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The design and assessment of net-zero buildings commonly focus exclusively on the operational phase, ignoring the embodied environmental impacts over the building life cycle. An analysis is presented on the consequences of integrating embodied impacts into the assessment of the environmental advantageousness of net-zero concepts. Fundamental issues needing consideration in the design process - based on the evaluation of primary energy use and related greenhouse gas emissions - are examined by comparing three net-zero building design and assessment cases: (1) no embodied impacts included, net balance limited to the operation stage only; (2) embodied impacts included but evaluated separately from the operation stage; and (3) embodied impacts included with the operation stage in a life cycle approach. A review of recent developments in research, standardization activities and design practice and the presentation of a case study of a residential building in Norway highlight the critical importance of performance indicator definitions and system boundaries. A practical checklist is presented to guide the process of incorporating embodied impacts across the building life cycle phases in net-zero design. Its implications are considered on overall environmental impact assessment of buildings. Research and development challenges, as well as recommendations for designers and other stakeholders, are identified.

The presented article will describe an 'effect-cause' model for the purpose of simulating the energy consumption of DC fed light rail vehicles. The model will assess the advantages of hybrid vehicles in terms of energy consumption, network power and voltage variations, line current and losses; and will help sizing and designing a supercapacitor based energy storage system (ESS) for both on-board, and stationary applications. The proposed modeling needs to allow the ESS sizing according to the objective that needs to be achieved, being braking energy recovery, voltage drop compensation and peak power shaving the most common goals of ESS use in hybrid vehicles. The needed power and energy levels will vary in function of the vehicle features and the driving cycle followed. This all can be determined by the quasi-static simulation tool to ease the design process. Another objective of the modeling tool is to evaluate the behaviour of the vehicle power flow controller, which manages the power from/to the ESS in function of the state of several variables.

Abstract The implementation of energy efficiency measures is an effective way to gain energy savings in the Italian residential sector. This paper assesses the embodied energy impact related to the envelope insulation and evaluates the energy and carbon payback of the efficiency measures. The proposed method consists of (1) an estimation of the baseline operational energy consumption, (2) simulations of realistic retrofit solutions and, (3) the assessment of the ‘retrofitting’ embodied energy and the energy and carbon payback time calculation. The payback is based on the comparison between the saved operational energy and the embodied energy of the materials selected for insulation. Ten Italian cities are analysed, and the results show a deep dependence on the climate zone. In Northern Italian cities, envelope insulation gains relevance as the energy and carbon payback periods are shorter, about 3 years against the 84 years for the Southern city of Palermo. The optimal thickness is estimated for the city of Milan considering the building’s typology, the insulation materials, and the energy payback. This study shows how the total energy savings can be used as a criterion to obtain design indications.

Urban environments provide opportunities for greater resource efficiency and the fostering of urban ecosystems. Brownfield areas are a typical example of underused land resources. Brownfield redevelopment projects that include green infrastructure allow for further ecosystems to be accommodated in urban environments. Green infrastructure also deliver important urban ecosystem services (UES) to local residents, which can greatly contribute to improving quality of life in cities. In this case study, we quantify and assess the economic value of five UES for a brownfield redevelopment project in Antwerp, Belgium. The assessment is carried out using the “Nature Value Explorer” modelling tool. The case includes three types of green infrastructure (green corridor,infiltration gullies and green roofs) primarily intended to connect nature reserves on the urban periphery and to avoid surface runoff. The green infrastructure also provides air filtration, climate regulation, carbon sequestration and recreation ecosystem services. The value of recreation far exceeds other values, including the value of avoided runoff. The case study raises crucial questions as to whether existing UES valuation approaches adequately account for the range of UES provided and whether such approaches can be improved to achieve more accurate and reliable value estimates in future analyses.

Active Magnetic Regeneration (AMR) is a configuration that allows magnetic refrigeration to be suitable also for room temperature applications. This work is intended to detect, by means of a 1-D numerical model, the influence on the regenerator performances of the working condition ambient temperature (T(CURIE) +/- 20 K) and of the operating parameters fluid mass flow rate (utilization factor 0.5 divided by 3.5) and cycle frequency (0.1 divided by 0.6 Hz). Simulations show that, tuning the fluid mass flow rate, a gadolinium AMR (395 g, f = 0.25 Hz, Delta B = 1.7 T) can reach a maximum cooling capacity of 130 W and a 40 W cooling power over a temperature span of 30 K. A COP of 5 can also be achieved with a temperature span of 30 K and a cooling power of 35 W. Frequency has a weak influence on the AMR's COP, while the ambient temperature is crucial. The system loses the 60% of cooling capacity if the ambient temperature is 20 K away from the material Curie temperature.

Abstract In order to develop a deeper understanding of the behaviour of commercial automotive lithium-ion pouch cells under short-circuiting conditions, two scenarios were experimentally investigated and compared. Firstly, experiments were conducted by internally shorting 15 Ah cells by full nail penetration using three different nail materials; copper, steel and plastic. A second set of experiments involved externally shorting the cell tabs using an external circuit with a range of resistance values. In both scenarios the cell electrical and thermal response were determined by the shorting resistance. In the case of nail penetration there was a clear distinction between the outcome of the conducting and non-conducting nails, although the outcome using conducting nails suffered from poor reproducibility. The poor reproducibility was attributed to the variation in the contact resistance between the nail and the cell layers. Correlating the outcome of both tests can be used to estimate the shorting resistance and construct the current profile during nail penetration test.

The technological development of preparing bio-oil from low-temperature hydrothermal conversion of agricultural and forestry waste has positive significance for alleviating the shortage of oil energy supply and reducing environmental pollution. This paper selects typical oxides (Al2O3, CeO2, MgO, SiO2, TiO2, and ZnO) as catalysts to set up a low-temperature (220 °C) hydrothermal conversion process of cotton stalk containing pretreatment processes including chopping. For moderate amplification estimation, lab-scale experimental data is used as a benchmark for calculation, and the functional unit for this study is set to be a 1 kg bio-oil product. The results suggest that the cerium dioxide-involved process with the highest bio-oil yield and highest synthetic consumption, and the silica-involved process with the lowest bio-oil yield, caused the highest environmental impact, resulting in greenhouse gas (GHG) emissions of 67.729 kg CO2e/kg and 60.001 kg CO2e/kg, respectively. It indicates that catalysts need to consider the balance between synthetic consumption and catalytic performance. Magnifying lab-scale data to an industrial scale using scale-up frameworks introduces a low model uncertainty, as the practical value had little effect on the overall evaluation results. However, existing equipment data should be used to reduce the uncertainty of the model itself. The environmental sustainability of bio-oil production by low-temperature hydrothermal liquefaction still needs to be improved, especially by catalyst recovery and bio-oil yield improvement.

In this article we present various issues that need careful design for the successful implementation of OFDMA-based multihop cellular networks which need incorporation of relay terminals. The first issue we present is synchronization. We show that it is not a problematic issue for infrastructure-based relaying, where the relay is deployed by a system operator at strategic points in the cell. Second, we focus on the advantage of adaptive relaying and provide a frame structure to enable adaptive relaying in a cellular network operating according to the IEEE 802.16e standard. The third issue we present is related to hardware implementation aspects. Hardware performance and resource usage analysis will show that cooperative diversity schemes increase hardware resource usage and power/energy consumption at mobile terminals. The last issue we present is within the context of link layer ARQ, where we propose a novel retransmission method, named local retransmission-ARQ (LR-ARQ), which is designed to take advantage of the multihop nature of the cellular network. Practically, we show that LR-ARQ improves performance with respect to its single-hop counterpart in terms of cell latency, goodput, and throughput.