How to prepare an HVAC maintenance strategy
Total Facilities 2012 speaker, DAVID CHOKOLICH from GHD provides guidance on how to prepare an HVAC maintenance strategy, how to assess the capability of a BMS and how to maintain an HVAC system’s optimisation.
Once seen as a ‘nice to have’, HVAC commissioning is now a must for facilities managers and owners. This is due to the fact that the Australian building industry has experienced significant changes over the past 10 years with the introduction of programs such as Green Star, NABERS, HVAC High Efficiency Systems Strategy (HESS) and, most recently, the Commercial Building Disclosure (CBD) legislation. A large part of these programs target the maintenance and operation of HVAC systems.
Guides such as Guide to Best Practice Maintenance and Operation of HVAC Systems for Energy Efficiency, which was recently released by the Department of Climate Change, are being produced with the objective of accelerating the industry to provide a sharper focus on improving the energy and water efficiency of HVAC systems.
How can an HVAC maintenance strategy be prepared, the capability of a building management system (BMS) tapped into and an HVAC system’s optimisation maintained to ensure a HVAC system meets and exceeds its efficiency requirements, and to ensure that all facility plant equipment is performing at its peak?
GETTING YOUR HVAC MAINTENANCE STRATEGY RIGHT
In order for an effective maintenance plan, it is vital to be aware of the environmental strategies for your particular facility or facilities. These include a NABERS target, Green Lease conditions or any other benchmarks associated with maintaining specific conditions within the various areas, along with understanding the corporate reporting requirements.
When preparing a maintenance strategy, there are several key areas that must be addressed:
- Asset register: prior to setting up and managing a maintenance contract it is essential to produce a comprehensive asset register. This is beneficial not only to you as the facilities manager, but also to the maintenance service provider. A comprehensive asset register this will assist with the long-term replacement and the upgrading of systems.
- Existing operating and maintenance documentation: key information to be collected includes the original HVAC system design intent documentation, manufacturer data, functional descriptions and control schematics for any BMS, and commissioning data, along with any installation certificates for the mechanical plant.
- Establishing benchmarks and KPIs: this should not only include energy and water targets, such as NABERS, but also targets to maintain the space’s conditions, such as temperature and humidity set points. Other important KPIs include the monitoring of service calls and expenditure, as this highlights the current system’s performance and any deficiencies.
- Maintenance specification: an important point to remember when preparing maintenance specifications is to customise each specification for every facility. It is also vital to determine the type of contract. This could be a service level agreement – fully comprehensive or preventative maintenance. The type of contract should match the maintenance strategy and available budget. AIRAH’s DA19 is a useful reference when producing a specification.
TOOLS OF THE TRADE
When contemplating the tools required in order to implement a maintenance strategy, it is important to not only consider the instruments within a refrigeration mechanic’s tool bag. The tools available to facilities managers have the greatest impact.
Nowadays, it is common for organisations to implement computerised maintenance management systems (CMMSs) to track service calls and work tasks down to individual pieces of equipment. A CMMS effectively works as an electronic logbook and can reveal much about the performance, cost and history of mechanical plant.
In addition, BMSs are frequently employed, with most systems including a head-end (on-site PC). It is also increasingly common for them to feature multiple user web access. If set up correctly, a BMS can give the best indication of current and trend data for the operation of a HVAC system, while newer, expanded systems also enable the connection of security, fire and electrical metering.
When assessing the capability of a current BMS or a future upgrade, the following should be considered:
- What is the development cycle of the software, and how often will upgrades be required for both software and the PC?
- How will BMS maintenance be incorporated into the main HVAC maintenance? Will it be subcontracted or stand-alone? What level of local support is available for both labour and materials?
- What software licensing is required? Is it based on database size? Does the proposed database size allow for future needs?
- Are the proposed graphics pages sufficient to display and compare all relevant data points for both the facilities manager and maintenance personnel? How will modifications to graphics pages be managed in the future; for example, if a tenancy fitout was undertaken?
- Will tenant pages be available to enable the scheduling of supplementary HVAC equipment for meeting rooms, or even to monitor their own tenancy energy consumption?
- How would the system perform in the event of a major failure with the on-site PC? Do the local BMS controllers store a back-up of the BMS program and data? What is the disaster recovery plan?
- What are the limitations for remote access and alarm capability?
- What are the energy efficient control strategies available? Does it enable night cooling or night purge and enthalpy control in low humidity environments, and does it feature carbon dioxide sensors, occupancy sensors and an economy cycle to fully utilise free cooling?
MAINTAINING SYSTEM OPTIMISATION
To retain system optimisation, it is important that maintenance be carried out more regularly than just a one-off annual check-up. Suggested maintenance intervals for key mechanical plant are:
- six months: chilled water valve controllers, supply, return and outdoor air temperatures
- 12 months: room temperature sensors, and
- 24 months: airflow measurement through variable air volume (VAV) boxes and air diffusers.
Effective maintenance and commissioning procedures require regular attention and cannot be viewed as ‘set and forget’.
David Chokolich is a principal ESD and building services consultant at GHD. He currently manages GHD’s Perth Building Services group. He is a NABERS accredited assessor and an accredited Green Star Professional. Chokolich is a director of the Facility Management Association of Australia, chair of the Property Council’s Western Australian Sustainable Development Committee and a member of the City of Perth’s City Switch Committee. He co-authored the Department of Climate Change and Energy Efficiency’s recently released Guide to Best Practice Maintenance & Operation of HVAC Systems for Energy Efficiency.