1st Passive House in Michigan Proves Shift
TecHome; August 25, 2016
A passive house is an example of an industry shift toward healthier homes that garner appeal without breaking the bank.
Detroit-based Phoenix Haus is a certified passive house builder and manufacturer with a focus on improved thermal performance, energy conservation and indoor air quality (IAQ). In fact, the company is so innovative that it built the first ever certified Passive House Institute U.S. (PHIUS) residence in Michigan.
The team hopes the home—called the Cech House—will serve as an example to other builders about the benefits of energy efficient building and how it increases homebuyer demand.
“We’ve found that a lot of folks simply aren’t aware that this type of building methodology exists. Their first question is always, ‘Why haven’t we always done it like this?’” says Kate McDonald, project manager at Phoenix Haus.
TOUR 1st Passive House Certified Home in Michigan (Scroll through to learn how you can see the home in person.)
A passive house encourages efficiency with superior airtightness and insulation standards.
What is a Passive House?
Passive house principles require that the home’s design combine superior insulation, airtightness, a balanced heat and moisture recovery system and solar gain orientation.
“This growing standard of building translates into a home that maintains a comfortable indoor temperature of 68-degrees, 365 days a year, with minimal energy use,” says McDonald.
The home was able to achieve net zero, passive house certification with superior wall and floor insulation.
The goal is to improve thermal performance, airtightness and R-Values. The home’s pre-built wall panels rely on 12-inches of dense-pack cellulose insulation plus an exterior treatment for thermal, bridge-free detailing of the fiberboard. This bridge-free detailing is used to provide a barrier between the wood framing and the outside temperature while allowing for vapor diffusion out of the structure.
Essentially, the insulation creates an efficient air-barrier that keeps the interior comfortable and safe from the weather and also allows vapor and moisture to escape through the open profile wall/roof assembly. This model prevents a buildup of mold in the wall cavity.
The 12-inches of insulation in the walls along with the 16-inches of insulation in the roof help boost R-Values. Total wall R-Values are at R-51 in the Cech House, while the roof stands at R-71.
The home’s efficient design helps prevent the need for an oversized rooftop array. “[The Cech House] only needs a small addition, somewhere around five thousand kW, to make the home net zero,” says McDonald.
According to the U.S. Energy Information Administration, the average American home uses around 10,000 kW of electricity, with Louisiana homes reporting the highest annual consumption in the country at 15,497 kW. The significantly higher energy needs of conventionally built home requires a much bigger solar array.
The smaller solar requirement enables builders to include solar as standard on passive homes without worrying about breaking the bank.
The net zero, energy efficient design helps this passive house consume significantly less energy, which, according to McDonald, is a major appeal point among buyers.
“A passive house causes energy loads to diminish so drastically that the home ends up consuming 90 percent less electricity,” says McDonald.
And that means cost saving for the buyer. “The homeowner has now occupied this home for three months, during one of the hottest summers of recent memory in Michigan. Her monthly electricity bill is $17. For a home that is close to 3,500-square-feet, that really is unheard of,” says McDonald.
Attention to IAQ was added to the passive house concept through the use of connected, high-efficiency HVAC equipment.
The Cech House’s HVAC system was able to be downsized because of the efficient building techniques. The main ventilation HVAC unit is a Zehnder 550 ComfoAir energy recovery ventilator (ERV) with two Mitsubishi mini-splits that provide conditioned air throughout the home. The use of the two mini-splits eliminates the need of a furnace or traditional air conditioning system.
“It’s as quiet as a mouse, yet it runs 24 hours a day to filter, circulate and recycle air in the home. The annual heating and cooling load of this house is just under 13,000 BTUs,” says McDonald.
According to McDonald, the cleaner, improved IAQ is one of the first things that visitors notice when entering the home. The ERV is able to capture up to 87 percent of escaping heat, which is then recovered and subsequently recycled to heat the incoming fresh air via recovery ventilators.
“This home acted as a prototype for Phoenix Haus and was the opportunity to perfect our prefab component system,” says McDonald.
It also helped the builder optimize shipping and design during the factory-assembly stage of the project. According to McDonald, the team learned that shipping the home’s components proved logistically difficult, forcing the team to make an investment, which has since saved the builder.
“Going forward, all panels are now loaded vertically via an overhead crane, which results in zero damage,” says McDonald. “We’ve streamlined our manufacturing and loading process to be as efficient as possible, which ultimately saves the client more money.”
Saving the client money helps the builder cut costs and generate appeal as an innovative, cost-effective option for homebuyers.
Aside from learning lessons that will impact the way Phoenix Haus builds homes, the team is also hoping to impact the broad TecHome market.
“I would say the first challenge is knowledge; there is a steep learning curve for professionals when it comes to passive house methodology,” says McDonald. “I really think folks believe it’s too good to be true, but it’s not!”
McDonald stressed the importance, and difficulty, of finding skilled passive house designers. The difficulty comes from the techniques not yet reaching the mainstream. “We know they’re out there, but sometimes they can be hard to find.”
When it comes to the passive house concept, McDonald says that other builders need to stop thinking of homes as individual systems.
“In a home like this, every decision is calculated and takes the entire performance of the home into consideration,” says McDonald. “One of the things I love most about passive house building is the fact that it forces designers to look at the home as one aggregate unit; it ends this commonplace practice of specifying mechanicals on a prescriptive, one-off basis.”
The Cech House team is confident that builders and homebuyers that experience a night in the passive home will be convinced about its design. The Cech House has been placed on AirBnb, and the team has invited builders and designers to see the home in person.