Exploring long-term building stock strategies in Switzerland in line with IPCC carbon budgets

Stringent limits and reduction strategies paths on greenhouse gas (GHG) emissions are being defined at different levels for long-term temperature stabilization. Given the nearly linear relationship between warming and cumulative net emissions, a carbon budget approach is required to limit global warming, as stated by the IPCC. In this setting, the built environment, as a cross-sectorial and transnational area of activity, plays a crucial role in today's carbon emissions and future reduction potentials. Previous research showed the need for effective and aligned carbon-targets to support and guide all actors in the construction sector towards these challenging global goals. In this context, previous research compared top-down derived carbon budgets for the Swiss built environment with a preliminary estimation of future cumulative emissions of the sector. Findings showed the misalignment of current best practices and the significant magnitude of effort that would be required to comply with such objectives. Nevertheless, limitations in the preliminary work emerged, such as the lack of dynamicity of the parameters included in the model restricting the representativity of its results. The current paper brings further this previous work by integrating the dynamic evolution of the energy supply, the materials' production, and the renovation rate. Results are then presented by mean of a parallel coordinate interactive graph. This interactive component allows the parametric exploration of the compliance with limited global budgets by varying the input parameters. This way the influence of macro-level strategies to decarbonize the Swiss building stock can easily be visualized with reference to the IPCC carbon budgets. Ultimately, the available interactive tool might support policy makers in decisions taken at the building stock level

Using collaborative approaches to improve internal displacement data

The magnitude, severity and diversity of internal displacement situations cannot be understood – and much less be adequately responded to – without comprehensive and accurate data. Initiatives such as the GP20 Plan of Action offer examples of good practice for the way forward in this complex area

Deriving global carbon budgets for the Swiss built environment

In order to limit global warming, remaining carbon budgets have been defined by the IPCC in 2018. In this context translating global goals to local realities implicates a set of different challenges. Standardized methodologies of allocation can support a target-cascading process. On the other hand, local strategies and norms are not currently designed to directly respond to limited carbon budgets in a 2050 horizon. The life cycle assessment of buildings implicates an intricate cross-industry and cross-border carbon accounting. For these reasons, effective and aligned carbon targets are needed to support and guide all actors in the construction sector. This research aims at addressing these challenges by developing a new methodology of allocation of a global carbon budget at different scales using the Swiss built environment as a case study. This approach allows the assessment of current best practices in regards to limited carbon budgets. Results show misalignment of global goals with current practices at all levels and present the magnitude of effort that would be required to have a chance to limit global warming to 1.5°C

Effects of earthworms on the fungal community and microbial activity in root-adhering soil of Lantana camara during phytoextraction of lead

Earthworms are known to stimulate soil microorganisms and to enhance phytoextraction of metals. This study was designed to test the hypothesis that the positive effect of earthworms on phytoextraction performance results from the stimulation of soil fungi that are known to be tolerant to heavy metals in contaminated soils. It set out to assess the relationships between lead phytoextraction and the changes in soil fungi in response to earthworm activity. The experiment was performed in outdoor microcosms combining: earthworms (Pontoscolex corethrurus), Spanish Flag (Lantana camara) and soil spiked with 500 and 1000 mg Pb kg(-1). Cultivable fungi were enumerated using plate counts. PCR-DGGE analysis targeting the 28S rRNA gene was used to determine the structure of the fungal community. Total microbial activity was measured by fluorescein diacetate (FDA) hydrolysis assay. Plant Pb uptake by L. camara increased by about 2.5-fold in the presence of earthworms, regardless of the Pb concentration. This was significantly correlated with the increase in total microbial activity, abundance of cultivable fungi and richness index of the fungal community calculated from DGGE banding patterns. In the presence of earthworms, there was a significant positive correlation between microbial activity, plant biomass and plant Pb uptake. There was no correlation for the control without earthworms. These results provide evidence that interactions between earthworms and soil microorganisms have a positive effect on Pb-phytoextraction yield. The study of the ecological context of phytoremediation should be broadened by considering the interactions between plants, microorganisms and earthworms that affect heavy metal uptake by plants

Integrating hourly life-cycle energy and carbon emissions of energy supply in buildings

Huge amount of energy resources greenhouse gas (GHG) emissions is devoted to the built environment. Therefore, an accurate assessment method of these indicators is compulsory. To take advantage of the temporal variation in the primary energy use and associated GHG emissions of the energy supply, we propose two ways of integrating hourly life-cycle conversion factors in building energy systems. First, to appraise the energy system design, we developed a versatile modelling and performance assessment framework using a multi-criteria approach. The simulated performances of possible energy systems are compared, and help designers systematically choose appropriate energy production and storage systems. Second, for the operation of the building, we propose an energy management procedure (EMP) that always feeds in the energy source with the least global warming potential (GWP). These two developments are tested on a case study consisting in an architectural project that should respect the 2000 W society targets. The running conditions of several energy systems are simulated and compared. The most promising scenario is identified. Compared to traditional methods, the assessment framework has a promising future but the GWP-based energy management procedure offers, in the context of the case study, limited GHG emissions mitigation at very high primary energy cost

Improvement of the phytoremediation efficiency of Neyraudia reynaudiana for lead-zinc mine-contaminated soil under the interactive effect of earthworms and EDTA

Abstract Slow plant growth, low biomass, and low bioavailability of heavy metals in soil are important factors that limit remediation efficiencies. This study adopted a pot cultivation method to evaluate the phytoremediation efficiency of Neyraudia reynaudiana, planted in contaminated soil from a lead-zinc mining area. The soil was inoculated with earthworms (Eisenia fetida), and mixed with the chelating agent ethylenediaminetetraacetic acid (EDTA) one month after planting. The addition of earthworms significantly increased the aboveground biomass of N. reynaudiana and activated heavy metals in the soil, thus facilitating heavy metal uptake by N. reynaudiana. The addition of EDTA significantly increased the incorporation and transport of heavy metals, reduced the uptake of heavy metals by the plant cell wall, and increased the proportions of cellular soluble constituents. Especially with regard to lead, inoculation with earthworms and EDTA application significantly promoted the accumulation efficiency of N. reynaudiana, increasing it 7.1-16.9-fold compared to the control treatment without earthworms and EDTA, and 1.5-2.3-fold compared to a treatment that only used EDTA

Influence of earthworm bioturbation on metals phytoavailability and human gastric bioaccessibility.

International audienceAt the global scale, urban agriculture is increasingly developing in cities due to demographic growth and sustainable food concerns. But, urban soils are frequently polluted with metals. In urban gardens, organic matter is also commonly added both to valorize organic household waste and to promote biophysicochemical fertility. As earthworms promote the decomposition and the recycling of soil organic matter, they can also influence the biogeochemical cycle of metals in urban polluted soils. In order to produce safe vegetables in urban areas, it is crucial to highlight the mechanisms involved in complex soil-earthworm-plant ecosystems. An experiment was set up to examine these relationships using lettuce cultivated in controlled conditions with RHIZOtest® devices. Thanks to the RHIZOtest® devices, metal transfer and bioaccessibility were for the first time compared for urban polluted soil without (1-urban soil polluted with Pb, Cd, Cu, and Zn: essential or toxic metals currently found in environment, SNB) and with bioturbation (2-this metal-polluted soil subjected to earthworm bioturbation, SB) and earthworm casts (3-earthworm casts produced in this polluted soil and naturally enriched in organic matter and microorganisms, T). Metal concentration, phytoavailability, and human gastric bioaccessibility were determined in the different samples. Results showed that earthworm bioturbation increased the phytoavailability of all the metals. For the experimental condition SB, the phytoavailability of metals was increased up to 75% compared to SNB. In addition, surprisingly, metal phytoavailability was always superior in SB compared to earthworm casts (T). Moreover, earthworms led to an increase in Zn gastric bioaccessibility up to 10% in the soils in the same way as for phytoavailability, meaning Zn bioaccessibility in SB > T > SNB, whereas it remained unchanged in the lettuces. These data are important to promote sustainable agriculture activities in urban areas; actually, databases concerning different experimental conditions are needed to develop decision support tools