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Home Performance Terminology

Infiltration and Exfiltration

You pay to heat and cool the air in your home. For every cubic foot of air that leaves the house through cracks and gaps (exfiltration), another cubic foot of air must enter (infiltration). When unconditioned outside air is pulled into the home, it can make the heating system work harder and introduce contaminated air from crawl spaces and basements.

Stack Effect

The Stack Effect is two pronged: it results from warm air rising and escaping through the top of the home as well as cold air being drawn in to replace the warm air that escaped. This driving force actively pushes the conditioned air out of the house. The more air leakage opportunities, the greater the driving force. Two story houses and homes with high ceilings are more susceptible to the stack effect than single story homes with average ceiling heights.

Indoor Air Quality

We spend much of our time indoors. Recent studies have found that poor Indoor Air Quality, or IAQ, are a leading factor to asthma and other negative health effects. Crawl spaces are dirty and can contain moisture, animal waste, gases, dust, insulation fibers and debris; none of which contribute to healthy air. A study from Washington State University found that up to 40% of the air in homes comes from the crawl space. To keep that unhealthy air out of the house, the air leakage opportunities between the living spaces and crawl spaces needs to be properly sealed. Build it tight and ventilate right!

Moisture Movement


Did you know that air currents are responsible for 98% of the moisture and water movement in your home? The removal of bulk moisture through bath and kitchen fans is critical for healthy indoor air quality.


Many homes have large open chases that connect the crawls space and attics. If these chases are not properly sealed, they can pull moisture-laden crawl space air through the home and into the attic.


Once in the attic, the moist air condenses and can cause excessive moisture problems. Air sealing and an effective vapor barrier in the crawl space is the first steps towards a healthy home


Don't be afraid of a tight building shell! Leaky homes use uncontrolled ventilation through gaps and cracks, which can introduce unhealthy air. A tight home with good ventilation will control where the air in your home comes from. Quality bath exhaust fans are a great place to begin. We can help to measure the air flow of bath fans and confirm that they are properly ducted to remove moisture. Homes that test too tight may want to consider better fans with automated controls such as count down timers, humidity sensors or occupancy sensors. Exceptionally tight homes may require fresh air intakes or even Energy Recovery Ventilators (ERV) to provide fresh air to the home and its occupants.


Fans that move air from inside the house to outside (bath fans, kitchen exhaust hoods, dryers, central vacuums) can cause sections of the home (or even the entire home) to become depressurized. This can create a potentially hazardous situation in homes that use natural gas, wood stoves or fireplaces. Severe depressurization can cause these appliances to backdraft. We use diagnostic equipment to identify and provide solutions to these potential hazardous situations.

Insulation R-Values

Insulation comes in many different forms such as fiberglass, cellulose or foam insulation. All forms of insulation are rated with an R-Value. The higher the R-Value, the greater thermal performance. R-Values can be added together to get a total R-Value. R-Values can be greatly diminished if materials are not installed properly. If air leakage opportunities are not addressed prior to installing or if insulation materials are compressed or not in contact with the surface the R-Value is greatly diminished.



Energy Efficiency Rebate & Loan Programs

Most utility companies offer cash incentives or loans to make energy efficient upgrades to your home. You may be eligible for utility incentives for making your home more comfortable and efficient. To find out if your home qualifies and what your utility offers, check the link for the utility that serves your home. Rebate programs are based on the primary heating fuel (gas or electric) used by your home. If you heat with electricity use the link for the electric company. If you heat with natural gas, use the ETO link



Home Inspection Resources

The following videos are from INTERNACHI.

Home Energy Score

What Really Matters in a Home Inspection

Infrared Inspection

Home Performance Resources​

Home Performance can be a confusing and sometimes overwhelming. Here are some links to programs and companies that are dedicated to advancing the Home Performance industry.


Home Performance Video References

The following videos are from Home Energy Pros. 

Ventilation Basics #1

Ventilation Basics #2

Airtight, Tested Right: Blower Door Tests for Contractors

Measured Home Performance: Assessment with an Infrared Camera

Weatherization: Attic Air Sealing

Home Performance Terminology
Home Inspection Resources
Home Performance Video References

Looking for Hazardous Pollutant in Kitchens

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