Global Decarbonisation (GD) is a peer-reviewed, open-access journal committed to advancing the global transition to a net-zero carbon future. The journal serves as a platform for researchers, policymakers, industry experts, and practitioners to share innovative solutions, critical analyses, and emerging trends in decarbonisation across all sectors. GD aims to foster interdisciplinary dialogue on decarbonisation strategies at local, national, and global levels, exploring technological, economic, policy, and social dimensions. It publishes original research articles, comprehensive reviews, case studies, and policy analyses that provide actionable insights for mitigating climate change and achieving international targets like the Paris Agreement.
Computational Fluid Dynamics in Hybrid Passive–Active Heat Recovery Systems for High-Performance Buildings: A Critical Review
Hybrid passive–active heat recovery systems are increasingly used in high-performance buildings as a practical response to the growing pressure for lower energy use and more stable indoor environmental conditions. These systems combine passive heat transfer elements, such as heat pipes, with limited mechanical ventilation support in order to balance energy efficiency with operational controllability. As a result, they occupy a middle ground between fully passive solutions, which are often sensitive to boundary conditions, and fully active systems, which tend to impose higher energy and operational costs. Computational Fluid Dynamics (CFD) has become the main analytical approach for studying the behaviour of these hybrid systems. It is commonly used to investigate airflow patterns, heat transfer processes, pressure losses, and ventilation effectiveness under a wide range of operating conditions. At the same time, the existing literature shows substantial variation in how CFD models are constructed and applied. Differences in turbulence modelling, boundary condition definition, validation strategy, and performance metrics make it difficult to compare results across studies or draw general conclusions. This review critically examines published CFD-based studies on hybrid passive–active heat recovery systems in high-performance buildings. The focus is not on individual case studies, but on identifying recurring modelling practices, common simplifications, and their implications for predicted system performance. Particular attention is given to the treatment of mixed-mode ventilation, conjugate heat transfer, and the interaction between passive components and mechanically assisted airflow. The review also highlights areas where current CFD practice remains limited, including validation against field measurements and representation of climate-driven variability. By consolidating these findings, the paper aims to clarify the role of CFD as a supporting analytical tool for design and retrofit decisions, rather than as a stand-alone predictor of system performance.
Copyright (c) 2026 The Author(s) https://creativecommons.org/licenses/by/4.0
How do Sustainability Ideologies Manifest in Local Planning Decisions?
Sustainability underpins planning within the United Kingdom and is applied to all scales of development management decisions, ranging from small-scale householder planning applications to major urban regeneration schemes. Although sustainability has long been a guiding principle in spatial planning, no academic research exists on how sustainability manifests across development scales within planning decisions in England. This research applies Davidson’s novel typology for an exploratory categorization of sustainability ideologies within 21 planning reports from three outer borough London local authorities. It aims to advance an understanding of how sustainability manifests across development scales and to contribute to the literature at the junction of sustainability and development management. The research finds that sustainability adopts different sociopolitical ideologies across development scales. In large schemes, planners adopt a neoliberal approach where technology and the substitutability of capital justify sustainable outcomes. While in smaller householder and minor schemes, planners adopt radical (micro) and social democratic (macro) approaches that insist on limits to growth and follow traditional authority-applicant power relationships when justifying sustainable outcomes. The paper argues that sustainability in planning practice is not a fixed concept but a fluid and negotiated discourse. This has significant implications for policy coherence, democratic accountability, and the legitimacy of planning decisions. By illuminating the interpretive flexibility of sustainability within planning decisions, the research provides an inroad to better governance for the practice-led sector and offers recommendations to improve outcomes for private and public sector planners in England.
A Passive Decarbonisation Approach for Hot-Arid Residential Structures: CFD Study of a Courtyard Earth-Air Heat Exchanger in Baghdad Assisted by Thermal Thrust
One of the biggest contributors to the world's energy consumption and carbon emissions is the building industry, especially in hot and dry countries where the yearly building energy use is dominated by the need for cooling. Passive cooling techniques that can lessen reliance on traditional air conditioning systems are desperately needed in Iraq due to the country's severe summer heat and ongoing electricity problems. The effectiveness of a thermal thrust-assisted courtyard earth-air heat exchanger (EAHE) as a passive cooling option for residential structures in Baghdad is examined in this study. Using ANSYS Fluent, a three-dimensional computational fluid dynamics (CFD) model was created to simulate heat transfer and airflow in an underground pipe system under typical local soil and climate conditions. The impacts of pipe diameter (0.2–0.4 m), pipe length (30–80 m), pipe burial depth (1–5 m), and inlet air velocity (1–5 m/s) were methodically assessed. According to simulation results, an ideal balance between thermal performance and pressure losses is achieved with a burial depth of roughly 3 m, pipe length of 60 m, and pipe diameter of 0.25 m. At an intake velocity of 1 m/s, the suggested system was able to reduce the air temperature by up to 20.75 °C during the hottest summer months. Passive airflow and cooling performance are greatly improved when thermal buoyancy (stack effect) is integrated with a courtyard-based EAHE. The findings show that the suggested solution can help hot, dry residential buildings lower their cooling energy consumption and related carbon emissions. These results show how low-carbon building design in Iraq and other climates can be supported by combining contemporary passive cooling technologies with traditional courtyard architecture.