Before there was air conditioning, there was wind. Passive cooling has been used as a reliable source of ventilation since the beginning of time. Thankfully nature provides the resource in abundance, more in some places than others. Just about everywhere on the planet, there’s a way to use natural ventilation to your advantage.
What Is Natural Ventilation Cooling?
Natural ventilation is a passive design technique that starts with cool breezes and adds efficient architectural elements. Coupled together, it results in a cooler space without the need for mechanical systems, or at least a reduction in energy use via air conditioning systems.
How Natural Ventilation Works
In its most basic form, natural ventilation is simply leaving the windows open. However, there are many ways to amplify the effect so you can keep your home cool.
What Are the Advantages of Natural Ventilation Cooling?
The primary advantage of passive cooling is money savings. Cooling and heating a space makes up the majority of any electrical bill.
The more methods we employ to avoid having the furnace kick on, the more money we save on energy costs.
Of course, saving energy means less reliance on fossil fuels, which is great for the environment too.
Coal, oil, and natural gas, commonly used to heat and cool homes, contribute to air pollution, deplete the planet’s resources, and advance global warming through carbon emissions during drilling, transport, and use.
A third advantage of natural ventilation is improved air quality inside the home. Read more about that below.
What Are the Disadvantages of Natural Ventilation?
Depending on your location, the climate may just not be agreeable in your efforts to cool a space naturally.
Also, poor outdoor air quality requires filtration for healthy indoor consumption.
Finally, natural ventilation won’t compare to the quick efficiency of modern mechanical systems.
Structural Aspects of Natural Ventilation
Architectural elements are a huge consideration when optimizing the flow of air throughout the home. Known as passive cooling, it’s actually an entire system that works together.
Primarily, window placement that facilitates cross breezes is at the cornerstone of passive design. A well-thought out system places windows and doors in such a way as to maximize airflow through the home.
Placement also takes into consideration the direction the wind chiefly blows to further amplify the effect.
Many other structural factors optimize natural ventilation too.
It starts with passive house design elements such as orienting the home to take advantage of shading from the sun during the summer months.
To build on that, roof overhangs, options for the facade of the home, and effective landscaping all contribute to keeping the home cool.
With architectural elements in place, natural ventilation effectiveness increases.
Since natural ventilation is part of a more comprehensive plan to cool the home, keeping the blinds and curtains closed during the heat of the day can help keep indoor temps from rising.
In fact, blackout curtains can make the difference between a house that remains cool most of the day and one that becomes unbearable.
One key component of natural ventilation is tapping into cooler air when it’s available. Depending on where you live, the coolest air in any 24-hour period comes after the sun goes down.
Open all the windows overnight, if possible. If there are safety or other concerns, open all screened doors and windows as soon as the temperature outside is lower than the temperature inside.
Leave them open until you go to bed and open them again as early as possible in the morning.
Remember the basic law of thermodynamics is that heat rises. It’s important in helping to clear the warm air out of your home and there are several ways to implement this law into your natural ventilation.
First, drive air from the lower levels to the upper levels through fans and/or open windows. This allows cooler air to replace warmer air on upper levels.
It’s called the chimney effect and it’s driven by convection. When cool air enters the home on the lower level and mingles with the heat in the space, the combined mass rises to the upper level where it escapes out the open windows.
The lower space then refills with air from the open window, creating a vacuum effect that continuously pulls air through the space. The chimney effect is particularly effective in homes with cathedral ceilings or open skylight windows.
Fans help to circulate air. Moreover, they can be used as a tool to control the temperature in the home.
On lower levels, place fans in front of open windows and doors when the air is cool. This will drive cooler air into the space. Upstairs, aim fans towards the openings to drive warm out.
If you live in a single level home, place fans away from one opening and facing another opening to guide air through the rooms.
You can also rely on ceiling fans to help with temperature control. Most ceiling fans have a setting that allows you to reverse the direction of the blades.
Rotating one way, the blades push warmer air down into the room (during winter). Rotating the other direction, the blades pull warm air up towards the ceiling, keeping the living space cooler.
Even if natural ventilation isn’t your sole source for cooling and improving air quality, it can significantly reduce your energy bills.
Simply using passive ventilation at night while leaving the AC off lowers consumption considerably. That’s good for the environment and your pocketbook.
In addition to cooling, the primary function of natural ventilation is to improve the quality of indoor air.
Have you ever stopped to think about the air you breathe when you’re indoors? Probably not.
Since we’re still feeling the effects of the COVID-19 pandemic, the new normal has many of us working and schooling from home.
Those daily routines mean moving from the bedroom to the living room instead of battling a commute and logging hours in an office building.
With the kids tackling remote learning and your office in the dining room, the carbon dioxide to oxygen ratio under your roof is likely different than it was a few years ago.
An increase in the number of people at home affects the overall indoor air quality (IAQ) within the space. With that in mind, it’s important to give some consideration to the quality of the air you and your family are breathing in.
There is more to the equation than just making sure there is adequate oxygen in the building. Pollutants can float through your home, moving from one space to another. These pollutants can lead to allergic reactions and breathing difficulties.
There might be other issues that go unnoticed too. Yet according to a study from Broan-NuTone, only 22 percent of Americans worry about their home’s indoor air quality.
In fact, there are many often overlooked clues that point to less than optimal IAQ. While you might recognize an increase in dust, most Americans don’t associate lingering food odors or allergy symptoms with poor IAQ.
When evaluating IAQ, homeowners and renters should consider how effectively vent fans remove odors, smoke, and moisture from the space. Lingering food scents, foggy mirrors and windows, and mold are all strong indicators that vent fans are not doing their job.
Time spent cleaning and cooking can contribute to the toxins in your air. Then there is dust, pet dander, and dirt thrown into the mix.
Depending on the daily activities of your household, the number of people in the space, and the products you use, your IAQ might suffer more than you think.
In addition to frequently replacing the furnace filter and ensuring the exhaust fans in the bathrooms and kitchen work properly, natural ventilation is the primary tool in battling stagnant, grease-laden, pet-dandered, stale, dusty air.
Drive out the irritants in the air and open the door to dry out the space before mold and mildew can develop.
On a bit of a side note, if you find that your home has excessive moisture in the form of damp towels, musty smells, and foggy mirrors you may want to use absorption products such as Dri-Z-Air. The pellets are easy to refill and are versatile enough for the RV, garage, or closet.
A dehumidifier is another option to consider when moisture levels are high.
Connection to Nature
If the benefits of cost savings and better air quality aren’t motivating enough, remember that natural ventilation is, well, natural.
In a world where we’re all desperate for a deeper connection with the land, simply opening the windows is a great place to start.
While you may not have a trickling stream, raging river, melodic mountainside, or calming ocean outside your window, you may have the sounds of birds, the feeling of a breeze on your face, and the pleasant smell after heavy rain. Connect.
When people think of landscaping, they often envision colorful flowers, shade-creating trees, and a lush lawn. However, landscaping holds the power to enhance natural ventilation in the home as well.
Start by planting those large trees in locations that shield the home from the intensity of the sun. Then buffer the patio with a pergola or complete roof.
Train some climbing plants to create shade on the front and back entrances for additional temperature control. In the yard, calculate the wind direction and place shrubs in a way that provides an air corridor directly towards the windows and doors.
Some homes are better equipped to take advantage of natural ventilation than others. For example, a home perched on the top of a hill or in a valley with a natural wind tunnel will make the process automatic.
Other locations may suffer from long periods of stagnant air or high heat that makes natural ventilation inadequate.
Another significant factor in the success of natural ventilation is the layout of the home. If you have the luxury of designing a home from the ground up, you can create a passive home with all the elements that promote natural ventilation.
Within an existing home, however, the layout will have a significant influence on the airflow. A tightly-stacked two-story home with windows on only one side will lack efficiency.
A sprawling home with multiple openings, however, will offer a high degree of potential for natural ventilation.
The Human Component
The human component might be the most impactful part of the natural ventilation equation.
Once again, effective ventilation for cooling relies heavily on keeping the space from getting too warm in the first place. There are myriad ways to minimize heat retention within the home.
Start with some of the suggestions above, such as closing all blinds and curtains during the day and opening all windows and doors overnight. Also put effort into fan placement and moisture control.
In the kitchen, avoid running the dishwasher during the day and turn off the heat dry setting. Skip the oven in favor of a slow cooker or grill that won’t heat up the house.
In the bathroom, take cool showers, open the window, turn on the fan, and skip the hair dryer. Showering at night is also helpful.
Save laundry for the evening hours and hang clothes instead of running the clothes dryer. Remember, all the heat you create has to have some place to go.
Mind the thermostat. If you do have central air conditioning, put some thought into using it. Every degree you adjust is a decision between saving and spending--conserving or consuming. Turn it on if you need to, but consider redefining your definition of comfort by a few degrees rather than being wasteful.
If you have a window unit or a portable air conditioner, the same guidelines apply. For mild climates, resist putting window air conditioners in place until the heat really sets in, and remove them as soon as nighttime temps begin to drop. That way you can use the window for free and natural ventilation rather than expensive AC.
For other ways to save money and the resources of the planet, check out What is Passive Solar Heating? and The Efficiency of Ancient Passive Heating and Cooling Techniques