Fourth: Air Sealing and Dedicated Ventilation
“People say a house has to breathe. That is essentially a fallacy,” Hindle says. “People in the house have to breathe. Do you want them breathing air that has been sucked in through gaps in the insulation, which may have mold in it and is full of pathogens, or do you want to seal up the envelope and bring in air through dedicated ventilation?”
To meet both the efficiency demands of the structure and the respiratory demands of its inhabitants, the home’s tight shell should be ventilated with an energy recovery ventilator (ERV). ERVs provide a continuous flow of fresh air from outside while conserving energy through the use of a heat recovery mechanism in which incoming air is conditioned for both temperature and humidity by outgoing air, reducing the load on the home’s electrical systems. Some ERV systems operate at up to 96% efficiency.
“Everything should be run through that system,” Arthur says. “Bathroom vents. Everything.”
The result is fresher, cleaner air than standard-built homes offer without the heat loss associated with the air leaking through the envelope.
But while these changes can make a large difference in energy savings and reducing carbon output, in the end, Hindle and the other consultants Builder spoke with strongly encouraged going the full distance to build to Passive House requirements or those of a similar program, due to the exponential improvements in energy savings when all the elements in the home are working together.
“One of the intriguing aspects about [a passive home] is that it combines a lot of little things, and in the end, the whole is then greater than the sum of the parts,” Denton says.
“The economics suggest that the pay off is more substantial if you can reduce loads enough to significantly reduce the size of systems as a component of first cost,” Hindle says. “And when you look at the cost of operational energy over the life of the home, it is the proverbial no-brainer.”
Claire Easley is a senior editor at Builder.
