Advanced HVAC Technology Demonstration Project to Reduce Natural Gas Use in Hospitals

Ventilation rates in hospitals are higher than in most other building types, resulting in high energy consumption. Hospital designers, operators, and code officials generally assume that these higher rates are necessary to protect patients, staff, and other occupants from infection from the many disease organisms that may be present in a hospital at any given time. However, very little available information justifies the specific ventilation rates in hospital codes.

This project measured airborne contaminant levels in several different spaces within an operating hospital and at varying airflow rates to determine the relationship between ventilation rates and contaminant levels. The intent was to propose that active indoor air quality measurements directly control ventilation rates. However, the research demonstrates that varying the ventilation rate has minimal effect on contaminant levels such as carbon dioxide and particulates. Further, this study concludes that code-required ventilation rates are much higher than necessary for contaminant control and can be significantly reduced without adverse impacts on building occupants.

Reducing ventilation rates in the studied hospital saved 95,000 therms (21 percent) of natural gas and 2.8 million kWh (25 percent) of electricity. Carbon emissions reductions were more than 2,480 metric tons of CO2. Replicating this project in all 340 hospitals in California could save more than 26 million therms of natural gas, 763 million kWh of electricity, and could additionally reduce carbon emissions by more than 670,000 metric tons of CO2 annually. In many cases, the conversion may be accomplished in controls software, so the cost of implementation would be quite low relative to savings.