2,673 research outputs found

    On the relation of thermal comfort practice and the energy performance gap

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    The ambivalence of personal control over indoor climate - How much personal control is adequate?

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    Literature sets personal control over indoor environmental conditions in relation to the gap between predicted and actual energy use, the gap between predicted and observed user satisfaction, and health aspects. A focus on building energy performance often leads to the proposal of more automated and less occupant control of the indoor environment. However, a high degree of personal control is desirable because research shows that a low degree (or no) personal control highly correlates with indoor environmental dissatisfaction and sick building syndrome symptoms. These two tendencies seem contradictory and optimisation almost impossible. Based on current efficiency classes describing the effect of room automation systems on building energy use during operation, fundamental thoughts related to thermophysiology and control, recent laboratory experiments, important lessons learnt from post-occupancy studies, and documented conceptual frameworks on the level of control perceived, we discuss the ambivalence of personal control and how much personal control is adequate. Often-proposed solutions ranging from fully automated controls, over manual controls to dummy controls are discussed according to their effect on a) building energy use during operation and b) occupants perceived control. The discussion points to the importance of adequate personal control. In order to meet the goals for nearly zero energy buildings and for a human-centric design, there is the need to establish design procedures for adequate personal control as part of the design process

    The potential of the adaptive thermal comfort concept in longterm actively conditioned buildings for improved energy performance and user wellbeing

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    Technological progress in conditioning practice combined with prevailing thermal comfort criteria, created stable, tightly controlled indoor temperature bands. Research shows indoor temperatures to be increasing in the heating period, leading to higher building energy use than planned. Field studies provide proof that occupants not in control of their indoor climate are more dissatisfied and report problems in wellbeing. Widening temperature bands could be an effective measure leading to energy conservation, increasing satisfaction and, as shown recently, helping to mitigate health problems related to our way of life. The adaptive approach to thermal comfort postulates that people\u27s thermal comfort perception adapts to the indoor and outdoor climatic conditions they normally experience. However, according to standards, the adaptive model is applicable only to passively conditioned (free-running) buildings, even though the adaptive principles may well apply also to actively conditioned buildings. Our review found studies demonstrating positive health effects and energy conservation potential in permanently or seasonally conditioned buildings. On this basis, the potential of the adaptive approach and translations into concrete design or operation solutions for actively conditioned buildings are discussed in this paper. We conclude that the adaptive concept offers a potential for indoor climate control in actively conditioned buildings in the temperate and cold climates

    Carving Out Legacy Assets: A Successful Tool for Bank Restructuring?

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    Beginning with the proposal by Enria (2017), the paper discusses the scope for successful bank restructuring through a carveout of impaired assets and a transfer of these assets to a government-sponsored asset management company. The paper argues that the success of such an operation requires a use of public funds, either outright or through contingent commitments. Clawback provisions are problematic because they create contingent liabilities that merely shift risks from the assets side to the liabilities sides of banks’ balance sheets. The paper distinguishes between asset impairments coming from considerations of prospective returns and asset impairments coming from frictions in the markets in which these assets are traded. It also distinguishes between threats to bank solvency and threats to bank funding/liquidity. In each case, the success of bank restructuring from asset carveouts depends on the extent to which threats to the bank’s solvency is eliminated. If these threats concern bank funding and asset liquidations at depressed prices, public funds may eventually not be needed. If threats to bank solvency come from nonperforming loans, taxpayer support may be essential. The notion of “real economic value” as the price at which assets should be transferred is problematic and leaves ample room for hidden subsidies. The success of restructuring of the individual bank may itself come at a risk to financial stability as the preservation of existing capacities maintains competitive pressure and depresses bank profitability. Additional risks may come from the burden on the government’s fiscal stance

    The ambivalence of personal control over indoor climate - how much personal control is adequate?

    Get PDF
    Literature sets personal control over indoor environmental conditions in relation to the gap between predicted and actual energy use, the gap between predicted and observed user satisfaction, and health aspects. A focus on building energy performance often leads to the proposal of more automated and less occupant control of the indoor environment. However, a high degree of personal control is desirable because research shows that a low degree (or no) personal control highly correlates with indoor environmental dissatisfaction and sick building syndrome symptoms. These two tendencies seem contradictory and optimisation almost impossible. Based on current efficiency classes describing the effect of room automation systems on building energy use during operation, fundamental thoughts related to thermophysiology and control, recent laboratory experiments, important lessons learnt from post-occupancy studies, and documented conceptual frameworks on the level of control perceived, we discuss the ambivalence of personal control and how much personal control is adequate. Often-proposed solutions ranging from fully automated controls, over manual controls to dummy controls are discussed according to their effect on a) building energy use during operation and b) occupants perceived control. The discussion points to the importance of adequate personal control. In order to meet the goals for nearly zero energy buildings and for a human-centric design, there is the need to establish design procedures for adequate personal control as part of the design process

    Diagnostic performance of the specific uptake size index for semi-quantitative analysis of I-123-FP-CIT SPECT: harmonized multi-center research setting versus typical clinical single-camera setting

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    Introduction: The specific uptake size index (SUSI) of striatal FP-CIT uptake is independent of spatial resolution in the SPECT image, in contrast to the specific binding ratio (SBR). This suggests that the SUSI is particularly appropriate for multi-site/multi-camera settings in which camera-specific effects increase inter-subject variability of spatial resolution. However, the SUSI is sensitive to inter-subject variability of striatum size. Furthermore, it might be more sensitive to errors of the estimate of non-displaceable FP-CIT binding. This study compared SUSI and SBR in the multi-site/multi-camera (MULTI) setting of a prospective multi-center study and in a mono-site/mono-camera (MONO) setting representative of clinical routine. Methods: The MULTI setting included patients with Parkinson’s disease (PD, n = 438) and healthy controls (n = 207) from the Parkinson Progression Marker Initiative. The MONO setting included 122 patients from routine clinical patient care in whom FP-CIT SPECT had been performed with the same double-head SPECT system according to the same acquisition and reconstruction protocol. Patients were categorized as “neurodegenerative” (n = 84) or “non-neurodegenerative” (n = 38) based on follow-up data. FP-CIT SPECTs were stereotactically normalized to MNI space. SUSI and SBR were computed for caudate, putamen, and whole striatum using unilateral ROIs predefined in MNI space. SUSI analysis was repeated in native patient space in the MONO setting. The area (AUC) under the ROC curve for identification of PD/“neurodegenerative” cases was used as performance measure. Results: In both settings, the highest AUC was achieved by the putamen (minimum over both hemispheres), independent of the semi-quantitative method (SUSI or SBR). The putaminal SUSI provided slightly better performance with ROI analysis in MNI space compared to patient space (AUC = 0.969 vs. 0.961, p = 0.129). The SUSI (computed in MNI space) performed slightly better than the SBR in the MULTI setting (AUC = 0.993 vs. 0.991, p = 0. 207) and slightly worse in the MONO setting (AUC = 0.969 vs. AUC = 0.976, p = 0.259). There was a trend toward larger AUC difference between SUSI and SBR in the MULTI setting compared to the MONO setting (p = 0.073). Variability of voxel intensity in the reference region was larger in misclassified cases compared to correctly classified cases for both SUSI and SBR (MULTI setting: p = 0.007 and p = 0.012, respectively). Conclusions: The SUSI is particularly useful in MULTI settings. SPECT images should be stereotactically normalized prior to SUSI analysis. The putaminal SUSI provides better diagnostic performance than the SUSI of the whole striatum. Errors of the estimate of non-displaceable count density in the reference region can cause misclassification by both SUSI and SBR, particularly in borderline cases. These cases might be identified by visual checking FP-CIT uptake in the reference region for particularly high variability

    Evidence for a dynamic phase transition in [Co/Pt]_3 magnetic multilayers

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    A dynamic phase transition (DPT) with respect to the period P of an applied alternating magnetic field has been observed previously in numerical simulations of magnetic systems. However, experimental evidence for this DPT has thus far been limited to qualitative observations of hysteresis loop collapse in studies of hysteresis loop area scaling. Here, we present significantly stronger evidence for the experimental observation of this DPT, in a [Co(4 A)/Pt(7 A)]_3-multilayer system with strong perpendicular anisotropy. We applied an out-of-plane, time-varying (sawtooth) field to the [Co/Pt]_3 multilayer, in the presence of a small additional constant field, H_b. We then measured the resulting out-of-plane magnetization time series to produce nonequilibrium phase diagrams (NEPDs) of the cycle-averaged magnetization, Q, and its variance, Var(Q), as functions of P and H_b. The experimental NEPDs are found to strongly resemble those calculated from simulations of a kinetic Ising model under analagous conditions. The similarity of the experimental and simulated NEPDs, in particular the presence of a localized peak in the variance Var(Q) in the experimental results, constitutes strong evidence for the presence of this DPT in our magnetic multilayer samples. Technical challenges related to the hysteretic nature and response time of the electromagnet used to generate the time-varying applied field precluded us from extracting meaningful critical scaling exponents from the current data. However, based on our results, we propose refinements to the experimental procedure which could potentially enable the determination of critical exponents in the future.Comment: substantial revision; 26 pages, 9 figures; to appear in Phys. Rev.
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