How to Optimize Your Home’s Airflow to Save Money on Your A/C

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Many smart thermostats claim they can save you money on your heating and air conditioning bills. Indeed, you might save a considerable amount of money by getting a Nest or Ecobee3, but they can also cost you more money if your house itself isn’t optimized for good airflow.

If you constantly dread looking at your energy bill every month, it might not be the thermostat causing the problems, so a smart thermostat alone won’t be able to save you. But here are a handful of things you should keep in mind so that your HVAC system is heating and cooling your house in the most efficient way possible.

Don’t Close Too Many Vents

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If the downstairs area in your house is usually cooler than the upstairs, you might be tempted to close most or all of the vents downstairs in order to push all of the air from the A/C to the upstairs. This is actually a really bad idea.

Closing off vents uses more energy, because your system is working harder in order to push past the increased pressure that closed vents create, especially if you have a variable-speed system fan that can change speeds automatically. If you have an older system, then it’s likely that the fan remains at a constant speed, which is still bad news if you close too many vents, as the increased pressure will simply slow down the fan’s speed, resulting in less airflow.

Plus, if your ductwork isn’t sealed (which it most likely isn’t), then that increased pressure can also push out fresh heated or air conditioned air through the small cracks in the ductwork and into your attic instead of your living space.

On paper, closing vents to push air to places where it’s really needed makes a lot of sense, and it should work, but because of how HVAC systems are designed, it’s actually the direct opposite. This is why smart vents are mostly a bad idea.

You might be fine closing a few vents around the house, but even then, if your HVAC system and ductwork are old and inefficient, it’s probably not ideal.

Keep an Eye on Your Air Filter

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Most air filter manufacturers will tell you to change out your system’s air filter every three months, but depending on how often you run your heating or A/C, you may need to change the air filter more often. A good rule of thumb is to check it every week and replace it when it gets visibly dirty.

Also, take into account the thickness of the air filter. Each one comes with a MERV ratingwhich stands for Minimum Efficiency Reporting Value. This is technical speak for how good the air filter is. A MERV rating of 1 is the worst rating, while a MERV rating of 16 is the best. What this means is that a MERV 16 air filter will catch more dirt, dust particles, allergens, etc. than a MERV 1 air filter.

You might think that a MERV 16 air filter is the one to get without question, but if your HVAC system isn’t capable of handling such an air filter, you’re in for some trouble. Thicker air filters are great at catching dust particles and allergens, but they also heavily restrict airflow from passing through, so you need to make sure that your HVAC system has a powerful-enough fan to handle something like a MERV 16 filter. You can usually find this information in the owner’s manual.

Only Run Your HVAC Fan When You Need to

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Many people think that running the HVAC fan non-stop to circulate the air (whether or not the A/C is on) can cool down their house even more, but it actually doesn’t. Yes, it circulates the air in your house, but that’s it–circulating air doesn’t necessarily mean cooler air.

Of course, circulating the air in a space where the air is getting kind of stale can make the room seem less stuffy, but it won’t drastically cool the room by any means. Plus, running the fan non-stop can actually make your house more humid.

Furthermore, running your system fan 24/7 is a great way to double your electricity bill, especially if you have an older, inefficient HVAC system, so it’s better to just leave it on “Auto” and let it run only when it needs to.

Inspect Your HVAC System

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Did you think only a professional would be able to inspect your HVAC system? While I’m sure there are a lot of things that they could look for that you would have no idea about, there are a still a handful of things you can inspect yourself to make sure that your heating and air conditioning are running in tip-top shape.

For starters, go outside and take a look at your A/C condenser (it’s the big, loud box with the huge fan). If there are obstructions in the way, get rid of them, and I’m not just talking about debris. Many homeowners like to hide their A/C condenser with bushes, lattices, shades, etc., but it’s a piece of machinery that likes being completely free with the wind blowing all around it, so let it be free.

Next, if it’s winter and you have the heating going, inspect the flames that the furnace produces. They should be steady blue flames that aren’t flickering orange (a teeny bit of flickering is okay). If they are flickering orange a lot, this indicates a problem that requires a professional to check out.

Also at the furnace is the air conditioning unit, which likely sits above the furnace portion of your HVAC system. You can remove the cover panel and inspect the evaporator coils and fins. If there’s dirt build-up, you can usually vacuum it out and clean it yourself, but if there’s ice freezing over the coils and fins, then you have a problem that requires a professional.

Improve Your Attic Insulation

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Your house’s insulation is one of the main features that keeps the inside cool during the summer and warm during the winter, so it makes sense that one of the best things you can do to keep your energy costs low is improve the insulation. However, while you can’t just tear down drywall and upgrade the insulation, you can easily get into your attic and improve the insulation there.

It’s very possible that you don’t have enough attic insulation, especially if you have the blown kind that looks like loose cotton candy all over the attic floor. So hiring a professional to add more or doing it yourself can go a long way to keeping your living space comfortable without spending a lot of money.

It’s also possible that the airflow in your attic isn’t optimal. Yes, in order for your house to stay cool (or warm) and have good airflow, the attic itself needs good airflow as well so that hot air can escape out of the house during the summer, and cold air can get into the attic during winter to prevent ice dams from forming and causing damage.

Your attic should have some kind of ventilation, and there needs to be both intake vents and exhaust vents. Intake vents usually come in the form of soffit vents or eave vents, and exhaust vents are usually in the form of ridge vents, gable vents, or general fan-operated vents. Your house probably has these, so you’re good to go there, but you’ll want to make sure that any insulation isn’t obstructing your intake vents and restricting airflow by seeing that the baffles aren’t causing any problems.

New Windows or Not?

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There’s no doubt that getting new windows for your house is a great way to cut down on energy costs, especially if your house is older and the original single-pane windows are still standing. However, the cost may not be worth it, and there are cheaper ways to modify your house to cut down in energy costs.

New windows are extremely expensive. The previous owner of our house paid around $8,000 just for the downstairs, while all of the upstairs windows still remain original. Let’s say we decide to replace the upstairs windows finally, spending $4,000 (they’re smaller windows overall and less of them). That’s $12,000 worth of windows when it’s all said and done.

If you end up spending that on new windows and save around $50 per month on your energy bill (which is a huge savings), it would take 20 years for the cost of the windows to pay off. Who knows if you’ll even still be living in the same house by then.

Instead of spending that kind of cash, you could instead improve the weather stripping around doors and windows, as well as use plastic film over windows during the winter. However, if you know you’ll be living in your house into the distant future, there’s certainly no harm in getting new windows, especially if you have the money, and they certainly won’t hurt your home’s resale value.

Images from zveiger/Bigstock, ToddonFlickr/Flickr

Craig Lloyd writes about smarthome for How-To Geek, and is an aspiring handyman who loves tinkering with anything and everything around the house. He's also a mediocre gamer, aviation geek, baseball fan, motorcyclist, and proud introvert.