The lower Midwest is known for its hot humid summers and frigid cold winters. New homes need both a heating and cooling strategy in this climate. In the summer, it’s common to have one or two areas in a house be uncomfortably warm, requiring the air conditioning system to be boosted to promote comfort. In leaky older homes, air infiltrates through cracks in the building envelope, making it difficult to control the purity of indoor air and the humidity levels in the home.
The new 3,700 square foot prairie-style Proud Green Home in Wildwood, Missouri, contains numerous advanced building science techniques and is designed for a family with three children around comfort, energy efficiency and high indoor air quality. A tight building envelope in the house allows less air to infiltrate through cracks and gaps and can help maintain comfort and reduce energy bills.
Photo courtesy Proud Green Home
Energy Efficiency Features
As homes get tighter, air quality and humidity issues can become an issue, requiring an effective ventilation strategy. To boost comfort and energy efficiency, Proud Green Home Saint Louis uses a Zehnder energy recovery ventilator. A stream of fresh-filtered air constantly enters the living areas of home, while stale air is removed from the bathrooms, kitchen and utility rooms.
This allows the builder to determine where the intake air originates, avoiding contaminants that would otherwise enter through crawl spaces, basements or attached garages in a leaky home. In a tight home without an effective ventilation strategy, stale air remains in the home and toxins are not sufficiently diluted.
The air from the energy recovery ventilator in the Proud Green Home is pre-cooled in the summer and pre-heated in the winter from the system's exhaust air, thus the supply air is nearly room temperature. This energy transfer feature keeps energy bills and fossil fuel use down, while maintaining comfort.
The intake air is filtered, removing dust, particles and pollen. Because the home is tight and the ventilation system supplies air to the home, the family has a lot of control over the quality of the indoor air. This was an important feature to the homeowners, as one of their children suffers from severe allergies and asthma.
"[The energy recovery ventilation system] works in conjunction with the HVAC system," says Matt Belcher, principal of Verdatek. "The V in HVAC stands for ventilation. This takes ventilation to the next level."
Because humidity levels impact comfort and indoor air quality, energy recovery ventilators lower humidity levels when needed, typically in the summer. This reduces the need for air conditioning, saving electricity.
"The temperature is only part of what leads to comfort," Belcher adds. "The ventilation is really what makes it comfortable in here."
Photo courtesy Proud Green Home
The house is expected to meet several green standards. A DOE Zero Net Ready Home achieves such a high level of energy efficiency that a renewable energy system can offset most or all of the annual energy use. Energy Star for Homes indicates that the home achieves a very high level of overall energy efficiency. The National Green Building Standard from the National Association of Homebuilders has a green scoring tool that encompasses numerous areas of eco-friendly design, including site development, indoor environmental quality and resource efficiency.
Sarah Lozanova is an environmental journalist and communications professional with an MBA in sustainable management. She recently relocated to BelfastCohousing & Ecovillage in Midcoast Maine with her husband and two children.