Raúl Castaño-Rosa

The construction and real estate sectors are major contributors to global environmental impacts, particularly through greenhouse gas emissions and high resource consumption. Consequently, increasing attention has been directed toward circular economy (CE) practices to address these challenges. While CE has gained significant traction at the European Union policy level and in several innovative research initiatives, there is a gap in its practical implementation in the construction industry. This study conducted a systematic literature review to examine how CE approaches are often implemented in residential apartment building projects. Following a transparent and replicable protocol, selected articles were analysed using qualitative content analysis. The study identifies five main challenges for CE implementation in apartment building projects: financial, technical, regulatory, cultural and infrastructural. Furthermore, study discussed key considerations for regenerative thinking to boost CE in apartment building projects. In conclusion, authors argue regenerative circularity presents multiple opportunities for developing more sustainable and social residential built environments.

The development of urban built environments requires innovative strategies to address cities’ resources, energy, and social equity challenges. One strategy is involving citizens in the design and operation of their urban environments, supported by digital tools. However, current technology rarely enables meaningful participation before, during, and after construction, with interactions often brief and based on incomplete information. Engaging forms of digital tools are needed to shift citizens from acting as planning phase informants to becoming active, long-term contributors to urban spaces. Emerging smart technologies offer opportunities for engagement through immersion, interactivity, and social connectedness. This chapter introduces UrbanEngagingTech, a multi-dimensional framework facilitating citizen engagement across buildings, neighbourhood blocks, and cities throughout planning, construction, operation, and renewal phases. Integrating social and environmental sustainability perspectives, it rethinks engaging smart technologies for participatory urban design. Three case projects demonstrate its practical application, supported by literature examples to guide both technology and urban developers.

Background: Heating is a key challenge for Europe’s decarbonisation goals, accounting for a large share of energy use and emissions while shaping everyday life, comfort, and vulnerability. This article compares home heating transitions in Finland, Romania, Sweden, and the United Kingdom through an integrated framework combining energy democracy, energy citizenship, and energy justice. The study examines how ownership, everyday practices, and inequality intersect to shape citizen roles in heating transitions across diverse political and infrastructural contexts. Results: Based on archival and secondary material, the analysis reveals strong contextual variation in how citizens engage with heating systems. In Finland and Sweden, municipally owned district heating offers collective stability but limited direct agency. In Romania, the collapse of state-controlled networks has left households dependent on individual and often inefficient systems. In the United Kingdom, liberalised markets promise consumer choice but deepen vulnerability through cost pressures and weak accountability. Across all cases, household participation is structured by infrastructures, welfare regimes, and historical legacies rather than by individual choice. Integrating democracy, citizenship, and justice highlights how governance models, daily practices, and inequalities interact in shaping heating transitions. Conclusions: Citizen-centred heating transitions require policy approaches sensitive to national contexts and social realities. Empowerment must go beyond rhetoric to include participatory governance in collective systems, equitable regulation in liberalised markets, and targeted support for vulnerable households. The study contributes an analytical framework that captures the social depth of decarbonisation and supports the design of heating transitions that are democratic, participatory, and just.

Human labour capacity is bounded by rigid biophysical heat thresholds that remain systematically misrepresented in current climate–economic models. In this study, we integrate four decades (1980–2020) of wet-bulb temperature (WBT) observations from 1,834 meteorological stations, CMIP6 climate projections and intensity-specific labour-response functions to identify a nonlinear productivity regime governed by thermoregulatory limits. Labour capacity peaks at 20.6°C WBT, declines sharply beyond 24°C and falls below 60% above 28°C. This sharp transition—a ‘productivity cliff’—marks the limit at which impaired heat dissipation imposes a biophysical ceiling on economic output, shifting the basis of impact assessment from empirical extrapolation to mechanistic boundary identification. We show that these constraints are distributed unevenly through thermal positionality: tropical populations are climatologically situated closer to physiological thresholds, so that equivalent warming produces disproportionately large losses relative to temperate regions. Global exposure to hazardous heat (WBT > 28°C) has nearly doubled since 1980, placing ~ 2.5 billion people at chronic risk by 2020. In labour-dependent economies with limited capital, such shocks trigger ‘productivity lock-in’ a self-reinforcing dynamic in which declining output erodes the very adaptative capacity needed to reduce future vulnerability. We further demonstrate that localized labour losses propagate as systemic economic risk. Multi-regional input–output analysis reveals that heat-induced disruptions in manufacturing and agricultural hubs transmit across supply chains to high-income economies, while the increasing synchrony of extreme heat events undermines the buffering capacity of global trade networks. Under SSP5–8.5, tropical WBT approaches survivability limits (~ 35°C) by the late century, threatening the viability of labour systems and global economic connectivity. By embedding intensity-specific physiological thresholds within a global economic framework, this study provides a mechanistic foundation for revising climate damage functions, occupational heat standards and adaptation finance priorities.

Climate velocity is rapidly shifting bioclimatic zones, creating a mismatch between evolving exposures and static, location-based building codes. Codes anchored in outdated data and infrequent revisions risk undermining efficiency, thermal safety, and exacerbating inequities, particularly in transition belts and capacity-constrained districts. High-resolution climate records (2006–2023) combined with building-physics diagnostics were used to track spatial and seasonal realignment of thermal loads. Subtropical conditions advanced northward by up to ~7° latitude (~700 km), moving warm-temperate cities toward subtropical regimes and reshaping seasonal risk profiles. In warm-temperate zones, winter heating burdens declined, while temperate and sub-temperate regions experienced intensified summer cooling and latent loads, signaling a broader transition from winter-dominant to multi-season stress. These heterogeneous patterns reveal mismatch hotspots where rapid climatic shifts coincide with low adaptive capacity, magnifying thermal risk and potential energy burdens. The findings support a transferable framework for dynamic codes, that routine remapping of climate zones, trigger-based revision of design parameters, and equity-oriented targeting of finance and retrofit resources toward vulnerable regions. Prioritizing no-regrets passive upgrades can provide equitable and low-carbon adaptation worldwide.

Apartment overheating is increasingly an issue due to rising global temperatures, likely exceeding 2°C in Finland over the next few decades. This overlooked issue in Nordic housing is exacerbated by building characteristics ill-suited to keeping cool indoor environments, such as lack of solar shading or large operable windows and the use of glazed balconies. However, there is limited empirical evidence on summertime overheating in glazed-balcony apartments in the Nordic climate. To bridge this gap, this exploratory case-study investigation assessed summertime overheating in 10 apartments with glazed balconies in Finland during the summer of 2025 and investigated how occupant behaviour affected overheating risk. In-situ temperature measurements were collected in the balcony and apartment spaces alongside semi-structured interviews and balcony-use diaries. Findings highlighted that apartments built to the current Finnish building code failed to meet overheating criteria, and the presence of a glazed balcony was one of several variables linked to apartment overheating. Glazed balconies became uncomfortably hot for extended periods, limiting the intended year-round usability. Moreover, the balcony door was often the apartment’s sole purge ventilation route and was found to be ineffective. These findings are increasingly relevant internationally as glazed balcony solutions are gaining adoption in other contexts. PRACTICE RELEVANCE There is a pressing need to implement overheating mitigation strategies for glazed balconies, as well as the apartment more generally, to reduce associated risks. Designers and manufacturers must provide robust balcony-glazing solutions with proven operability that support pet-safe intensive ventilation, shading, furniture placement and everyday usability. Apartment window systems outside of the glazed balcony should also enable large and safe openings for effective natural ventilation. Indirect factors to be considered include: (1) updating regulatory climate datasets to consider current and future climate scenarios; (2) the balcony glazing should systematically be drawn with ‘glazing fully open’ as the default state during design ensuring usability in this condition; and (3) occupant behaviour should be supported through explicit guidance, including recommending to fully open balcony glazing during warm periods.