“Snowslide” Passive House
Edgemont Highlands meets High Efficiency
From the exterior the home fits right in amongst similar dwellings in the subdivision. The landscaping made use of the natural sandstone from the site and the colors were chosen to blend in with its natural surroundings. Great care was taken to preserve the large ponderosa pines and gambel oaks on the site.
Designed using Passive House Principles
- Create continuous insulation layers and minimize thermal bridging through the buildings structural components.
- Ensure an airtight building envelope.
- Specify high performance triple pane windows and well sealing doors.
- Installation of a balanced heat and moisture recovery ventilation system.
- Management of solar gains for reduced heating loads in the winter and avoid overheating in the summer.
- Size the heating system according to reduced loads from above increased efficiencies.
Building Science – Wufi Passive Energy Modeling
- In conjunction with the design phase a 3-D model of the home was loaded into the German “Wufi Passive” software program. The software will model expected performance based upon comprehensive inputs of all the exterior envelope components of the home. The solar gains through glazing are calculated as well based upon the exact orientation of the home. The software was developed initially to monitor the flow and accumulation of heat and moisture in building assemblies and the “WUFI” acronym translates to heat and moisture transiency. The program we use is set up to specifically verify if the home as modeled will meet stringent 2015 Passive House Institute US standards.
- Climate specific data for the homes location and elevation are entered and used to gather precise heating and cooling loads. The software will also dynamically model performance of the home throughout an entire year based on this climate data.
- Once a baseline is determined the building assemblies and insulation layers can then be adjusted to meet the desired performance for the home.
- The final performance data can then be used to properly size the ventilation and HVAC equipment needed.
Advanced Framing Techniques:
- Floor joists: 16” I Joists were set at two feet on center = More insulation, less thermal bridging, and sturdy construction.
- Wall framing: Studs were framed at two feet on center. All structural headers were insulated with 1 ½” -2” of EPS insulation.
- Raised heel Trusses: Engineered raised heel trusses allowed for a thicker insulation layer over the top plate of exterior walls.
- 2 Stud Corners: Outside corners of the structure were framed using just 2 studs to allow for insulation to reach the corner and limiting thermal bridging.
Extreme Air Sealing Details:
- Exterior wall and floor sheathing: Standard ½” OSB sheathing is considered an air barrier, the gaps necessary for expansion and contraction however are not. A liquid applied membrane with elasticity was used to seals these gaps, weatherproof exterior openings, and seal all penetrations and gaps between exterior doors and windows.
- Polyurethane Closed Cell Foam: A three inch layer of closed cell foam was installed over the top of the sheetrocked ceilings to create an air barrier. This also seals any electrical, plumbing, and HVAC penetrations into the attic
Superior Insulation Layers:
- R-35 Wall Assembly: Blown in fiberglass was used at all exterior walls. The exterior of the home was then wrapped with a 2” layer of fire resistant rigid Polyisocyanurate insulation.
- R-62 Ceiling Assembly: Three inches of Polyurethane closed cell foam was covered with 16-18” of blown in fiberglass insulation.
- R-60 Floor insulation: The entire 16” floor joist cavity was filled with blown in fiberglass insulation.
Controlled Efficient Ventilation:
- Zhender Energy Recovery Ventilator: A high performance balanced continuous ventilation system that recovers the existing heat and humidity inside the home and delivers constant filtered fresh air within a tightly built structure. Zhender was chosen because of their low energy usage and high energy recovery rate.
- In a tight house fresh air is key to indoor air quality and comfort. The ERV is constantly exhausting air at low flows from both bathrooms, the laundry room, and the kitchen. That air is indirectly exchanged at the ERV core with a balanced amount of fresh filtered outside air. That fresh pre-conditioned air is then distributed to the bedrooms and living spaces of the home.
High Efficiency Heating and Hot Water:
- Navien Combi Boiler: This 95% AFUE unit handles the entire hot water and heating loads for the whole house.
- JAGA low flow Radiators: These low flow low heat radiators were the perfect fit for the low heating loads.
- Myson Towel Warmers: A radiant heat source for small rooms with the added bonus of dry warm towels.
- One radiator for each room delivers heat through the in wall mounted radiators and the convection currents flow from the floor up through the heating elements and out the opening at the top.
- Each bathroom was fitted with a hydronic towel warming radiator that was sized to handle the bathroom heat requirements.
3rd Party Verification:
- HERS Index Scoring: The Home Energy Rating System(HERS) is the industry standard by which a homes energy efficiency is measured. It was developed to give an indication to how efficient a home would be versus a duplicate home built to the 2009 IECC code standards for our climate.
- The rating of the code built home starts at 100 and any number below 100 represents a percentage point in improved performance.
- Having a 3rd party contractor rating the insulation install and performing a blower door test is a critical step to ensure the quality and performance of the home.