The Green Home

Seasonal allergies inside? Look to home's air quality

Posted May 18, 2012

Early summer is a wonderful time of year – sunny warm weather, blooming flowers and lots of outdoor activities to keep families busy. Unfortunately, it’s also peak season for allergy sufferers.

If it seems like you get an unending cold at the same time every year, the culprit might be seasonal allergies, or hay fever. In the spring, tree pollen is the primary culprit in triggering hay fever, although in more humid areas outdoor mold can also spawn similar symptoms. With so many allergy causing particles in the air outside, allergy sufferers often retreat indoors, not realizing that their home can exacerbate instead of alleviate the runny nose, itchy eyes and sneezing.

Air seals in your home

Previously in this blog, I’ve talked about your home’s “envelope” – the seal around your home that helps to regulate the air intake and exhaust from your house. The envelope is comprised of many parts – windows and doors, attic and fan vents, the HVAC system and the rising air flow from the crawl space under the house.

A well-sealed envelope around your home ensures that you’re able to not only control your heating and cooling more effectively (improving your home’s energy efficiency), it also helps to seal out allergens that cause problems in the early summer.

Benchmarking your home’s air leakage

One of the first steps to reducing indoor airborne allergens is simply measuring the air leakage of your home. Reputable home contractors quantify this by performing a blower door test.

A blower door is a powerful fan that mounts into the frame of an exterior door. After closing all windows and opening all interior doors in the home, the fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings. The auditors may use a smoke pencil to detect air leaks. These tests determine the air infiltration rate of a building: how much outside air is passing unfiltered or uncontrolled into the home, often carrying pollen or mold with it.

Resolving air leakage

Steps taken to resolve air leakage vary depending on the home’s issues, and may include replacing and/or re-caulking windows or doors, sealing crawl spaces, or improving duct work in the house. By ensuring that all unintentional air leakage into (and out of) the home is repaired, the contractor can then focus on the systems which regulate the air intake into the home, namely the HVAC systems. The contractor will make sure that the heating and air conditioning units are the proper size the home, and that the filters are properly configured to reduce airborne allergens entering the home.

Indoor Allergens

Although these steps resolve the problem of outdoor allergens entering the home, what about indoor allergens?

If allergy symptoms persist throughout the year, instead of just being seasonal, homeowners should have their home evaluated for indoor problems. Most commonly, a contractor performing an energy audit may discover indoor mold in the attic, moisture issues in the crawl space, or even simply an extreme buildup for dust and particulate in the duct system – all of which can be easily fixed and immediately solve the never-ending allergy problem that’s plaguing the homeowners.


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About this Blog:

Bobby Ferrel, founder of Green Horizon oversees The Green Home blog. Ferrel is co-founder of Green Horizon, with offices in the Triangle and Charlotte, offering home owners and builders a one-stop shop for energy efficiency and green building. Services include home performance assessments, weatherization, closed crawl spaces, all types of insulation, HVAC and geothermal installation and maintenance. Reach Bobby directly at or visit him online at