AM11 Building Performance Modelling
It has been more than 17 years since the Application Manual (AM11) Building energy and environment modelling was first published. A few years ago, the CIBSE Building Simulation Group felt it was necessary to update this manual to reflect the vast progress that has taken place in the modelling area in the last two decades, and late 2015 the new AM11 “Building Performance Modelling” was published. This new AM has been written by experts in a variety of building design and modelling software, from both academia and engineering practices.
In writing the new AM it has been assumed that readers of the manual have at least the basic building physics knowledge for the specific type of modelling and simulation tool that is described in the manual. This article provides a brief description of each of the key chapters.
Highlights of the Main Chapters
Chapter 2, whose principal author is Foroutan Parand, sets out the quality assurance (QA) procedures that are recommended to ensure that the modelling process is performed according to defined criteria. Matters related to software capabilities including software selection, limitations, and validation are also discussed.
The focus of Chapter 3 is on modelling building performance in compliance with energy performance regulations and certification, see Figure 1. It particularly focuses on the UK regulations but also considers compliance with the European Directive on Energy Performance of Buildings (EPBD), and directives in some other countries. The chapter, whose principle author is Rokia Raslan, also outlines well-known building assessment and rating schemes, such as BREEAM (Building Research Establishment Environment Assessment Method) LEED (Leadership in Energy and Environment Design), Green Star of the Green Building Council of Australia and Estidama Pearl of the UAE.
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| Figure 1 Compliance/rating assessment process |
Chapter 4 focuses on the application of hourly energy simulation methodologies and was principally authored by David Williams. The processes involved are described in detail, i.e. defining the design questions to be considered, transforming the concepts into modelling objectives, preparing the most appropriate models, executing the simulations and interpreting the results. The chapter also briefly describes the various modelling approaches for estimating a building energy demand and their limitations and gives a more detailed description of Dynamic Thermal Modelling (DTM).
Chapter 5, with Malcolm Orme as the principal author, addresses the needs for applying thermal environment modelling to provide the necessary indoor environment for providing human thermal comfort. The personal parameters and their interaction with predicted environmental parameters are all described for the purpose of assessment of the modelling process with regards to human perception, e.g. operative temperature profiles as in Figure 2. A range of thermal comfort standards and the comfort models recommended by these standards are described in this chapter including PMV/PPD and adaptive thermal comfort models.
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Figure 2 Operative temperature profiles using dynamic simulation of a mixed-mode ventilation system
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The provision of daylighting is always one of the priorities for the building designer as spaces without daylight and external views are not favoured by building occupants. The emphasises of Chapter 7, whose principal author is John Mardaljevic, is on the modelling of daylighting and to a lesser extent artificial lighting, although many of the modelling principles involved are common to both. The chapter also describes the basic principles of climate-based daylighting modelling and artificial lighting, including their energy use assessments.
Chapter 8 deals with the modelling of HVAC plants, controls and renewable energy systems and its principal author is Chris Underwood. Key principles used in treating plant and control systems that are used in building simulation are discussed in this chapter, e.g. idealised control functions, steady-state component level modelling as well as fully dynamic modelling. The modelling approaches used are complemented by examples and some case studies involving plant and renewable energy systems, such as PV panels, solar thermal collectors, building-integrated wind generators and ground-source heat pumps. A number of different types of available computer programs dedicated to plant modelling are described to offer the user of this manual a choice of selecting the relevant program for the particular modelling tasks of the system being considered.
Chapter 9, which includes case studies that cover various aspect of building simulations, is principally authored by Darren Coppins with support from a number of co-authors who provided case studies based on real projects. The aim of this chapter is to help users of this manual in the selection and application of different modelling tools and make them aware of some relevant issues and diversities of the modelling tools available and how they are used in practice.
The case studies presented under this section cover a wide range of buildings and simulation tools used and three such examples are shown in Figures 3 to 5.
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| Figure 3a Image of thermal model |
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Figure 3b Wind speed at ground and first floor levels for two wind directions
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| Figure 4 Track illuminance and light uniformity from daylight simulation of the London 2012 Velodrome |
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| Figure 5a The VAV control logic |
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| Figure 5b Weekly energy consumption of the VAV system -VAV system for an office building |
Hazim Awbi
Chair, AM11 Steering Committee
