A tight building envelope seals the Proud Green Home from unwanted sound and air flow (video)
Standing on the porch of the Proud Green Home at Serenbe with an ear at the door, it’s tough to tell what activity — if any — might be going on inside. The home is sealed so tight, neither sound nor air leaks out.
The superior enclosure is one of the marvels of the Proud Green Home, preventing unwanted drafts from outside and keeping conditioned air in. It also could have been a detriment without adequate airflow.
Designers realized early on the importance of moving air around the structure, as a means of heating, cooling and keeping air from stagnating. Without flow, occupants could be subjected to some of the health risks high-performance homes are designed to prevent, like mold and mildew.
Teaming with manufacturers, designers implemented advanced techniques and technology that will long make the home — and other high-performance structures like it — a comfortable and efficient place to live.
To understand the tightness of the seal of the Proud Green Home at Serenbe, consider this: Construction of the average American home leaves enough gaps and drafts to equate to a window being left open all the time. Construction of the Proud Green Home leaves an opening about the size of the mouth of a foam cup.
The heart of the Proud Green Home's ventilation system is the energy recovery ventilator, commonly referred to as the ERV. Barry Stephens, business development and technical director for ERV manufacturer Zehnder America, refers to it as the "lungs of the home."
Anchored in the attic, the ERV is a whole home solution that works by constantly providing fresh air while maintaining a constant interior temperature.
External air is taken in through an external vent and into a heat exchanger. The fresh air is filtered into the ERV, and heat (energy) is pulled from the air. Filtered air is distributed through tubes strategically laid within the ceilings and walls of the home and into the rooms.
Watch builder Luis Imery explain the ERV in the Proud Green Home at Serenbe.
The ERV continuously extracts moist, stale air from wet rooms such as kitchens, bathrooms and utility rooms, and supplies fresh, filtered air to bedrooms, living rooms and dining rooms. Up to 90 percent of the heat in the extracted air is recovered by a heat exchanger in the unit and used to heat incoming fresh air as needed. Stale air goes into a collection chamber, where it is routed into the ERV, the energy removed and the remainder pushed out of the home.
The ERV uses silencers so the sound of it running won't travel through the ducts. Air is filtered into rooms in such a way that no drafts can be felt.
Because the ERV maintains the temperature of conditioned air, large air conditioners and heat pumps aren"t required, thus reducing construction costs and energy expenses to run them. Instead, builders only need smaller units, such as mini-splits, to cascade air through a home.
"We hope to set an example here and show people what can be done," Stephens said.
Building codes require increasingly tight seals of homes. However, they employ outdated ventilation methods.
The traditional way of ventilating a home has involved installing vents and fans and opening doors from time to time. The problem is that the homeowner has little control over how quickly air can circulate through. In many cases, they're at the mercy of Mother Nature.
Studies are being conducted about the impact of tightly sealed structures. Stephens said he believes that attention will gravitate toward using equipment that ventilates with high efficiency.
|Architect Chris Laumer-Giddens inspects the Zehnder ERV in the attic of the Proud Green Home at Serenbe.|
As deep-green building becomes more prevalent in residential construction, environmental experts predict a focus on airflow and ways in which to make it as efficient as possible will be among the industry"s top trends over the next few years.
Heating, ventilation and air conditioning systems (HVACs) have long been key components in the development market. But the ventilation aspect of HVAC has long been overlooked, said Dennis Creech, co-founder and executive director of Southface, a non-profit organization dedicated to efficiency and sustainability.
Fueling the change is the connection proper ventilation has with home durability in minimizing moisture and keeping the interior dry and sound. Proper ventilation isn't necessarily a one-size-fits-all solution. It requires specific design and functionality based on the home itself and the climate in which it sits.
Ensuring a home is outfitted with the most beneficial ventilation system demands proper planning. Otherwise, mistakes can be made in installing too few ducts to circulate air or in construction that inadvertently blocks flow.
"If they're just winging it, you miss opportunities," said Luis Imery of the Imery Group and builder of the Proud Green Home.
Read more about the Proud Green Home at Serenbe.