Breathe Easy

Natural ventilation used to be the best way to allow fresh outdoor air to replace contaminated indoor air in a home. But because todays energy-efficient homes are air-sealed and built more tightly for heating and cooling control, its essential to have a mechanical ventilation strategy for todays homes.

To maintain a safe and comfortable indoor environment, we must now mechanically ensure that contaminantshumidity, odors, dust, pet dander, grease, mold, formaldehyde and other chemicalsare constantly removed from the building. A proper ventilation system maintains indoor air quality and reduces the probability of mold formation.

There are two general types of ventilation: local (or spot) and whole-house.

SPOT VENTILATION

Spot ventilation focuses on removing contaminants from a specific place at a specific time, such as the ventilating fan in a bathroom that helps eliminate steamy mirrors, foggy windows and stale odors. Architects, builders and designers should consider a number of factors when installing a bath fan for spot ventilation use.

The Home Ventilating Institute (HVI) recommends that fans should have airflow of roughly 1 cubic foot per minute (cfm) for every square foot of a bathroom area up to 100 ft. For bathrooms larger than this, HVI recommends a ventilation rate based on the fixtures present in the bathroom, with a basis of adding together 50 cfm for each traditional appliance (toilet, shower and so on) and 100 cfm for larger items such as a jetted tub. If additional showerheads are installed, additional or increased ventilation should also be installed. These are rules of thumbgenerally, more cfm will take care of issues faster.

The loudness of the fan is also important to consider. Sound levels in fans are measured in sones, with lower numbers being quieter. A typical builder-grade fan is 4.0 sones while any fan rated at 1 sone or less is very quiet (1 sone is roughly the equivalent sound of a quiet refrigerator in a quiet room).

The HVI recommends that a fan remain on for a minimum of 20 minutes after each use of the shower or bath. Using a timer can help ensure that the bath fan is on for the allotted time needed. For those of us who may be hesitant to turn on the fan for fear of forgetting to turn it off, timers are great alternatives. Another great substitute to a fan switch is a humidity-sensing fan, which automatically turns ON when humidity rises and then turns OFF when the humidity returns to normal. This is a great solution for a bathroom used by the kids, who are notorious for forgetting to turn on the fan. Some models that have the sensor incorporated right into the fan itself are particularly effective as they sense humidity at the ceiling, where it is the most concentrated, and are triggered by a change in humidity over time rather than a set humidity level. These fans are also adjustable in terms of sensitivity and time delay.

Bath fan/light combinations are another great option. A builder can complete two remodeling tasks, lighting and ventilation, with one unit, and homeowners are always eager for a product that can fix multiple household issues at once. Many of these bath fan/lights come in decorative models that blend with existing fixtures but are actually fully functional ventilation fans. On top of that, theyre very easy to install. A fan/light can be installed in the same footprint of the existing fan, which means you can use the original wiring and wall switch.

WHOLE-HOUSE VENTILATION

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Breathe Easy