10 Handy Air Conditioning Tips to Keep Your Home Cool – This Old House

When summer shows up like it owns the place, your air conditioner becomes the hardest-working appliance in the houseoften while your energy bill quietly starts doing stand-up comedy (at your expense). The good news: staying comfortable doesn’t always require cranking the thermostat into “meat locker” territory.

This guide breaks down 10 practical, homeowner-friendly tips to keep your home cooler, help your A/C run smarter, and reduce that “why is my living room a sauna?” feeling. Some tips cost nothing. Some cost a little. A few are “call a pro,” but they can pay you back in comfort and efficiency.

Quick note: If you (or someone in your home) is sensitive to heat, has certain medical conditions, is very young, or is older, comfort and safety come first. Use these tips as adjustable dialsnot rigid rules.

1) Set Your Thermostat Like a Strategist (Not a Gladiator)

Your thermostat isn’t a gas pedal. It’s more like a cruise control that works best when you use it intentionally.

Start with a realistic “home base” temperature

A common efficiency-minded target in summer is 78°F when you’re homethen adjust for your comfort. If 78°F feels like you’re living inside a toasted marshmallow, try 77°F or 76°F and use fans and shading to make it feel cooler without forcing your A/C to do all the heavy lifting.

Use a schedule: raise temps when you’re away

Many households save money by letting the temperature drift warmer when nobody’s home. A programmable or smart thermostat makes this painless: it raises the temp automatically while you’re away and cools down before you return.

Know the “7–10 degrees for 8 hours” idea

A widely cited rule of thumb is that setting your thermostat back (warmer in summer, cooler in winter) by 7–10°F for about 8 hours a day can save up to ~10% annually on heating and cooling costs, depending on home and climate. Translation: small daily changes can add up.

Don’t play thermostat whiplash

Turning your A/C completely off for short errands often saves less than people expect, and in humid climates it can let moisture build up fast. A “set it a bit warmer while away” approach usually hits a better balance of comfort, efficiency, and humidity control.

2) Use Ceiling Fans Correctly (They’re Not Just Decorative Frisbees)

Fans don’t actually lower the room temperature; they cool you by moving air across your skin. That’s still extremely usefulbecause perceived comfort is the whole point.

Make sure the fan spins the right direction

In summer, most ceiling fans should run counterclockwise to create a downward breeze. If you stand under it and feel airflow, you’re in business.

Raise the thermostat a bit when fans are on

Using a ceiling fan can let you raise the thermostat by about 4°F without reducing comfort. That can be real savings over a long, sticky season.

Turn fans off when you leave the room

Remember: fans cool people, not empty chairs. Don’t pay to “chill” your houseplants.

3) Block Sun Heat Before It Hits Your Couch

The sun is generous, but in July it’s also basically a laser pointer aimed at your living room. Stopping heat before it enters is one of the most effective cooling moves.

Close blinds and curtains during peak sun

South- and west-facing windows are usually the biggest heat magnets. Close coverings during the hottest parts of the day, especially if you notice that one room always feels like a greenhouse.

Go bigger: exterior shading works even better

Outdoor shadingawnings, shutters, exterior solar shades, even well-placed treescan cut heat gain dramatically. For example, awnings can reduce summer solar heat gain substantially (especially on south- and west-facing windows). If you’re serious about comfort, this is one of the highest-impact upgrades that also improves “sun glare rage.”

Target the worst offenders first

You don’t have to redo every window today. Start with one or two rooms that overheat and test the difference. If you feel the improvement, expand the strategy.

4) Seal Air Leaks and Upgrade Insulation (Because Cold Air Is Expensive)

If your home leaks air, your A/C is basically trying to cool the neighborhood. The fix is often simple and surprisingly satisfying.

Check common leak zones

• Gaps around windows and exterior doors
• Attic access hatches and pull-down stairs
• Plumbing and wiring penetrations under sinks and behind toilets
• Recessed lights (especially older, non-sealed cans)

Use the right tools

Caulk is great for small, fixed gaps. Weatherstripping is best for moving parts (doors and operable windows). Foam sealant can help around pipes and larger penetrations (use carefullyfoam has strong “commitment issues” once it expands).

Don’t ignore the attic

In many homes, the attic is where comfort goes to die. Good insulation and air sealing up top can make the whole house easier to cooland can help reduce those “why is the second floor 6 degrees hotter?” arguments.

5) Seal and Insulate Ducts (So You’re Not Cooling Your Attic)

If you have central air, your ductwork is the delivery system. And like any delivery system, it doesn’t help if half the package falls out of the truck.

Why ducts matter

In a typical home, a meaningful chunk of air moving through ducts can be lost due to leaks, holes, or poor connectionsoften in attics, crawlspaces, or basements. That wasted conditioned air can lead to higher bills and uneven temperatures.

DIY-friendly steps (for accessible ducts)

• Look for disconnected joints, obvious gaps, or crushed flex duct
• Seal leaks with mastic or metal foil tape (not “duct tape,” ironically)
• Insulate ducts running through unconditioned spaces

Don’t sabotage airflow

Keep supply vents and return grilles open and clear. Blocking vents can create pressure problems, reduce overall airflow, and make certain rooms miserable. If one room is consistently too cold or too hot, it’s usually a balancing or duct issuenot a “close more vents” issue.

6) Change Filters and Do Basic Maintenance (The Easiest Efficiency Win)

If your A/C isn’t cooling well, the culprit is often something boringlike a dirty filter. Boring fixes are the best fixes because they’re cheap and effective.

Check filters monthly during cooling season

A common best practice is to inspect (and replace if needed) HVAC filters about once a month during heavy use. Homes with pets, allergies, dusty conditions, or constant A/C runtime may need more frequent changes.

Keep the outdoor unit breathing

Your outside condenser needs airflow. Clear leaves, grass clippings, and debris around it. Make sure shrubs aren’t crowding it like fans at a backstage door.

Schedule a professional tune-up

An annual service visit can catch issues like low airflow, dirty coils, worn capacitors, and drainage problems earlybefore your A/C decides to take a vacation during the first heat wave.

7) Treat Humidity as the “Hidden Thermostat”

Humidity is the reason 78°F can feel totally fine one day and absolutely unbearable the next. Lower humidity makes the same temperature feel cooler.

Aim for a healthy range

A commonly recommended indoor humidity range is 30% to 50%. Too high can encourage mold and make the air feel sticky. Too low can irritate skin and sinuses (more common in winter, but it happens).

Use exhaust fans like they’re part of the cooling system

Run bathroom fans during showers and kitchen exhaust while cooking. You’re not just removing smellsyou’re removing heat and moisture that your A/C would otherwise have to fight.

Know when a dehumidifier makes sense

If your home feels clammy even when the A/C runs, a dehumidifier (portable or whole-home) can improve comfort. Sometimes the problem is an oversized A/C that cools too quickly and doesn’t run long enough to pull moisture outsomething a pro can evaluate.

8) Stop Making Heat Indoors on the Hottest Days

This tip is basically: “Don’t cook Thanksgiving dinner in a shoebox during a heat wave.” Your A/C can only do so much if you’re adding heat nonstop.

Cook smarter

• Use a microwave, toaster oven, slow cooker, or air fryer instead of the full-size oven when possible
• Grill outdoors to keep heat outside where it belongs
• Meal-prep early in the day and reheat later

Shift heat-heavy chores

Run the dishwasher, washer, and dryer in the evening or early morning. If your utility offers time-of-use rates, this can also cut costs during peak demand hours.

Swap bulbs and tame electronics

LED bulbs run cooler than incandescent bulbs and use less energy. Also, shut down unused electronics (and chargers) that quietly add heatespecially in small rooms.

9) Fix the “Hot Room” Problem with Airflow, Not Arguments

Most homes have at least one room that’s always too hotoften an upstairs bedroom, a sunroom, or that one office where your computer runs like it’s mining crypto (even if it’s just email).

Try simple airflow tweaks first

• Make sure vents aren’t blocked by furniture, curtains, or rugs
• Clean dusty registers and return grilles
• Use a fan to move cool air toward the problem room (not just swirl it around)

Create a “cooling path”

A neat trick: place a fan in a hallway to push cooler air toward hotter rooms, or set a fan near the floor to move the coolest air where people actually live (your feet will thank you). In multi-story homes, running a ceiling fan upstairs plus a slightly higher thermostat can improve comfort without forcing the system to overcool downstairs.

Know when it’s a duct/design issue

If one room never matches the rest of the house, duct sizing, dampers, insulation, or return-air pathways could be the real problem. A qualified HVAC pro can measure airflow and diagnose imbalance. That’s much more effective than “closing vents in the living room and hoping for magic.”

10) Upgrade with Purpose When It’s Time (Not Just Panic-Buy in a Heat Wave)

If your A/C is old, struggles to keep up, or needs frequent repairs, upgrades can improve comfort and efficiencyespecially paired with sealing and insulation.

Smart thermostats can pay off in comfort

Smart thermostats help you schedule setbacks, avoid overcooling, and fine-tune routines. The biggest win is consistency: they prevent those “I forgot to change the thermostat” moments that turn into all-day overcooling.

Look for high-efficiency equipment

ENERGY STAR-certified cooling equipment and fans can reduce energy use compared with less efficient models. If you’re replacing equipment anyway, it’s worth comparing efficiency ratings and features like variable-speed operation, which can improve humidity control and even out temperatures.

Consider zoning (or mini-splits) for tough layouts

Homes with additions, finished attics, or chronic hot spots sometimes do better with zoning or ductless mini-split systems. It’s a bigger step, but it can solve comfort problems that smaller tweaks can’t fully touch.

Real-World Cooling Stories & Lessons (Extra Experiences)

Tips are great on paper. But homes are messy, quirky, and occasionally built like puzzles designed by someone who hates airflow. Here are some “real-life style” experiences homeowners often run intoand what tends to work.

Experience #1: The “Afternoon Sun Oven” Living Room

A classic scenario: a living room with big west-facing windows that looks gorgeous at sunsetand feels like a toaster oven at 4 p.m. The A/C runs, the thermostat reads a reasonable number, and yet the couch area is still uncomfortable. In cases like this, the fix isn’t usually “lower the thermostat.” It’s “stop the heat at the window.”

Homeowners who add blackout curtains or reflective shades often report an immediate difference in how the room feels, even if the thermostat reading doesn’t change much. The bigger leap comes from exterior shading like awnings or solar screens, because they block heat before it enters the glass and radiates into the room. Combine that with a ceiling fan and suddenly that room becomes usable againwithout turning the rest of the house into a refrigerator just to make one corner tolerable.

Lesson: If one room overheats predictably at the same time each day, treat it like a solar problem, not an A/C problem.

Experience #2: The Upstairs Bedroom That’s Always Hot

Two-story homes often have “thermal drama”: downstairs feels fine, upstairs feels like a different climate zone. Warm air rises, attics get hot, and upstairs rooms can be more exposed to sun and roof heat. In many homes, the upstairs isn’t “hot because the A/C is weak”it’s hot because the building envelope and airflow are working against you.

Homeowners often see improvement from a layered approach: sealing attic leaks, adding or improving attic insulation, keeping return grilles unobstructed, and running ceiling fans counterclockwise. Another surprisingly common win: making sure doors don’t choke off return airflow. If you close a bedroom door tightly and there’s no return vent (or the return is in the hallway), the room can become pressurized and airflow can drop. Some people solve this simply by leaving doors slightly ajar at peak heat times or using door undercuts, transfer grilles, or other airflow solutions recommended by HVAC pros.

Lesson: When an upstairs room is consistently hotter, think “attic + airflow + shading,” not “turn the A/C down until the downstairs freezes.”

Experience #3: The House That “Never Cools Down” Even with a New Thermostat

Sometimes a home feels warm and clammy no matter what you do with the thermostat. The air might be cool near a vent but uncomfortable overall. In humid climates especially, comfort is a two-part equation: temperature and moisture. If humidity stays high, you feel sticky and the house feels warmer than the thermostat says.

Homeowners who monitor indoor humidity (with a simple, inexpensive gauge) often discover the real issue: humidity hovering above the comfort range. Solutions vary. Sometimes it’s as simple as using bathroom exhaust fans consistently and fixing minor moisture sources (like a damp basement corner or a leaky supply line). Sometimes the A/C is oversized and short-cyclingcooling too fast to dehumidify effectively. In those cases, a pro might recommend equipment changes, airflow adjustments, or adding dehumidification.

Lesson: If the house feels “sticky,” measure humidity. You can’t solve what you don’t measure.

Experience #4: The “Why Is My Bill So High?” Mystery

Plenty of homeowners assume high summer bills mean the A/C is old or inefficient. Sometimes that’s truebut just as often, it’s the supporting cast: dirty filters, duct leakage, poor sealing around doors and windows, and sun blasting through uncovered glass. The sneaky part is that each issue might only add a little inefficiency, but together they force the system to run longer and harder.

People who tackle the basicsfilter changes, debris cleared from the outdoor unit, sealing obvious leaks, shading windowsoften report that the home becomes more evenly comfortable. The bill improvement may not be dramatic overnight (especially during extreme heat), but it’s usually noticeable over a full season. And the best part? These fixes reduce wear and tear, which can help avoid mid-summer breakdowns.

Lesson: The cheapest “upgrade” is often maintenance plus stopping air leaks. Efficiency loves boring habits.

Conclusion: A Cooler Home Is a System, Not a Single Setting

Keeping your home cool isn’t about one magic thermostat number. It’s about stacking small, smart choices: shade the sun, seal leaks, keep airflow clean, manage humidity, and use fans to improve comfort. If your home still struggles after the basics, that’s when duct improvements, insulation upgrades, or professional HVAC evaluation can make a big difference.

Pick two tips to try this weekespecially shading and filtersand you’ll likely feel the payoff fast. Your A/C will run more smoothly, your rooms will feel more even, and your energy bill may stop auditioning for a horror movie.