10 Technologies Used in Green Construction

Cool roofs are specially designed to offer increased solar reflectance and decreased thermal emittance. In other words, they reflect more of the sun's rays than your average shingle roof, and prevent the warm or cool air inside from escaping through the top of a building. Under the intense heat of the summer sun, dark shingle roofs can reach temperatures of 150 degrees Fahrenheit (65.5 degrees Celsius). The reflectance of a cool roof can cut that down by more than 50 degrees [source: EnergySavers].

Lowering the temperature of the roof itself is an advantage, of course, but the real savings are inside. A cool roof improves the interior temperature of a building, either by reflecting intense heat or trapping the air inside. That reduces the strain placed on air conditioning systems, thereby reducing the emissions that result from powering our heating and cooling. Cool roofs can be constructed with a number of materials, including special reflective paint and cool roof shingles and tiles. If you need an environmental reason to believe in the cool roof, look no further: Their reflectance can help lower the heat island effect of urban and suburban areas, which causes dramatically higher temperatures under harsh sunlight compared to surrounding rural areas [source: EPA].

Insulation is some of the nastiest stuff in construction, as anyone who's gotten fiberglass shards stuck in their skin can attest. The stuff doesn't need to be pretty or pleasant, since it's essentially wall filler. If it's going to stay out of sight, why not make insulation out of any old junk? That's the basic gist of green insulation, which uses recycled materials to line our walls. Cotton insulation is a great example: The soft blue insulation is primarily composed of recycled denim -- aka old jean scraps [source: GreenYour]. Did you ever imagine the material that makes up your favorite pair of pants could also be used to insulate your house?

Cellulose insulation takes an equally common product and recycles it. Any guesses as to the identity of the mystery material? It's the humble newspaper. Recycled paper insulation comes in several forms, but one of the most common is blow-in cellulose, which can be sprayed into walls or attics rather than being laid out in sheets [source: GreenFiber]. Even fiberglass insulation can include recycled glass, but there's a downside: Melting down the glass and forming fiberglass insulation is far more energy-intensive than producing cellulose insulation from paper. Cellulose insulation often consists of 75 to 85 percent recycled material, higher than fiberglass' 30 to 40 percent, and cellulose is even better at preventing airflow than fiberglass [source: HouleInsulation]. Cellulose and cotton are definitely better choices when it comes to green insulation, and neither poses the discomfort or health concerns of fiberglass [source: Bonded Logic].

Since construction is all about building something new, we sometimes forget about the flip side of the coin: tearing something down and disposing of building materials. Biodegradable materials can change that disposal process into something more eco-friendly: Instead of a giant scrap heap of waste products and chemicals, they result in products that degrade naturally without contaminating the soil. An excellent example is biodegradable paint, which mimics the old practice of creating paint from a milk-based recipe. The Old Fashioned Milk Paint Co. uses milk protein, lime and mineral pigments to create an organic paint mixture [source: MilkPaint].

Using recycled products -- like recycled fiberglass insulation, for example -- is a good start toward being eco-friendly, but products that naturally break down without releasing toxins into the Earth are even better. Outside of the United States, hemp is used in construction for everything from building foundations to insulation [source: Hemphasis]. United States laws forbid the growth of industrial hemp -- a low-THC cousin of marijuana -- but at least one company is importing the hemp to create Hemcrete, a hemp and lime mixture similar to concrete [source: BuildingGreen].

Hemp isn't the only biodegradable structural material on the block -- in fact, our next green building technology has been in use for thousands of years.

Rammed earth is an ancient construction technique similar to adobe that uses the raw materials of the Earth to form sturdy buildings through a simple process. Rammed earth has been around for thousands of years -- portions of the Great Wall of China were constructed using the rammed-earth technique. Today, the process of forming a rammed-earth structure isn't so different than it was centuries ago. A moist mixture of earth and hard substances such as clay or gravel are combined with a stabilizing element like concrete and compressed to form dense, hard walls. After forming, rammed earth must cure for months -- or as long as two years -- in a humid climate to fully cure and completely harden [source: USC].

The density of rammed earth makes it an ideal material for regulating the temperature of a building. It will stay cool in the summer and warm in the winter, and constructing rammed earth produces fewer emissions than the typical building process [source: USC]. Modern rammed-earth equipment makes the compacting process a bit easier than it was thousands of years ago, but there are still tools out there specially designed to compress the walls by hand.

Rammed-earth construction isn't exactly the norm for the 21st century, but it still exists, and there are contractors out there who specialize in designing homes with the Earth's minerals. Rammed-earth construction does have to take special care to properly regulate water to prevent damage, which is much like our next green technology, a system designed to harness water runoff.

In rural areas, water runoff from heavy rains and snowfall can carve out large swaths of land and wash away plant life. Erosion can be a seriously damaging phenomenon, and the power of storm water in urban areas is similarly dangerous; overflowing sewer systems can flood streets and buildings, creating hazardous driving conditions and millions in property damage. That's where storm water management comes in: it involves landscaping and designing systems to properly manage large volumes of water. The U.S. Environmental Protection Agency is dedicated to managing storm water with a green infrastructure, which involves using plants and soil in urban areas to control absorption and purify storm water.

The EPA's green infrastructure offers a wide range of benefits: By encouraging the growth of greenery in urban areas, the infrastructure helps lower the heat island effect produced by heat-absorbing pavement and metal, reduces sewer overflow by absorbing water, and simultaneously reduces the pollution of storm water as it passes through plants and soil. An increase in green coverage reduces overall runoff, and the plants improve air quality by absorbing carbon dioxide [source: EPA]. The EPA employs a number of techniques to build a green infrastructure. Plant boxes, small installations of dirt and greenery along the street, are among the most basic solutions. Some of its other green technologies, including green roofs that are entirely covered in plant life and permeable pavements, which allow water to flow down to the sediment layer, demonstrate the powerful potential of green storm water technology [source: EPA].

Where storm water management uses plant life to control water, geothermal heating taps into the Earth's natural energy to generate power. Like wind power or solar power, geothermal is an efficient renewable energy resource that's far more environmentally friendly than coal-powered electricity or natural gas. You might think that cold weather would make geothermal heating ineffective, but that's not the case. Pipes buried a few feet underground escape the effects of freezing temperatures. The ground there stays close to 60 degrees Fahrenheit (15.5 degrees Celsius), making it a warm source of energy in winter and a cool source of energy in summer [source:GreenSolarCafe].

A water/antifreeze mixture is pumped through pipes buried underground to collect thermal energy, then routed to a heat pump and takes that energy and puts it to use to heat or cool your house. While it does take electricity to power the heat pump, the efficiency of the geothermal system means that you'll get far more energy from the pump than you pour into it [source: GreenSolarCafe].

Geothermal heating does have its disadvantages -- digging up ground space to lay the energy-collecting piping is a large undertaking. But our next classic renewable resource, solar energy, presents no such problem.

What do you think of when you picture solar power? Massive fields of gigantic solar panels? Solar power doesn't necessarily require tons of equipment. In fact, some solar power doesn't require any equipment at all. There's a difference between active solar power -- what you probably picture when you think of solar energy -- and passive solar power, which is based on smart home design rather than advanced technology. Passive solar home design simply uses the sun's rays to heat a home through strategic placement of windows in a home. Large sets of windows let in solar energy, and a heat-absorbing surface like a dark wall retains the heat to warm the home [source: EnergySavers]. Fans and air vents can help spread that air around the house.

Active solar systems obviously provide more heat than passive solar design. Solar panels absorb the sun's radiation and use the heat to warm air or water, cutting down on gas or electricity consumption in the process. The more we rely on solar energy, the fewer greenhouse gases we produce from using nonrenewable energy sources [source: EnergySavers]. The efficiency of solar panels varies based on the size of the system and the local climate. However, given the right conditions, a solar system will make up for the up-front costs of installation over the long term with years of free energy.

Passive solar energy relies on windows to let in beams of sunlight to use for heat. But what happens in the summer months when you want to keep all that solar radiation out? Awnings, shades and roof overhangs can cut down on that incoming light, but there's a much cooler solution coming that promises to cut down on HVAC costs and change the way we look at sunlight from indoors. It's called smart glass.

Smart glass, or electrochromic glass, uses a tiny burst of electricity to charge ions on a window layer and change the amount of light it reflects. While low-emittance windows that block some of the sun's radiation already exist, smart glass gives you the ability to choose how much light you want to block. Tied into smart building control systems, skyscrapers could have thousands of windows tint automatically during peak hours and return to complete transparency in the evenings. Smart glass developers expect a 25 percent reduction in HVAC costs thanks to the dynamic windows [source: Tested]. Electrochromic glass is still being perfected for commercial use, but expect to see more of the glass in the coming years as competing developers bring this smart energy-saving technology to the market.

Today's modern appliances are smarter than ever. Our kitchens might not look like something out of the Jetsons quite yet, and there's still no Rosie around to cook and clean, but the latest appliances are designed to save energy and simplify our lives. LG's products from the 2011 Consumer Electronics Show perfectly illustrate the trend in appliances: Its SmartGrid refrigerators, dishwashers and washing machines all tie into a smart meter to be as energy efficient as possible. Smart meters are essentially electrical meters that gather real-time data and can communicate with devices to provide useful power data. With that data, LG's smart appliances can determine energy rates and automatically run when electricity rates are at their lowest [source: Danko].

New appliances are also incorporating the technology we're used to seeing in dedicated computer systems -- LG's smart refrigerator uses an LCD screen to help you organize and inventory the refrigerated food, for example. By programming in the expiration dates, you can have the fridge notify you when food's going bad -- and your entire grocery inventory is available on a mobile device like a smart phone, essentially giving you an omnipresent shopping list based on what you already have in stock [source: Danko].

Still, the improvements in energy efficiency are what make smart appliances a fantastic green technology. They're one small part of our final eco-friendly element of construction, which takes elements from nearly everything we've talked about and combines them into one super green design: the zero energy home.

Zero energy buildings, or zero net energy buildings, are constructed to successfully operate independent of the normal electric grid. In other words, they provide their own power through renewable energy. The "zero" refers to both energy consumption and carbon emissions -- a zero energy building consumes zero net energy yearly, and produces no carbon emissions since it relies on renewable energy supplies like solar or wind power.

Zero energy homes are specially built to be extremely energy efficient with excellent insulation and techniques like passive solar design. Of course, efficient design is just the start -- the buildings still need power from somewhere. Active solar panels and wind collectors are common solutions, while some buildings use biofuels for heating. Zero energy construction is most efficient in small communities where several homes can benefit from a shared renewable resource.

Building a zero energy home is obviously no easy task. It's not cheap, either, but some governments are slowly moving to support zero energy construction with subsidies to incentivize the green environmental benefits. The U.S. government offers a Solar Investment tax credit of 30 percent off the total system cost, and the state of California offers additional money back for consumers who opt into renewable energy [source: GoSolarCalifornia]. Zero energy is still a niche form of construction with high up-front costs, but the reward is a perfect blend of technology that barely affects the environment compared to today's average construction project.