The importance of a fresh air intake vent.

Does your building or home have a fresh air intake vent? Would you know if it did? The tell-tale openings can be found on the building envelope, hopefully at least 10-feet away from contaminant sources. If you place a hand by the opening, you should feel air being drawn into the building envelope. A simple set-up will employ a non-corrosive screen and/or louver to prevent undesirable elements such as critters or water from entering the vent. In more complex applications—such as larger buildings where the ventilation equipment might be tucked further into the building, an intake system might involve louvers, dampers, ductwork, and other accessories.

No fresh air intake vent? Many older homes and buildings were not built with them. The oldest structures relied on natural ventilation. Such envelopes brought in fresh air through a network of small openings and cracks around windows, doors, soffits, the foundation—let’s just say older buildings were not built ‘tight’. While this might sound like a simple solution for ensuring air flow as well as preventing humidity issues, heating or cooling an indoor environment under such conditions can be an energy bill nightmare.


Thanks to the 1973 Oil Embargo, folks were inspired to build a wave of super-tight new structures to save energy. Little air would go in or out and the combination of recycled air, off-gassing of materials, and VOC-laden cleaning products began to cause ‘sick building syndrome’ in some cases. To boot, ASHRAE standards went from 15 cfm of fresh air per person to 5 cfm. Even 500,000-sq.ft. buildings were assumed to be receiving fresh air from sources such as passage through doors leading in and out of the structure. What was good for people’s wallets was horrible for their health. Still, it would take another 20 years for people to reconsider airflow and bring it back up to around 20 cfm.

Was a compromise between better indoor air quality and energy budgets in order? You bet! The solution? Simply put, tighten those buildings like a milk container, but stick in a straw. What you do with that straw is where the magic can happen. What works best? Set an Energy Recovering Ventilator sucking on that straw. If you use an outdoor air intake to draw air into a balanced mechanical ventilation system engineered around a high-efficiency ERV, you reap superior benefits, including:

  • Minimized energy costs thanks to the ERVs recycling efforts. In winter, you’re heating incoming cold air by syphoning heat energy from the warm stale air on its way out, but using cooler inside air in summer to lower the temperature of the incoming warmer air.
  • Minimized operational costs, thanks to nearly insignificant power requirements. (A smaller, high efficiency unit consumes less than half the energy produced by one solar cell.)
  • Year round humidity control. ERVs transfer moisture along with heat between the incoming and outgoing airstreams. Necessary humidity levels are maintained during winter, but minimized during summer.

Questions? Need an outdoor air intake or want to make better use of the one you have? Contact us at Haglid Engineering and we’ll have you breathing better and saving money in no time!