Satu Huuhka

In housing, ‘adaptability’ denotes the capacity of the dwelling to accommodate residents’ changing needs. Adaptable housing was first put forward in the early 20th century and has been debated ever since. Recently, adaptability has also been recognised as a focal contributor to buildings’ sustainability and circular economy. Nevertheless, adaptable housing is rarely built. This paper studies what hinders the mainstreaming of adaptable housing in Finland. Semi-structured interviews were conducted with professional stakeholder groups involved in developing, financing, regulating, inspecting, and designing housing. The interviews were construed around five adaptability concepts that have sporadically been built in Finland. The specific barriers and preconditions to implementing each concept were found to vary. However, the fact that in general, developers do not find it meaningful to incorporate adaptability in their projects would appear to form the main barrier. Contrary to previous research, the results of this study challenge the idea that additional costs allegedly incurred by adaptability would necessarily play a major role.

Take-back and reuse schemes of bricks reclaimed from end-of-life buildings could reduce the environmental impacts of the brick industry. This study assesses the practical viability and environmental impacts of reclaiming fired perforated clay bricks bonded with cement-based mortar from a brick veneer. The life-cycle assessment is executed according to European Standard EN 15804 across 19 environmental impact categories using empirical Finnish case study data. Two deconstruction methods were analysed: hand-held power tools, which yields more intact bricks, but is labour intensive; and an excavator, which yields 40% fewer bricks but is easier to adopt by the industry. Regardless of the method, reclaimed bricks have only 20% of the total environmental impact of virgin bricks and outperform them in all relevant impact categories. Given emerging European Union climate regulations for buildings, global warming potential (GWP) is of particular interest. In comparison with virgin bricks, reclaimed bricks have 86–88% lower fossil-based GWP and 94–95% lower total GWP. While some limitations follow from the case study design, the environmental benefit is so substantial that reclaimed bricks can reliably be deemed as ultra-low-carbon construction products. Transport is the main fossil GWP contributor, but reclaimed bricks remain environmentally competitive even over extensive transport distances. PRACTICE RELEVANCE Most modern brick buildings were built using cement-based mortars. Previous literature has considered such bricks as having a low potential for reclamation. This study challenges this belief, as such bricks could be reclaimed at high rates from a brick veneer. Brick reclamation was also found to be possible using an excavator. Contrary to previous beliefs, modern brick building stocks can thus form substantial ‘urban mines’ for brick reclamation. Reclaiming bricks does not necessarily require substantial changes to existing building decommissioning practices, which lowers the adoption threshold for current demolition industry operators. Bricks reclaimed with an excavator have a low environmental impact compared with new bricks. Several European Union member states are introducing environmental regulations that incorporate greenhouse gas benchmarks for buildings, and this is increasing demand for low-carbon construction products. Reclaiming bricks for reuse can be a viable option for this, both practically and environmentally.

In the circular economy, building stocks are valuable urban mines of secondary resources and reserves of space whose utilization has the potential to substitute for virgin resources. The purpose of this study is to compare patterns in construction (inflows) and demolition (outflows) and how they shaped the building stock in two Finnish cities, Vantaa and Tampere between 2000 and 2018. By attributing flows to distinct urban development patterns (such as greenfield, replacement, infill, etc.) and investigating population and labour force structure, the goal is to recognize differences and similarities between the case studies. In doing so, the aim is to understand how a comparative approach may help to identify drivers and patterns in the building stock dynamics of the two cities which further aids the development of a circular building stock management. The methodological foundation for this research is Urban Metabolism in form of Material Flow Analysis with a focus on the product i.e., building level but also space as a service provided by buildings. Tampere and Vantaa are the third and fourth largest cities in Finland, with a population of circa 230,000 each. Despite their similar sizes, differences in their geographical properties, contexts, and roles in Finland make them interesting targets for comparative research. The results show that growth in population and labour force led to a substantial increase in both cities’ building stocks. While Vantaa’s more rural character allowed a higher amount of sprawl by loose-built housing typologies, geographical restrictions and the already dense building stock in Tampere often led to more compact housing and an overall higher amount of demolition in relation to construction. The development of both non-residential building stocks shows a clear tendency towards typologies that support respective economic operations. Alas, material intensity coefficients, which would enable quantifying the material and CO2 impacts of these developments, do not yet exist for Finnish building typologies. Nevertheless, this study’s findings provide a preliminary understanding of how different mechanisms of urban development, such as construction and demolition, shape environmental strains and support the development of pinpoint circular strategies.

A simple method is presented to improve the evaluation of past and/or future CO2 emissions of heating and/or cooling a building. The degree-day—energy emission coefficient (DD-EEC) method relies on two established techniques. It starts with a building’s known annual heating and/or cooling energy consumption. Degree-days are employed to estimate the consumption in other years, unveiling how climate warming influences the annual energy need for heating and/or cooling. The resulting emissions are then quantified by associating the energy need in each year with the emission factor for energy production that year. A case study demonstrates an application of the method: a 1950s’ school building in Finland. Its past heating-related operational CO2 emissions are reconstructed from its erection until today, and the future heating and cooling emissions are forecasted until 2100. The case demonstrates the impact of climate warming and projected energy decarbonisation on emissions, showcasing that the past may not be the best future predictor. In the 2010s, the emissions were estimated to be 57% of the 1960s’ level. In the 2090s, they could be as little as 5% of the 2010s’ level, even though the building’s technical properties remain unchanged. Practice relevance This new method is a straightforward technique that can be replicated and easily used by researchers and, most importantly, practitioners. The method is based on degree-days, which are widely used in building energy practice. The technique refines existing methodology, which does not yet consider the impact of a warmer climate and energy decarbonisation on a building’s emission generation, at least not together. The availability of robust research-based data determines whether the method can be applied only retrospectively or also prospectively; such data are available in the European Union and other places. The practice relevance of this method is it can improve decision-making based on whole-life life cycle analysis (LCA), where the ratio between a building’s embodied and operational emissions is a focal consideration in many kinds of decision-making situations. Too simple modelling of operational emissions risks getting this ratio wrong, potentially leading to decision-makers drawing incorrect conclusions with real-life adverse effects.

This paper explores the environmental impacts of retaining or replacing buildings by extending the consequential replacement framework (CRF) for life-cycle assessment (LCA) from individual buildings towards the urban scale. It addresses a gap in previous studies by examining the broader consequences of building-level retention or replacement decisions in the built environment, namely greenhouse gas (GHG) emissions from associated infrastructure construction. The case study, which is located in Finland, investigates alternative ways to densify a growing city, some of which can be achieved within the urban structure, while others require greenfield construction elsewhere in the city. The results reveal that refurbishing and extending already existing buildings is worthwhile in terms of GHG emissions, even if some of the additional floor area targeted in densification were to be built on a greenfield site. After 50 years, the accumulated GHG emissions of scenarios that develop existing buildings are 0.2–12% less than those from replacement scenarios, depending on whether the targeted densification is minor or major and the amount of infrastructure construction involved. This is primarily due to the 11–35% smaller upfront embodied GHG emissions of refurbishment compared with new construction—which 50 years do not offset. Policy relevance This paper reinforces the notion from previous research that developing the existing building stock holds major emission-savings potential, even more so than replacement with energy-efficient new build. It highlights the potential contribution of existing building stocks in low-emission city development, even in growing city contexts. The case study results challenge the common belief in urban planning that if replacement involves densification, it must be a more low-emission alternative than retention, and conversely, if retention leads to greenfield construction, it must be higher in emissions than replacement. Low-emission urban planning should base its conclusions on urban LCA. This paper introduces an infrastructure-extended CRF that accounts for building retention and replacement scenarios, ensuring methodological robustness. The approach is essential for policymakers to base their decisions on evidence and prioritise low-emission development alternatives. Which policymakers hold power over such decisions and which instruments are suitable to pursue these goals depend on the context.