Cities generally adopt territorial- or production-based rather than consumption-based emissions accounting systems but they find difficult to adopt a specific emissions standard. Due to the diverse calculation methodologies cities use, inter-city emission reductions and climate action comparisons remain challenging. It is crucial to learn how cities address climate change mitigation and adaptation in terms of the emissions accounting methodologies they use, their links to existing city-level international emission standards, and the consistency of those methods used by cities to improve the quality of emissions standards. Normative case study method was applied to explore these issues in three different case cities: Helsinki (Finland), Stockholm (Sweden), and Copenhagen (Denmark). The current calculation methods used in these cities exclude many indirect emissions, and these cities have not adopted consumption-based emissions. Cities also face several dilemmas in system boundaries and baseline year setting, emissions factors calculations, and data collection methods using current calculation methods. All three case cities have adopted amendable emissions accounting systems which exclude certain amounts of emissions from several sectors. Therefore, emission calculation methods must be improved to include all possible sectors and to produce more robust and transparent calculation methods.

Carbon neutrality represents one climate strategy adopted by many cities, including the city of Helsinki and the Helsinki metropolitan area in Finland. This study examines initiatives adopted by the Helsinki metropolitan area aimed at reducing energy-related carbon emissions and achieving carbon neutrality through future actions. Various sectorial energy consumption rates per year and carbon emissions from various sectors within the city of Helsinki and the metropolitan area were extracted from an online database and re-calculated (in GWh, MWh/inhabitant and MtCO₂e, KtCO₂e/inhabitant). We employed a backcasting scenario method to explore the various carbon reduction measures in the Helsinki metropolitan area. About 96% of the emissions produced in the Helsinki metropolitan area are energy-based. District heating represents the primary source of emissions, followed by transportation and electricity consumption, respectively. We also found that accomplishing the carbon reduction strategies of the Helsinki metropolitan area by 2050 remains challenging. Technological advancement for clean and renewable energy sources, smart policies and raising awareness resulting in behavioral changes greatly affect carbon reduction actions. Thus, strong political commitments are also required to formulate and implement stringent climate actions.

Residential wood combustion (RWC) is a significant source of gaseous and particulate emissions causing adverse health and environmental effects. Several factors affect emissions, but the effects of the fuel wood species on emissions are currently not well understood. In this study, the Nordic wood species (named BirchA, BirchB, Spruce, SpruceDry, Pine and Alder) were combusted in a modern stove, and the emissions were studied. The lowest emissions were obtained from the combustion of BirchA and the highest from Spruce and Alder. The fine particle mass (PM_2.5) was mainly composed of elemental carbon (50–70% of PM_2.5), which is typical in modern appliances. The lowest PAH concentrations were measured from BirchA (total PAH 107 µg/m³) and Pine (250 µg/m³). In the ignition batch, the PAH concentration was about 4-fold (416 µg/m³). The PAHs did not correlate with other organic compounds, and thus, volatile organic compounds (VOCs) or organic carbon (OC) concentrations cannot be used as an indicator of PAH emissions. Two birch species from different origins with a similar chemical composition but different density produced partially different emission profiles. This study indicates that emission differences may be due more to the physical properties of the wood and the combustion conditions than to the wood species themselves.

Helsinki Metropolitan area possesses significant solar potential, which can be utilized by installing solar panels and collectors in the cities’ public and private premises to fulfill the emission reduction targets. However, current development of solar energy production in the region is in its infancy. This paper outlines how current state of solar energy utilization can be improved in public and private buildings and utility companies in the Helsinki Metropolitan area in terms of costs and financial mechanisms. We applied document analysis and semi-structured interview methods to study the role of solar energy for carbon neutrality in this area. The analyses showed that the Metropolitan cities do not have clear electricity production targets from solar energy yet. Furthermore, their subsidy schemes and financial measures for solar energy productions are not attractive for the promotion of solar energy. Thus, we propose the Metropolitan cities to adopt a policy outlining that a certain percentage (e.g. 20%) of energy should be produced from solar energy to achieve the 20% renewable energy target by 2020. Financial incentives and subsidy schemes for solar power installations should be more tempting and accessible to private and public building owners.