Investigating an Adequate Level of Modelling for Energy Analysis of Domestic Buildings

This paper investigates what level of modelling is required to appropriately support energy analysis of domestic buildings. The paper analyses the effect of simplications made in thermal zoning and internal loads scheduling through a case study of a UK domestic building. The case study provides quantified effects of common simplications made in practice on the accuracy of energy predictions by making simplications in the model incrementally and estimating the effect of individual simplications on electricity and heating demand predictions

Investigating an adequate level of modelling for retrofit decision-making: A case study of a British semi-detached house

This paper investigates what level of modelling (zoning or internal load scheduling) is required to support heating related retrofit decision-making. First, this paper tests the effect of thermal zoning by incrementally reducing the number of thermal zones from modelling every room as a separate zone to modelling the house as a single zone. Second, this paper examines the influence of internal load schedules (occupancy, lighting and equipment schedules) on prediction accuracy. Actual internal load schedules were derived from the smart meter data of 666 households collected by the Customer-Led Network Revolution project. Cluster analysis was applied to extract a set of prototypical schedules to capture major variations across all households. Last, this paper evaluates the effects of the zoning and internal load scheduling modelling assumptions in the context of thermal retrofit decision-making. For the specific parameters studied and the specific building design, the use of different zoning strategies and different internal load schedules yielded the same ranking of top retrofit options. For the specific climate and the baseline assumptions for the retrofits, different cluster schedules resulted in different magnitudes of energy savings, but the ranking of top retrofit options was not impacted by the choice of household internal load schedules. However, the actual internal load schedules affected the energy-saving potentials achievable by the same set of retrofit options. The case study highlights that the optimal set of retrofit options selected given the specific physical characteristics of a house is the same regardless of differences in the input of internal load schedules. However, it was found that energy-saving potentials achievable by the same retrofit option substantially vary according to the actual internal load schedules. This finding implies that energy retrofit policies can be tailored to target certain groups of households selected by clustering their actual energy use profiles to cost-effectively maximise energy savings from the domestic sector

Analysis Methodology for Large Organizations' Investments in Energy Retrofit of Buildings

This paper presents a formal methodology that supports large organizations' investments in energy retrofit of buildings. The methodology is a scalable modeling approach based on normative models and Bayesian calibration. Normative models are a light- weight quasi-steady state energy models, which makes them scalable to large sets of buildings due to highly enhanced modeling efficiency. Then, Bayesian approach calibrates normative models such that calibrated models quantify uncertainty in the model while representing a building as operated. Calibrated models can further incorporate additional uncertainty from ECMs, and provide information about underperforming risks of ECMs. This paper illustrates the proposed retrofit analysis process through a case study, and demonstrates its feasibility to support large-scale retrofit decisions under uncertainty in the context of the ESCO industry

Magnetic interactions in transition metal doped ZnO : An abinitio study

We calculate the nature of magnetic interactions in transition-metal doped ZnO using the local spin density approximation and LSDA+\textit{U} method of density functional theory. We investigate the following four cases: (i) single transition metal ion types (Cr, Mn, Fe, Co, Ni and Cu) substituted at Zn sites, (ii) substitutional magnetic transition metal ions combined with additional Cu and Li dopants, (iii) substitutional magnetic transition metal ions combined with oxygen vacancies and (iv) pairs of magnetic ion types (Co and Fe, Co and Mn, etc.). Extensive convergence tests indicate that the calculated magnetic ground state is unusually sensitive to the k-point mesh and energy cut-off, the details of the geometry optimizations and the choice of the exchange-correlation functional. We find that ferromagnetic coupling is sometimes favorable for single type substitutional transition metal ions within the local spin density approximation. However, the nature of magnetic interactions changes when correlations on the transition-metal ion are treated within the more realistic LSDA + \textit{U} method, often disfavoring the ferromagnetic state. The magnetic configuration is sensitive to the detailed arrangement of the ions and the amount of lattice relaxation, except in the case of oxygen vacancies when an antiferromagnetic state is always favored.Comment: 11 pages, 17 figure

Direct measurement of the intermolecular forces confining a single molecule in an entangled polymer solution

We use optical tweezers to directly measure the intermolecular forces acting on a single polymer imposed by surrounding entangled polymers (115 kbp DNA, 1 mg/ml). A tube-like confining field was measured in accord with the key assumption of reptation models. A time-dependent harmonic potential opposed transverse displacement, in accord with recent simulation findings. A tube radius of 0.8 microns was determined, close to the predicted value (0.5 microns). Three relaxation modes (~0.4, 5 and 30 s) were measured following transverse displacement, consistent with predicted relaxation mechanisms.Comment: 11 pages, 3 figure

Dirty Black Holes and Hairy Black Holes

An approach based on considerations of the non-classical energy momentum tensor outside the event horizon of a black hole provides additional physical insight into the nature of discrete quantum hair on black holes and its effect on black hole temperature. Our analysis both extends previous work based on the Euclidean action techniques, and corrects an omission in that work. We also raise several issues related to the effects of instantons on black hole thermodynamics and the relation between these effects and results in two dimensional quantum field theory.Comment: 13 pages, Latex, submitted to Physical Review Letter

Changes in inorganic aerosol compositions over the Yellow Sea area from impact of Chinese emissions mitigation

Substantial mitigation of air pollutants emissions has been performed since 2013 around Beijing, and changes in the atmospheric characteristics have been expected over the downstream area of Beijing. In this study, both WRF-Chem simulation and on-site measurements were utilized for the Baengnyeong (island) supersite, one of the representative regional background sites located in the Yellow Sea, the entrance area of the long-range transport process in Korea. The changes in the chemical compositions of inorganic aerosols were examined for spring-time during the Chinese emission mitigation period from 2014 to 2016. The measured ratio of ionic species to PM2.5 at the Baengnyeong supersite showed changes in aerosol inorganic chemical compositions from sulfate in 2014 to nitrate in 2015–2016. The modeling results also showed that nitrate was low in 2014 and significantly increased in 2015 and 2016, and the acidic aerosol condition had also changed toward a more neutralized status in both the simulation and the observations. The WRF-Chem modeling study further indicated that the sulfur was not neutralized in 2014. However, in 2015 and 2016, SO2 was more sufficiently neutralized as sulfur emissions were substantially reduced in China, while at the same time nitrate had begun to increase in such a ‘SO2–poor’ condition in Beijing area in China, and thus approaching more enhanced neutralization over the Yellow Sea area. The causes of the higher nitrate based on the modeled characteristics of the ammonia-sulfate-nitrate aerosol formation in response to the SO2 emissions reduction in China are also discussed in this paper