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Abstract Increased extreme heat events draw attention to the potential of urban nature as a heat adaptation strategy for cities. This is reflected in multiple scientific perspective pieces, policy documents and science media publications advocating for urban greening as a cooling approach. Although attention to the dangers of heat and the benefits of urban nature is welcomed, it is vital that nature-based approaches to cooling are underpinned by diverse knowledge and a sound understanding of what nature in cities can and cannot do. We explain why an evidence-driven and cautious approach to heat adaptation through urban greening is so important, and propose three actions that urban actors can take towards effective and equitable long-term cooling through urban nature: enabling dialogue between different sectors with multiple remits; including diverse knowledge systems in planning and governance processes; and investing in long-term stewardship for the climatological and societal conditions of the coming decades. Policy and practice recommendation • Create fora for dialogue between governments, residents, civil society and developers from planning stage for green cooling; • Cooling through nature must be driven by expertise spanning diverse knowledge systems, combined with local knowledge and community needs; • Consider future climates and stewardship when planning urban cooling via nature. Science highlights • Understanding link between urban thermal environment and nature is an inter- and transdisciplinary task; • Critical need for evidence of how greening reduces heat impacts across different social and cultural contexts; • Evidence of how species perform under future climates required for stewardship of urban nature.

Current adaptation theory tends to consider individual buildings or the city level, which cannot address decisions related to masterplan developments on large brownfield sites. This paper investigates the drivers for building demolition or retention and adaptation decisions at the masterplan scale. Expert interviews and three case studies are used to explore how and why decisions to demolish, or to retain and adapt, are made at this scale. The research compared three different geopolitical contexts: Cambridge in the UK; Eindhoven in the Netherlands; and Sydney in Australia. Additional factors and complexities that should be considered at the masterplan scale are identified. The theoretical underpinnings of urban development processes are used to explain these complexities in relation to four existing models and demonstrate that no one model is adequate to describe the interactions. With increasing awareness of climate change impacts, it is critical that demolition decisions on masterplan developments are reviewed in the light of retaining carbon as well as heritage. Practice relevance This research demonstrates the different and specific concerns applying to demolition and retention on masterplan scale sites compared with the individual building scale. Although the evidence shows that decisions are context specific, the criteria as identified and categorised within this research offer a useful tool for stakeholders when establishing their priorities and approaches to decisions to demolish or retain and adapt within a masterplan context. This should help to avoid contested decisions and can help community groups hoping to have an influence over the long-term decisions, as well as developers looking to retain good relationships with the local community. The identified criteria can support planners and local authorities responsible for approving masterplan developments to better understand the factors relevant to each decision, including the importance of retaining flexibility throughout to enable response to changing circumstances.

The carbon embodied in buildings is an important proportion of our emissions and needs to be radically reduced in order to support climate change mitigation. The highest proportion of embodied carbon is usually emitted during the product stage, and within the structural elements. Therefore, reducing the carbon embodied in the structural materials is likely to have a major impact. In most buildings, the majority of embodied carbon comes from steel and concrete. But although there are now hundreds of registered Environmental Product Declarations (EPD) for cements and concretes, there has been very limited independent published information comparing the embodied carbon of different concrete mixes and raw materials. This lack of comparative data limits the potential to make appropriate decisions at early design stages leading to low carbon buildings. The authors have recently conducted a review of verified EPD for concrete mixes and for concrete’s key constituents, including cement, identifying the range of carbon coefficients. This paper provides guidance on making use of the coefficient ranges provided in that research: to support the verification of EPD for concrete and its raw materials; in material selection; in assessing building level embodied carbon; in benchmarking; and in the setting of reduction targets.

Reducing energy and associated carbon emissions from the built environment is fundamental to meeting our climate goals. Retrofit of existing buildings is therefore a key strategy. Heritage buildings present particular challenges for retrofitting because of their traditional construction and need to retain historic values. Replacing windows is often a critical element of a low energy retrofit, but for heritage buildings this can be problematic. This paper explores the values that residents invest in their windows, and the opportunities and challenges for retrofitting heritage fenestration. Qualitative data from 16 case studies of heritage buildings in the county of Cumbria, UK, is examined to gain a greater understanding of residents’ views, which are often neglected in policy approaches. Findings show that residents, in both designated and undesignated heritage buildings, value their original windows and appreciate the thermal benefits of traditional features such as shutters or curtains. Residents generally considered complete window replacement unacceptable but were more positive about options such as secondary glazing or internal shutters. Challenges, including costs and finding skilled tradespeople to produce shutters or undertake restoration were identified. The paper concludes with the implications of these findings for retrofitting heritage fenestration for carbon reduction.

Abstract Galactic cosmic radiation (GCR) composed of high-energy, heavy particles (HZE) poses potentially serious hazards to long-duration crewed missions in deep space beyond earth’s magnetosphere, including planned missions to Mars. Chronic effects of GCR exposure on brain structure and cognitive function are poorly understood, thereby limiting risk reduction and mitigation strategies to protect against sequelae from exposure during and after deep-space travel. Given the selective vulnerability of the hippocampus to neurotoxic insult and the importance of this brain region to learning and memory, we hypothesized that GCR-relevant HZE exposure may induce long-term alterations in adult hippocampal neurogenesis, synaptic plasticity, and hippocampal-dependent learning and memory. To test this hypothesis, we irradiated 3-month-old male and female mice with a single, whole-body dose of 10, 50, or 100 cGy 56Fe ions (600 MeV, 181 keV/μm) at Brookhaven National Laboratory. Our data reveal complex, dynamic, time-dependent effects of HZE exposure on the hippocampus. Two months post exposure, neurogenesis, synaptic plasticity and learning were impaired compared to sham-irradiated, age-matched controls. By six months post-exposure, deficits in spatial learning were absent in irradiated mice, and synaptic potentiation was enhanced. Enhanced performance in spatial learning and facilitation of synaptic plasticity in irradiated mice persisted 12 months post-exposure, concomitant with a dramatic rebound in adult-born neurons. Synaptic plasticity and spatial learning remained enhanced 20 months post-exposure, indicating a life-long influence on plasticity and cognition from a single exposure to HZE in young adulthood. These findings suggest that GCR-exposure can persistently alter brain health and cognitive function during and after long-duration travel in deep space.

This paper is the second output of a project that examines the embodied greenhouse gas emissions (‘embodied carbon’) from the use of concrete in buildings. In the current absence of either regulation or widespread industry practice in quantified carbon assessment, it seems likely that messaging will play a powerful role in influencing designers’ perceptions and decisions. Using the UK as a case study, this paper considers the current messages about the carbon implications of concrete in buildings from professional institutions and the cement and concrete trade body. Three mechanisms through which it is claimed carbon emissions are significantly reduced are identified: thermal mass, durability, and carbonation. By assessing each of these in turn against the available scientific literature, it is shown that they are likely to have a far more limited effect on the total impacts than suggested. More accuracy is needed from trade organisations if real carbon reductions are to be achieved. 'Practice relevance' In the current absence of whole life carbon assessment for buildings, messaging about the carbon impacts of different materials is likely to have a strong impact. The paper recommends that the cement and concrete industry should be more accurate with the messages it is sharing. In particular the claims that thermal mass, durability and carbonation are effective mechanisms, which suggest concrete is a low carbon option, should be reconsidered. Meanwhile designers should use the excellent advice being produced by the professional institutions and undertake whole-life carbon calculations to ensure the lowest carbon design. These should include a best estimate of future trends towards warming climates and decarbonisation of electricity, but should also recognise the importance of the immediate effects of the emissions from construction materials. There is also a key role for policymakers in legislating to make the measurement of embodied impacts of buildings mandatory.

What are the opportunities and challenges for upscaling the energy retrofit of heritage buildings? Heritage buildings comprise approximately 20% of the UK building stock and are challenging to retrofit sensitively because of their heritage values and traditional construction. These buildings may therefore be unconducive to standard retrofitting approaches. Twelve case studies in the UK are examined. Three key findings are presented together with their implications for upscaling retrofit. First, heritage residents are found to engage in positive energy behaviours, which differ from standard assumptions and have a significant impact on energy demand. Second, standard energy models are shown to considerably overestimate the energy use within heritage buildings, failing to accurately portray both traditional construction and residents’ behaviours. Third, residents consider many common retrofits, such as replacement windows and wall insulation, to be unacceptable to their heritage values. A number of more acceptable and less invasive ‘soft retrofits’ were modelled and shown to have significant potential for reducing energy and carbon. Therefore, a more holistic approach to heritage building retrofitting needs to be taken, treating the complex interrelationship of buildings and their users as a system, and expanding notions of retrofitting to include soft retrofits and user behaviour. 'Policy relevance' This research identified the importance of appropriately retrofitting heritage buildings, which include around 20% of the UK building stock. Standard solutions such as wall insulation and window replacement are unlikely to be enacted by most heritage residents because they are not acceptable to their heritage values, suggesting the need to prioritise other measures. Standard energy models such as Reduced data Standard Assessment Procedure (RdSAP) were found to be inaccurate for heritage buildings, overestimating energy use by both buildings and occupants, and should not be used to inform retrofit decisions for these buildings. Notions of retrofit should be expanded beyond fabric alterations to include behavioural changes and non-technical measures, including thermal curtains or shutters, which are more acceptable to residents and therefore more likely to be actioned. The potential exists to upscale retrofitting in heritage buildings, but approaches must consider specific user behaviour and view buildings and their occupants as interconnected systems.

Cement is responsible for 7% of global greenhouse gas emissions, and is predicted to grow with increasing development. The majority is used in concrete, globally the most common material in buildings. Reducing emissions from the use of cement and concrete in buildings is therefore critical in order to limit global warming. However there remain multiple gaps in knowledge about the extent of these emissions. This paper is the first output of a project that aims to understand better the embodied impacts from the use of concrete in buildings, in order to inform and advise policy-makers and industry practitioners, and to provide clear evidence for the path forwards. In order to do so, the project collates, analyses and critiques evidence from multiple sources, reported over three papers. This first paper focuses on the basic data on materials impacts. Over the last few years, several hundred individual Environmental Product Declarations (EPD) have been published for cements, aggregates and concrete mixes, but no publication offers a comparison or overview. Therefore understanding the range and opportunities for the reduction of impacts from concrete remains very limited. This paper provides the first detailed analysis of the EPD for concrete and its constituents. 'Practice relevance' The graphs developed in this paper can be used by designers and manufacturers to understand and reduce the impacts from cement and concrete. Designers will have a better idea of an appropriate coefficient to use at the early design stage before more details are known. As the design progresses, they will be able to use the graphs presented to choose a lower impact cement or concrete with the same performance, as well as to check the likely validity of any EPD. The graphs also provide an incentive to manufacturers to reduce impacts, since they will now be able to compare their products with others. Finally, for those involved in producing EPD, the paper demonstrates the necessity of more detailed rules for consistency, and in the meantime the necessity of full transparency in EPD reports.