TM22 : Energy Assessment and Reporting Methodology
TM22 : Energy Assessment and Reporting Methodology
CIBSE TM22 Energy Assessment and Reporting Methodology
(inc CD-ROM) 2nd Edition
This publication is supported by a number of supplementary files that are freely available here.
This document describes a method for assessing the energy performance of an occupied building based on metered energy use, and includes a software implementation of the method. Recent UK and European initiatives mean that the benefits of performance assessment are being backed by legislation. TM22 and its software provides support for these assessment needs. While primarily directed at assessing energy performance, the procedure has a wide range of uses for building managers, design professionals, and energy management specialists contributing to the 'virtuous circle' of good building management and satisfied occupants.
1. Executive summary
2. The EU Directive on Energy Performance of Buildings
3. Tools for Building Professionals
3.1 Energy assessors
3.2 Building managers
3.3 Facilities managers
3.4 Building designers and procurers
3.5 Energy management specialists and surveyors
4. Description of the TM22 Method
4.1 Main procedure options
4.2 Quality assurance
4.3 Selection of buildng types, energy supplies and services features
4.4 Allowing for systems not included in the benchmarks
4.5 Allowing for different use and occupancy
5. Specifying an assessment
6. Using the Software
A3: Principles of Energy Assessment
A4: System Requirements and Installation
A5: Annotated List of Sheets
A6: Special Functions Used in Calculations
A7: Sector Data and Benchmarks
A8: Energy Tree Diagram Assessment
Review of changes to TM22 energy assessment tool
April 2012 (courtesy of BSRIA), referrinig to the 2006 edition of TM22. This extract is provided with permission of BSRIA.
Making sense of energy use has got a bit easier with a major revamp of CIBSE's TM22 energy assessment tool. An article by Peter Tse in BSRIA’s Delta T magazine explains the changes:
The energy analysis tool TM22 has long provided a systematic framework for undertaking an energy survey, and reporting and benchmarking the results. CIBSE's latest version of the spreadsheet tool now allows a building's energy use to be calculated in greater detail, with more scope for using submeter data and different benchmarks. Technical Memorandum 22 is an excellent aid for operational feedback, and makes energy analysis simple, unambiguous and robust. It has undergone significant development by the CIBSE since its previous release, with the latest reincarnation partially driven by the Technology Strategy Board's (TSB) £8 million programme for building performance evaluations of domestic and non-domestic buildings. So what are some of the major changes over the old versions of TM22?
The first item to note is the building types now align with the 237 options for a Display Energy Certificate (DEC) from CIBSE TM46: Energy Benchmarking. This is a significant development, as initially the tool was developed just for offices. It was expanded later to include hotels, mixed use industrial buildings and high street banks and agencies. As many non-domestic buildings seldom have one particular function, the new TM22 allows up to five different building functions to be modelled. This provides a mixed-use building benchmark that is also area-weighted. The energy benchmarks in TM22 now cover all types of non-domestic building. Users can choose one of three reference benchmarks: those from a Display Energy Certificate (DEC), from CIBSE TM46: Energy Benchmarks, or benchmarks specified by the user. The DEC benchmarks for electricity and heating are building-specific, accounting for location, degree days, typical hours of use and any mixed use. If a DEC is not available benchmarks from CIBSE TM46 can be used. However these are median benchmarks that need to be modified to suit the study building. User-specified benchmark data can be derived from a property portfolio of energy studies. A simple assessment is confined to one worksheet, which gathers basic information for the building including floor area, energy use, input and output energy of CHP or renewables, separables and metered data. This is all that is required to benchmark the energy consumption and carbon dioxide emissions, with and without separables.
Furthermore, it begins to provide an understanding of the building's energy efficiency, as the contribution of renewable sources is included in the section on building energy use. All energy consumption is assigned against 20 end-use categories. Fifteen of these are pre-defined and five are user specified, including the six official DEC separable energy uses. There is a maximum of 30 items that can be assigned to each of the 20 categories, and each item is referenced to the appropriate sub-meter. The latest version of TM22 allows for 50 sub-meters. Where a building has more than 50 sub-meters the user will have to aggregate loads of a similar nature. A certain degree of judgement is required, especially if the aggregated load turns out to be a significant fraction of the total. TM22 allows the user to account for energy in three distinct periods; core hours based on occupied period, out of hours (normally weekday nights) and weekends. This can provide a valuable insight into the building's energy consumption during occupied and non-occupied hours, helping to identify base load consumption and wastage. Once the level of detail is complete, TM22 will sort the data and complete reconciliation of the energy use against each of the sub-meters, and total energy use recorded by the utility meters. If half-hourly or quarter-hourly data is imported, the model can compare the amount of energy it thinks is being consumed at different times of the day with actual energy consumption being recorded. TM22 will automatically generate a graphical breakdown of the building's energy use by kilowatt hours and carbon dioxide emissions per annum. Detailed analysis can deliver a breakdown for the 20 categories of electrical end use. The latest edition of TM22 has the potential to be a powerful tool of analysis, providing a common reference point for designers and operators alike throughout a project. It is a useful aid for aligning expectations and providing a check mechanism for regulatory tools like SBEM and similar.
Designers can use the tool with the client at briefing stage of a project to discuss a building's likely load profile, and use that information to set realistic (but also stretching) performance targets.
Peter Tse MEng, CEng, MCIBSE is a senior design consultant with BSRIA. This article is based on material provided by Robert Cohen of Cameo, developers of the latest edition of TM22.