“Akamai Hale” Off Grid
About this Project:
This “smart home” was built off the grid just below the Hermosa Cliffs at 8600 Ft. elevation North of Durango. Although a very private picturesque site, it was quite challenging to build upon since a solid layer of Hermosa Limestone was only inches below the ground. An efficient small cabin was the plan from the start, building an off-grid home altogether came about because of the high costs associated with bringing power to the remote build site. The home was oriented to face due south to take advantage of passive solar heat gains in the winter and with deep 4’ eaves and a steel awning to the south to create shade in the summer. The design and location of the windows was meant to bring the outside in with strategic placement not only to allow for passive solar gain but to bring the scenery and views outside into every room.
Off Grid Living Principles:
The concrete slab on grade foundation was pinned directly to the limestone that covers the site. A 4” layer of rigid foam was added to create a thermal separation from the ground/limestone. In floor hydronic heating tubes were added above the foam and a 4” concrete slab that was later stained as the finished floor was poured on top.
Advanced Framing Techniques:
Advanced Framing Techniques were utilized in multiple places for either material conservation or better thermal performance. The 2 story section of the home was built out of continuous engineered lumber on 2’ O.C. spacing. This allows for straight tall walls to be built quicker with less lumber. The loft floor system was then built to the inside of the tall walls to allow for continuous floor to ceiling insulation in the walls. Raised heel parallel chord trusses allowed for extra thick insulation to be installed in the attic spaces and over exterior walls. 2’ O.C. spaced studs and two stud corners reduce lumber usage and also allow for the trusses to bear directly on top of the framing.
Blown in fiberglass used in the walls helps to fill the entire cavity around electrical and plumbing without gaps and is rated at R23 versus a standard R19 batt in a 2”x6” wall. All of the exterior penetrations and gaps in the sheathing were sealed with a liquid applied flashing for airtightness of the building envelope. All windows and doors integrate with this liquid barrier to create a more durable water resistant structure where it is most vulnerable. The entire exterior of the structure was then covered with a 1” of layer of EPS foam before the exterior finishes were installed. This creates a thermal separation from the framing of the home to the exterior elements increasing the homes efficiency.
A 95% efficient propane fired combination boiler instant hot water heater was used not only for its low energy usage but for its size. It fits in a coat closet sized space and creates endless hot water and more than enough heat for the 960 square foot home. The largest electrical draw on the system is its circulation pump that can run for seven days on the fully charged lithium batteries of the Solar off grid PV system. A high efficiency wood burning stove is centrally located in the home to provide extra heat, but is more for ambiance. Due to the tight construction of the home a pint sized centrally located ERV system will bring in fresh air from outside as well as exhausting stale interior air from the home.
Low maintenance stucco and metal exterior finishes were chosen for their fire resistant characteristics. A metal standing seam roof allows the snow to slide effortlessly even at just a 1 ½” in 12” roof pitch. A light colored EPDM roof covers the high flat roof and helps to keep the heat down in that attic space. The standing seam vertical metal siding with a Charred Wood “Shoi Sugi Ban” finish will hold up well to the elements and looks great as well.
Solarworks of Durango designed a 3.6 KW roof mounted PV array with Lithium battery storage and a backup generator that generates enough power for the home. The racking for the panels was set on the roof to just hang over the South edge of the 2 story home so that any snow that accumulated could slide off to the ground 2 stories below, thus not blocking the panels with built up snow over the winter. Over the 2018/19 winter the system was tested when for 8 days straight it snowed and the panels became covered. The batteries had stored enough power before the storm to keep the heat on and running in the house for seven days. After those 7 days the generator automatically kicked on using about 2 gallons of propane to re-charge the batteries. On the ninth day the sun finally came out and melted the snow from the panels on the roof. Back to free energy all automatically controlled with an Outback Power management system and inverter.