Whole-House Mechanical Ventilation
A whole-house ventilation system with dedicated ducting in a new energy-efficient home. | Photo courtesy of ©iStockphoto/brebca.
Energy conservation over the last few decades in homebuilding has resulted in homes being built “tighter” — in other words more resistant to infiltration by outside air. However, the solution to one problem has created another: the need to get fresh, outdoor air into homes that are sealed against the elements. Unless provided with mechanical ventilation, many existing homes do not get adequate fresh air.
A whole-house mechanical ventilation system can resolve this issue by introducing outdoor air into the conditioned space through dedicated outdoor air intakes and/or through gaps and cracks in the building envelope rather than through window operation. In this configuration, ventilation of the conditioned space is provided by a system of controls, fan(s), duct(s), and damper(s). A whole-house mechanical ventilation system should always be complemented with local exhaust systems that work to remove excess moisture and pollutants generated in the house from activities like cooking, cleaning, and bathing.
There are four major categories of whole-house mechanical ventilation systems: exhaust, supply, hybrid, and balanced. Exhaust ventilation uses a fan to remove indoor air from a building. In a tight house, this creates negative indoor pressure that pulls outdoor air in through dedicated or unintentional openings in the walls, floor, and ceiling. Supply ventilation uses a fan to deliver outdoor air to a building. In a tight house, this creates a positive indoor pressure that pushes indoor air out through dedicated or unintentional openings. Hybrid ventilation systems operate in supply mode at times (generally when the central fan is operating) and in exhaust mode at others to reduce the system’s overall fan energy use. Balanced ventilation uses at least one supply and one exhaust fan to supply and exhaust similar volumes of air, so it does not affect indoor pressure. When balanced systems are equipped with heat exchangers or enthalpy exchangers, they are referred to as “HRVs” (heat recovery ventilators) or “ERVs” (energy recovery ventilators), respectively. For more information on whole-house mechanical ventilation systems, visit http://www.energy.gov/energysaver/articles/whole-house-ventilation.
Whole-house mechanical ventilation is critical in an energy-efficient home to maintain adequate indoor air quality and comfort. Code updates and customer demand are increasing the demand for adequate ventilation to combat indoor air pollution. As many as 30 percent of the houses built in the United States in the next five years could have whole-house ventilation systems, compared with 10 percent or less today.
Need Help Selecting a System – Use Broan’s CodeKey Tool
Broan-NuTone has developed a product selector that helps builders, contractors and architects select home ventilation products that conform to code and green building standards.
“Broan-NuTone is the first manufacturer to offer assistance to builders and other professionals who need to abide by new ventilation codes but may be unsure of which ventilation solution is most appropriate for a project,” said Patrick Nielsen, the company’s marketing manager for ventilation fans.
The CodeKey Whole-House Mechanical Ventilation Specifier is a web-based tool that gathers all of the growing number of statewide codes that affect ventilation standards. It’s designed to help professionals identify code-compliant, customized whole-house ventilation systems based on factors such as site location, square footage, number of bedrooms and whether or not the home is Energy Star V3 or LEED certified.
Go to Broan’s CodeKey Tool