Attic Ventilation Savings Tips
No-to-Low Cost Improvements
- Your home needs ventilation - the exchange of indoor air with outdoor air - to reduce indoor pollutants, moisture and odors. Contaminants such as formaldehyde, volatile organic compounds, and radon can accumulate in poorly ventilated homes, causing health problems.
- Excess moisture in a home can generate high humidity levels which can lead to mold growth and structural damage to your home. To ensure adequate ventilation, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) notes a home's living area should be ventilated at a rate of 0.35 air changes per hour or 15 cubic feet per person per minute, whichever is greater.
- Heating ducts in the attic move air to and from a forced air furnace or heat pump and are often big energy wasters because they are not insulated properly. Even if your system is new, ducts running through the attic may have leaks before the system is even turned on.
Improvements requiring investment
- The greater the R-value of your insulation, the more heat flow is reduced, saving you energy. In Missouri, the DOE recommends a minimum of R-38 to R-60 in the attic.
- Heating and cooling ducts often suffer from air leakage through cracks in the ducts, joints and registers.
- Sealing your ducts to prevent leaks is even more important if the ducts are located in an unconditioned area such as an attic or vented crawl space.
- Attic blankets installed either on the bottom of the rafter or under the shingles reflect heat allowing the home to be cooler in the summer and warmer in the winter.
- Shading and evaporative cooling from trees can reduce the air temperature around your home. Studies conducted by the Lawrence Berkeley National Laboratory found summer daytime air temperatures to be 3° to 6°F cooler in tree-shaded neighborhoods than in treeless areas.
Other saving tips to consider
- Focus first on sealing ducts that run through the attic, crawlspace, unheated basement or the garage.
- In Missouri, the DOE recommends a minimum of R-15 to R 21 in outside walls.
- When selectively placed around a house, trees provide excellent protection from the summer sun and allow winter sunlight to reach and warm your house. Consider the height, growth rate, branch spread, and shape when choosing a tree. Trees can be selected with appropriate sizes, densities and shapes for almost any shading application.
- Trees that lose their leaves in the fall are the most effective at reducing heating and cooling energy costs.
- A cool roof is one that has been designed to reflect more sunlight and absorb less heat and can be painted with a reflective type of paint. Cool roofs will reduce air conditioning costs by reflecting the heat from the sun and, by reducing roof temperatures, may extend the life of the roof. Cool roofs can be as much as 50 degrees cooler than a dark roof, so climate should be a factor with considering cool roofs.