Rocky Mountain Low: Colorado Passive House Battles Winter Temps
High in the Hogback Mountains of Colorado, a 1,200-square foot dwelling is said to be the first Passive House in Colorado.
Built by consultant and writer Andrew Michler, the home was profiled by 5280 magazine.
According to the magazine, Michler built his home using a German design style called Passive House, which has caught on in Europe, but is much less common in the U.S. than LEED-certified or Energy Star buildings. Michler, who is the founder of Passive House Rocky Mountains and a certified Passive House consultant, says the difference between these certifications and Passive House is fundamental. With LEED and Energy Star, builders rely on technology, such as energy-efficient equipment or solar electric panels, in order to make a basic building perform better. Passive House takes it a step further, greatly reducing the need for common equipment such as heating or air conditioning.
According to green building consultant Baosol, the 1200 square foot building holds a guest room, bath, sleeping loft, office and shop which can be easily reconfigured for multiple uses in the future. The unique wedge shape is informed and inspired by the local hogback mountains in the area. The angled face of the building also increases solar gain improving performance while reducing materials and cost.
The advanced Intus triple pane windows are a pivotal technology, providing excellent solar gain and low energy loss with a tilt and turn operation that encourages natural ventilation and cooling. A 1,500-gallon rainwater catchment tank feed from the roof supplies non potable water needs including the toilet and gardens. Firewise construction adds to the fortification of the building. An Air Pohoda Heat Recovery Ventilation unit running on a dedicated power inverter uses tempered air from the earth tube to replace stale air with fresh air at more than 92 percent efficiency.
Michler told the magazine that he moved to Colorado from California 22 years ago with a desire to live independently in the mountains, and he realized that the Centennial State was a great place to test the Passive House concept. The frigid winters in the Rockies make a reliable heating system necessary, so Michler decided to use something Colorado has plenty of: sunshine. The house is designed to keep the heat it receives from the sun from escaping, and as such, the home stays between 67 and 77 degrees for most of the year and only needs a heating source in the winter.
“That’s what Passive House is about,” Michler says. “Rather than relying on technologies to create a comfortable living environment, you rely more on things such as solar gain, lots of insulation, and even the occupants. Even the devices the occupants use inside become a heating source for the building.”
Michler’s abode is 90 percent more efficient than a standard house. But the home is also comfortable, even in the coldest winter months in the Rockies, Michler says.
Green Building Features
- Air tightness: .45 ACH@50 Pascals; PassiveHouse Standard is .60 ACH.
- Windows: Triple pane windows from Intus
- Insulation: Primary insulation material is Applegate cellulose, sandwiched with Roxul mineral wool batt on the inside and Drainboard on the exterior.
- HRV: Air Pahoda
- HVAC: Passive solar heat gain, waste heat of the occupants and appliances, and a small hydronic heating loop.
- Water supply: A 1500 gallon rainwater catchment tank feed from the roof supplies non-potable water needs including the toilet and gardens.
- Sustainability: Cradle-to-Cradle model using materials that are either fully recyclable or completely organic.
All photos by Andrew Michler. Read more about Passive House homes.
Topics: Building Green, Certification / LEED, Energy Recovery & Heat Recovery, Energy Star, Heating & Cooling, Home Design & Plans, Insulation, Passive House, Photovoltaic / Solar Panels, Radiant Heat, Solar Power, Thermal Envelope