e) emissions were considered and systematically analysed with costs. Findings show that when the discount rate is decreased from 7% to 3% the total costs are increased significantly, by 44% for a 100-year lifespan, while for a 50 years lifespan the total costs show a minor increase by 18%. The construction costs represent a major part of total LCC, with labor costs making up half of them. Considering costs and emissions together, a full correlation was not found, while a partial relationship was investigated. Results can be useful for decision-makers in the building sector.