Humidity
Humidity is measured in percentage of relative humidity. This is the amount of moisture in the air compared to how much moisture the air can hold at any given time.

The higher the humidity, usually the more uncomfortable you are in the cooling season. However, higher levels of humidity can make us feel warmer in the heating season.

If the relative humidity is too high, moisture problems can develop. Fungus can grow, dust mites thrive and a host of other undesirable conditions can occur. If the relative humidity is too low, we lessen those effects, but could have static electricity, skin disorders, nose bleeds, etc. Humidity must be controlled for us to feel comfortable and healthy.

Lennox recommends 25-50% as being the optimum range for comfort and IAQ issues.

Often air conditioners control a good portion of the humidity during the warmest months, however, dehumidifiers may also be helpful. Most home owners choose portable units. In the most extreme cases, an automatic whole house dehumidifier can be installed as a permanent part of most home comfort systems. This has successfully served homes with greater moisture, mold and mildew issues, but is more costly. Two major advantages are: 1) it empties through a permanently installed drainage pipe, requiring little physical labor; and 2) it serves the entire home through your home comfort system, rather than just the closest areas.

Whole House Humidifiers are a very affordable option for increasing and maintaining desired humidity levels during colder, drier months. The major advantages are: 1) there is never a bucket to re-fill; and 2) it reaches all areas of your home through your comfort system, rather than the limited area that stand alone humidifiers reach.

Duct Work-Duct Issues-Air Flow
The duct system is the conduit for moving conditioned air throughout the house. Installers spend more time on this during the construction process of a new home than any other part of the heating and cooling system.

Good installation practices are very important:

• Strapping and supporting ducts should be firm so duct work stays intact for the lifetime of the home.
• The straighter the installation, the better. If ducts are crooked or have many bends, the blower has to work very hard to move air through the duct. The solution is a straighter shot, not a bigger blower. It is much easier to get air flowing in a straight line as opposed to having it continually change direction.
• Ducts should be sealed well at every joint. Sealing ducts prevents dust from being sucked into the system. Equally critical, if it leaks air, it’s not good enough. Air flow to distant areas of the home will be compromised and energy wasted on conditioned air that escapes on the way to its destination. (Would you like a straw with holes in your favorite soda?) Return air ducts should also be made of sheet metal and completely sealed. They should not just use joist space as it is not tight enough.

If duct cleaning is necessary, there are two basic methods: 1) rotating brush with a vacuum connected to it; and 2) negative pressure system that uses brushes, whips, or airflow to move the dust to a remote vacuum system (often mounted on a truck.)

Ideally ducts should never require cleaning. Having said that, we recognize that we do not live in an ideal world. The key is to install ductwork well with appropriate sealing, perform regular maintenance, and properly include filtration in the home comfort system.

There are solutions available to homes with even the most complicated ductwork issues. Homeowners are often pleasantly surprised to learn there is hope. Finding the source of the problem with a Flow Hood Test or Whole House Comfort Check-Up, are excellent places to start.

Filters
Particulate is a fancy name for dust. It is basically anything that can become airborne that we can breathe in our home. We breathe in dust everyday, and our bodies have their own filtering system. The hairs in our noses and the mucus membranes help filter dust and keep our lungs clear.

Problems occur when dust becomes so small that our bodies cannot do an adequate job of filtering. Air in our homes can contain tremendous amounts of this very fine dust, causing respiratory problems in adults and children.

Solutions involve improving the home filtering system as well as getting to the source of the particulates and eliminating the problem.

Filtering systems may be improved by changing the filter on a regular basis, upgrading the system to handle a better filter with a higher MERV rating, or adding on a specialized filtration product such as a HEPA bypass filter or Electronic Air Cleaner (EAC).

Ultimately, the source of the problem should be corrected. This involves testing the home with diagnostic equipment developed by Department of Energy Scientists, then determining home improvements to seal where particulates may be entering.

Ventilation
Ventilation is one of the most overlooked areas of the home comfort system. As homes get tighter and the products homeowners use in their homes become more toxic, this becomes an important issue. It is estimated by the EPA that the air inside the home is 40 to 100 times more polluted than outdoor air. Inside today’s tighter homes, both moisture and pollutants are being formed.

The moisture comes from cooking, washing clothes/dishes, and taking showers. Even our breathing contributes.

Other pollutants can include the very materials from which the home is constructed; insulation, plywood, particleboard, foam sealants, caulk, paints, carpets and glues. All of the products when exposed to higher temperatures or humidity will off-gas at higher rates. Off gassing is when these products let off VOC’s (Volatile Organic Compounds) into the air we breathe.

Recommended methods for controlling these VOC’s are:
1. Removal of products from the living space
2. Ventilation

Heat Recovery Ventilators (HRV) or Energy Recovery Ventilators (ERV) can be used to provide ventilation. They temper the incoming air by running it side by side through a heat exchanger core.