An air conditioner and humidifier side by side

During summer it’s tough to escape the heat. While living a sustainable, eco-friendly lifestyle, you have to look for options that save money, are energy-efficient, and are long-lasting. 

Perhaps, you may have several options to cool your room, including a humidifier, air cooler, air conditioner, and dehumidifier. Of these, people tend to go with a humidifier and air conditioner.

If you want to purchase one of these for your home, you need to know which is better regarding cost and energy usage. 

What is the Difference Between a Humidifier an AC?

A humidifier and an air conditioner are two different entities. An air conditioner eliminates moisture, controls humidity, and reduces temperature. In contrast, a humidifier improves the water level in the air and purifies air by maintaining warm temperatures. 

Is a Humidifier Better Than an Air Conditioner?

Humidifying air requires 127-545 kW per year while cooling the air consumes over 2,000 kW per year. An air conditioner emits sulfur dioxide at an average of 31 pounds. A humidifier is more energy-efficient and cheaper than an air conditioner, but the former does not cool the air.

Taking that into consideration, it is time to look at their differences to determine the best one for your net-zero home.

Air Conditioner vs. Humidifier: A Comparison 

To know which is better, you should first begin with how they work and the features you can expect from each.

Perhaps you can save more energy with an air-conditioner, but let’s understand both devices’ functionality and internal mechanism. 


A humidifier is a device meant to add water to improve the relative humidity in the living space. As the water content increases, inhabitants feel the warmth. 

A humidifier is ideally purchased for personal wellbeing and comfort. When you go to a shop to buy a humidifier, you can see three types—warm, cool, and ultrasonic. The types vary based on the temperature of water used and the humidifying process.

A humidifier on the living room floor with a homeowner resting her arm on top

A warm mist humidifier involves boiling water, while cool mist, as the name implies, involves cool water. Contrarily, an ultrasonic humidifier involves a fan and constantly vibrates at ultrasonic frequency levels. 

How Much Water Does A Humidifier Consume?

Water-saving is one of the fundamental factors you should pay attention to when leading a sustainable lifestyle. Every gallon of water consumption adds up to the energy used. 

Let us consider a particular cool-mist humidifier—the Honeywell HCM-350. This model needs around two gallons to warm air in a room of 500 sq. ft. When it runs for a day, it consumes 50 watts. 

A warm mist humidifier requires two gallons of water to warm air in a room of 1,000 sq. ft. This model’s power consumption is comparatively lesser because it does not cool air. The energy is saved on that aspect. Maintaining warmth involves limited energy and more productivity. 

Moving on to an ultrasonic humidifier, it takes around 1.68 gallons of water to warm air in a 538 sq. ft space. This model consumes about 30 watts of electricity. 

Out of the three types of humidifiers, the most energy-efficient option is an ultrasonic humidifier. This efficiency is because it uses optimal water level and ultrasonic frequency to warm air. Efficiency also implies that an ultrasonic humidifier costs lesser than a cool-mist humidifier. 

According to a study on energy associated with humidification, water humidification is considered more economic than steam, and the energy usage is also better.

Here’s the calculation:

The electricity cost per unit for residential purposes in Florida is 12.21 cents

When you use an ultrasonic humidifier for about eight hours a day, the electricity cost is: 

  • Cost = Power x Time used x Cost per unit x Days
  • Cost = 30 watts x 8 hours/day x 12.21 cents x 30 = 240 watt-hours x .12 dollars x 30 days
  • Cost for one month = 7.2 kWh x .12 dollars = $0.86/month

When you use a cool-mist humidifier for about 8 hours a day, the electricity cost is: 

  • Cost = Power x Time used x Cost per unit x Days
  • Cost = 50 watts x 8 hours/day x 12.21 cents x 30 = 400 watt-hours x .12 dollars x 30 days
  • Cost for one month = 12 Kw x .12 = $1.44/month

Hence, you can notice the vast difference between a cool-mist humidifier and an ultrasonic humidifier. 

When you use an ultrasonic humidifier, you can achieve a positive return on investment (ROI) 50% sooner than other models of humidifiers.

Air Conditioner

An air conditioner, as you likely know, is meant to cool indoor air and comes with auto-timer systems to cut off usage automatically. 

When you visit a store to purchase an air conditioner for your home, you’ll see two options—central units and room units. According to Energy Saver, a room air conditioner is cheaper than a central unit, but the energy efficiency is not equivalent. 

There are energy-efficient air conditioners on the market; those with a high energy efficient rating (EER) are more appropriate for a sustainable lifestyle. According to Energy Saver, there are also air conditioners that incur less than 7.5 A for small rooms.

Central air conditioner units on the exterior of a home

According to Arcadia, an air conditioner’s annual energy use is around 1,850-4,759 kWh. This costs in the range of $202-$519.

The electricity costs vary based on the size of the air conditioner. For example, a small window unit incurs $170, while medium and large units incur $270-$350.

So, what happens to the cost of running a central unit? As central units tend to dehumidify the air, the comfort level is high, unlike humidifiers. A central air conditioner consumes about 3.5 kW for a running time of 4.4 hours. 

Total Watt Hours = watts x time = 3,500 x 4.4 = 15.4 kWh. 

As they don’t run continuously, it is appropriate to divide it by half, which averages 7.7 kWh. 

Cost = kWh x cost/unit = 7.7 kWh x .12 USD = 0.92 USD per day.

Cost per year = 335.8 USD

Which Is Better For Your Home—An Air Conditioner Or Humidifier?

If you live in a warm, dry region, opt for an ultrasonic humidifier that saves energy, warms indoor air, and achieves a better ROI. 

If you live in a humid or hot region, go with an air conditioner. However, you can choose a central unit instead of a room unit as the former cools air faster, saves energy, and achieves a positive ROI more quickly. 

To sum it up, a humidifier is better than an air conditioner for limited usage in a warm region. In contrast, an air conditioner is ideal for long hours of use, especially in hot areas.

However, as the number of hours increases with an air conditioner, so does the cost.

How To Save With an Air Conditioner

As fans and followers of the zero-waste lifestyle, we have tried several ways to improve the energy efficiency of air conditioners in our homes. Here are a few tips that worked:

Use a Smart, Programmable Thermostat

As Twintech Heating and Cooling highlights, a programmable thermostat takes care of the temperature when you are sleeping. 

Even if you have set it to 71.6ºF (22ºC) before sleeping, the thermostat still regulates the temperature. 

A smart thermostat on the wall in our second net-zero home
A smart thermostat in our second net-zero home

As a result, the room stays cool throughout the night and does not disturb your sleep. This method is also an excellent way to reduce energy consumption and achieve a positive ROI faster. 

Check the Energy Efficiency Rating 

It is always a good idea to look at the energy efficiency rating when buying an air conditioner. 

We purchased a five-star rated unit a couple of years ago, and it changed our lives. It worked as promised, and electricity costs were cut by over half with this model. 

  • Maintain a cleaning routine for the unit. 

Sundays are for home! This has been our ideology for the last few years. We work on cleaning the entire house along with devices like the air conditioning unit. 

Cleaning your air conditioner’s filter every week lets it cool faster and improves the overall indoor air quality. As a result, it also consumes less electricity than an uncleaned unit. 

  • Insulate doors and windows. 

Can you believe that the temperature of a room reduces substantially when doors and windows are insulated? It did for us, and it will work for you too. 

The rule of thumb is to use suitable material to insulate doors and windows. According to Astral Energy LLC, using caulk or weatherstripping to protect can reduce energy consumption by at least ten percent. Sealants are also a fascinating way to keep the room cool for a long time. 

Using a central air unit, you can further increase energy efficiency due to its even cool air distribution.

  • Use fans, in addition to AC, for better air circulation. 

It can sound weird to install multiple devices in your room to promote air circulation. However, the goal is to reduce energy and achieve better productivity irrespective of the accumulation of several devices. 

Initially, we limited ourselves to an AC unit but found our electricity bills dropped by at least 10-20% after installing the fan. It promotes faster air distribution and maintains the wind-chill effect when you install fans. 

A closeup of a dormant ceiling fan

When you are sleeping, you can use both devices. However, remember that you should go with a smart, energy-efficient ceiling fan that does the job more efficiently, is cheaper, and is eco-friendly.

There are fans on the market with built-in systems like sensors to regulate temperatures better. 

If you try implementing all the tips mentioned here, you can save more energy with your air conditioner and may not require a humidifier.

Can a Humidifier Replace an Air Conditioner?

A humidifier cannot replace an air conditioner as a humidifier focuses on warming the air, gradually regulating the temperature, and purifying the space. In contrast, an air conditioner cools the air. 

When a humidifier is used in the place of an AC, it can safeguard your skin condition and also let you breathe better. However, you cannot expect the benefits of an air conditioner with your humidifier. 

If you live in a warm region, you can try a whole-house humidifier, but this is not cost-effective if you are unsure about your needs and desired features. 

Does an Air Conditioner Humidify Air?

The air conditioner humidifies the air to a moderate extent during operation. When you use it for several hours, it minimizes humidity levels. 

The downside is that this type of humidification does not improve your skin condition, unlike a humidifier. 

Modern cooling units include an internal humidification system that maintains temperature and regulates moisture. However, it does not have similar effects to a humidifier. 

Can I Use a Humidifier and AC at the Same Time?

Using a humidifier and an air conditioner together can decrease energy efficiency, increase the cost of operations, and waste electricity. 

As a zero-waste proponent, you should avoid the usage of both entities simultaneously. It can work contrary to your desired notion. 


A humidifier is an excellent investment as you can achieve a positive ROI faster, add water to air, and improve relative humidity. However, although it is energy-efficient, it is not always ideal as an air conditioner rapidly cools the space and humidifies the room to a significant extent. 

Though an AC unit is not as cheap and energy-efficient as a humidifier, it is still recommended when you pay attention to energy star ratings, maintenance routines, and proper operating hours. 

Over the years, we’ve saved more with a central AC by following quick tips like using a fan, a smart thermostat, and regular cleaning. 

If you want to choose a device that works in the long run, saves energy, and your pocketbook, go for an air conditioner.


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