The mantra “build tight, ventilate right” has been a calling card of the high-performance building community for decades. Tight, properly ventilated buildings make it easier to manage indoor air quality, comfort, durability and energy use—especially in a climate that is becoming more extreme and prone to wildfires. Indoor air quality and attention to detail in air sealing and ventilation is critical for many reasons.
Mechanical ventilation systems are designed to introduce fresh outside air and improve the indoor air we breathe, until an event like a wildfire brings in smoke and particulates. Poor outdoor air quality prompts us to find ways to stop the smoke from getting in. The answer in new construction is to focus time and money on air sealing details that turn an average building into a truly well-sealed home. Tight buildings reduce the amount of smoke and particulates that enter a home and allow a well-designed and installed HVAC system to better capture the particles that are harmful for people and their pets to breathe.
Filtration and mechanical ventilation in well-sealed homes are critical because these systems are responsible for removing unwanted pollutants while introducing much needed fresh air throughout the year. The 2021 Oregon Residential Specialty Code added new requirements that emphasize the importance of ventilation, but these systems also have the potential to introduce additional smoke and particulates during a wildfire event. When installing a central HVAC system, plan to use a filter with a Minimum Efficiency Reporting Value (MERV) of 8, with a MERV 13 or higher recommended where smoky conditions can be expected.
If there is a fresh air intake, either through the central return or a dedicated supply fan, make sure it has a MERV 8 or higher filter and that there is a way to close off the fresh air duct without preventing the system from conditioning the home or running in “circulation” mode. Controls should be easily accessible, and you should consider providing instructions for occupants to maintain their system, as well as how to turn the whole house ventilation system off during a wildfire event. Just make sure to instruct them to turn it back on when air quality is back to normal!
One last thing to remember is that buildings don’t need to breathe—but people do.
Set a goal to “build tight, ventilate right” and take advantage of Energy Trust’s EPS™ New Construction incentives in the process. Email eps@energytrust.org to learn more.