This blog series is focused on different methods to evaluate and reduce energy consumption of buildings. The demand for energy is increasing at an alarming rate and the building sector is one of the largest consumers of energy; gaining more and more prominence over the past few decades. Retro-commissioning is a proven process to help combat this problem. Let’s start with a quick overview of what building commissioning is.
Commissioning is a quality assurance process that provides documented confirmation that a building is operating at optimum level of the owner’s requirements. Commissioning ensures that building systems are planned, installed, tested, operated and maintained the way the owner intended. Commissioning often provides:
• Increased energy efficiency
• Maximized occupancy comfort
• Extended life cycle of equipment
• Reduces O&M costs
During the retro-commissioning process, existing building systems are inspected for physical, functional and performance conditions. All issues are documented and presented in a comprehensive report to the owner. Diagnostic test equipment is used to assess existing equipment efficiency and operating characteristics. This analysis is used to identify opportunities for energy conservation. The retro-commissioning process usually occurs in four distinct phases as illustrated below:
A research study on commissioning and retro-commissioning performed by Lawrence Berkeley National Laboratory in 2009 found that the average retro-commissioning project cost $0.30 per square foot with energy savings of 16% and with a simple payback of 1.1 years. Which brings us to the glaring question, why isn’t everyone doing this? Some possible reasons could be unfamiliarity with the retro-commissioning process and fear of any upfront costs. In order to overcome these hurdles, many cities across the nation are recognizing the importance of retro-commissioning/energy audits and are developing legislation that makes it a mandatory procedure. For example, New York City has developed PlaNYC, an agenda to meet energy challenges to building a greener, greater New York. Included in this plan is Local Law 84: Benchmarking and Local Law 87: Energy Audits and Retro-commissioning. In my next blog, I will discuss these laws in detail.
Do you have any questions regarding retro-commissioning? Drop me a line in the comments section below!
Now that we have an understanding of what ASHRAE is, let’s discuss how their standards are applied, particularly with the retro-commissioning process.
When it comes to maintaining a building, it is important to keep up with the continuous environmental and economic factors attributed to occupancy and utilization patterns. This blog series is intended to highlight the different trends and avenues towards reducing a building’s carbon footprint for an optimized and energy efficient building system. We have identified that buildings present the best opportunity to make a large scale impact towards reducing energy usage. In my earlier posts, we have discussed energy audits and benchmarking as great starting points to access your building’s energy consumption and as a pathway to understanding the functionality of a building. ASHRAE has led the way in providing standards and guidelines to conduct an energy audit, benchmarking and, commissioning and retro-commissioning.
Energy auditing is a practical tool to help determine capital improvement plans. Developing a plan to replace outdated equipment with energy efficient measures is a great way to reduce energy costs. However, this method’s initial costs tend to be higher and return on investments (ROIs) take longer than those of retro-commissioning.
Retro-commissioning enables you to improve the performance of your existing systems by helping you to return your building to optimum performance. It is the number one process that can provide energy efficiency, improved tenant comfort, training for operations staff and improved documentation. Retro-commissioning is a systematic process for optimizing the energy efficiency and operations of existing base building systems. Adjustments that occur throughout this process include, but are not limited to: repairs of defects, cleaning, adjustments of valves, sensors, controls or programmed settings, and/or changes in operational practices. These items are typically low cost to no cost measures that yield high ROIs. Median commissioning costs: $0.30 and $1.16 per square foot for existing buildings and return on investments are typically 13%-15% with payback times of anywhere between 1.0 and 4.2 years. In some cases you are seeing cash on cash returns of 91%.
Good candidates for retro-commissioning include underperforming buildings, older buildings and facilities with large loads. Do you manage and/or own any of these types of buildings? What are common problems you are experiencing? Share your thoughts in the comments section.
In my next blog, I will be walking you through the retro-commissioning process and going into details about each of the four phases.