Traditionally, the emissions embodied in construction materials have not been considered important; however, they are becoming crucial due to the short time-frame in which the emissions should be reduced. Moreover, evaluating the environmental burden of construction materials has proven problematic and the reliability of the reported impact estimates is questionable. More reliable information from the construction sector is thus urgently needed to back and guide decision-making. Currently, the building sector environmental impact assessments predominantly employ commercial software with environmental impact databases and report results without knowledge about the impact of the software/database choice on the results. In this study, estimates for the embodied environmental impacts of residential construction from the two most widely used life cycle assessment (LCA) database-software combinations, ecoinvent with SimaPro software and GaBi, are compared to recognize the uniformities and inconsistencies. The impacts caused by two residential buildings of different types, a concrete-element multi-story residential building and a detached wooden house, both located in Finland, were assessed, including all building systems with a high level of detail. Based on the ReCiPe Midpoint method, fifteen impact categories were estimated and compared. The results confirm that the tool choice significantly affects the outcome. For the whole building, the difference is significant, around 15%, even in the most widely assessed category of Climate Change, and yields results that lean in different directions for the two cases. In the others, the estimates are entirely different, 40% or more in the majority of the categories and up to several thousand percentages of difference. The main conclusion is that extensive work is still urgently needed to improve the reliability of LCA tools in the building sector in order to provide reliable and trustworthy information for policy-making.

Some cities have set carbon neutrality targets prior to national or state-wide neutrality targets, which makes the shift to carbon neutrality more difficult, as the surrounding system does not support this. The purpose of this paper was to evaluate different options for a progressive city to reach carbon neutrality in energy prior to the surrounding system. The study followed the C40 Cities definition of a carbon-neutral city and used the City of Vantaa in Finland as a progressive case aiming for carbon neutrality by 2030, five years before the national target for carbon neutrality. The study mapped the carbon neutrality process based on City documents and national statistics, and validated it through process-owner interviews. It was identified that most of the measures in the carbon neutrality process were actually outside the jurisdiction of the City, which outsources the responsibility for the majority of carbon neutrality actions to either private properties or national actors with broader boundaries. The only major measure in the City’s direct control was the removal of carbon emissions from municipal district heat production, which potentially represent 30% of the City’s reported carbon emissions and 58% of its energy-related carbon emissions. Interestingly, the City owns electricity production capacity within and beyond the city borders, but it doesn’t allocate it for itself. Allocation would significantly increase the control over the City’s own actions regarding carbon neutrality. Thus, it is proposed that cities aiming for carbon neutrality should promote and advance allocable carbon-free energy production, regardless of geographical location, as one of the central methods of achieving carbon neutrality.

Climate change mitigation is an important goal for cities globally. Energy production contributes more than half of the global greenhouse gas emissions, and thus the mitigation potential of local municipal energy systems is important for cities to recognize. The purpose of the study is to analyze the role of local municipal energy systems in the consumption-based carbon footprint of a city resident. The research supplements the previous carbon footprint assessments of city residents with an energy system implication analysis. The study includes 20 of the largest cities in Finland. The main findings of the study are as follows: first, the municipal combined heat and power energy system contributes surprisingly little (on average 18%) to the direct carbon footprint of city residents, supporting some previous findings about a high degree of outsourcing of emissions in cities in developed countries. Second, when indirect emissions (i.e., the implication of a municipal energy system on the national energy system) are allocated to city residents, the significance of the local energy system increases substantially to 32%. Finally, without the benefits of local combined heat and power technology based electricity consumption, the carbon footprints would have increased by an additional 13% to 47% due to the emissions from compensatory electricity production. The results also show that the direct application of consumption-based carbon assessment would imply a relatively low significance for municipal energy solutions. However, with a broader understanding of energy system dynamics, the significance of municipal energy increases substantially. The results emphasize the importance of the consequential energy system implications, which is typically left out of the evaluations of consumption-based carbon footprints.

The purpose of this paper is to compare, from an urban planning perspective, the choice between combined heat and power (CHP) and a ground-source heat pump (HP) as the energy systems of a new residential area in the light of the uncertainty related to the assessments. There has been a strong push globally for CHP due to its climate mitigation potential compared to separate production, and consequently it is often prioritized in planning without questioning. However, the uncertainties in assessing the emissions from CHP and alternative options in a certain planning situation make it very difficult to give robust decision guidelines. In addition, even the order of magnitude of the climate impact of a certain plan is actually difficult to assess robustly. With a case study of the new residential development of Härmälänranta in Tampere, Finland, we show how strongly the uncertainties related to (1) utilizing average or marginal electricity as the reference; (2) assigning emissions intensities for the production; and (3) allocating the emissions from CHP to heat and electricity affect the results and lead to varying decision guidelines. We also depict how a rather rarely utilized method in assigning the emissions from CHP is the most robust for planning support.

Waste heat utilization is shown to have the potential to decrease greenhouse gas emissions globally. The purpose of this case study is to illustrate how the utilization of waste heat to decrease municipal boundary greenhouse gas emissions may increase such emissions within wider boundaries. The case study assesses the utilization of waste heat generated by a data center. In this paper, we analyze the implications within scopes 1-3 of the Greenhouse Gas Protocol together with attributional and consequential life cycle assessment principals. Only Scope 1 showed negative greenhouse gas emission implications. In order to achieve negative Scope 2 emissions, approximately half of the waste heat would need to be utilized, which is the purpose of further site development. In order for negative Scope 3 emission implications, electricity production changes are needed or local municipal replaceable greenhouse gas emissions would need to be much higher.

We noticed that the Figures 2 and 3 have become the same in the final version of this paper