Birling Consulting Ltd
Birling Consulting Ltd

Avoiding BMS Issues

Some causes of poor control are inexcusable, but many are a combination of factors which can be difficult to resolve without a good understanding of all the relevant disciplines. The following can significantly reduce the risk of problems and contribute to a controllable, comfortable, energy efficient building:


  • Controllability Review - Controllability should be reviewed at design stage, however, reviews after construction can also be very beneficial identifying issues that may not be identified from trend logs, data analysis or other observations. 
  • Good Specification – A good control specification should not just include standards, but include a detailed description of control functions. Specifications that have vague descriptions of operation to be interpreted by the controls supplier are not fit for purpose. Points and valve schedules, etc. should all be included together with accurate detailed schematic drawings.
  • Design Checks – Manufacturer’s/Systems Integrator’s working drawings and descriptions/control logic diagrams all need to be carefully checked to ensure compliance with specification and proposed system operation.
  • Pre-Commissioning – The Manufacturer/Systems Integrator should provide a report to show all items have been correctly wired and function. A percentage of points may be witnessed.
  • Commissioning – The operation of the control system/BMS should be checked with all plant operating across as wide a range of operating conditions as possible. Coordination with other disciplines is necessary. Change of setpoints or inhibiting plant may be required to simulate a change in conditions. With the complexity of modern plant it is often necessary to log and analyse BMS data to prove effective operation.
  • Post-Commissioning – Operation should be checked under different climatic and load conditions during the first year of operation. Again data logging and analysis should be used to prove satisfactory operation.
  • Documentation – Controls and BMS need effective documentation at all stages from design to maintenance.

All too frequently the basics are forgotten and poor performance results.


Initiatives such as Soft Landings should improve building performance, although performance monitoring may highlight fundamental issues that need to be addressed.


Care needs to be taken to ensure that performance analysis is effectively carried out and needs to be considered as part of the overall system operation, not just to show the controls are working.

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