We rely on air conditioning to keep our indoor spaces cool and comfortable. It works best in closed spaces. But what happens if you run your AC with a window open? While it might seem harmless, doing so can reduce efficiency, raise energy bills, and even damage your AC over time.
In this article, we’ll explore why it’s important to keep windows closed when the AC is on, debunk common myths, and provide tips to maintain your AC’s performance and lifespan.
How Air Conditioning Works
To understand why air conditioner performs efficiently in a closed environment, it is important to understand how an AC works.
Air conditioner works by moving heat from indoors to outdoors. Generally, a chemical called refrigerant carries this heat. The refrigerant converts into gas when it consumes heat and transforms back into liquid after releasing heat.
Key Parts of an Air Conditioner
- Refrigerant
- Compressor
- Condenser
- Evaporator
- Expansion valve
The Cooling Process
- Warm air from inside the room flows over the cold evaporator coil. Refrigerant within the coil cools the air by absorbing its heat.
- The refrigerant turns into a hot gas after absorbing the heat. It travels to the compressor. The compressor raises the refrigerant gas’s pressure.
- The hot, high-pressure refrigerant releases heat as it flows to the condenser.
- After releasing heat, the refrigerant condenses back into a liquid and returns to the evaporator coil.
The whole process is designed to push out the heat from a closed space. When the window or door is open, the hot air keeps coming inside and the AC has to repeat the cycle over and over again to cool the space. As a result, it will get to the desired temperature slowly and have to run constantly at full power.
What Happens When You Run AC with Windows Open?
There is no real benefit of opening the windows with your AC on. You’re essentially creating a very inefficient and costly situation. Here’s what happens when you run AC with window open:
1. Inefficient Cooling
Your AC works hard to cool the temperature inside your room. When the air escapes through open windows and doors, the cool air gets outside too.
This means your AC uses more energy to provide the necessary cooling. Besides, it has to use more energy to keep the same temperature as the temperature is bound to get high again when mixed with outside air. The extra work reflects on extra energy bills.
This is comparable to filling a bucket with a hole. You have to put in excess water to fill it up. And, it won’t fill no matter how much water you put in it. A lot of effort for minimal results.
2. Increased Wear and Tear
The constant struggle to cool new air because of open windows puts excessive strain on the system too.
When your indoors reaches a desired temperature, the AC cycle turns off. If it needs further conditioning, the cycle turns on again. The cycle continues to run with open windows. As a result, you will notice irregularities and extra damage to your system.
Besides, this excessive load can lead to:
- Wearing out components like compressors
- Overheating or malfunctioning
- Reduced lifespan of the overall cooling system
Wears and tears are inevitable in any machinery. However, you are wasting your air conditioner’s precious life with windows open without getting any valuable results from it.
3. Excess Humidity and Dust Buildup
An air conditioner works to control indoor humidity too.
When your windows are open, the outside air gets inside. The humidity and moisture get welcomed along with it. With the extra humidity, you not only feel muggy and uncomfortable but also the extra work to remove it adds up to the wear and tear and energy bills.
The same goes for dust too. With extra dust coming from outside, the indoor gets dusty overall. The air filter also gets clogged easily and you get a lower-performing air conditioner.
4. Irregular Temperature
Because the hot air continuously enters your home through open windows, the temperature gets irregular in your home. You can notice cooled air from the AC in different spots and hot air from outside in different areas. As a result, your living environment won’t be as comfortable.
Even if the air conditioner is working to cool the air inside, it won’t be enough to compensate for the hot air coming from outside.
5. Environmental Impact
Most electricity is generated from burning fuels like coal, natural gas, oil, etc. This process contributes to greenhouse gas emissions. The released gases contribute to the global warming.
When your window is open while the AC is on, it is consuming more energy. The increased demand causes more damage to the environment indirectly. Although your particular scenario won’t seem to affect much, all the little steps add up to a significant global problem.
Common Myths About Using AC with Open Windows
Myth 01: Fresh air is good for cooling
People generally associate “fresh air” with good air. However, this is always not the case. When there is a little breeze, people tend to open windows a bit to “balance” the air.
The fresh air is good for overall air quality but the ventilation manages that. The air conditioning system is engineered to cool the existing air. No matter how cool it is outside, as long as there is a temperature difference (the reason you are turning on your AC), there will be energy loss with windows open.
Myth 02: AC works better in humid conditions
This is the same fallacy of “balancing” the air. The truth is humid air coming from the open windows makes AC’s job much harder.
Myth 03: Running a fan with the windows open and the AC on helps cool the room faster
Fans circulate the air inside your room. Instead of “cooling” the air, it creates a wind chill to affect the skin. When you open windows and the warm air gets in, it keeps circulating the hotter air. The AC will end up being responsible for cooling the excess hot air coming inside the room.
Myth 04: If the is powerful enough, it won’t make a difference if the windows are open
A powerful AC can cool your room fast enough to get the desired temperature. However, that doesn’t mean it can do so with indefinite air and any weather conditions. Even powerful air conditioners struggle to cool efficiently with open windows.
Besides, the excess energy coming from the powerful AC will consume even more energy. So, you will have higher energy bills and a higher carbon footprint.
Read also: Guide to Smart, Energy-Saving AC Solutions for Houston Homeowners
Myth 05: It’s okay to open windows in winter with AC on
It’s true that the air conditioner doesn’t have to work as hard with colder air coming from the outside. The scenario of an air conditioner running is less common in winter. However, in some exceptional cases where you open windows with AC on in winter, the temperature can cause extra pressure on the system.
In cold climates, the refrigerant pressure drops significantly. The air conditioner highly depends on this pressure to perform. Besides, there are possibilities of oil thickening and coil freezing with winter air, if it enters the AC.
So, it is always better to keep the windows closed when the AC is on, even though it’s winter.
Tips for Maintaining AC Efficiency
- Always close windows and doors while using AC.
- Regularly maintain your AC and your overall HVAC system to get the optimal performance.
- Use air purifiers, ventilation systems, etc. properly instead of opening windows to get fresh air inside your home.
- Seal leaks around windows and doors, so no air gets pass through the closed ones either.
- Look for higher efficiency units such as ones with high SEER ratings and ductless mini-splits while purchasing.
FAQs
1. Can you open a window with an AC unit in it?
No, you generally should not open a window with a window AC unit installed. It compromises support, breaks the air seal, and makes the AC inefficient. However, some newer models allow such for limited window opening. Confirm that with your manufacturer before opening windows regularly. If the AC is off, you can open the windows.
2. Is It OK to Run AC with Windows Open Temporarily?
The short answer is no. Even if it’s just a few minutes, the hot air coming from outside disrupts the cooling process. If you do it enough times, it will have the same effect of keeping the windows open for a long time. Moreover, there is no real benefit to opening the windows temporarily when the AC is on.
3. Does closing vents in unused rooms save energy?
Some people believe that restricting airflow to certain rooms improves overall efficiency. In many central AC systems, however, this can lead to an imbalance in airflow and increased operational strain.
