Build Tight, Ventilate Right

Mechanical Engineers hold a crucial role in meeting energy codes, earning tax credits, and providing a comfortable home filled with fresh, clean air. So, we want to help you understand the importance of proper ventilation. Here’s a basic overview of ventilation and HRV/ERVs.

Ventilation 101
Ventilating a home involves exchanging indoor and outdoor air to maintain good indoor air quality. And there are three types of ventilation: exhaust, supply, and balanced. We’ll cover those later in this article.


Navigating the Complexities of Modern Homes
Homes these days are getting tighter and tighter, right?

Navigating and implementing energy codes and advanced building methods can be a bit tricky. But with our expertise and partnership, we can help guide you and break it down for you. From tight homes to codes, and why "build tight, ventilate right" is the go-to mantra. 

Why Ventilation Matters:  
Proper ventilation matters because it ensures the effective removal of indoor pollutants, regulates air quality, contributes to the overall comfort of occupants in a home, and is often required by building and energy codes.
Code Compliance- Adhering to these regulations is crucial in the design and construction. 
Energy Efficiency – contribute to sustainable and cost-effective solutions. 
Moisture Control- avoid potential problems associated with excessive or insufficient moisture. 
System Optimization- use ventilation systems that work seamlessly. 
Health and Comfort – occupants can breathe clean and fresh air, reducing the risk of respiratory issues and improving comfort in the home.

The Result of the Tightening Envelope
More airtight homes lead to varied indoor climates, ranging from dry to humid, leaving some spaces slightly uncomfortable and increasing risks of mold and mildew buildup. The risks of depressurized dwellings, back-drafting, and the inflow of poor air pose complex challenges that require an engineering-based approach.

Trapped Indoor Pollutants
Excess moisture, particulates, gasses/VOCs, carbon dioxide, and odors trapped in the home pose significant challenges. The tighter the home with new improved sealing technologies, and fewer open windows effectively seals these pollutants in the home even more these days.
All these challenges can be overcome with proper ventilation.


Three Ways to Achieve Proper Ventilation
The three primary ways we can achieve proper ventilation are exhaust ventilation, supply ventilation, and balanced ventilation. Each method offers its own set of advantages. 

Exhaust Ventilation: 
Exhaust ventilation fans pull stale air out of the home and thus depressurizes the home.​This method relies on natural leakage in the envelope to provide a source of new air. Often that source is uncontrolled which can lead to all sorts of issues including moisture intrusion and the introduction of allergens. Exhaust ventilation is often the lowest-cost ventilation solution, but it rarely, if ever, meets energy codes or tax credit requirements.

Supply Ventilation: 
Supply ventilation brings fresh air directly to the home via a fan. The idea here is to push fresh air into the home, thus pressuring the home and forcing the stale/bad air out of the nooks and crannies left in the envelope.​

There are two basic supply methods​:

·      Central Fan Integrated Supply (CFIS)– This method uses a supply damper that is attached directly to the air handling unit and relies on that fan to draw fresh air into the home. Our FIN-6MD is a supply damper that references the outdoor temperature and humidity to determine the best time to bring fresh air into the home.

·      Dedicated Supply Fans​ – Supply fans are more energy efficient than a CFIS because they do not rely on a large central fan to do a smaller job. These fans make it easier to control airflow, as well. It can be challenging to measure and set the correct airflow with central fan integrated systems​. Some models feature temp/humidity control, such as the Broan FIN-180P.

Both exhaust and supply ventilation provide fresh air to the home but neither brings in pre-treated air. Broan supply fans come with MERV filters and, when ducted into the home's ductwork, use the air handler’s filter to remove pollutants. But, neither option tempers the air nor helps maintain humidity levels.

Balanced Dwelling Unit Ventilation: 
Balanced systems, sometimes called air exchangers, are the most energy-efficient approach to home ventilation. Balanced ventilators simultaneously exhaust and supply air at equal levels, with a CFM or two added to the supply side to slightly pressurize the home.

The most effective of these types of ventilation systems are called Energy Recovery Ventilators (ERVs) or Heat Recovery Ventilators (HRVs). Inside an ERV is a core. In that core both the incoming and outgoing air streams pass by each other, transferring both heat and moisture. In the winter, cold, dry air passes by warm, humidified air and the heat and humidity from inside the home pass to the incoming cold dry air, warming and humidifying it.

A common question is, why would I bring in air at all if it’s going to be too hot/cold/humid/dry? Won’t that make the home less comfortable and cause potential moisture issues?

The short answer is, you don’t have a choice, in most cases. A tightly sealed home, one that is very energy efficient, keeps air in the home, but doesn’t allow for stale air to be exchanged with fresh air, naturally. To do that exchange, a mechanical system is needed. An ERV is the most efficient way to accomplish the exchange of air in a home.

Our Slim AI Series ERVs have an SRE of 82%, meaning they retain 82% of the energy in the air in the form of heat and moisture.

Learn more about our HRV & ERVs

Read More and Stay Updated

Interested in learning about how a Broan ERV can help you meet energy codes, earn HERS points and tax credits, and provide a more comfortable home?

Great! We invite you to join a webinar where we will talk, in-depth, about energy codes and their application, HERS points, tax credits, and how our products can help you with all of those items while reducing costs.

Better air leads to a better life; we can create a path toward creating healthier and more comfortable living spaces.


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