Ventilation: Maintaining the flow of fresh air

When most people think of HVAC, they think of heating and air conditioning first. Ventilation doesn’t always get the same attention. But it does an important job. It helps bring fresh air into a building and expel air that has become stale, warm, damp, or full of unwanted smells.

Imagine a kitchen after someone prepares a big meal. The room can become hot, smoky, and full of food smells. Or think of a bathroom after a long shower. Steam fogs the mirror, and humid air fills the room. A good ventilation system helps to push that air out.

The same concept applies to offices, homes, schools, warehouses, shops, restaurants, and many other buildings. The system may vary depending on the location, but the goal is to keep the air moving and help improve indoor air quality.

You don’t need to be an HVAC expert to understand ventilation. You can also learn what system may be right for your building. A little basic knowledge can go a long way in helping you compare your options. And that’s what we provide you at hvacpool.com

What is Airflow?

Ventilation means bringing fresh outdoor air into a building while removing indoor air. And this can happen organically. If you open a window or a door, then air can come in from outside, and air can go out from inside. Temperature and wind can also circulate air through a building.

Another alternative is mechanical ventilation. Fans, ducts, vents, and other equipment move air around to do this. Mechanical systems are useful when opening windows is not enough or where a building needs a more controlled flow of fresh air.

The ventilation system can be simple or very sophisticated. A very simple example is the bathroom exhaust fan. A whole-house ventilation system uses a more complex design to move air around different areas of a home.

The right setup depends on the building, local weather, how many people are in the space, and what you need.

Why is it important to ventilate?

The air inside a building is not fresh in itself. We do a lot of things indoors, we use air fresheners, we breathe, we cook, we clean, we take showers, we wash clothes and much more. All of these can affect the air. Pets, furniture, cleaning products, dust, and outside pollutants can also be a factor.

If there isn’t enough air movement, the space can begin to feel stuffy. Odours might linger longer. Moisture may stay. Some buildings can have a real problem with indoor air quality.

Good ventilation provides this unwanted air a place to exit. It does not mean opening every window all day long. In fact, that wouldn’t make sense in very hot or very cold weather. A well designed system will provide fresh air and help keep the building comfortable.

Ventilation and IAQ

One of the biggest reasons people look at ventilation is indoor air quality. The air inside a building can contain dust, odours, moisture, smoke, and other particles or pollutants. Some sources are easy to see; others are not.

Ventilation works by exhausting indoor air and replacing part of it with outdoor air. This can also reduce stale air inside the building. Ventilation replaces the air in the room. Air purifiers work on the air already in the room.

A homeowner, for instance, might use a ventilation system to bring in fresh outdoor air. They might also use an air purifier to filter certain particles. The systems can work together, but they do different things.

Ventilation and Air Purification Are Different

These two terms are sometimes used as if they mean the same thing, but they do not. Ventilation brings outdoor air into a building and removes indoor air. Air purification focuses on cleaning or treating air that is already inside. For example, a filter or air purifier may help capture certain particles.

Ventilation can reduce stale indoor air by replacing it with outdoor air. Some buildings may benefit from both. Good ventilation can support fresh air, while indoor air purification can provide another layer of air treatment.

You should not choose either system blindly. The right option depends on the problem you are trying to solve.

Types of Ventilation

There are many ways of ventilating a building. When you are researching HVAC systems, you may find different names, but the basic types are quite easy to understand.

Natural Ventilation

Natural ventilation does not use fans or mechanical equipment. Windows, doors, vents, and other openings can allow outdoor air to enter a building. It is the simplest form of ventilation and can work well when conditions outside are good.

The problem is you don’t have total control over it. If it is very hot outside, opening windows may not be a good idea. If it is very cold outside, opening windows may not be a good idea either. Also, If it is very humid or windy outside, opening windows may not be a choice. The quality of outdoor air may also determine the usefulness of natural ventilation at a given time.

Exhaust Ventilation

Exhaust ventilation is the use of fans to remove indoor air. You probably use this sort of ventilation all the time without thinking about it. Examples include bathroom fans and kitchen exhaust fans.

A bathroom fan pulls the moist air out after a shower. A kitchen exhaust fan can eliminate cooking odours, smoke, steam and heat. You can normally install it easily, and it can prove very useful in places that create humidity and odours.

Supply Ventilation

Supply ventilation is the other way. It uses equipment to bring in outside air instead of pushing most of the indoor air out. The system might filter incoming air before it enters the building. The system may also heat or cool the air, depending on the setup.

Supply ventilation gives you more control than just opening a window. This can be useful if the building needs a continuous supply of outdoor air.

Balanced Ventilation

A balanced ventilation system does both of these jobs. It pulls in outside air and blows out inside air simultaneously. This allows for a more controlled exchange of air. You can arrange the system to bring fresh air into some areas and exhaust stale air from others.

Buildings requiring continuous ventilation rather than occasional air changes often choose balanced systems.

Heat recovery ventilators

Heat recovery ventilators replace indoor air with outdoor air. They also recapture some energy that would otherwise escape.

Imagine that it is cold out. You need to let the warm indoor air out of the building, but you don’t want to lose all the heat you have already paid for. A heat recovery system can pass some of that heat to the incoming outdoor air. This can help to reduce energy waste, but still provide fresh air.

Actual performance depends on the system, building, weather, and installation. It may not be the best option for every home, but when energy use is a big concern, it can be worth a thought.

Getting Rid of Unwanted Odors

Nobody wants a home or workplace that smells stale. Cooking, pets, bathrooms, garbage, smoke, and many other things can create odors. If the air does not move properly, those smells may stay around for hours.

This is where odor control ventilation can help. A kitchen exhaust system, for example, can remove cooking air before it travels into bedrooms or living areas. Bathroom ventilation can do the same with odors and moisture.

Apartment buildings can have their own challenges. Apartment ventilation and odors may become an issue when air from different areas does not move as it should. In these cases, the ventilation design needs to match the building.

Ultimately, the goal is not to cover a bad smell with another smell. It is to remove the air that is carrying the odor.

What About Attic Ventilation?

The attic is another place where air movement deserves attention. During summer, an attic can become extremely hot. Moisture can also become a problem when ventilation is poor or when there are issues with the roof or insulation. Attic ventilation allows air to move through the attic space and helps remove excess heat and moisture.

Different ways to ventilate an attic include intake and exhaust vents. The setup needs to work with the roof and insulation rather than functioning as a separate add-on. Adding a vent without looking at the rest of the attic may not solve the problem.

In some cases, the real issue is poor insulation. It may also be caused by air leaks, the moisture from another area, or the poorly designed roof.

Ventilation Helps Escape Moisture

Moisture is a normal part of living. The problem starts when it’s too much inside. Showers, cooking, laundry and other activities put water vapour into the air. If the moisture can’t escape, it can gather on windows, walls, ceilings and other surfaces.

One reason why householders may have difficulty with the humidity in their house is this. Bathrooms and kitchens often need good ventilation as these areas generate more moisture than many other rooms.

A fan in a ventilator will draw the moist air out before it has a chance to circulate through the house. A bigger ventilation system can help air exchange over multiple areas.

Ventilation is not a panacea for all humidity issues. There are times when the building needs a dehumidifier, better insulation, air sealing, or some other solution. “It helps to look at the real cause and not assume one piece of equipment is going to fix everything.

Ventilation for Different Buildings

A small house does not have the same ventilation needs as a large office or warehouse. In a home, ventilation may focus on bathrooms, kitchens, bedrooms, and general living areas. Commercial buildings can have much larger and more complicated requirements.

Offices, restaurants, schools, medical buildings, retail spaces, and warehouses all use their spaces differently. A restaurant, for example, produces a lot of heat, moisture, smoke, and cooking odors. A warehouse may have different concerns related to workers, equipment, dust, and the size of the space. This is where proper HVAC duct design becomes important. Ducts need to move air to and from the right places without creating unnecessary restrictions or uneven airflow.

How to Choose a Ventilation System

• The building, not the equipment, is the starting point for choosing a ventilation system.
• Consider how you will use the space before you make up your mind. Keep in mind the number of people. Consider if there are any spots where dampness tends to collect. Keep in mind the existing ducts in the building. Also, what kind of HVAC system is in place.
• Your local climate is also a factor. A ventilation strategy may work well in one part of the country. It may not work well in areas with very different weather.
• So, think about the local weather when you’re picking a system.
• Another factor is the energy use. When outdoor air is brought inside, the HVAC system may need to heat or cool that air. Reducing energy loss is important in places where heat recovery ventilation systems are useful.
• Consideration should also be given to installation and maintenance. A system that sounds great on paper won’t work if there is no good place to put the equipment or the ductwork.
• Well-designed systems can provide all the fresh air a building requires without moving more air than is necessary. Efficient fans, proper ductwork, good controls, and systems designed for energy recovery can all play a part.
• And this also has to do with the environmental impact of a building’s air conditioning. Smart design of ventilation and efficient HVAC equipment can help reduce wasteful energy use.

Frequently Asked Questions