Vibrantcy’s post construction services comprise a significant portion of the company’s workload via one year post-occupancy retro-commissioning (RCx) and energy measurement and verification (M&V). The diagnostics required to perform these services vary based upon building type and systems complexity, however in all cases building automation system (BAS) trends are setup and heavily scrutinized.
When performing RCx services BAS data is evaluated against weather-data, design intent, energy consumption, base energy-loads, and peak energy demands. Correlations among these datasets are drawn based upon the usage patterns of facilities, giving our engineers the ability to recommend small operational changes and set-points to remain within design parameters. In many cases these post-occupancy services lead to improved thermal comfort and reduced HVAC run-time.
More specifically in recent projects for the Central NM Community College, RCx services were performed for 450,000 square-feet of facilities resulting in over 80 energy conservation measures. In a recent post-RCx implementation instance a central chiller was observed to operate 20% less than pre-RCx assessments, extending the useful life of the chiller plant and associated equipment.
Similarly, Vibrantcy’s M&V services have helped facility owners understand the value of capital investments one year post-occupancy. Using data very much like the RCx datasets, M&V requires detailed energy model calibration, using design-phase models to understand how a facility is truly operating. In most instances Vibrantcy’s design-phase energy models are within a 15-20% margin of accuracy, through calibration these models are much more accurate (within 5-10%). Using as-built drawings, submittals, ASIs, and other construction phase information calibrated models allow building owners to determine the replicability of design features for future projects.
In one recent instance measured and quantified documentation of before and after performance suggested an annual savings of $20,086 by choosing the building systems in a Colorado High School. Should the school have implemented other alternative systems than those chosen for construction, they may have saved an additional $13,087, as indicated by calibrated energy models.
Measurable energy savings are best determined when sub-meters are implemented as part of construction, and are accessible subsequent to occupancy. Diligent specifications are necessary in order to develop a useful monitoring and data-archival system, which can produce extremely useful performance data for inclusion in both RCx and M&V analysis. In some cases sub-hourly sub-meter can be used to populate calibrated energy models, which is helpful when performing guaranteed savings calculations through regression analysis.
In either case, RCx and M&V services help building owners and manager gain a deeper understanding of actual systems performance, often spurring small operational recommendations to save significant amounts of energy. We’ve recently completed our 43rd RCx analysis for PNM customers, and would love to share our findings with you!
Matthew Higgins, Founder & Chief Analyst
CEM, HBDP, LEED-AP (BD+C), MBA