The Attic Effect – How it influences home comfort and energy efficiency

The Attic Effect

How Home Comfort and Energy Efficiency are Affected

What is the attic effect?

The attic effect is the impact the attic space has on your home’s overall comfort and energy efficiency. Three factors are at play.

  1. Warm air rises and cold air sinks. That’s basic gravity.
  2. Temperature naturally wants to balance between two spaces so there is an exchange of hot and cold air. That’s a heat transfer thing. And…
  3. Air movement caused by pressure differences naturally wants to balance itself. High pressure moves to low pressure.

And that, my friends, is the physics of building science.


of all energy loss occurs through the attic and ceiling area. The Department of Energy has called attic insulation one of the most important energy-efficient upgrades a homeowner can make.

This home's air is trapped in the attic. It is not venting properly.

Summer heat.

In the summer, the attic’s midday temperature produces the most extreme temperature difference in your home. This is because your attic’s temperature can climb to 140 or 150 to 170 degrees. Your attic acts like an “oven” that radiates heat, fighting your air conditioners. The hot attic wins most of the day.

Attic with insulation at bottom

Winter chill.

In the winter, it’s the opposite. Heat from the home moves into the attic space. This causes comfort issues in the home, forcing you furnace to work harder. This causes higher heating bills.

Besides the lack of energy efficiency, such conditions can also lead to excessive moisture and problems with mold.  Roof ice damming can also be a resulting problem.

Large icicles are typically the result of ice damming. Ice dams result from the ice build-up of melting snow on the colder eaves and gutters of sloped roofs.

There are three culprits contributing to these attic issues.

The three issues to identify when determining if the attic space has a positive or negative impact on the home’s comfort and energy efficiency are: 1) Ventilation, 2) Insulation, and 3) the Air Leakage Rate between home and attic space.

Air Leakage and Air Sealing

Ceiling breaches (e.g., for wires, lighting and bath fans) and small gaps in construction framing allow air to move freely between attic spaces and living spaces. In the winter, warm air escapes, creating a vacuum effect at the base level of the home.  In the summer, hot air from the attic infiltrates the home through the same gaps, cracks, leaks and penetrations.


A proper thermal barrier, in the form of insulation, slows radiant heat and cold-air conduction transfer in both summer and winter. The insulation’s type, depth and consistency must be calculated to determine the most “effective R-value” of the thermal barrier separating home from attic.

A home energy audit report may recommend additional insulation. It will keep your home cooler in the summer and warmer in the winter.


If the attic deck has been well sealed and properly insulated, then the attic space can be considered a “breathable” area. The key is to have the proper amount of ventilation running through the attic. This is calculated based on the square footage of the attic space. Also, the ventilation must be equally balanced between the high roof vents and the low soffit vents.

The attic effect is the impact the attic space has on your home's overall comfort and energy efficiency.

Solve your home's attic issues.

Take the first step to understand if your attic is costing you money and comfort.

An energy audit evaluates all three attic components. The resulting report identifies the attic’s impact on the home’s comfort, safety and efficiency. The amount and balance of the attic’s ventilation is calculated. The insulation is inspected, and its R-value determined. To calculate the amount and locations of air leakage, a blower door test and infrared scan are performed as part of the home energy audit.

The resulting home energy audit report outlines attic issues and provides recommendations to correct attic problems. Improve your home’s comfort while optimizing energy efficiency.

COMFORTABLE! - An energy audit can help you make your home more comfortable.
Get recommendations tailored to your home to make it energy efficient, comfortable and safe.
Get recommendations tailored to your home to make it energy efficient, comfortable and safe.

Start by scheduling your home energy audit now.

Contact us by email, form or call 720.400.4233.


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