A comparative study of benchmarking approaches for non-domestic buildings: Part 1 – Top-down approach

Benchmarking plays an important role in improving energy efficiency of non-domestic buildings. A review of energy benchmarks that underpin the UK’s Display Energy Certificate (DEC) scheme have prompted necessities to explore the benefits and limitations of using various methods to derive energy benchmarks. The existing methods were reviewed and grouped into top-down and bottom-up approaches based on the granularity of the data used. In the study, two top-down methods, descriptive statistics and artificial neural networks (ANN), were explored for the purpose of benchmarking energy performances of schools. The results were used to understand the benefits of using these benchmarks for assessing energy efficiency of buildings and the limitations that affect the robustness of the derived benchmarks. Compared to the bottom-up approach, top-down approaches were found to be beneficial in gaining insight into how peers perform. The relative rather than absolute feedback on energy efficiency meant that peer pressure was a motivator for improvement. On the other hand, there were limitations with regard to the extent to which the energy efficiency of a building could be accurately assessed using the top-down benchmarks. Moreover, difficulties in acquiring adequate data were identified as a key limitation to using the top-down approach for benchmarking non-domestic buildings. The study suggested that there are benefits in rolling out of DECs to private sector buildings and that there is a need to explore more complex methods to provide more accurate indication of energy efficiency in non-domestic buildings

Duality Based A Posteriori Error Estimation for Quasi-Periodic Solutions Using Time Averages

We propose an a posteriori error estimation technique for the computation of average functionals of solutions for nonlinear time dependent problems based on duality techniques. The exact solution is assumed to have a periodic or quasi-periodic behavior favoring a fixed mesh strategy in time. We show how to circumvent the need of solving time dependent dual problems. The estimator consists of an averaged residual weighted by sensitivity factors coming from a stationary dual problem and an additional averaging error term coming from nonlinearities of the operator considered. In order to illustrate this technique the resulting adaptive algorithm is applied to several model problems: a linear scalar parabolic problem with known exact solution, the nonsteady Navier–Stokes equations with known exact solution, and finally to the well-known benchmark problem for Navier–Stokes (flow behind a cylinder) in order to verify the modeling assumptions

Weakly Consistent Regularisation Methods for Ill-Posed Problems

This Chapter takes its origin in the lecture notes for a 9 h course at the Institut Henri Poincaré in September 2016. The course was divided in three parts. In the first part, which is not included herein, the aim was to first recall some basic aspects of stabilised finite element methods for convection-diffusion problems. We focus entirely on the second and third parts which were dedicated to ill-posed problems and their approximation using stabilised finite element methods. First we introduce the concept of conditional stability. Then we consider the elliptic Cauchy-problem and a data assimilation problem in a unified setting and show how stabilised finite element methods may be used to derive error estimates that are consistent with the stability properties of the problem and the approximation properties of the finite element space. Finally, we extend the result to a data assimilation problem subject to the heat equation

Children’s experiences of domestic violence and abuse: siblings’ accounts of relational coping

This article explores how young people see their relationships, particularly their sibling relationships, in families affected by domestic violence, and how relationality emerges in their accounts as a resource to build an agentic sense of self. The ‘voice’ of children is largely absent from domestic violence literature, which typically portrays them as passive, damaged and relationally incompetent. Children’s own understandings of their relational worlds are often overlooked, and consequently existing models of children’s social interactions give inadequate accounts of their meaning-making-in-context. Drawn from a larger study of children’s experiences of domestic violence and abuse, this paper uses two case studies of sibling relationships to explore young people’s use of relational resources, for coping with violence in the home. The paper explores how relationality and coping intertwine in young people’s accounts, and disrupts the taken for granted assumption that children’s ‘premature caring’ or ‘parentification’ is (only) pathological in children’s responses to domestic violence. This has implications for understanding young people’s experiences in the present, and supporting their capacity for relationship building in the future

Numerical Computations with H(div)-Finite Elements for the Brinkman Problem

The H(div)-conforming approach for the Brinkman equation is studied numerically, verifying the theoretical a priori and a posteriori analysis in previous work of the authors. Furthermore, the results are extended to cover a non-constant permeability. A hybridization technique for the problem is presented, complete with a convergence analysis and numerical verification. Finally, the numerical convergence studies are complemented with numerical examples of applications to domain decomposition and adaptive mesh refinement.Comment: Minor clarifications, added references. Reordering of some figures. To appear in Computational Geosciences, final article available at http://www.springerlink.co

Calibrating Energy Performance Model of a Hospital Building: Dealing with Practical Issues of Data Availability and Granularity in a Case Study Building in the UK

Calibration of energy models is mathematically a highly-parameterized and under-determined problem. Hospitals are energy intensive buildings that have complex and varying specifications for their functions and operations. Calibration of energy models of hospitals is further challenging due to difficulties such as base-load estimation and end-use disaggregation of a 24-hour running facility’s measured energy use (specially end-uses such as specialist equipment and plug loads). This paper attempts to calibrate the energy model of a hospital building in the UK. Along with design stage building construction documentation, on-site observations and semi-structured stakeholder interviews, energy and Indoor Environmental Quality (IEQ) data is collected for a period of one year. A calibrated energy model is then used to quantify the effects of the observed energy performance gap issues found in the building. The energy and IEQ for the building are compared against design stage targets and industry benchmarks. The paper also reflects on practicalities of data collection such as shortcomings in metering, monitoring and observations that could be addressed for model calibration in hospitals

Results from the LSND Neutrino Oscillation Search

The Liquid Scintillator Neutrino Detector (LSND) at the Los Alamos Meson Physics Facility sets bounds on neutrino oscillations in the appearance channel nu_mu_bar --> nu_e_bar by searching for the signature of the reaction nu_e_bar p --> e^+ n: an e$^+$ followed by a 2.2MeV gamma ray from neutron capture. Five e^{+/-} -- gamma coincidences are observed in time with the LAMPF beam, with an estimated background of 6.2 events. The 90\% confidence limits obtained are: Delta (m^2) < 0.07eV^2 for sin^2 (2theta) = 1, and sin^2(2theta) < 6 10^{-3} for Delta (m^2) > 20 eV^2.Comment: 10 pages, uses REVTeX and epsf macro

Managing energy performance in buildings from design to operation using modelling and calibration

To manage the concerns regarding the energy performance gap in buildings, a structured and longitudinal performance assessment of buildings, covering design through to operation, is necessary. Modelling can form an integral part of this process by ensuring that a good practice design stage modelling is followed by an ongoing evaluation of operational stage performance using a robust calibration protocol. In this paper, we demonstrate, via a case study of an office building, how a good practice design stage model can be fine-tuned for operational stage using a new framework that helps validate the causes for deviations of actual performance from design intents. This paper maps the modelling based process of tracking building performance from design to operation, identifying the various types of performance gaps. Further, during the operational stage, the framework provides a systematic way to separate the effect of (i) operating conditions that are driven by the building’s actual function and occupancy as compared with the design assumptions, and (ii) the effect of potential technical issues that cause underperformance. As the identification of issues is based on energy modelling, the process requires use of advanced and well-documented simulation tools. The paper concludes with providing an outline of the software platform requirements needed to generate robust design models and their calibration for operational performance assessments. PRACTICAL APPLICATION: The paper’s findings are a useful guide for building industry professionals to manage the performance gap with appropriate accuracy through a robust methodology in an easy to use workflow. The methodological framework to analyse building energy performance in-use links best practice design stage modelling guidance with a robust operational stage investigation. It helps designers, contractors, building managers and other stakeholders with an understanding of procedures to follow to undertake an effective measurement and verification exercise

Managing the risk of the energy performance gap in non-domestic buildings

Energy use in buildings accounts for one-third of the overall global energy consumption and total building floor area continues to increase each year as new developments are constructed and delivered. If stringent climate goals are to be met, these buildings will need to consume less energy and emit less carbon. However, design intentions for energy efficient buildings are not always met in practice. This performance gap between calculated and measured energy use in buildings threatens the progress necessary to meet these energy targets. The aim of this paper is to identify the factors that contribute to the performance gap and propose solutions for reducing the gap in practice. A quantitative and qualitative analysis of two research programmes completed in the past few years was utilized for an in-depth look at the performance of around 50 non-domestic buildings in the United Kingdom. While no direct links were found between any one variable and the performance gap, several correlations exist between contributing factors indicating a complex, entangled web of interrelated problems. The multitude of the variables involved presents a formidable challenge in finding practical solutions. However, the results indicate that the combination of the ventilation strategy of a building and the building services control strategy during partial occupancy is a key determinant of the performance gap. A more straightforward procurement approach with clearly delineated targets and responsibilities, along with advanced and seasonal commissioning instituted at the beginning of a project and implemented after building completion can also be very effective in reducing the gap. Finally, mandatory requirements or an appropriate system of incentives for monitoring and disclosure of performance data can help identify many of the underlying issues affecting performance in-use and untangle some of the web of complex issues across the building sector