First things first. Getting your home on the path to zero carbon/zero energy begins with minimizing your home’s energy needs by making it as airtight, well insulated, and energy efficient as possible. Follow our 12 Steps to Affordable Zero Energy Design and Construction for new construction or our suggestions for Remodeling on the Path to Zero for existing homes and buildings. Once you’ve done that, you will be ready to install solar collectors to produce your own renewable energy.

But what happens when there is no way that you can make solar work on your home or building site? This can happen when the roof or open area on the property is shaded by buildings or trees. Maybe the roof structure can’t handle the weight or wind stress from solar panels. Or maybe you rent your home and can’t install solar panels. In these situations, there are several options that can replace or compensate for the lack of solar panels on the site.

Getting the Energy

Before looking at the options for replacing or compensating for the lack of onsite solar, there is one question that immediately comes to mind. Is the off-site renewable energy you’re paying for actually getting to your building? The short answer is no. But it doesn’t matter. By following one of the options below society is getting the benefit of renewable energy just as if you were producing your own renewable energy.

Think of the electric grid as if it were a very large energy pool. Electricity goes into the grid pool from many sources, while it is drawn out for use by a wide variety of homes, businesses and industries. Each of these input and output points is measured with a meter. By purchasing a clean resource for the energy pool, you displace the energy that used to come from dirty, conventional sources. Over time, the clean sources will totally replace the dirty ones. Your investment in clean electricity helps fill the energy pool from which everyone draws. Your choice of sourcing clean energy speeds that process.

The atmospheric carbon pool works in a similar way. When you buy carbon offsets, you are reducing the carbon in that pool just as effectively as if you were using renewable energy from rooftop solar collectors. While rooftop solar may be the ideal source of clean energy, pumping more renewable energy into the grid pool in other ways or reducing carbon from the atmospheric carbon pool is an equally worthy undertaking.

Here are four ways anyone can contribute to cleaning up the energy pool or the atmospheric carbon pool even though they are unable to produce their own renewable energy:

Utility Renewable Energy Programs

Many electric utilities offer an optional rate that supports renewable energy. In essence, you’re paying a bit more for electricity so the utility can add more renewable energy to the mixture of its energy sources. In some cases, that energy is purchased from outside sources or the utility may purchase Renewable Energy Certificates (see below). In some cases, such as Pacific Power’s Blue Sky program, the additional funds are used to support local renewable energy projects. Recently, building renewable energy resources from wind and solar in some locations has become cheaper than building new fossil fuel sources, such as coal and natural gas. In San Jose, California, clean energy is slightly less expensive than conventional electricity from nearby PG&E.

Community Solar

When solar is not an option for individuals, they can join forces to invest in a community solar program. These programs are gaining popularity around the country and can be run by nonprofit organizations, utilities, or government entities. These local projects build solar arrays with member funds. Members can be local organizations, businesses, or individuals.

Some community solar projects follow an ownership model in which each member purchases a share of the project. To keep things simple, many community solar programs allow members to invest in one or more solar panels. The member receives a credit for the amount that their share generates. In some cases, the credit shows up directly on the member’s utility bill. In other cases, the member receives a payment for their share. In either case, the electricity is supplying energy to the local grid pool and does not flow directly to your home or place of business.

Other programs operate under a subscription model. In this model, the project is owned by a local organization and subscribers purchase a certain amount of energy each month. Whether you are an owner or subscriber, community solar offers a stable source of clean energy to the grid that is often less expensive than conventional utility electricity.

Renewable Energy Certificates

When electricity flows through your meter, there is no way to tell where it came from or how it was generated. If you want to promote clean energy by investing in a wind or solar farm, you need to know that your investment is legitimate. Renewable Energy Certificates (RECs) can be purchased by individuals or companies who want to support clean energy and claim its environmental benefits without actually buying that energy. For example, a wind farm earns RECs as it generates power. These RECs can be purchased separately from the power itself and are expressed in megaWatt-hours (1,000 kiloWatt-hours). This allows the wind farm to sell power in one region, while marketing the environmental benefits to customers in another region. The REC documents who owns the environmental benefits and prevents clean power generators, such as the wind farm, from selling the same renewable benefits to more than one customer. While this seems like a bit of an accounting game, it allows energy consumers to purchase clean energy with the confidence that their investment is carefully documented. RECs can be purchased from Bonneville Environmental Foundation, Blue Spruce Energy, or NativeEnergy.

Carbon Offsets

A key driver of climate change is the systematic extraction and burning of fossil fuels that overloads the natural carbon cycle and allows CO2 to build up in the atmosphere. Carbon offsets allow individuals and companies to invest in clean energy generation or projects that reduce greenhouse gas (GHG) emissions in ways other than renewable energy generation. The Environmental Protection Agency defines a carbon offset project as “a specific activity or set of activities intended to reduce GHG emissions, increase the storage of carbon, or enhance GHG removals from the atmosphere.” Offsets are expressed as metric tons of CO2, so they are not limited to power generation projects or building energy use. Offset activities might include planting trees, restoring coastal wetlands, supporting healthy ocean ecosystems, sustainable agriculture, clean transportation, and even carbon friendly consumer products. The key elements of a genuine carbon offset are that they must fund a project or activity that is verified, permanent and would not have occurred without the investment. Carbon offsets can be purchased from companies such as Terrapass and The Gold Standard. The credibility of offsets is maintained by third-party certifying organizations, such as Green-e which lists dozens of certified offset providers.

Whether your home or building is decades old or still in the planning stages, the first step to truly sustainable building is making it as efficient as possible in order to minimize the size and expense of the renewable energy or offsets needed to get to zero. Installing a solar rooftop is the next step for many buildings where it is possible.But when the roof isn’t an option, don’t let that stop you from pursuing zero carbon/zero energy for your home or building.