by Brian Bieker and Ryan Walsh of Ross & Barruzzini
Operating rooms (ORs) are one of the most critical aspects of Hospital Operations. They must be available at all times to support critical operations and procedures. As a result, most hospital ORs operate HVAC systems 24 hours per day.
ORs are incredibly profitable when they are active, but healthcare facilities lose money when they are unused. Operating costs for ORs are susceptible to a variety of factors that affect profit such as disposable medical supplies, drug prescription waste, schedule delays, etc. But one money-saving factor is often overlooked: HVAC systems setbacks.
ORs within healthcare facilities require a significant amount of supply air by code for infection prevention. This airflow is typically 4-5 times more than what is required to meet the temperature and humidity requirements for the space. These ORs are unused for a significant portion of a typical day for a lot of facilities. One St. Louis area hospital was recently assessed and found to only be utilizing its ORs 40% of the hours in a year. There are 8,760 hours in a year. You can do the math, but that is a lot of energy wasted. The good news is that this kind of waste can be prevented. Healthcare facilities can experience significant energy savings by reducing airflows when their ORs are unoccupied.
Reduce Airflow Using ASHRAE Standards & Local Code
ASHRAE 170 – Ventilation of Health Care Facilities is the most commonly used standard for hospital HVAC systems. This standard establishes criteria for the minimum amount of supply and ventilation air, temperature, and humidity requirements to be provided in healthcare facilities. ASHRAE 170-2017 requires ORs to be supplied with 20 Air Changes per Hour (ACH) of supply air and 4 ACH of ventilation air when occupied. These air change requirements have been reduced over time, but many hospitals are still operating at air change rates well over this requirement. In some cases, as high as 30 air changes per hour.
Airflow rates can typically be reduced by as much as 75% when the space is not occupied depending on local codes. Reducing these airflow rates will allow these facilities to achieve energy savings in
- fan energy (reduced airflow)
- heating energy (reheat)
- cooling energy (air handling unit cooling coil, especially for a 100% outdoor air system)
- pump energy (reduced water flow)
The opportunity to reduce airflow rates and achieve energy savings potential will vary depending on the local code requirements and the frequency that the OR rooms are used in each facility.
Airflow Setback Strategy in Action
The St. Louis area hospital mentioned above implemented an airflow reduction and setback strategy for its ORs resulting in an annual savings of $55,000 per year. This facility utilized an occupancy schedule to keep ORs fully active during normal business hours and push button for un-occupied period overrides. In addition to energy savings, the hospital received the added benefit of reduced maintenance and increased system life by reducing the overall demand on the HVAC systems. Local utility incentives were utilized to help fund the project and the overall project paid for itself in less than 4 years.