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Can You Have an Air-Conditioning System Off Grid?

Having pioneered many of the green technology features found in today's new homes with my luxury home building company, Bryan Smith Homes, founded in 1977, I tried a lot of new products and energy saving approaches long before building green became a real focal point. Because of all the large homes we built, and the subdivisions my company developed were tied to the grid, I never built an off-grid home before, or one with a solar system included. When I launched Texas Tiny Homes in December of 2012, I began to realize many of our plan customers around the world were planning to build off grid, so decided to educate solar and wind generated power.

One of the first questions I had was; can an off-grid solar system handle an air-conditioning system? That is also one of the first things people in Texas and most southern states want to know as they consider an off grid lifestyle in a tiny house, or small home. This video, by DIY Homesteading provides some helpful information and his personal testimony on their own tiny RV home they just constructed in Arizona. Heating a tiny, or a small off-grid home doesn't require solar, so that's not the problem. You can go with a wood burning iron stove or some of the popular tiny home propane heaters work well. You can also go with a heat pump system as discussed below. 

The good news is; it IS possible to have air-condition system with a reasonable size and priced solar system, but you have to plan wisely when designing and building the home; including minimizing your exposure to the west sun. How you situate your home on the property is an important part of the equation. If your home is going to be one on a trailer, or it's one of our tiny or small homes that are too wide for trailers, they are usually rectangular in shape.  And because of that you will want to place the trailer, or build the home with the narrow ends facing east and west, therefore minimizing your exposure to the sun. It would be best if there were no windows on the end that catches the west sunset, but if you do have windows, you would want to go with super efficient units with triple pane glass that are argon filled. Making that exterior wall, 2" X 6" or 2" X 8" thick would also be an excellent idea. You will want to foam insulate that wall too, as well as all the exterior walls in the home as well as any ceilings that are also the roof rafters.

We plan to add 4' X 8' X 1" foam board sheathing on the exterior wall first before adding radiant barrier sheathing and then siding. Adding radiant barrier decking on the exterior walls before the siding goes on will reflect 97% of the radiant heat entering the home. The additional "R" value those items add to the exterior walls will help make the home even much easier to heat and cool, as well as maintain the temperature inside the home. Once the home is acclimatized to your desired temperature, it's much easier, and more economical to maintain that temperature with a super insulation design and installation as outlined above.

Image result for radiant barrier roof deckingAnother important step you will need to take in an effort to reduce the heat from the sunlight during the hot months is to use a radiant barrier roof decking before the the roof material is applied. That type of decking can reduce attic temperatures dramatically by reducing the radiant waves by 97%, and a cooler attic or roof keeps the inside of your home cooler. Using reflective, light colored roofing material is also an important part of the off-grid home when cooling it down. You would want to avoid a dark colored roof.

Image result for galvanized roofUsing this type of roof will reflect the sunlight rather than draw it into the home as popular, darker colored composition roofs will do, unless they have been manufactured with energy saving elements in the materials used. The good thing about a metal roof, manufactures apply paint to the metal that reflect infrared wavelengths, and you can actually receive a tax credit when installing energy saving roof materials.

Another requirement with having an air-conditioner in your off-grid home is installing a low-voltage, high-seer mini split-system, which is much more economical to operate and uses a lot less valuable wattage from the battery bank. Because of how the tiny or small home is designed and built that include all these energy saving features mentioned, it will be much easier on the solar system to keep the home cool and also warm if you use the heat pump in the mini-split system. Having large shade trees on the end of the home that faces west is also another great idea, as long as it doesn't interfere with the solar panels sun exposure.

France Declares All New Rooftops Must Be Topped With Plants Or Solar Panels | CSGlobe

A new law recently passed in France mandates that all new buildings that are built in commercial zones in France must be partially covered in either plants

Benefits of Green Roofs

There are so many benefits to green roofs. Here are just a few:

  • Adding natural beauty and major aesthetic improvement to buildings, which in turn increases the investment opportunity.
  • Helping contribute to landfill diversion by prolonging the life of waterproofing membranes, using recycled materials, and prolonging the service of heating, ventilation, and HVAC systems through decreased use.
  • Green roofs assist with storm water management because water is stored by the substrate, then taken up by plants, and thus returned to the atmosphere through transpiration and evaporation. They also retain rainwater and moderate the temperature of the water and act as natural filters for the water that does run off. They delay the time at which runoff occurs, which results in decreased stress on sewer systems during peak periods.
  • The plants on green roofs do a great job of capturing airborne pollutants and other atmospheric deposition. They can also filter noxious gasses.
  • They open up new areas for community gardens, commercial and recreational space in busy cities where this space is generally quite limited.

France is definitely on the right track, but it should be a mandate that all new buildings being built in North America, and even worldwide, adopt this amazing idea to reap all of the potential benefits.

Source: France Declares All New Rooftops Must Be Topped With Plants Or Solar Panels | CSGlobe


All About Green Roofs

Green roofs, grass roofs, roofs with grass, roofs with plants, green roofing membranesGreen roof inspiration for homes, sheds and arbors

Green roofs, grass roofs, roofs with grass, roofs with plants, green roofing membranes

Green roofs, grass roofs, roofs with grass, roofs with plants, green roofing membranes

In Germany, it is estimated 12% of all flat-roofed buildings are living roofs, a number that is rapidly increasing as the German green roof industry continues to grow 10 to 15% per year.

Green roofs, grass roofs, roofs with grass, roofs with plants, green roofing membranesThere are two main types of green roofs.

Intensive (labor-intensive) – Found on flat roofs and require about 4-24 inches of planting medium that is able to grow conventional lawns, vegetable gardens, small shrubs and even small trees. Intensive rooftops require sophisticated structural support and possibly irrigation. Typically weigh 80-120 lbs. per square foot, fully saturated. Are often park-like gardens for public or private use.

Green roofs, grass roofs, roofs with grass, roofs with plants, green roofing membranesExtensive (sedum or grass) – Designed to be virtually self-sustaining and require low to no-maintenance. Needs a planting medium of 1-4 inches on a flat or gently sloping roof. Best with native vegetation or drought-resistant, cold-resistent, shallow-rooted plants, sedum, herbs, mosses or grass which generally grow no higher than several inches. They typically weigh 10-50 lbs. per square foot, fully saturated, depending on what type of growing medium is used.

Green roofs, grass roofs, roofs with grass, roofs with plants, green roofing membranesBenefits:

Green roofs are excellent insulators. Studies have shown that a green roof can reduce your cooling costs by 50% and more during the summer months and in the winter your home will retain 15-30% more heat than if you had a conventional roof. On a sunny, 80-degree-F day, a black roof can reach 180 degrees F; a white roof 120 degrees; and a plant-covered roof 85 degrees. Save money and use fewer energy resources.

Cost. There are many modular green roof kits available that might bring the costs down. Extensive green roof: $8 to $20 per square foot. Intensive green roof: $15 to $50 per square foot. A 2006 study by the University of Michigan comparing costs of conventional and green roofs showed that, on average, installing a green roof costs about $22.00/sq. ft. versus $16.00/sq. ft. for a conventional roof. In its life, however, it was estimated the green roof would save over $200,000 (in 2006 energy prices) with two-thirds of that coming from reduced energy needs.

Reduced storm water runoff. When the water falls on a typical roof, it’s often funneled off into storm water drains, collecting pollution along the way and polluting our waterways or increasing the amount of sewage to be treated. Green roofs ‘harvest’ rain water and put it to beneficial use.

Increased longevity of roofing membranes. The plants and growing medium are absorbing the solar rays, protecting the roofing materials from UV breakdown.The green roof also shields the membrane from extreme temperature variations, another cause of hastened degradation. According to Penn State research, a green roof will lengthen roof life by two to three times.*
Sound proofing. An extensive green roof can reduce sound from outside by 40 decibels, while an intensive roof can reduce sound by 46-50 decibels (Peck et al. 1999).

Aesthetic appeal. Nature relaxes, promoting psychological well-being.

Carbon is sequestered.  Through the process of photosynthesis, carbon dioxide is removed from the atmosphere and stored as carbon in biomass.

Urban Heat Island Effect – if an urban area has numerous green roofs, heat island effect is lowered.

Habitat. When planted with native vegetation – a green roof becomes a habitat for indigenous species and migrating butterflies, birds and bees.

Green roofs, grass roofs, roofs with grass, roofs with plants, green roofing membranesResources:

Green Roofs for Healthy Cities

See Lots More: Green Roofs