Photo: Green Passive Solar Home

Set on a south facing slope, the house takes advantage of natural daylight. A south-facing glazed Green House absorbs sun to heat the house during the cold winters, relies primarily on convection to move heat from the sunny space to other adjacent rooms. The clerestory located high in a central wall near the eaves allows additional daylight into a building interior, and may be used for ventilation and solar heat gain. As the sun travels across the sky, its rays hit and reflect through the glass at different angles for an ever-changing spectrum of color and shape.

To understand how a passive solar home design works, you need to understand how heat moves and how it can be stored. As a fundamental law, heat moves from warmer materials to cooler ones until there is no longer a temperature difference between the two. To distribute heat throughout the living space, a passive solar home design makes use of this law through the following heat-movement and heat-storage mechanisms:

• Conduction

• Conduction is the way heat moves through materials, traveling from molecule to molecule. Heat causes molecules close to the heat source to vibrate vigorously, and these vibrations spread to neighboring molecules, thus transferring heat energy. For example, a spoon placed into a hot cup of coffee conducts heat through its handle and into the hand that grasps it.
  

  Convection

• Convection is the way heat circulates through liquids and gases. Lighter, warmer fluid rises, and cooler, denser fluid sinks. For instance, warm air rises because it is lighter than cold air, which sinks. This is why warmer air accumulates on the second floor of a house, while the basement stays cool. Some passive solar homes use air convection to carry solar heat from a south wall into the building’s interior.
  

  Radiation

• Radiant heat moves through the air from warmer objects to cooler ones. There are two types of radiation important to passive solar design: solar radiation and infrared radiation. When radiation strikes an object, it is absorbed, reflected, or transmitted, depending on certain properties of that object.
• Opaque objects absorb 40%–95% of incoming solar radiation from the sun, depending on their color—darker colors typically absorb a greater percentage than lighter colors. This is why solar-absorber surfaces tend to be dark colored. Bright-white materials or objects reflect 80%–98% of incoming solar energy.
• Inside a home, infrared radiation occurs when warmed surfaces radiate heat towards cooler surfaces. For example, your body can radiate infrared heat to a cold surface, possibly causing you discomfort. These surfaces can include walls, windows, or ceilings in the home.
• Clear glass transmits 80%–90% of solar radiation, absorbing or reflecting only 10%–20%. After solar radiation is transmitted through the glass and absorbed by the home, it is radiated again from the interior surfaces as infrared radiation. Although glass allows solar radiation to pass through, it absorbs the infrared radiation. The glass then radiates part of that heat back to the home’s interior. In this way, glass traps solar heat entering the home.
  

  Thermal capacitance

• Thermal capacitance refers to the ability of materials to store heat. Thermal mass refers to the materials that store heat. Thermal mass stores heat by changing its temperature, which can be done by storing heat from a warm room or by converting direct solar radiation into heat. The more thermal mass, the more heat can be stored for each degree rise in temperature. Masonry materials, like concrete, stones, brick, and tile, are commonly used as thermal mass in passive solar homes. Water also has been successfully used.

Credit to:

US Department of Energy

http://www.energysavers.gov/

One of the most frequent objections to renewable energy systems is that their production is too variable. But technologies continue to be developed that will allow storage of power generated from wind, solar, and other intermittent renewable sources. The latest development comes from researchers at Isentropic in Cambridge, England who propose giant batteries filled with gravel and argon gas. These batteries would provide a number advantages over pumped hydro, which is presently used for almost all electricity storage today, as well as over underground compressed air storage.

The gravel battery system would use excess capacity generated by a renewable source to heat and pressurize the argon gas and then pump it through a gravel filled silo to store energy. Then, when demand calls for electricity, the system is simply operated in reverse to generate electricity. According to the company, the system’s “round trip efficiency is over 72% – 80%.” This is comparable to the efficiency of pumped storage hydro, which has an efficiency of 70% – 85%. But gravel batteries are much more compact, and can be more readily installed in relatively flat areas characteristic of many areas with good windpower potential, such as the American Great Plains. A gravel battery can use far less land (1/300th) than that required for a pumped hydro lake, as well.

Underground compressed air storage is another technology that has been suggested, but that requires the presence of underground caverns, which are not always present where you might want to put a power storage facility. In addition to being able to be located anywhere, gravel batteries could be relatively inexpensive because they do not need costly materials. Costs could be as low as $55/kWh, and $10/kWh at scale for large installations.

Credit to:  Philip Proefrock

By Loretta White

Want to save money on heating this winter? Here are five steps you can take to keep the heat in.

The previous post in the Simple Ways to Save Money This Winter series focused on with exterior walls.  Here we discover five other insulation solutions that are not only inexpensive but can be done in a short amount of time and don’t require you to tear down walls to accomplish.

Save money and heat with these easy insulation tips:

To determine the best place to start in your home, take an energy audit.  You can either find a local energy auditor, or take your own free energy audit.  Once you’re ready, here are some of the quickest, easiest, and least expensive places to insulate.

1. Plumbing:

Inadequate insulation can create substantial heat loss, in and around your plumbing.

• Stuff steel wool in gaps around the pipes using gloves and a chop stick or fondue fork to push in. Then fill with fiberglass or foam insulation
• Caulking afterwards will give the project that “finished” look.
• Add foam covers to hot water pipes. This will save on the loss of heat as the water travels to its destination. Of course, tank-less water heaters are the greenest way to go, and most luxurious!
• Gas pipes should be checked as well.
  

  Tip: Look under sinks, in the laundry room, in cellars, and around anywhere else that plumbing comes out from the wall.

2. Duct work:

Seal around heat ducts and AC vents. The cellar is a good place to start here.

• Stuff steel wool in gaps around the pipes using gloves and a chop stick or fondue fork, then fill with natural fiber, fiberglass or foam insulation.
• Caulking afterwards gives the project a “finished” look.

3. Sill:

This is the area where the ceiling meets the floor of your first floor.

• Go around the sill plate and fill in gaps with natural fiber or foam.

4. Seal foundation with moisture block:

Foundation repair can be very expensive if left untreated.

• Consider using liquid rubber waterproofing to keep moisture from damaging your foundation.

5. Attic door or hatch

• Place a blanket on fold-down stairs, making sure the blanket is touching the edges. When closing the stairs, you create a insulated seal.
• Bead or squirt caulking or use spray foam around the gaps in the hatch.
• Use fiberglass to insulate around the hatch.

Remember: Choose natural insulation whenever you can. As you can see, there are many options to fix these areas.  If you have other ideas, please add them in a comment. We’d love to hear your heat saving solutions.

About the author:  Loretta White is a respected member of the global manufacturing industry and brings over 20 years experience in consulting. Loretta lectures on: Sales, Business Development and Green Business practices and is a published author on sustainability techniques.

Credit to:

http://green.yahoo.com/