Prefab home is aiming for Passive House
Proud Green Home; October 16, 2015
A striking rural home, named the "Cech House", is expected to be the first pre-certified Passive House Institute U.S. (PHIUS) residence in Michigan (PHIUS certification expected in 2015).
The project is situated on nearly 3 acres of rural land and bordered by woods and farm field in Freeland, Michigan. The home was developed by Detroit-based Phoenix Haus.
Passive House building methodology comprises a set of design principles used to attain a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. “Maximize your gain, minimize your losses” summarizes this approach.
This 3 bedroom, 2 ½ bath home was designed using Passive House principles – which require super insulation, airtightness, a balanced heat and moisture recovery system and solar gain orientation. This growing energy efficiency standard of building translates into a building that maintains a comfortable indoor temperature of 68 degrees 365 days a year, with minimal energy use. Mechanical units recover, reuse and recycle all internal energy as minimal as hair dryer or oven heat, thus wasting nothing. It also has the potential for Net Zero status, which means the home is creating more energy than it is consuming. This can be accomplished with the addition of on-site renewable systems such as a small solar array of PV.
“We chose a piece of land that complimented the style of the house”, said Hilde McDonald, owner of Phoenix Haus. “The rolling hills, south facing exposure and rural setting made an ideal spot for a Passive Home.”
When completed at Thanksgiving of 2015, the "Cech House" will feature a 45-foot Cedar pergola breezeway connecting the home to a two-door detached garage. With a protected courtyard for entertaining guests in the summer months, a refrigerated wet-bar and a corner kitchen eckbank– a tribute to the owner’s German heritage – comfort, beauty and functionality will be the main tenants of its design.
Phoenix Haus’ decision to build the Cech House was two-fold; first, they wanted to bring Passive House science knowledge to the Midwest and educate homeowners of its numerous benefits. Secondly, Phoenix Haus wanted to use its innovate pre-built component system to demonstrate that the complexities and high price tag often associated with this type of home, could be substantially reduced.
Bill McDonald, principal of Phoenix Haus, conceived the idea of fabricating wall and roof panels in a controlled environment as a solution to the high cost associated with Passive House, when constructed onsite. “Europeans have been building these for years”, said McDonald. “I knew we could take that fundamental building science and bring it to the Midwest. Component building is ideal for the Passive House standard because such a high level of detail is necessary and can be easily accomplished in a controlled setting.”
This pre-built component process all begins behind a computer, utilizing powerful modeling software. With the help of a 3D CAD model, the highest level of accuracy could be achieved when designing the home. Additionally, this model was able to interface seamlessly with a CNC wood cutting machine, the heavy piece of machinery cutting lumber for the home. CNC code files were created and the manufacturing process then began. Most importantly, each step taken during this progression never left the side of the aggregate energy performance model, ensuring proper performance at the end of the design process. After the package of wood parts was precut and finalized, it arrived to the production facility. Wall and roof panels were assembled, pre-insulated and secured with a vapor diffusion system, thereby allowing moisture to escape but not enter back through the pre-built assemblies. The panels were then delivered to the job site, assembled and secured.
“Home owners’ greatest misconceptions come from their belief that pre-fabricated components either limit their ability to be creative or they assume low quality – this is totally not the case,” said McDonald. “We can deliver the utmost quality and performance [Passive House] andkeep costs low because of our production facility that runs 356 days a year, despite inclement weather, combined with our innovative assembly technique.”
Furthermore, PHIUS (Passive House Institute U.S.) has improved and optimized the Passive House certification criteria. Requirements for project certification now rely on a climate specific annual energy use metric. “The heating and cooling criteria are determined from formulas based mainly on local climate factors including degree-days, outdoor design temperatures and design humidity, and annual solar radiation,” according to the Passive House building standards. Add footnote here (http://www.phius.org/phius-2015-new-passive-building-standard-summary). In addition, PHIUS has developed adaptations to the passive building approach for 2015, while preserving the same high-level standard. First, they reconsidered airtightness requirements based on the avoidance of moisture and mold risk. This approach for the airtightness requirement, scale appropriately with building size when “before, a larger building that met the 0.6 ACH50 requirement could actually be up to 7 times more leaky in terms of air leakage per unit area than a small single family home that tested the same by volume air change rate”, according to Passive House Institute. The second adaptation for 2015 came in terms of source energy limits, which now encourage inventive and creative building designs that allow for costs to by off-set by cutting edge renewable systems, lowering total energy costs and allowing potential for Net Zero status.
Because the home was built to the Passive House standard, energy bills will be reduced by nearly 90%. The residence also has the potential for net zero (a zero-energy building), with the addition of a small solar array of PV.
Phoenix Haus, based out of Detroit, Michigan designed and produced the components of this innovative pre-built system. This home is set to be completed by Thanksgiving 2015.
General Specs and Team
Location: Freeland, MI Climate Zone 5b
Treated Floor Area: 3,234 ft2
Gross Enclosed Volume: 51,095 ft2
Designer: Sedgwick & Ferwerda
Builder: Phoenix Haus
Energy Consultant: Bill McDonald
PHPP Specific Space heat Demand: 4.46 kBTU/(ft2yr)
Blower-Door Test Results: 0.6 ACH50
Below Grade Foundation: R50.7
Above Grade Walls: R51.0
Roof Panels/Section: R71.7
Read more about Passive House construction.