By: Nick Neiley
INTRO: Horizon Engineering Associates, LLP (HEA) provided building commissioning services for a large, higher education, laboratory facility. HEA was able to identify a major deficiency regarding the operation of the teaching laboratories.
PROBLEM: There are 23 teaching labs in the project scope that were outfitted with keyed occupancy switches. The intent was that the end user would turn the key switch for the fume hoods to unoccupied mode manually when the labs were not in use. During testing, HEA found that the key switches were not being used and had been locked in occupied mode. This resulted in the labs operating at full occupied airflow 24/7.
SOLUTION: HEA reviewed with the Owner and it was determined the best course of action was to use a combination of time schedule, occupancy sensor status and key switch position to automatically set airflows through the building automation system to occupied/unoccupied mode. All three inputs were required to be active to place the lab at occupied airflow ensuring that the space was only at maximum airflow when needed.
RESULTS/ENERGY SAVINGS: This change will result in minimum energy savings of $128,000.00/year with the potential for over $200,000.00/year of energy savings. These savings cover the cost of commissioning the project in a little over 6 months.
OA cost per cfm $6.00/year
Total CFM reduction in unoccupied mode 42,000 cfm
Maximum savings based on 12 hours of occupancy 7 days a week -$128,000.00