Housing Authority (TNHA)
The TNHA Sustainable Housing Project Phase IV house is framed with an integrated wood truss, a single prefabricated unit that combines the exterior walls, floor joists, and roof framing into one structural assembly. This creates a thick cavity that allows ample space for high R-value insulation and speeds up the process of framing construction.
The entire envelope is filled with 10 inches of polyurethane spray foam, which is airtight and moisture resistant, for an R 60 rating (3 times higher than a conventional 2 x 6 wall). Steel siding provides shear strength and prevents moisture from infiltrating the building. (CCHRC, 2014)
Integrated Solar Hot Water
One of the largest energy users in a home is the domestic water heater. On an annual basis in a very well insulated home, the energy consumed to heat domestic water can often equal the energy required to heat the home. The simplicity, efficiency, low maintenance and life-expectancy of solar thermal systems can make them an excellent renewable energy source, even with the variable sun exposure found in Alaska. With appropriate storage capacity, they can also be utilized for space heating.
One of the challenges with using photovoltaic solar collectors in northern climates, especially high latitudes, is that the peak energy use comes during the cold, dark winters, when solar energy is relatively unavailable. However, the summer months in arctic Alaska bring 24 hours of sunlight, warm temperatures and mild weather. This is an optimal environment for solar thermal technologies, according to research by the University of Alaska Fairbanks Alaska Center for Energy and Power. Heat derived from these systems can be used to meet domestic hot water demands, which remain fairly constant throughout the year, or supplement low-grade heating requirements sometimes necessary during arctic summers.
TNHA utilizes a Gobi Heliodyne three (4’x8’) panel system to heat a Superstor 80 gallon water tank. It is estimated that this system will offset 7 million BTUs March through September. That equates to approximately 50 gallons of fuel. Data TNHA is collecting in the village of Kaktovik already indicates that the BTUs produced by this system far exceed these estimates.
The cost of these systems is steadily decreasing. Technology for storage of thermal heat is continually being heat developed. The cost of fuel is increasing rapidly. It is sensible to offset our dependence on fossil fuels in a variety of ways. Using the sun to water is an ancient idea that resonates in Alaska. (CCHRC, 2014)
Most homes on the North Slope rest on wood pilings driven into the ground. This accelerates permafrost thaw by conducting heat into the frozen ground. As the permafrost thaws, the ground around it settles. The prototype has a post-on pad foundation that rests atop the ground, isolating the house from the soil and preventing heat from affecting the permafrost. With the threat of permafrost melt and intensifying coastal erosion, the foundation incorporates beams that act as skids designed to facilitate easy relocation of the house if necessary.
In order to further mitigate environmental impact, the foundation has sliding steel posts attached to pads which may be adjusted up or down to accommodate variable movement or irregularities in the building site of up to 8 feet. This also has added benefit in that absolutely no gravel or invasive site preparation (i.e. clearing, fill, earthwork) is required for the new home construction. (CCHRC 2014)
Lifewater ExtremeSTP ® On-Site Residential Sewage Treatment System
In recent years village sanitation has expanded beyond “honey buckets” and high maintenance flush and haul systems to include multimillion dollar utilidor systems and sanitation treatment facilities. On the North Slope of Alaska connection to existing utilidor systems is either unavailable or is cost prohibitive. Low-maintenance, affordable alternatives must be found and utilized. TNHA has implemented Lifewater Engineering Company’s “custom built,” proprietary, above ground or below ground ExtremeSTP® residential sewage treatment plant as the preferred solution to this problem. The above ground units are specifically designed for areas where permafrost, bedrock or other ground or soil conditions make it impractical to install a below ground system. Lifewater’s residential ExtremeSTP® sewage treatment plants: Will operate at -60oF (-53oC), provided reliable electrical power is available; will not corrode and never need painting; can be sized for aircraft transport to remote northern communities; utilize submerged fixed film activated sludge aerobic sewage treatment unit; utilize UV disinfection; include an effluent pump; and, the $30,000 systems use minimal electricity and do not disrupt the delicate Arctic tundra and permafrost. Lifewater systems require very minimal service every 12 to 18 months.
The TNHA Sustainable Home home designs all incorporate the Lifewater Model SST600 self-contained, DEC approved, sewage treatment plant at per unit average cost of $39,000 as opposed to utilidor systems costing several times that figure. (CCHRC, 2014)