Building tuning provides significant economic and environmental benefits.
I’ve spent a large part of my career modelling and designing green buildings. While I’ve seen many energy-efficient buildings being designed, once constructed very few seem to reach their design potential unless building tuning is carried out. Having experienced first-hand the significant energy savings that comes from building tuning, I’ve often wondered why it isn’t carried out on a more regular basis. Could it be because of a lack of awareness around the value building tuning offers, or is there still an expectation that buildings will operate efficiently from day one? Or, maybe it’s because building tuning is seen to be expensive add-on, and not budgeted for at the outset of a project?
What is building tuning?
Commissioning of building services in a new building is usually completed right at the end of the construction stage. During which, energy efficient controls are rarely considered, if considered at all. As the responsibility of building services changes following commissioning, the original design intent can be misunderstood. Any energy efficient controls often get adjusted to respond to extended hours of operation, occupant comfort requirements, or to ‘the way we’ve always done it’. All of this can result in a building using significantly more energy than originally anticipated; this overshoot, between the anticipated and actual performance, is often referred to as the ‘building energy performance gap’.
Building tuning on the other hand involves monitoring and improving the performance of building services systems during operation. The goal is to ‘tune’ the building services controls for optimal energy efficiency throughout the seasons, while maintaining or improving occupant comfort.
The process of building tuning is assisted by the use of a Building Management System (BMS), and an energy monitoring system. While a BMS is intended primarily to control building services, it can also store a large level of useful performance data. However, unless this data is interrogated with an understanding of the design intent (and an energy efficiency hat on), it will not be obvious how efficiently the building is operating or the opportunities to save energy.
Energy modelling during the design stages of a project can be useful to inform the benefits of energy efficient design opportunities, and benchmark energy performance. But it’s during the operational stage of a building where real energy savings are realised. A building design may include many energy efficient features with the potential to be energy efficient, but without effective building tuning during the first years of operation, it will very seldom operate at its design potential.
The benefits of the building tuning process include:
- Reduced energy consumption and associated greenhouse gas emissions. This will vary from building to building, but minimum savings of 20% are typically achieved. Based on energy cost savings, the building tuning process generally results in rapid payback periods of less than one to two years.
- Lower maintenance costs.
- Improved occupant comfort and less staff (or tenant) complaints.
- A potentially higher NABERSNZ rating for commercial office buildings (a system for rating the energy efficiency of office buildings in New Zealand) - the highest NABERSNZ rated buildings in New Zealand so far, have all undertaken building tuning.
Key observations from the building tuning process
Some key observations from the building tuning process I’ve found are:
- Understanding energy efficient building operation and identifying control anomalies requires good data. To assess operation during varying seasons, this data must be accessible and cover a reasonable period of time.
- Effective building tuning requires a thorough understanding of the original design intent, particularly if the design incorporates any low-energy HVAC (heating, ventilation and air conditioning) strategies, for example, mixed mode ventilation, displacement ventilation, night flushing controls etc.
- It can enable the inclusion of additional low-energy control strategies, not originally considered during the initial design stage.
- It can be an opportunity to improve occupant comfort. Conversely the requirement for energy savings can often contradict occupant comfort and may require a balance to be sought between the two.
- Good communication with end users, tenants and landlords is required during the tuning process. Once recommendations are made, continuous monitoring must be carried out to ensure the recommendations have been correctly interpreted and implemented. Waiting a month to review results may be too late. An automated real-time monitoring procedure would be ideal!
Building tuning is a continuous process and should not stop after an initial tuning period. As the building user requirements and fit-out changes during the life of the building, so should the building services controls.
The New Zealand government has committed to significantly reduce CO2 emissions, but to date has not presented a clear path on how they will get there. As building tuning can deliver real CO2 emission savings, it should be considered a key strategy to reduce greenhouse gas emissions associated with the existing New Zealand building stock.
Recent funding by the EECA (Energy Efficiency and Conservation Authority) has provided an added incentive to complete building tuning. New building projects can apply for funding assistance through the Commercial Building Performance Advice programme, while existing buildings can apply through the Systems Optimisation programme.
So why isn’t building tuning carried out on more projects?