There's considerable interest in the market right now for renewable energy sources for homes, like photovoltaics, solar water heaters, geothermal heat pumps, etc. In addition to the desire to save money, we all want to be self-sufficient, reduce our dependence on foreign oil, and minimize our carbon footprints. Surely, these are all worthy goals.
However, most of us are working on limited budgets and must prioritize the order in which we tackle home energy projects. The question then becomes, "Do I invest in renewable energy or energy efficiency first?" The answer is it depends.
At King Pine Homes, we feel that energy saved is as good as energy produced from clean sources, but we also want to get the most bang for our buck. So, here are some considerations for tackling the energy efficiency vs. renewable energy priority issue:
Start with an Energy Audit
After purchasing a home, we hire an independent energy auditor to come evaluate and model the home's energy efficiency. Using equipment like a blower door, the energy auditor can determine the overall leakiness of the home, which is the amount of undconditioned air entering the home from outside. In addition to doing a visual inspection, energy auditors use infrared cameras to see through the walls or ceilings to identify areas of insufficient insulation.
Following the energy assessment, the energy auditor provides us with a detailed report and remedial plan. Often he/she will outline the problem areas, which if fixed, will give us the greatest gains in efficiency at the lowest cost. We then get estimates for this work to better understand our total costs of addressing home energy efficiency.
You can also go get estimates for installing renewable energies. This will allow for a simple cost comparison among your various options. For historic prices of renwable energy installed, check out the EPA's website. It's not just about cost, though, as you'll need to also think about energy production and how it aligns with the needs of your household.
Note, that our analysis assumes you will be purchasing the renewable energy system outright. Recently, though, several innovated financing models for solar have gained prominance. In particular, solar leasing and power purchase agreements allow you to put solar on your roof with little or no money down, and make a monthly payment similar to your current electric bill.
Climate Considerations
Averaged nationally, the majority of energy consumed residentially is for heating and cooling purposes. However, homes in colder areas will obviously use more energy to heat during the winter months than homes in warmer climates. The inverse is true for cooling in the summer months--warmer climates will have greater cooling costs than colder climates. Yet, there are also areas with moderate temeratures all year long, such as San Diego, where you only heat or cool in the shoulder months.
You need to ask yourself how much of your energy needs are devoted to heating and cooling your home? In climates where there are significant heating or cooling needs (measured in heating degree days), energy efficiency general is generally considered the low hanging fruit. Projects like air sealing and don't require much sophisticated equipment, but are highly effective in reducing your heating and cooling bills.
On the other hand, if heating and cooling aren't a big issue, as in San Diego, the payoff for a energy retrofit will be significantly longer. In this case, more of your energy might go toward plug load issues, such as powering up your big screen. In this case, a photovoltaic array will directly address the issue whereas air sealing won't do much. Note, however, efficiency gear is available for reducing your electrical load, such as Energy Star appliances or smart strips for your entertainment center.
Heating Type and Future Energy Costs
Next, at King Pine Homes we consider what type of heating unit is in the home and what types of energy are available in that area. In rural Maine for example, most homes are heated with oil, since natural gas lines don't extend beyond the urban areas. In Southern Calfornia, though, natural gas lines extend everywhere. Since heating oil is quite expensive, the payoff for tasks like insualtion and air sealing is relatively quick.
We then look at the condition of the heating and cooling equipment. Was it recently installed? Does it make financial sense to remove it and convert to a more efficient source? The ROI of converting heating or cooling equipment depends in large part on predicted energy prices for particular sources. Predicting energy prices over the useful life of the HVAC equipment is genreally a difficult task, but here's are a few decent resources:
http://www.bloomberg.com/energy/