Home Air Sealing: The Best Path to an Energy Efficient Home

Sealing Air Leaks Can Save 25% on Utility Bills.

Most homes leak so much air, it's equal to leaving a window open 24 hours a day. Energy Star notes that air leakage accounts for 25% - 40% of residential energy usage per day.

If you need more protection than standard home insulation, effective air sealing is the answer — no matter where you live. Air sealing a home protects from warm air infiltration in hot climates, and keeps valuable heat from escaping your home during cold winter months.

We spoke with Dr. Sarma Pisupati, Professor of Energy and Mineral Engineering at Penn State University. Dr. Pisupati is a leading expert on energy efficiency and heat loss. He provided valuable insights on proper air sealing, heat loss and home insulation.

Here's what we'll cover in this guide to home air sealing:

• Home air sealing has DIY solutions. If you're a DIYer, start your air leak search with a quality thermal camera. These cost between $150-200 apiece and help diagnose the location of drafts.
• Hiring an air sealing professional? Ask for a blower door test to diagnose thermal transfer problem spots. Your contractor may credit this cost towards other home energy efficiency improvements.
• Older homes are most prone to air leakage. If your home was built before 1971, it wasn't subject to modern insulation requirements. Most homes over 50 years old have significant deficiencies in attic insulation and basement insulation..
• Air sealing your home has health and financial benefits. The average payback period on $500 of home air sealing is under 2 years. Insulation companies report reduced asthma and allergic concerns from customers who seal their homes.

Home Air Sealing: Gaps Matter, Even Small Ones.

The key to effective air sealing is locating gaps between unconditioned and conditioned spaces. These gaps can be located in several areas of your home:

• Deficient or worn-out insulation
• Doors
• Windows
• Vents

Gaps cause warm air and cold air to circulate between unconditioned spaces and conditioned spaces. This forces your HVAC system to work harder — and your energy bills to increase.  

Dr. Pisupati explains that upgrading one facet of your home's insulation isn't enough to solve the problem. “You may have the state-of-the-art window," he says,  “but even a 1/16” gap between the wall and the window is killing the R value overall."

Start every home energy audit — DIY or pro — by finding and diagnosing the gaps and drafty areas in your house.

2 Effective Ways to Find Drafts in Your House

Whether you're a DIYer or hiring a pro, identifying air leaks starts with one primary step. They'll help find the gaps in your home where outdoor air leaks in, and conditioned air leaks out.

DIYers: Use Thermal Cameras to Detect Drafts

Prefer the DIY life? Purchase a quality thermal camera to detect air leaks in your home. A good thermal camera costs $150-200 and works in every area of your house.

Be sure to use your thermal camera in these 7 thermal transfer trouble spots:

1. Attic
2. Around vents
3. Exterior wall surfaces
4. Doors
5. Windows
6. Basement
7. Crawl space

Ask Your Insulation Pro for a Blower Door Test 

Professionals now use advanced tools to identify air leaks: Chief among these is a blower door rest — if you're hiring an insulation company, you should pay to have one done.

Blower door tests cost between $225 and $450 in most areas. They may be included in the cost of an overall home energy audit, which costs roughly $375-550.

What's a Blower Door Test: is the gold standard in efficiency testing and is how companies certify their construction is up to code. “They inject air and measure the pressure loss through windows, [and] whatever is not sealed properly,” explains Dr. Pisupati.

Why are our houses so dang leaky?

Air sealing significantly benefits homeowners with older houses. But why are older homes so leaky?

"Before 1971, there was basically no insulation at all —.because there were no [building] standards [for energy efficiency], Professor Pisupati states. 

In the early 1900s, most building codes focused on fire protection, and structural soundness — not on insulation. “But as energy became an important component of our utility bills,” Dr. Pisupati continues, "we needed to become more and more aware of not only that, but the environmental aspects."

Older homes were designed to mask these air infiltration and leakage issues. Dr. Pisupati noted in our conversation that older homes have multiple fireplaces. This wasn't for style — it compensated for how drafty they were.

Attic Air: The Biggest Culprit of Heat Loss

Energy Star and expert insulation reports estimate that 40% or more of your total home heat loss occurs through the attic. This is due to 4 problems:

1. Insulation: Poor insulation causes heat loss through your roof and the attic floor. 
2. Air Leaks: Gaps and cracks around the attic hatch, chimneys, vents, and other openings allow warm air to escape.   
3. Unsealed Ductwork: If your ductwork runs through the attic, it can lose conditioned air.   
4. Poor Ventilation: Insufficient ventilation leads to heat buildup in the attic. This leads to hot air infiltration and decreased indoor air quality.

Properly sealing attic air leaks can reduce your overall home heating and cooling bills by 25%. But the trouble with leaky attics doesn't stop at heat loss — they also affect the indoor air quality of your house.

How Dirty Attic Air Leaks Into Your Living Areas

Your home's HVAC system has 2 jobs: regulate the indoor air temperature, and filter outside air before it reaches your family. 

Unsealed attics allow too much dust, insulation particles and other pollutants into your conditioned air. They put a strain on your HVAC system, and these pollutants make it into the indoor air your breathe.

How to Air Seal Your Home: The Weekend Warrior's DIY Guide

DIY enthusiasts should use the following steps to effectively air seal their homes. This section teaches you in 4 stages:

1. How to identify air leaks in your house
2. The essential materials you'll need
3. How to properly seal problem areas
4. When it's time to call expert insulation services

DIY air sealing isn't for everyone — only attempt these projects if you're extremely handy around the house!

Identifying Air Leaks

We've already explained the value of a quality thermal camera. If you're ready to attempt DIY air sealing, you can also pick up an infrared thermometer. They’re point and shoot, and won’t show you a visual picture, but they work in a pinch. The main advantage? Price: infrared thermometers cost about $30 at most hardware stores.

Choose a day that matches your air loss concerns. If you're worried about losing air conditioning, pick a hot day. If you want to find heat loss drafts, pick a cold day.

Here's how to use your infrared thermometer:

1. Turn on your heating or cooling system.
2. Wait about an hour for temperatures to stabilize.
3. Use the infrared thermometer to check temperatures around your home.
4. Look for sudden temperature changes – these often indicate air leaks.

Focus on these 10 common “hotspots”:

• Window frames and door frames
• Electrical outlets and switch plates
• Baseboards
• Weather stripping around doors
• Fireplace dampers
• Attic hatches
• Crawl space insulation
• Where dryer vents pass through walls
• Recessed lights
• Cable TV and phone line entries

Remember: you're looking for unexpected temperature differences. If an area is significantly warmer or cooler than surrounding areas, it's likely leaking air.

When in doubt, trust your senses! If an area feels drafty, it's probably worth sealing, even if the temperature difference isn't dramatic. Preventative sealing can only save you money in the long run.

Essential Air Sealing Materials and Tools

1. Caulk: Choose a high-quality, contractor-grade polyurethane caulk (e.g., Dymonic, Sikaflex, or Vulkem)
2. Spray foam: For sealing large gaps around vents and other penetrations
3. Weatherstripping: For windows and doors

How to Seal Each Area:

1. Caulk around windows and door frames
2. Seal gaps around electrical outlets and switches on exterior walls
3. Apply weatherstripping to doors and windows
4. Use spray foam to seal larger gaps around pipe and wire penetrations

Did You Know? Dr. Pisupati emphasizes the impact of taking these seemingly small steps: "About 30% of [lost] energy can be saved just by caulking."

When to Call Insulation Pros (and Why)

While many air sealing tasks can be DIY projects, some areas are significantly easier and safer with professional expertise. Call local professional insulation services for these 3 tasks:

1. Air sealing your attic: This typically requires the removal of existing insulation, which should be handled by a professional team.
2. Crawl space sealing: Trust professionals to safely navigate, install or remove crawl space insulation.
3. Complex or hard-to-reach areas: If you wouldn’t send a friend or family member up a ladder or into an area, don’t do it yourself either.

Cost of professional air sealing

Professional air sealing is often more affordable than homeowners might expect. 

The average cost to air seal a 2000 square foot, two-story home is between $300-500. This service is frequently performed as part of a larger insulation project, particularly when sealing the attic.

Given the potential energy savings, many homeowners find that professional air sealing quickly pays for itself through reduced utility bills.

Air Sealing (Almost) Always Pays for Itself

The EPA estimates that the average home air sealing project saves homeowners 25% on annual energy and utility bills. The average payback period on air sealing your house is under 2 years.

Table: Estimated Utility Savings of Air Sealing

Some parts of the country spend more depending on their local climate, but the numbers generally support a strong payback period across all regions.

"The more tight the home is in general, the less energy is lost,” Dr. Pisupati says. “It doesn't matter whether it is cooling or heating. If I live in Boston, it is heating costs. In Houston, it is cooling costs."

Better Comfort and Health

Insulation professionals note that effective air sealing has a net positive effect on your health and well-being. This includes positive trends in respiratory health, allergies, asthma, and pest control.

Impact on Respiratory Health and Allergies

A properly sealed home can reduce the infiltration of outdoor allergens and pollutants, potentially improving indoor air quality. 

An insulation company we interviewed recently told us: “We’ve had cases where asthma and allergies died down after air sealing, because your dust level drops significantly.”

Pest Reduction

Air sealing your home reduces the influx of outdoor air through gaps like vents, door frames and windows. This makes it harder for pests like mosquitoes and ants to enter your home.

Projects to Target After You Air Seal

Dr. Pisupati asserts that homeowners should look into the overall efficacy of their insulation and windows as part of the air sealing process.

"A typical homeowner should look into the tightness of the house,” he explains. “Then they need to go to the Insulation and windows."

Synergy with Insulation Upgrades

Air sealing and insulation work hand in hand. Dr. Pisupati noted this synergy when he built his own home.

"When I built my house, in the basement I used ICF (insulated concrete forms),” he explains. “Typical basement R values would be around R8. If we go for superior windows, superior basements or slabs and things we may go up to R14 or R15. And my R value is 53."

It’s important to follow the right order of operations. Better insulation won’t do as much good in a leaky home with poor air sealing. 

The good news: air sealing is often an inexpensive add-on to insulation replacement quotes. Ask your contractor if they offer this service.

Synergy with Window Upgrades

"Believe it or not, one square foot of a plain glass window can lose as much as at least 60 to 70% of the entire house’s heat loss,” Dr. Pisupati warns.

Going from a single pane to double pane glass can improve your window’s heat resistance by more than 50%

How Air Sealing Affects HVAC Efficiency and Sizing

When you air seal your home, you're not just saving on energy bills – you're also doing your HVAC system a big favor. Here's how:

1. Smaller Systems: With a tightly sealed home, you may not need as powerful a heating or cooling system. A smaller HVAC unit can be less expensive to purchase and operate.
2. Longer Life: When your HVAC doesn't have to work as hard to maintain comfortable temperatures, it experiences less wear and tear. This can potentially add years to its lifespan.
3. Fewer Repairs: Air sealing reduces the workload on your HVAC system. It's like the difference between a car cruising on the highway versus constantly stopping and starting in city traffic. Less stress on the system means more efficient operation and potentially fewer repairs.

Conclusion

Air sealing is the first step in any home efficiency project. From adding solar panels to replacing your windows - stop air leaks before big capital investments. 

Often the costs of these small improvements are pennies compared to large projects and pay themselves back quickly. On top of that you can gain benefits for your health, and the environment too! Good luck with air sealing your house.