Understanding Mechanical Ventilation

Whole-house mechanical ventilation is the intentional exchange of indoor air with fresh outdoor air at a controlled rate using fans. Its purpose is to improve indoor air quality. Without mechanical ventilation, you will find that odors and pollutants will build up.

How Mechanical Ventilation Systems Work

Numerous mechanical ventilation systems are on the market. You should choose one based on your local climate as well as your home’s heating and cooling system. No matter which system you choose, you should consider spot fans for your kitchen and bathroom as these rooms receive concentrated odors and moisture.

There are three main types of systems that are ideal for different climates. These systems are:

  • Supply Ventilation Systems: These systems work best in either hot or mixed climates. They work by drawing in fresh air through intake vents and distribute it to multiple rooms using a fan and duct system.
  • Balanced Ventilation Systems: These can work in all climate types. They work by bringing in and sending out equal quantities of air. Many systems use two fans, one to draw in the air and one to remove the indoor air. Two of the most commonly used systems are the energy recovery ventilation system (ERV) and the heat recovery ventilation system (HRV).
  • Exhaust Ventilation Systems: Exhaust ventilation systems are best for colder climates. They work by continuously exhausting indoor air to the outdoors through one or more fans typically located in the home’s bathrooms. The house becomes slightly depressurized from the constantly flowing air, which makes it bad for hot or humid climates. There is a risk of drawing outdoor air that is hot into the remaining cracks and holes. If the hot air reaches the home’s cooler interior surfaces, it can condense and lead to moisture problems.

 

Benefits of Mechanical Ventilation

There are significant benefits to mechanical ventilation.

  • A consistent supply of outdoor air for improved indoor air quality and occupant comfort
  • Control over the amount and source of outdoor air
  • Dilution of indoor contaminants, such as odors and allergens
  • Helps control relative humidity and reduce moisture accumulation during the heating or temperate seasons

Common Home Ventilation Issues

If you aren’t familiar with some of the most common home ventilation issues, you may not understand the need for a mechanical ventilation system. Indoor pollutants are a significant problem. Poor air quality is a health hazard for homes. Common household items like plastics and paints emit particulates called volatile organic compounds, or VOCs. In small amounts, they are not harmful. However, without the proper ventilation in your home, they can create respiratory issues, including conditions prime for mold to grow.

Another potential problem is when negative pressure accumulates. Homes that are too airtight can have air drawn into gaps, crevices, and other spots not intended for the air to flow.

Signs of Air Quality Problems

Learning to identify signs of poor air quality in your home is important. These problems may indicate that you need to install a mechanical ventilation system or that your current one may need servicing. The four main issues you should be watching out for include inadequate air exchange, too much air exchange, excess moisture, and excess filtration.

Inadequate Air Exchange 

One way to spot inadequate ventilation is the presence of odors. How often do you smell them? In what part of the house do you smell them? Odors that persist for hours may mean the source is continuing to release the chemical or the air carrying these odors has no quick and controlled way to exit the house.

Too Much Air Exchange 

Too much air exchange can be an issue, especially for those people who live in dry climates. If you find the inside of the house uncomfortably dry, check your ventilation system’s fan speed. Then, consider buying a humidifier if you need one. In humid and hot climates, ventilation rates that are too high can increase your indoor humidity beyond what your air conditioning unit can handle. You may need supplemental dehumidification in some instances.

Excess Moisture

Recognizing excess moisture is often a pretty simple one to diagnose. If you see mold, condensation, or excessive ice building up, you have a moisture problem.

Excess Filtration 

Excess filtration can be when you feel a draft, especially during winter months and when you are close to exterior walls. Watch for “ghost tracks” of dark dust near any poorly sealed areas, especially on light carpets near your exterior walls, or black edges on your attic fiberglass insulation batts. Another sign that is less obvious is frequent static electricity discharges during winter months when your indoor humidity levels are not high enough.

Solving Ventilation Problems

You can start by opening your windows for at least 15 minutes per day to help relieve negative pressure and reduce indoor air pollutants. You need to open two windows to facilitate airflow so one acts as an exhaust and one as an intake vent.

Next, you should contact an expert in the field to test your insulation and ventilation system. At Energy Diagnostics, we have been in business for  30 years and have received numerous awards and accolades. We have trained contractors, builders, and code officials in multiple states on International Energy Conservation Code (IECC). If you require assistance with your ventilation system or need to have one installed, let our skilled team assist you.