3 tips on energy audit
1. Three Steps To Improve HVAC Performance: Audits, Retrocommissioning, Ongoing Commissioning
Today's tip from Building Operating Management comes from David Callan and Kyle Hendricks of Environmental Systems Design: Facility managers should consider three steps to improve HVAC performance: audits, retrocommissioning, and ongoing commissioning.
Over time, HVAC systems start to "drift" and performance declines. The good news is that there are a few things owners and facility managers can do to reveal operational deficiencies as well as to enhance performance, to varying degrees. From a simple energy audit to retro- and ongoing commissioning, reexamining the building's HVAC systems is the first step to optimizing efficiency.
ASHRAE's Level I Energy Audit is a general, walk-through energy assessment which identifies immediate options to save energy that are obvious to the naked eye, including lighting, fan operation, and other low hanging fruits. Mainly used to identify if a building should continue to the next step, this will satisfy the LEED-EBOM Energy and Atmosphere energy efficiency best management practices prerequisite.
Retrocommissioning builds on the ASHRAE Level I study. Retrocommissioning is a low-cost opportunity to save energy and optimize performance, helping a facility run the best it can with its current equipment and systems. Ideally performed every three to five years, retrocommissioning includes a review of trend data from the building and testing of the HVAC systems and their sequences of operations, including how each should be reacting to various scenarios.
Retrocommissioning will likely uncover three scenarios: space use changes that necessitate system operational changes; systems that aren't working as they're supposed to; and systems that are working as designed, but can still be optimized with new technologies and strategies. Onsite functional testing will ensure that systems are operating as the controls sequence tells them to, and a review of the trend data will identify opportunities to optimize the parameters that are working as intended. Typically, the higher the energy use of a facility, the more it will benefit from retrocommissioning. For example, a hospital or commercial building with long hours of operation and a significant HVAC load can save as much as 5 percent annually from retrocommissioning efforts.
Ongoing or monitoring-based commissioning is similar to retrocommissioning in that it reveals equipment and scenarios that aren't functioning as designed and those that can work better, but with the added benefit of doing this on an ongoing basis. Continuous monitoring of all points in the system is conducted by a team of engineers, while a weekly download of all information, either to a dashboard or through a software platform with fault diagnostics, alerts the operators when there is an opportunity to make an adjustment. Pre-programmed alerts may include an alarm when a chiller is below a certain efficiency, simultaneous heating and cooling is occurring, or a temperature gets too warm or cold.
Monitoring-based commissioning provides the opportunity to see the long-term operations and re-evaluate the building's systems on an ongoing basis, and therefore makes building optimization more robust, based on more real-time data over a longer period of time. Also, because the process is ongoing by nature, it will prevent HVAC system performance "drift" after the initial opportunities are implemented.
2. Energy Audits: Developing a Plan
This is Chris Matt, Managing Editor of Print & E-Media with Maintenance Solutions magazine. Today's tip is developing a game plan for an energy audit.
Energy audits vary in complexity, so determining the exact scope and content of the audit is an important step for maintenance and engineering managers. Managers need to make sure those conducting the audit look for ways to optimize systems and reduce energy where possible.
The following four tasks help properly focus the auditors' efforts:
Understanding the building and building systems. Performing a walk-through survey of the building provides a better understanding of the facility's construction, equipment, and energy-consuming systems. Managers need to identify opportunities for equipment replacement and upgrades, as well as identify system modifications that might improve the overall performance of a major building system, such as the chilled-water system.
Understanding operation and maintenance. Talk with the engineering and operations staff regarding the operation and maintenance of a building's energy-consuming systems. Identify maintenance problems and practices that affect energy efficiency. Use the building-automation system or energy-management system to better understand the facility's operation.
Analyzing building energy use. Start with a review of utility bills. Managers can use these bills to understand a building's current energy use and, if possible, the trend of energy consumption in years past.
Reviewing utility rate options. Review current utility rates, including monthly demand and consumption charges. Managers also should identify on-, mid-, and off-peak charges.
3. How In-Depth Should My Energy Audit Be?
Today’s tip is about identifying how extensive an energy audit should be
There are three levels of energy audit. The first is focusing on low- and no-cost ways to improve energy efficiency through optimization of existing equipment or through operational changes. Some facility executives regard this as a retrocommissioning, i.e. examining each piece of energy-using building equipment to determine if equipment has gone out of spec. A retrocommission means analyzing and optimizing building equipment to bring it back to as close as new as possible.
A level two energy audit focuses on particular pieces of equipment that may need to be replaced. This means a capital outlay and an ROI calculation. A level 2 audit can logically follow a level 1 audit. In other words, if you identify a piece of equipment that can’t be brought back into spec with a few tweaks, it’s time to make the argument to replace it. And the best way to do that is with an energy efficiency ROI justification.
A level three audit is all the bells and whistles – an investment-grade engineering study after all the low- and no-cost strategies have been exhausted. This is often the most costly and facility executives should have a preconceived set of specific goals for energy savings, and be ready to justify the cost of the study itself on savings it will produce. If you’re already running very efficiently, this may be tough – but it may be the last way to squeeze even more energy out of your monthly bill.
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