Improving Design, Commissioning, Operation and Maintenance in New Residential Ventilation Systems

Single-family and low-rise multifamily homes in the United States have become tighter to save energy and enhance comfort. To ensure acceptable indoor air quality (IAQ), mechanical ventilation is also required. As these systems become commonplace in the U.S., various improvements and updates have been made to codes, standards, and voluntary programs such as ASHRAE Standard 62.2, International Mechanical Code, International Residential Code, USEPA Energy Star Home and Indoor Air Plus, and USDOE Zero Energy Ready Homes. 
This paper will summarize historical and current issues and challenges to improvement related to design, commissioning, operation, and maintenance of whole-house ventilation systems in new single-family, low-rise multifamily, and factory built dwellings. It presents findings from field research over the past 30 years on occupied dwellings. A discussion of improvements that were made, are underway, and may be coming in the future is provided. Incorporating ventilation into codes and standards is a critical path, as are the broader implementation challenges in the “real world” over the dwelling’s useful life cycle. This paper will help to identify what progress has been and needs to be made. 
In the U.S., the most popular ventilation system is an exhaust fan capable of continuous operation. These are often quiet, energy efficient, dual-duty fans that are also used for local exhaust in bathrooms, laundry rooms, or kitchens. Many homes use their central forced air heating and cooling systems to distribute, filter, and temper outdoor air that is ducted directly to the return side of the forced air system, either passively or sometimes with a dedicated outdoor air fan to ensure the correct air flow. These supply ventilation systems are generally harder to commission because air intakes are often not easily accessible and testing is more prone to issues of repeatability.  
The introduction of variable speed blowers may increase commissioning challenges associated with flow rate measurement. Zonal ductless heat pumps may require exhaust fans or balanced dedicated outside air systems, operating in unison while maintaining interior pressure balance, typically using energy recovery ventilators or heat recovery ventilators, with pressure taps and fan calibrations and electronically commutated motors (ECMs). Systems with real time digital flow indicators will assist designers, builders, code officials, and HVAC contractors. Smarter ventilation controls may help to provide improved commissioning, operation, and maintenance, and help stakeholders from design to long-term replacement. 
The paper will highlight opportunities for improvements in control labelling; optimizing designs for different climates; training of HVAC technicians and all critical stakeholders; ventilation controls; and lower-cost, reliable air quality sensors. These improvements must focus on every link in the chain to improve on “build tight, ventilate right