New houses are built too tight to breathe on their own

How houses got too tight

For most of the territory’s building history, houses leaked enough that fresh air took care of itself. Jalousie windows, unsealed penetrations, attic duct with gaps: the 1970s block ranch in Palm Coast changes its air several times an hour without trying. The cost was humidity and power bills, and the benefit, never intended, was that indoor pollutants never built up.

Energy codes and construction practice changed that. The stucco two-stories going up in St. Johns and Clay counties, and the newer homes in every market, are wrapped, foamed and sealed. They’re cheaper to cool and far better at holding humidity. They are also tight enough that cooking, showers, cleaning products, new finishes and the people themselves raise indoor pollutant and CO2 levels with nothing to flush them. Modern residential codes now call for mechanical ventilation in new homes for exactly this reason.

That’s a new problem for Florida, and the product category to solve it is new to most homeowners here.

The equipment that fits a sealed house

For a tight home: an energy recovery ventilator. An ERV brings in a controlled stream of outside air and exhausts an equal stream of stale air, passing them through a core that transfers both heat and moisture from one to the other. In a Florida summer that means the incoming air arrives cooler and drier than the outdoors, so the air conditioner isn’t swamped. A heat recovery ventilator, the HRV, transfers heat only and leaves the moisture in; it belongs in cold, dry climates and Cook’s doesn’t recommend it here.

For a simpler budget: a motorized fresh-air damper on the return, controlled to open for a set number of minutes per hour. Less effective, no energy recovery, but a real improvement over nothing in a sealed house.

For businesses: ventilation is code, not choice. Restaurants, classrooms, salons and clinics have required outside-air rates, and the equipment ranges from an ERV to the economizer and outside-air section on a rooftop unit. Cook’s sizes these to the occupancy and the code.

For older, leaky homes: none of the above. The right spend is on sealing and dehumidification, and Cook’s will say so.

Putting an ERV in

An ERV mounts in the attic or a mechanical space with two insulated ducts to exterior hoods, placed apart so exhaust doesn’t re-enter, and two to the house’s duct system or dedicated registers. Airflow is balanced at startup with a flow hood so the house isn’t pressurized or depressurized. The control is a timer, a humidistat or an air quality sensor. A fresh-air damper is simpler: a duct from an exterior hood to the return with a motorized damper and controller.

Cook’s installs ventilation equipment of the types above in all ten markets and maintains it afterward; ERV cores need periodic cleaning and filters need changing, which join the maintenance visit. Manufacturer warranties are registered by Cook’s; ask for the labor warranty term and which brands beyond Lennox’s line are offered. [[CONFIRM WITH JERRY: labor term and brands]]