While the phrase 'net zero' may have called to mind a free dial-up internet company in the past, these words have taken on greater significance as one of the loftiest green building goals. For a building to qualify as net zero, or a zero energy building (ZEB), it must generate enough energy to meet its needs without relying on municipal sources, all while producing zero carbon emissions. Some buildings even produce a surplus of energy that may be purchased back by energy companies.

Though it may sound easier to design a zero energy building from scratch, it is possible to remodel your existing home to achieve net zero or near zero status. Learn how to implement one of more of these passive or active strategies to cut your reliance on electricity and gas.

Passive Strategies to Reduce Your Carbon Footprint

Solar panels are probably one of the first images that come to mind when you think of generating your own energy; and while they do play a significant role in the design of many net zero homes, you should first take smaller steps-passive strategies-to tighten your home's shell and reduce your energy use. Begin with a home energy audit, and depending on the results, implement some of these energy-saving strategies:

• Beef up the insulation in your floors, walls and especially in your attic and around air ducts.
• Service your HVAC system regularly and replace outdated elements with energy-conserving models.
• Replace or improve your windows to increase energy-efficiency
• Invest in Energy Star-rated appliances.

• Switch incandescent bulbs for more efficient CFLs or LEDs.
• Reduce "ghost loads," energy suckers such as computers, TVs and other appliances. If you don't use it daily, unplug it.

These upgrades go a long way in reducing your energy use, but to truly go net zero, you have to make your own. Energy, that is.

Renewable Energy Systems

Can you really produce enough energy to meet all of your home's needs? Yes, but be aware that installing renewable energy systems requires a significant, upfront financial investment. However, one way to think about it is that you are pre-paying your energy costs for the lifetime of your home, and you will likely recoup most of these expenses within a few years. And don't forget the tax credits!

There are five basic sources for renewable energy:

Biomass
Biomass is energy stored within organic matter, such as wood, plants and manure. Heat your home with a biomass stove that burns wood or pellets.

Geothermal
Harness the energy within the earth to heat your home. Dig a geothermal well and a system of pipes will transport heat from deep underground. In the summer, the reverse occurs: heat is extracted from your home and deposited into the earth as a "heat sink," or used as a source of free hot water.

Solar
The most common way to harness renewable energy, solar panels transform the rays of the sun into electricity you can use. Photovoltaic panels can be attached to your roof and you may not even notice they're up there.

Wind
Forget the charming windmills that dot the Dutch countryside-modern wind turbines are usually slender and white. They harness wind energy and convert it to electricity. If you have the space in your yard and live in a windy-enough climate, you can install a turbine that will meet your energy needs.

Water

While water power is not an option for most of us, those who live next to a river can install micro-hyrdo power systems. It's not exactly a novel concept: moving water turns the generator and produces electricity.

Off-Site Renewable Energy

If you are unable to meet your energy needs via on-site renewable systems, you can still make your home net zero by purchasing some your energy from off-site renewable sources. Look for Green-e certified producers in your area who use wind or solar to generate their power, or consider purchasing emissions credits.