Passive Solar in the Home


While solar power has become prevalent in the mainstream construction business in the past decade, passive solar design has been used around the world for thousands of years. Ceramic tiles and stones walls in the Mediterranean made it possible to keep homes cool even under the scorching heat of the summer sun. Likewise, small window openings and semi-subterrain living spaces in northern climates promoted efficient heat retention. Today, the basic principle of passive solar design is to utilize the power of the sun by simply situating your home, building it with specific material, and installing design features that promote a good balance of heat reflection and absorption.

Placement of home

The most important element of passive solar design is the proper placement of your home.  In fact, many home companies consider this to be a crucial first step when designing a new home such asthese home builders here. Not using mechanical equipment to utilize solar power means that you will have to maximize the advantages of the varied strength and availability of the sun’s rays. For instance, the sun is higher during summer than winter. Awnings and movable shades will keep out the heat of summer sun for cooling your home and allow it in through large windows during the winter months for passive heating. The exact pitch of your awnings will change according to your latitude to compensate for the exact angle of sunrays reaching your windows. In general, buildings using passive solar design are stretched out from the east to the west with large windows placed on south facing walls. Simultaneously, builders also reduce the number and size of windows on the north façade of the building.

Passive cooling 

The second most important element of passive solar design is making sure that excess heat can escape from your home during the warmer months. You can strategically place windows, vents and door openings throughout the house to use the naturally occurring breeze and wind for cooling your home as well as for venting out allergens and superfluous moisture. This type of cooling is not to be confused with poor insulation that prevents a controlled venting. You can also select specific building materials such as stone, brick, or concrete that absorbs, transfers, and radiates heat well for a delayed release during the cooler night hours.

Solar panels

Most likely, you will wish to install a series of solar panels in conjunction with your passive solar design. When installed on your home’s roof, these photovoltaic panels will not only produce electricity but also prevent overheating in your attic space. There are a great variety of solar systems on the market today from ready to install kits to DIY solutions. They can fit all budgets and situations as well as designs and building methods. You can choose to have stand-alone off-grid solution or have your solar system tied in to your local electric network depending on your lifestyle and personal needs.

All things considered, solar passive design is a great option for those who wish to pursue an environmentally friendly building project that utilizes naturally renewable resources for heating and cooling without any carbon emission. It will also provide considerable savings to homeowners in the long run, and produce better quality air and a cleaner local environment.

Original Article on 2GreenEnergy


Passive Solar Tech Alive and Well at 2013 Solar Decathlon


When you stroll through the pop-up neighborhood of 19 solar-powered homes along an abandoned airstrip at The Great Park in Irvine, Calif. this week, you might get a kink in your neck.

It’s hard not to gravitate toward the homes lining the north side of the runway at the 2013 U.S. Department of Energy’s Solar Decathlon. Big glass windows and open patios beckon visitors to gawk and drool over the ultra-modern, airy designs inside.

The houses on the south side, by contrast, look small and closed. There’s good reason for that, however. And the truth is that all of the homes have those beautiful glass windows and open airy decks – even the ones on the south side of the street.  So why the stark contrast?  All of the homes are oriented to the south to take advantage of passive solar heating and cooling techniques.

All 19 of the solar-powered houses lined up in Orange County’s burgeoning Great Park were designed by college students from around the globe. They have brought their ultra energy efficient and modern architectural designs to compete in the Solar Decathlon, a competition that judges the houses on 10 criteria, including architecture, engineering, energy production and affordability.

The Solar Decathlon started in 2002 and takes place every two years. The DOE-sponsored event has historically taken place on the National Mall in Washington, D.C. Fortuitously, the year Congress shut down the federal government  – and most of the National Mall –the decathalon was already scheduled to take place elsewhere.

“We believe the cleanest energy is the energy that is never consumed,” said an architecture student guiding visitors through the AIR House designed by Czech Technical University in the Czech Republic.

While this is the mantra of the Czech team, it’s a principle embodied in all of the Solar Decathlon entries. Each team used advanced insulation techniques to reduce energy loss and all of the teams have incorporated passive solar designs.

Most homes, like the one designed by Stanford University, have large windows that stretch from floor to ceiling, spanning most of the south side of the home. This allows for direct solar gain. When the windows are closed in the winter, the sun will shine through them, heating the home in the process.

Many of the homes also have overhangs that shade the windows from too much direct sunlight in the summer. Nearly all of the glazing opens wide to let fresh air flow into the house during warmer months.

The teams from Stanford, Kentucky and Indiana, University of Nevada Las Vegas, Santa Clara University and Missouri University of Science and Technology all included vaulted ceilings on a slant in their designs with operable windows located high on the north wall. When both the southern glazing and northern windows are open, a cross breeze cools the home naturally on hot summer days.

Teams from West Virginia University and Missouri incorporated indirect solar gain technology into their designs, with a narrow sun room to collect and concentrate solar heat that could be let into the house by opening inner doors or out by opening exterior doors.  This use of passive solar heating and cooling technology saves energy when HVAC systems are in use, giving certain teams a stark advantage in the engineering, energy balance and comfort zone competitions.

Original Article on  Cleanenergyauthority

How “Passive Activities” Hurt Clean Energy

If you care about the future of the American renewable energy industry, you need to learn what the Internal Revenue Service (IRS) calls “passive activities.”  Because these important rules mean that as long as the U.S. relies on the tax code to provide renewable energy incentives, renewable energy can only grow as fast as Wall Street tax equity and it will remain difficult to have locally-owned renewable energy projects.

The “passive activities” issue has to do with an important IRS determination to prevent wealthy people from creating more tax shelters.  The basic idea is that if you earn tax credits from investments that you don’t “materially participate in” (e.g. investing in a wind farm) then you can only use those to offset taxes that you pay on the same kind of income (e.g. renting property).  Both activities are considered “passive,” because the rich person isn’t the wind farm mechanic, nor are they typically the rental property superintendent.

In renewable energy, it means that the two major federal incentives – the Production Tax Credit and the Investment Tax Credit – can only be used to offset passive income tax liability.  And since few Americans own rental property or have other passive income liability, it means few Americans can effectively invest in renewable energy projects.

The rules on passive income taxes and credits can’t be effectively changed because, as tax attorney Greg Jenner puts it, “it would be like pulling on the thread in a sweater.  The passive loss rules are the primary defense in the tax code against tax shelters and once you start to unravel them, there will be no turning back.”

Thus, using the tax code to boost renewable energy creates two major problems: artificially capping the renewable energy market and curtailing local ownership.

I outlined the first issue in December, in Federal Tax Credits Handcuff Clean Energy Development:

Since clean energy projects must rely on a limited set of tax equity partners and a limited-size tax equity market, when tax equity dries up, so do wind and solar projects.  The economic crisis of 2008 made the problem particularly evident, as the tax equity market shrank by 80 percent from 2007 to 2009.  Only the cash grant program saved the wind and solar industries from total collapse in the intervening years (2009-11), and the cash grant will likely expire at the end of 2011.  The following chart from a SEIA presentation illustrates [pdf] the problem, even though it was devised before the 1-year extension of the cash grant in 2010.

A chart of the limited capacity for tax equity to finance renewable energy projects

The problem of limited tax equity isn’t just short term.  Marshal Salant, managing director of Citigroup Global Markets Inc., said in a recent interview: “There’s more demand for tax equity to finance renewable energy projects than we will ever have in the way of supply.” 

Local ownership of renewable energy also suffers when incentives come through the tax code.

The logical entities like cooperatives, schools, or cities are ruled out because federal wind and solar incentives are for taxable entities, not these rooted community organizations. Instead, communities seeking local ownership have to either perform complex legal acrobatics to set up private corporations or sacrifice as much as half of the value of the tax incentives by forming a partnership with a tax equity partner.  When community wind projects succeed, like the South Dakota Wind Partners, organizers admit that repeated the success is unlikely in light of the legal and financial complexities.

It’s understandable in today’s political climate that renewable energy boosters spend more time on keeping existing incentives alive, but if Americans hope to (someday) achieve a 100% clean energy future, they will need energy policy that’s no longer handcuffed to the tax code.

Original Article on Energy Self Reliant States

Active vs. Passive Solar Systems

It’s a sunny, clear, fall day. You get out of bed, pour your coffee, and shiver. It’s still a bit cold, but you want to conserve energy and it’s way too early in the season to turn on the heat. So you put on your robe and open the blinds so the south-facing sun comes pouring through your bay windows. As you bask in the glow, staring at the leaves that turn your suburban neighborhood into a palette of color, and sip your coffee, you begin to warm up. Congratulations! You’ve started your morning taking advantage of passive solar energy!

A passive solar system can be as simple as letting the sun pour through your windows to heat up your room, or a solar hot water system installed on your roof, which uses the warmth of the sun’s rays to heat your water, then stores it until you need it. This is sometimes called a thermal solar system.

But that’s not how an active solar PV array works. Many people get confused between a passive solar system and an active solar system — understandably!

What Is An Active Solar System?
The key difference between an active solar system and a passive solar system is this: Passive solar energy uses the heat of the sun, while an active solar system uses the sun’s irradiance, or radiation (the sun’s rays), which it converts to electricity to power systems in your home.

One example of an active solar system is a photovoltaic solar array. In a solar PV array, it doesn’t matter how hot the sun is by the time its light and warmth reach your home, as long as some of the sun’s rays are hitting the solar panels. The photovoltaic panels — made from silicon or something the solar industry calls thin-film technology (a variety of elements shown to effectively conduct electricity) — convert the sun’s rays into electricity, which is used to power your home.

When your solar PV array is connected to the grid, the excess power can be sold back to the electric company for credits on your electric bill. At times when your solar array isn’t powering your home, you’ll pay for the electricity with those credits in a process called net metering. That’s why a solar array may permit you to see electric bills as low as $5 (the average monthly charge just to be connected to your electric provider.)

Active or Passive Solar: Which Benefits You More?
When we think of all the ways the sun can help us live better, more comfortable lives, we realize it’s no wonder solar power is gaining popularity every day. Using passive solar energy in easy ways every day (like opening your blinds for the sun’s warmth on a cool morning) can lower your electric bills, but you’ll see real savings by combining these practical, everyday passive solar measures with a solar PV installation.

Original Article on