Inconsistent and low ventilation rates lead to a build up of airborne pollutants such as volatile organic compounds (VOCs) that can be harmful to human health. Adverse affects of poor ventilation can include sick building syndrome and other respiratory illnesses (Seppanen et al, 1999, Wargocki et al. 2002, Erdmann et al. 2002). The American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) Standard 62.1-2004 (ASHRAE, 2004), as well as the State of California Building Standards and Occupational Safety and Health Codes require a minimum ventilation rate of 15cubic feet per minute (CFM) per person (CA Title 24, 2001; CA CCR Title 8, 1995) in classrooms. Current RC ventilation rates often do not meet these requirements and thus VOCs and other pollutant concentrations in classrooms can frequently be found at elevated levels. As it is difficult and expensive to measure levels of many other indoor air pollutants directly and in real time, indoor carbon dioxide (CO₂) concentrations are often used as an indicator for indoor air quality. High levels of CO₂ in occupied rooms imply poor ventilation and increased pollutant concentrations while lower levels of CO₂ correspond to increased outdoor air supplied to the classroom and decreased levels of indoor pollutants.

A contributing factor to low ventilation rates, the high levels of CO₂ and other compounds in RCs is the manner in which HVAC systems are currently operated. The CARB/CDHS (CARB/CDHS 2003) study found that about 60% of teachers turned off their RC ventilation system during class time due to the high level of noise generated by the system thereby reducing the amount of classroom ventilation. Because of this the advanced HVAC system is being designed to significantly reduce operational noise levels when compared to currently available HVAC systems. This will allow the new HVAC system to continuously operate and provide ventilation to the RC without producing distracting levels of noise.

In addition to reducing noise, the IVSE study hopes to show that the new HVAC system uses at least 30% less energy than the 10 Seasonal Energy Efficiency Ratio (SEER) systems within varying climate conditions in California, while at the same time providing sufficient outside air ventilation to RCs so that CO₂ concentrations can be maintained below 1000 ppm.

The current IVSE HVAC system under development is being designed to be interchangeable with systems that are currently in use. The reason for this is that the ability of the new system to work with existing RC HVAC configurations will speed up the market transition from current HVAC systems to new advanced HVAC systems. In addition, it will also reduce the cost of replacement and the financial burden placed on school districts that choose to replace their current RCs HVAC systems. In order to maximize the speed of the transition throughout the HVAC industry, a public specification for of the advanced HVAC system will be available after the analysis of the field study data is completed so that other manufacturers of HVAC systems can make similar improvements.

Study Goals