Evaluating operational energy use at the design stage (TM54)

Julie Godefroy

• Publisher: The Chartered Institution of Building Services Engineers
• Year: 2022
• Print ISBN:
  9781914543197
• eBook ISBN:
  9781914543203
• Topic: Technology & Engineering
• Subtopic: Construction & Architectural Engineering
• Index: Technology & Engineering

The climate emergency is driving a requirement to deliver highly performing buildings, with operational energy use consistent with net zero targets. To deliver this, design teams need access to tools and techniques that can reliably model in-use energy performance based on design proposals, and that can help inform design proposals.Built environment clients are increasingly interested in the operational energy performance of the buildings that they invest in, procure, or occupy. This can lead to targets being set in the project brief to achieve energy performance in line with the design estimates. As a result, building services engineers and energy consultants are being asked to provide estimates of the likely operational energy performance of buildings at the design stage, and accordingly to inform the design proposals.This document aims to help building services engineers and energy modellers to respond to this request in a robust way.The TM54 methodology covers all types of modelling. 'Modelling' is used in this document to encompass calculations of energy performance in a wide sense, including spreadsheet and steadystate tools as well as dynamic simulation modelling (DSM). 'Simulation' is used to specifically refer to DSM. 'Modeller' is used in this document but on some projects, some of the activities may be carried out by or with a building services engineer or other discipline, working together with a modeller.The previous version of this methodology was tested using a case study building and further validated using another building with both design and operational energy data. The main principles remain valid in this edition, but CIBSE aims to provide further case studies on this revised methodology. Users of TM54 are invited to contact CIBSE if willing to provide case studies and support further validation and illustration of the TM54 methodology.The aims of this document are to: help engineers deliver on a project brief where an annual operational energy target has been set, by informing the development of the design, controls and operational strategyprovide a methodology that engineers can use to undertake better-informed calculations of energy use in operation and to produce performance targets (and possibly budgets) against which measured performance in use can be compareddemonstrate that energy performance is dependent on how the building is run and maintained, as well as how it is designed and constructed.This document is written mainly for engineers and consultants working in the UK. The methodology can be applied to other countries, with the appropriate adjustments to the references, weather data etc.The methodology can be applied to any type of building, new or existing.Table of contentsPrinciples of evaluating energy useWhy estimate energy use?Current situation and the performance gapBasis for the methodologyLevels of modellingScenario testing and sensitivity analysisRisks, assumptions and limitations of evaluating energy useLimitationsAssumptions and simplificationsRecommended processesHow evaluating energy use fits within a projectOverviewTargets and benchmarksDesign and modelling for in-use evaluationThe methodologyStep 0: Choosing the modelling approachStep 1: Constructing and building the modelStep 2: Estimating operating hours and occupancy factorsStep 3: Evaluating lighting energy useStep 4: Evaluating energy use for lifts and escalatorsStep 5: Evaluating energy use for small powerStep 6: Evaluating energy use for cateringStep 7: Evaluating energy use for server roomsStep 8: Evaluating energy use of additional plant and equipmentStep 9: Evaluating energy use of domestic hot waterStep 10: Adding internal heat gains to the model, for energy uses calculated outside the modelStep 11: Modelling HVAC systems and their controlsStep 12: Taking management considerations into accountStep 13: Sensitivity analysisStep 14: Scenario testingStep 15: Reviewing the results against targets and benchmarksStep 16: Reporting and implementation matrixStep 17: Quality assurance (QA)Post occupancy evaluationAnnex A: TM54 implementation matrixAnnex B: TM54 Outline Report headings

Table of contents

• 1 Introduction
• 2 Aims of this document
• 3 Scope of this document
• 4 Principles of evaluating energy use
• 5 Risks, assumptions and limitations of evaluating energy use
• 6 How evaluating energy use fits within a project
• 7 The methodology
• 8 Post occupancy evaluation
• Annex A: TM54 Implementation Matrix
• Annex B: TM54 Outline Report headings
• References and bibliography
• TM54 index.pdf