Healthy Residential Air Through Proper Ventilation
The Need for Fresh Air
Modern construction practices have resulted in much tighter houses than those built just a few decades ago. As a result of homes being built tighter, indoor pollutants are trapped and have nowhere to go, and thus creating an unhealthy environment. As healthy homes have become a top priority for homeowners Broan-NuTone® has developed innovative ventilation products to improve indoor air quality. Let’s explore a few options.
Code and Standard Basics
As building practices have evolved the need to ensure good air quality has increased. As a result, homes must be equipped with ventilation that meets code. ASHRAE 62.2 is a residential ventilation standard that is revised every three years. It recommends requirements for both spot/local ventilation in bathrooms and kitchens and whole home, continuous ventilation.
Ways to Achieve Fresh Air
Spot ventilation requirements for the bathroom and kitchen are straightforward. Bathrooms require a minimum of 50 cfm delivered and kitchens 100 cfm delivered. Whole-home mechanical ventilation requirements are generally less well-understood. The idea is to deal with whole-home indoor air quality by continuously exhausting stale air while bringing in fresh outdoor air. The basic formula to determine the amount of air exchange needed is based on the home's square footage and the number of bedrooms. There are three different types of systems for WHMV to choose from: exhaust, supply, and balanced.
In the exhaust approach, stale air is pulled out of the home with a ventilation fan. The home is somewhat depressurized, allowing fresh outdoor air to naturally make its way in through small holes in the building envelope. Generally, this approach is low cost and low maintenance.
Many builders and contractors consider this to be a convenient way to add WHMV to a home, especially since new exhaust ventilation fans are generally quieter and more energy efficient.
The supply approach works in the opposite way. Fresh outdoor air is pushed into the home, thus pressurizing it, and forcing the stale air out of small holes in the building envelope. This method is more popular in the southeast, with higher humidity levels. There are two basic options for deploying this approach. Central fan-integrated systems and dedicated fan. The advantages are that it uses less energy, and the airflow is more controllable and measurable.
The third type of WHMV is a balanced system. This type is the most preferred for optimal indoor air quality as it combines a mechanical means to both exhaust and supply air. The home is neither pressurized nor depressurized and is, therefore, the most ideal for today's tighter homes. The most energy-efficient approach is to use a heat recovery ventilator (HRV) or energy-recovery ventilator (ERV). These systems mechanically exhaust stale air and introduce fresh air. Most importantly theypass the two airstreams through a core that recovers most of the temperature and/or humidity difference. This pre-tempers the incoming air and minimizes losses of already heated or cooled and dehumidified indoor air.
About Broan-NuTone® LLC
Broan-NuTone® LLC is North America's leading manufacturer and distributor of residential ventilation products including range hoods, ventilation fans, heater/fan/light combination units, balanced ventilation systems (IAQ), built-in heaters, attic ventilators and residential built-in convenience products including doorbells and central vacuum systems. Broan-NuTone® LLC is proud to be an ENERGY STAR®, partner.
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