HVI's Fresh Ideas Home Ventilation & Indoor Air Quality Guide Articles
Ventilating Living Areas
Bathrooms, kitchens and other rooms have individual needs for ventilation.
Proper ventilation of a home's interior living area requires two complementary strategies:
- Applying local, or "intermittent," ventilation in areas with short periods of poor air quality such as bathrooms, kitchens and other rooms using fans that exhaust polluted air to the outdoors. This limits the spread of contaminants to other areas of the home. Sometimes, it's necessary to combine local ventilation with intakes that provide outside makeup air.
- Applying whole-house continuous ventilation for the entire living area using quiet fans or heat or energy recovery ventilators that constantly work to expel stale air and bring in fresh, outside air.
Let's start with the first strategy, applying intermittent, local ventilation.
Moisture control where it's needed most
During a bath or shower, the humidity level in a bathroom can be like that in a tropical rain forest – uncomfortable, hot and damaging – a perfect breeding ground for mold, mildew and microorganisms that can impact your health.
Excess moisture has tremendous potential for damaging the home. It cracks and peels paint, ruins gypsum wallboard, causes exterior paint failure, warps doors and rusts cabinets and fixtures. Without control, it can even cause deterioration of joists and framing above the bathroom. As it condenses on windows, walls, ceilings and cabinets, it attracts dirt and makes more frequent cleaning and decorating necessary. It encourages mildew on tile grout and generally provides an environment for increased bacterial growth.
Exhaust fans, ducted to the outside, remove moisture and prevent these types of problems in bathrooms and spa areas. Not only will occupants be more comfortable after a bath, shower or spa, but the room will also be rid of odors, potentially hazardous aerosol vapors and other pollutants. In addition to healthier air, this minimizes the potential for home damage, saving the homeowner the cost of making repairs to correct problems that were simply preventable.
It is also possible to vent bathrooms with a central exhaust system using inline fans or heat or energy recovery ventilators.
Attractive options to complement every décor
Today, there are many attractive options for bathroom exhaust fans. Existing homes – where old fans may be ineffective and noisy – can benefit from quiet, effective, easily installed upgrades. In new construction, homeowners can use bathroom ventilation products to complement the interior design, in styles ranging from simple to lavish.
Bathroom exhaust fans can remove moisture many times faster than no fan at all. HVI recommends ventilation rates based on eight air changes per hour. For most bathrooms this works out to one CFM per square foot of bathroom area (70 CFM for a 7 x 10 bathroom), but a minimum of 50 CFM is required even for small bathrooms. Fans should be installed as near to the shower as possible and, if marked as suitable for this location, directly over it to capture the moisture as directly as possible. Your fan should have a control that will allow the fan to run at least 20 to 30 minutes after each shower to ensure that moisture levels are reduced.
Cooking and gathering in comfort
Kitchens are one of the most popular gathering places in today's homes. Cozy, comfortable and often connected to living areas, they serve as a place to relax, cook, catch up on daily events, do homework and make plans.
For all the warm images a kitchen may conjure, something hidden lingers – pollution! In fact, kitchens can be a main source of pollutants in a home. Consider all the grease, smoke, undesirable odors, gas cooking by-products and moisture generated during the cooking process – pollutants that cling to walls, ceilings, carpeting, upholstery and drapes – requiring frequent cleaning and all the effort and expense that entails.
An array of products is available to keep kitchens ventilated properly. They include a wide selection of kitchen range hoods, downdraft kitchen exhausters and kitchen fans – all designed to keep the air fresh and the environment comfortable.
Kitchen range hoods and downdraft kitchen exhausters
Kitchen range hoods not only expel heat, smoke, moisture and odors quickly and directly, they are also attractive and useful additions to the kitchen. Today, they are available in a variety of styles, designer colors or metal finishes. They provide bright cooktop lighting, and some models offer a variety of light levels including a subtle nightlight.
Kitchen range hoods installed directly over the range capture heated air, moisture, smoke, gas fumes and odors, while a fan exhausts them through ductwork to the outside. An easily removed and cleaned filter traps grease. A kitchen range hood should be at least the same width as the cooking surface it will serve and be mounted directly over it at a height of 18 to 30 inches above the burners.
For normal cooking conditions, two-speed or variable-speed controls provide a choice of a lower speed and quieter operation. Hoods with a wide variety of sound and airflow ratings are available. The appropriate airflow capacity is determined by evaluating the cooking unit and the occupants' cooking habits. More-demanding cooks usually require more exhaust capacity to handle loads resulting from moisture generated by boiling large pots of water or the grease and smoke resulting from grilling or frying.
What about cooking surfaces in peninsulas or islands? A larger-capacity kitchen range hood can provide better capture when there are crosscurrents and when the hood needs to be mounted higher. Downdraft kitchen exhausters are an acceptable alternative. Larger kitchen range hoods, as well as downdraft kitchen exhausters, are stylishly designed to complement the wide variety of styles of today's kitchens.
The majority of kitchens in newly built homes are equipped with kitchen range hoods. Older homes present an opportunity for new installations to upgrade kitchen ventilation with a kitchen range hood or a downdraft kitchen exhauster. However, if neither is an option, homeowners may select kitchen fans, which will provide good general ventilation in the kitchen. Kitchen fans may be used alone or with kitchen range hoods. They can also provide fresh airflow during periods when the cooking surface is unused.
It is important to note that nonducted, recirculating kitchen range hoods provide no real ventilation – they simply recirculate the air collected from the cooktop back into the kitchen. They do not reduce moisture and have limited value in managing odors. For optimum kitchen air quality, always use kitchen range hoods, downdraft kitchen exhausters or fans, which vent directly to the outside of the home.
Better air everywhere
There are many other rooms in the house that can benefit from ventilation. Examples include laundry rooms, workshops/hobby areas, family and recreation rooms. Removing contaminants such as tobacco smoke, odors, fumes, hot air and humidity from these rooms – thus encouraging air movement and a fresh air supply – provides better indoor air quality for the entire family and protects the home itself.
Ventilation products for use in these areas are similar to those used for baths and kitchens. Consumers will find a wide range of airflow capacities with designs that fit any décor.
One of the most important areas to ventilate is the laundry room. Consider all the mold and mildew that can accumulate in this area from damp clothes, splashing water or other factors. A ducted exhaust fan installed near the washing machine will remove heat and moisture that can make laundry an unwelcome chore.
Clothes dryers must be vented directly to the outside of the house. In many newer homes, the laundry room is located a considerable distance away from the exterior walls, resulting in long ducts and reduced airflow. In these cases, booster fans can be used to ensure proper airflow.