When the seasons change homeowners need to make sure that their heating or cooling systems can perform efficiently even when outdoor temperatures are extreme. This focus on the HVAC system may lead to the neglect of another important aspect of seasonal indoor comfort: ventilation. All year round, ventilation in your home can boost comfort levels by improving indoor air quality and helping maintain proper levels of humidity.
Why is Ventilation Important?
In many modern homes, the building's seal has been improved to make the entire structure more energy efficient. This includes sealing sources of air leaks, increasing insulation, installing energy efficient doors and windows, and preventing air loss through the HVAC system. These sealing techniques minimize the waste of conditioned air or energy. Unfortunately, a tightly sealed home often has insufficient amounts of ventilation.
Limited indoor ventilation can lead to three major issues:
- Poor indoor air quality: Reduced ventilation means there is little movement of air in and out of the house, so stale indoor air is not being removed and fresh outdoor air can't enter your home. This air stagnation creates a greater chance that indoor air will contain particulates, such as dust, pollen, fibers, tiny metal or wood fragments, mold spores, and other microscopic solids or liquids. Fumes and odors are more likely to be present, including substances such as formaldehyde, radon, volatile organic compounds, and sometimes even carbon monoxide. These substances can cause allergy or asthma attacks, as well as other health issues.
- Increased indoor moisture and humidity: In order to feel comfortable inside your home you need a certain level of humidity in the air. However, when there is not enough ventilation creating air circulation throughout your home, there is a greater chance that moisture will build up enough to cause problems that can affect your health and the structure of your home. Moisture produces an environment in which mold can easily grow; mold and mold spores can be extremely harmful to respiratory health. Other potentially harmful living things, including bacteria and insects, can thrive in moist environments and spread throughout your home. In an overly moist environment, your belongings can be damaged. In serious cases, excess moisture can cause damage to the framework and structure of your home, to insulation, and to walls and flooring.
- Excessive heat accumulation: During the summer, heat can accumulate in attics and in rooms that receive substantial amounts of sunlight. Extreme heat in attics can damage the building's structure in that area. At the same time, the heat will radiate downward into your home, increasing indoor temperatures that make your indoor spaces uncomfortable. Your cooling system has to work harder to compensate for that extra heat, which drives up your monthly energy bills. Excess wear on air conditioners and heat pumps can also mean a greater likelihood of equipment breakdowns.
There are several effective ventilation processes you can use to remove both heat and moisture. Some of these techniques are more appropriate in summer, while others may affect the energy efficiency of your well-sealed home. However, you can combine these ventilation methods throughout the year to create the indoor air circulation your home needs.
Natural ventilation is easy and simple to accomplish. It often requires nothing more than opening windows and doors to let fresh air in and stale air out. Breezes help improve the process and the amount of air that gets circulated. Placing a box fan in the windows can also help pull in more fresh, cool air. Natural ventilation is best used when outdoor temperatures are mild and humidity levels are low. Remember that opening doors and windows can eliminate the benefit of your home's energy-efficient seal, so use this ventilation technique only when your HVAC system is not running.
Sometimes, even natural ventilation will not be sufficient to provide enough air circulation. In cases like this, mechanical ventilation will have to be used to boost airflow. Mechanical ventilation includes equipment such as fans and specialized ventilation devices.
Mechanical equipment makes it easier to produce whole-house ventilation, which is intended to improve air quality and reduce moisture throughout the entire space of your home. Energy recovery ventilators (ERVs) are among the more common type of whole-house mechanical ventilation systems. They allow you to have plenty of air circulation in your home during all seasons without worrying about losing excessive amounts of heated or cooled air in the process of ventilating your indoor spaces.
The two main types of ERVs are heat-recovery ventilators (HRVs), also known as air-to-air heat exchangers, and energy-recovery (or enthalpy-recovery) ventilators. These devices work by pulling stale air out of your home and bringing fresh outdoor air inside. The two air streams are directed through a heat exchanger, where they pass close together without mixing. In the winter, outgoing warmer air heats the incoming cooler air. In the summer, incoming warm air is cooled by the outgoing indoor air. This process ensures that incoming ventilation air is preconditioned by the air that is leaving your home. As a result, your furnace or air conditioner does not have to work as hard to heat or cool incoming air to indoor temperature levels.
Energy/enthalpy recovery ventilators work similarly, but they transfer a small amount of moisture to incoming air. This is useful in hot, dry climates or during the winter when dry air is more common.
Spot ventilation is designed to improve ventilation in a smaller area, such as a specific room in your home. This type of ventilation uses exhaust fans to remove heat, moisture, and odors while increasing air circulation in the area. Kitchens and bathrooms are two of the most common locations where spot ventilation is used.
- Kitchens: Many of the activities required for preparing and cooking food, as well as cleaning kitchen surfaces, generate heat and moisture. Cooking can also generate odors that can become stale or unpleasant if they are not vented away. Kitchen exhaust fans, often installed either in the range hood of your cooking equipment or in the side of the wall, improve ventilation and remove any heat, moisture, and odors.
- Bathrooms: Bathrooms are probably the wettest and warmest rooms in your home. This consistent production of heat and moisture can lead to mold growth, encourage insect populations, and cause damage to the building structure inside the bathroom. Bathrooms usually have a ventilation fan installed either in the wall or in the ceiling, leading to vent pipes that direct heat, moisture, and odors out of the bathroom space. Make sure your bathroom ventilation fan is powerful enough to provide sufficient ventilation. On average, an average bathroom fan should draw out air at a rate of 50 cubic feet per minute, or 25 liters per second. Larger bathrooms will need correspondingly larger and stronger fans.
Heat commonly radiates into your attic through your roof. If your attic is uninsulated or unfinished, the likelihood of excessive heat buildup is even higher. Moisture gets into attics from sources such as holes and leaks in the roof, water vapor entering from both indoor and outdoor sources, and by air currents.
Look for signs of attic moisture, such as:
- Damp or wet insulation
- Warped, damaged, or rotting wood
- Mold or mildew on surfaces
- Warped shingles at roof's edge
- Bubbled paint on the boards and surfaces between the house wall and the underside of the eaves
You can improve conditions in your attic by:
- Using attic fans: Attic fans are extremely effective at removing both heat and moisture from your attic spaces. They are intended to move air out of your attic space alone and are not intended for whole-house ventilation. They produce air circulation that replaces the entire volume of air several times over a specified period. The most effective attic fans should be able to replace the area's air at least 10 times per hour.
- Installing attic vents: Ridge vents or rafter vents will improve attic ventilation. They should be placed at the location where the ceiling and attic floor connect. Soffit vents can also help with attic ventilation. When installing these types of vents, expect to put in 1 square foot of ventilation for every 300 square foot of attic space.
- Stopping moisture infiltration: Make sure your moisture-generating appliances are not vented into the attic. Instead, redirect their airflow directly to the outdoors. Seal leaks, cavities in the attic floor, and other areas where water can get into the attic.
- Installing insulation: Put sufficient amounts of insulation in the attic walls, floor, and ceiling to prevent heat accumulation.
Winter or summer, Comfort24-7 can help you with any HVAC needs in northwestern Indiana, southwestern Michigan, and the Chicago, Illinois area. Contact us today for more information on home ventilation for better air quality in every season of the year.
Written by Randy Gailit