Case Studies > General Simulation

CIBSE TM54 Energy Projection of a Office Building with Detailed HVAC Modelling

About	Detailed guidance on CIBSE TM54 modelling and projecting design-stage building performance, including interpretation and clarification on how TM54 can be applied through dynamic modelling tools using Detailed HVAC systems.
By	Nishesh Jain et. al., UCL, London, UK
Location	Keynsham, United Kingdom
Category	Compliance, Certification, Design Stage Modelling, CIBSE TM54
Highlights	Exploration of the most important aspects of design stage performance modelling using Detailed HVAC as described in TM54. The office building's HVAC system is atypical and has complex controls, so Detailed HVAC modelling with component-level energy breakdown is necessary. Step-by-step modelling per TM54, factoring in all energy end uses and operational details, resulted in an energy use projection of 61 kWh/m2/annum. Sensitivity tests show that the building’s performance is susceptible to underperformance and variations in server room loads and system operation. The risk of summertime overheating should be considered and managed in the future as the ambient temperatures rise.

Summary

CIBSE TM54 was recently revised and covers best practice methods to evaluate the operational energy use of buildings. TM54 is a guidance document on performance evaluation at every stage of the design and construction process, and during the occupied stage, to ensure that long-term operational performance is in line with the design intent. The main performance evaluation principles in TM54 are a step-by-step modelling approach and scenario testing, to improve the robustness of the design proposal calculations. The latest version brings an updated perspective to the modelling approaches, including dynamic simulation with Heating, Ventilation and Air Conditioning (HVAC) systems. It also incorporates more detailed guidance around risks, target setting, scenario testing and sensitivity analysis.

This case study presents an example of TM54 design stage building performance modelling for an office building using dynamic simulation with detailed HVAC modelling. First, the step-by-step modelling methodology proposed in CIBSE TM54 for this implementation route is described. Then, the case study building is introduced, and the modelling inputs and assumptions for each TM54 step are described. Finally, the results are presented per TM54 requirements, including deterministic calculations, sensitivity and scenario assessments, and benchmarking against industry standards.

The case study is published in BSER&T, CIBSE’s peer-reviewed journal and can be accessed from the links below

About the author Nishesh Jain, PhD, is a Research Fellow at the Institute for Environmental Design and Engineering (IEDE), University College London (UCL). He has worked as a researcher and practitioner in the field of energy modelling and operational performance of buildings. In collaboration with DesignBuilder Software, his current work focuses on developing new tools for operational performance assessments. He is a qualified architect, and for many years has been involved in performance simulation-related consultancy and research. Contact: n.jain@ucl.ac.uk https://www.linkedin.com/in/nisheshjn/