Sustainable Solar Home
Building with the Sun in mind
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Passive Solar Home Design

A Sustainable Solar Home (SSH) is a home that uses the resources provided by nature, including the sun, rain, wind and earth, in order to create a comfortable living environment that meets peoples’ basic needs. This is done without reliance on, or the expense of, public utilities. In fact, one of the primary benefits of living in an SSH is that there are no utility expenses for heating, cooling, power, water or sewage- it exists completely independent in an off-grid or net-metering situation. It is the unique design and construction of an SSH that makes this possible. SSH construction is basically a hybrid of both an Earthship (www.earthship.com) and a High Thermal Mass Home, or HTM (www.thenaturalhome.com). An SSH is built completely above the ground and looks like other traditional homes. In addition to providing a more traditional look, SSH above-ground construction provides a number of further benefits. First of all, windows can be placed on any or all sides of the home. This allows every room to have excellent daylighting, air flow and views of the surroundings. Second, exterior living spaces can be built around the entire perimeter of the home, allowing occupants to truly experience and enjoy the outdoors. Finally, because of its above ground design, an SSH is far less likely to experience moisture problems.



One of the great benefits of building an SSH is that it is DIY friendly- you can build an SSH yourself. In fact, we are in the process of completing our own SSH, pictured throughout this site, having had no previous building experience of any kind. We drew up simple plans on grid-paper (avoiding the cost of an architect) and used county engineers (included in the cost of our building permit) instead of hiring out our engineering. This combination reduced our costs by well over ten thousand dollars. SSH construction uses commonly accepted construction methods and materials, making it easy to not only draw up your own plans, but to permit as well. There is no waiting months, or even years, to receive a building permit, as can be the case with "alternative" construction methods. Also, by using your own labor, and perhaps the labor (skilled or unskilled) of a few helpers, you can save an amazing amount of money on construction costs. We further chose to use many recycled and reclaimed materials in the construction of this SSH in order to reduce costs and to enhance sustainability. Again, using our SSH as an example, it has a final construction cost projection of $60 per square foot. Furthermore, an SSH can be built on property that need not have access to any utilities (off-grid), and which is therefore much less expensive. Finally, if you "build slow, pay as you go", perhaps you can also avoid the need for a home mortgage, as we have done.



An SSH provides a complete highly sustainable living environment- including heating, cooling, water, sewage, electricity, solar cooking and food production, all with very little additional expense. Once built, an SSH will take care of you for the rest of your life. Furthermore, the principles that govern how an SSH functions will work in just about any climate around the world that receives a decent amount of sun, making an SSH an extremely versatile home. These principles, by the way, are primarily "passive" in nature. Passive systems minimize the use of mechanical systems which require electronics, moving parts and power usage for operation (defined as an "active" system), and which therefore  tend to break down over time. An SSH is what is referred to as a "Net-Zero" home. This means that an SSH will produce all of the energy that it will require to function, outside of a few gallons of propane. An SSH is also a nearly carbon-zero building, producing a much lower Co2/ greenhouse gas output in both construction and during its life-cycle than other mainstream forms of construction. Finally, an SSH is built to last for generations, further enhancing its sustainability.


 
A Sustainable Solar Home is a basically a group of inter-related systems, such as roofing, water supply, DWV (drain/waste/vent), PV electrical, glass, plumbing, etc. that must all work together. Therefore, an SSH project must be planned holistically. Using our SSH as an example, it was nearly two years in the planning stage. The SSH featured in this site has just over 3000 square feet of living space, and includes 3 bedrooms, 2.5 bathrooms, an office, a bonus room, a second living room and large mechanical/storage room. There are no hallways in this SSH. Other than its south facing glass wall, it looks similar to other southwestern style adobe or stucco homes. The floorplan is shown below.

 

An SSH must face within a few degrees of due south, and have unobstructed access to the suns heating rays year-round. An SSH is long east to west and shallow north to south. This house is approximately 80’ wide by 40’ deep, and consists of four "wings". An SSH can actually be as wide as you like (by adding or removing wings), as long as you limit the depth (north to south) to 40' or less. The entire south wall is sloped glass (receives more heating energy than vertical glass), allowing the house to have access to the suns heating rays throughout the entire day, all year round. The closer we get to winter solstice, the lower the sun rotates through the southern sky, and therefore, the farther the suns rays enter into the home. Likewise, the closer we get to the peak of summer, the less the suns light enters the home. This SSH also has a clerestory which houses 7 windows and two solar batch water-heater panes of insulated glass. A small selection of hi-quality low-E windows placed around the home provide for added light, ventilation and views of the beautiful scenery.



An SSH is constructed of 8x8x16” CMUs (concrete masonry units), otherwise known as concrete blocks, which are available at just about any building yard. These blocks are simply stacked in a running bond pattern, much like putting a Lego block wall together. The CMUs are dry-stacked (no mortar used), and then they are filled with concrete and rebar. Dry-stacking block not only reduces construction time by well over 50%, but also provides a simple construction method for the unskilled worker. Add insulation and a stucco exterior finish and you have the ultimate in strength, durability and thermal mass energy storage. You also have a home that is quite conventional in construction, and is therefore easier to finance, permit and re-sell than other solar-style homes. Further, because of this type of construction method, SSH walls are basically sound proof, draft proof, insect proof, and moisture proof.




The structure is super-insulated, being surrounded by 4” of rigid insulation on the exterior walls and 8” of rigid insulation in the ceiling. Due to this, it stores heat (thermal energy from the sun) quite well. We also use the principles of PAHS, or Passive Annual Heat Storage ( www.earthshelters.com), to further help heat and cool this house. PAHS basically illustrates how thermal energy can be "pushed" into the soil under and around an SSH, up to 20’ out over a six month period, as long as that soil is insulated and kept dry. Therefore, the floor in an SSH must be in contact with the earth (already at 58 degrees) so that the heat from the suns rays can penetrate directly through the flooring and into the ground. Here is how it works. During the warm months, the suns heating energy radiates down into the thermal mass below and around the house. It is this process of heat energy storage that will keep the interior temperature from overheating. Then, during the colder months, as the interior temperature of an SSH tries to dip below the temperature of the walls and floor, this stored heat energy is then gradually pulled out of the thermal mass and back into the interior living space. The insulated thermal mass on an SSH functions like a giant battery that gets recharged during half of the year and then is discharging during the following half year. This happens routinely throughout the year with zero controls or mechanical systems required. The only cost is the initial construction. It is this passive heating and cooling process that meets all of the heating needs of an SSH, there is no furnace required.




 An SSH is topped off with a standing-seam metal roof, providing a low maintenance, long lasting, fireproof roof which also allows for safe rainwater harvesting. In fact, much of this homes water will come from rainwater that will be stored in two large cisterns and cleaned by an in-house filtration system. Rainwater is excellent for in-home use because it is naturally soft (no expensive water softener required), while containing no chlorine or fluoride (commonly added by the local municipality). This rainwater will also be used for interior and exterior irrigation. Harvesting rainwater eliminates our need to pull all of our water from the aquifer through the use of our on-site well, which is now simply used for drinking water. Black water (toilets and kitchen sink) and gray water (sinks, showers, washing machine) will be separated. The resulting small amount of black water will flow to the on-site septic tank. The gray water will be diverted to exterior trees and plants for irrigation.



Adequate ventilation is a key element of healthy living in any home, but because SSH construction is extremely tight, it is even more important. This ventilation system begins with seven, 10” diameter ventilation ducts that allow hot interior air to escape straight up and out through the apex of the roof. There is also one whole-house fan that can be used to augment these ducts. As this hot air escapes it creates a vacuum. It is this vacuum that we use to pull air into the house through either windows and/or earthtubes. This SSH has eight earthtubes, 4” diameter PVC pipes up to 60’ in length, that are buried underneath and around the house. This process geo-thermally conditions the air as it moves slowly through these tubes. These earthtubes will provide air that is cool in the summer and warm in the winter. This SSH also has four awning windows on the south side glass wall which face this sites prevailing breeze. Finally, there will be ceiling fans in each living area in the home. These can be used for additional cooling during the summer months when there is an excess of electrical energy available from the sun to power these fans. These strategies, in combination with doors and additional windows placed around the home, will provide excellent air flow throughout the whole house. This entire ventilation system (other than the ceiling fans) operates passively, without the aid of energy-burning mechanical cooling systems. It is this ventilation system, in conjunction with the principles of thermal mass energy storage, that provide all of the cooling needs of an SSH, there is no air-conditioner required.





An SSH uses the suns energy to generate all of its own electricity. PV solar panels across the top of the house will feed a battery bank that will store power. If the maintenance of a batteries is not wanted, one one can hook to the grid in a net-metering situation, as we have. A net-meter measure the net difference between the power that we generate and the power that we use. We only pay the utility company if we use more power than we generate with our PV system. Essentially, net-metering allows us to store our power at the PUD rather than having a bank of batteries on premise, which add significantly to the cost of a PV system. The down side is that if the grid goes down so does our homes power supply. A wind generator can also be used to generate electrical power. We will have one battery which will allow D/C electricity to feed to the refrigerator and water pumps in the case of a power outage. This will ensure that we will  have both water and refrigeration in the event of a grid failure. A/C power will provide for all of the other household needs, including lighting, appliances, and entertainment electronics. Solar batch water-heater tanks, positioned on the roof, will provide most of the water heating needs of the home. A back up on-demand propane powered water heater will heat water when necessary. Cooking will be done in a built-in solar oven, with a standard propane kitchen range and microwave being available as well. Clothes will be hung to dry in the sun, but a standard propane powered clothes dryer will also be available. Therefore, a small amount of propane purchased on a yearly basis will be the only fuel this house will ever use- and in a pinch even that can be done without.




This SSH will have over 800 sq ft of covered outdoor living space (see Floorplan above). To the east of the house there is a large courtyard with a covered front porch area. To the north there is a 300 sq ft covered porch which will house a beautiful adobe Kiva-style fireplace, as well as an exterior kitchen that will include a built-in BBQ. To the west there is a 360 sq ft screened-in Arizona room. This area will house another exterior kiva fireplace, a built-in wood-fired adobe pizza oven and a large outside living area with lots of plants. The interior of the home will also showcase adobe fireplaces, one in the master bedroom and one in the living room. These will provide for wood-burning back-up heating when desired. The interior of the home will also have a planter bed that runs underneath the entire 80' length of southern sloped glass. This will provide a 200+ square foot interior greenhouse where we can grow organic plants all year long. 

 Finally, as stated earlier, the interior of this SSH makes use of a variety of recycled, second-use and reclaimed building materials- further decreasing this homes carbon footprint. Some of these materials include: dead-standing Lodge-Pole pine beams, or vigas, reclaimed ceiling decking, second use windows and doors, adobe block half-walls, concrete & can/bottle non-load bearing walls, framing, ceiling, flooring and cabinetry made from ponderosa pine harvested from the site, reclaimed brick flooring, second use tile, and mud plaster.

 

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