Gavin Bruce Murphy

Closing the gap in building performance: learning from BIM benchmark industries

It is clear that the current industry process needs to improve in order to routinely deliver comfortable low-carbon buildings. Overheating in buildings designed to be of low energy is one of the key symptoms of current problems. Many initiatives aim to improve building performance and the industry process. A selection of these initiatives are reviewed including: the EU Energy Performance of Buildings Directive; the Green Star, Leadership in Energy and Environmental Design, Building Research Establishments Environmental Assessment Method (BREEAM) and National Australian Building Environmental Rating Standards (NABERS) rating schemes; the Passivhaus standard; the Soft Landings process and Building Information Modelling (BIM). The BIM approach is being actively promoted based on the assertion that the building industry process has stagnated compared to other industries suggested as productivity benchmarks such as the electronics industry. This study highlights the potential role that could be played by BIM as a framework to address the performance gaps, and suggests that processes from the BIM benchmark industries should be investigated for potential adoption. The organizational context and processes of the electronics industry are described, and it is proposed that they could be usefully adapted to reduce the scale and impacts of the building industry performance gap. Key conclusions are that public domain performance data are important, and that the adoption of a quality systems approach will be required to deliver the intended performance in practice, eliminate overheating and avoid excess energy use.

A comparison of the UK Standard Assessment Procedure and detailed simulation of solar energy systems for dwellings

The drive to reduce worldwide carbon emissions that are directly associated with dwellings and to achieve a zero carbon home dictates that renewable energy technologies will have an increasingly large role in the built environment. The Standard Assessment Procedure (SAP), formulated by the Building Research Establishment (BRE), is the UK Governments approved methodology for assessing the energy ratings of dwellings. This article presents an evaluation of the advantage given to SAP ratings by the domestic installation of typical photovoltaic (PV) and solar domestic hot-water (SDHW) systems in the UK. Comparable PV and SDHW systems will also be simulated with more detailed modelling packages. Results suggest that calculation variances can exist between the SAP methodology and detailed simulation methods, especially for higher performance systems that deviate from the default efficiency parameters.

Are current design processes and policies delivering comfortable low carbon buildings

Gaps between intended and actual performance which impact on indoor environment, energy use and carbon emissions have been well documented and are nowhere more important than when they present in performance problems such as building overheating and consequent occupant discomfort and high energy running costs. Here, such gaps are explored through a review of relevant literature and related illustrative investigations. Key drivers of those performance gaps are identified and located in the stages of the building industry process. Three case studies, of one office and two houses, are provided, highlighting where faults arise and may or may not be effectively dealt with and the reasons why. These include faults at the Implementation, Validation and Operation stages and the paper concludes by summing up generic failings in the industry that lead into the following paper by the same authors that offers an approach and potentially effective solutions to reduce such performance gaps by correctly using a BIM approach to quality control in the construction industry.

Robust nonlinear HVAC systems control with evolutionary optimisation

Purpose – The purpose of this research is to design a robust high-performance nonlinear multi-input multi-output heating, ventilation and air conditioning (HVAC) system controller for temperature and relative humidity regulation. Buildings are complex systems which are subjected to many unknown disturbances. Further complicating the control problem is the fact that, in practice, buildings and their systems have static nonlinearities such as power saturation that make stability difficult to guarantee. Therefore, in order to overcome these issues, a control system must be designed to be robust (performance insensitive) against uncertainties, static nonlinearities and effectively respond to unknown heat load and moisture disturbances. Design/methodology/approach – A state of the art nonlinear inverse dynamics (NID) technique is combined with a genetic algorithm (GA) optimisation scheme in order to improve robustness against uncertainty in the systems modelling assumptions. The parameter uncertainty problem ...

Symbolic modelling and predictive assessment of air source heat pumps

This article extends a novel advanced dynamic calculation method (IDEAS – Inverse Dynamics based Energy Analysis and Simulation) of assessing the controllability of a building and its servicing systems. IDEAS allows confident (i.e. calibrated in SAP) predictions to be made regarding the impact of novel heating and renewable energy systems. IDEAS can be used as a dynamic sizing tool for a heating system in a building and can be used to benchmark control systems performance as it can represent near perfect control. The addition of an air source heat pump model to IDEAS is described. This allows for detailed analysis to be made of air source heat pumps in a SAP-compliant framework, taking into account the dynamic nature of the system efficiency and thermal capacity. Practical applications: ASHPs are still a relatively novel technology in the UK, yet it has been suggested they could play a significant role in efforts to de-carbonise the heating sector. However field trials have found performance varies widely from installation to installation. Whilst some of this variation is due to user behaviour, ASHP systems are also very sensitive to design and commissioning. Fundamental methodologies which can provide detailed analysis of ASHP performance, such as that presented in this article, could contribute to improving system design standards. This would ensure more installations achieve a good level of performance, boosting confidence in the technology.

Symbolic energy estimation model with optimum start algorithm implementation

The drive to reduce carbon emissions and energy utilisation, directly associated with dwellings and to achieve a zero carbon home, suggests that the assessment of energy ratings will have an increasingly prioritised role in the built environment. Created by the Building Research Establishment (BRE), the Standard Assessment Procedure (SAP) is the UK Government’s recommended method of assessing the energy ratings of dwellings. This paper describes a new, simplified dynamic method (hence known as IDEAS – Inverse Dynamics based Energy Analysis and Simulation) of assessing the controllability of a building and its servicing systems. The IDEAS method produces results that are comparable to SAP. An Optimum Start algorithm is explored in this paper to allow heating systems of different responsiveness and size to be integrated into the IDEAS framework. Results suggest that this design approach could enhance the SAP Methodology by the addition of advanced systems controllability and dynamic values.