There's understandably a lot of excitement about photovoltaics, solar water heaters, geothermal heat pumps and other sources of renewable energy for the home. We all want to be self-sufficient. It's part of our national psyche. And, particularly for the environmentally motivated among us, the desire to reduce our dependence on traditional energy sources is strong.

But when looking at potential energy upgrades for your home, you should keep in mind a few important considerations:

1) Energy Efficiency is about more than electricity. For cold climate North American homes, the biggest source of energy consumption is space heating; space heating, in turn, is largely fueled by oil and natural gas. Barring a wholesale conversion to a electric heat (which may be expensive), photovoltaics will do nothing to reduce the amount of oil and gas that your home consumes.

2) Should you decide to invest in renewables, the scale of your investment will depend on the amount of energy your home consumes. If you can cut your home's energy consumption in half through simple, low-cost measures, and thus reduce the investment necessary to take your home to net zero in half (think: 1 solar panel vs. 2), you've made a good investment.

3) Return on investment. Air sealing might be a $1,000 dollar investment upfront, and could save you $500 or more per year, which would give you a 2-year ROI. A wind turbine in your back yard, on the other hand, might cost somewhere in the ballpark of $15,000-$20,000. That would take a while to pay itself off.

4) Energy Efficiency is about more than energy efficiency. Done right, sealing air leaks and upgrading your insulation are both measures that have a high ROI, will reduce your carbon footprint, and will reduce your energy bills. But they will also reduce drafts, make your home warmer in the winter and cooler in the summer, and potentially increase the health and longevity of your house. That's a lot of bang for your buck. So if installing renewable energy sources at your house doesn't have quite the same impact, we won't hold it against renewables: it's a tall order to fill.

Home Performance is a philosophy and a science based on the premise that homes should be safe, healthy, comfortable, durable, and efficient.

After all, homes — probably the biggest investment most of us will ever make — are one of the few things we purchase that don't come with an instruction manual. Is a home comfortable? Reasonably energy efficient? Safe and healthy? These are all considerations that a homeowner will either take for granted (we would assume, after all, that the air inside a home wouldn't be a potential health hazard), or simply neglect.

These are the considerations that a home performance contractor sets out to address, while taking into account the interconnectedness of homes, and the relationships between each of the home's components. In accord with this holistic approach, a home performance contractor will assess, and then address, any of these potential problems within a home.

As mentioned above, home performance is based upon what we call the 5 pillars of home performance:

1) Safety: Assessing the safety of a home is an important part (maybe the most important) of a home performance contractor's job. Backdrafting appliances that may be sending carbon monoxide into the home, unsafe levels of formaldehyde from building materials, are all potential safety issues that a home performance contractor is trained to address.

2) Health: Indoor air quality is listed by the EPA as one of the top environmental threats to human health. A home performance contractor's job is to ensure that your home's indoor air quality is not a threat to you or your family's health.

3) Comfort: Our home is our refuge. It should be comfortable. Drafty rooms, cold spots, unpleasant humidity and heat in the summer, poor quality lighting or incandescent lighting that creates unnecessary excess heat in the summer, are all avoidable unpleasantries. A home performance contractor can help.

4) Durability: Imperfections within a building, in addition to causing discomfort raising health concerns, can also have long term repercussions. Moisture problems causing rot in framing, or insufficient insulation causing ice dams, are among the durability concerns that a home performance contractor will pinpoint, then tackle.

5) Efficiency: Last but not least, home performance is about ensuring that a home is cost effective to live in. If a mechanic told you that a few simple improvements could drastically improve the fuel efficiency of your car, that's something most of us would jump on. That's what a home performance contractor does for your house.

One of the key components of an effective home energy audit is infrared thermography. Infrared thermography (or infrared imaging, infrared diagnostics, a rose by any other name...) consists of a thorough visual inspection of a home, including the basement, attic, and all the nooks and crannies, with an infrared camera or another infrared assessment device. It essentially takes the guess-work out of pinpointing the drafts and the leaky spots within a home — registering, as it will, the exact temperature of various spots within the home, and, depending on the device used, providing you, the homeowner, with a precise visual representation of the imperfections in your home's thermal envelope. So if, after the energy audit, you forget where exactly it was you were supposed to caulk, you've got a big stack of pictures to show you exactly what spots need air sealing or insulation work.

If a picture, as they say, is worth a thousand words, an infrared picture could very well be worth a thousand bucks, because it reveals the spots where your house is wasting energy (and money), and gives you clear directions for fixing them. Some of the imperfections in your home's thermal envelope will be obvious: around windows and doors, for example. But chances are, there will be some big surprises, too; and that's part of what makes infrared imaging so valuable - you might discover that the constant draft in your living room could be taken care of with a simple bead of caulk along the baseboard, or that your perennial ice dam could be forever prevented by insulating a hot water pipe in the attic.

One last thing to bear in mind when scheduling an infrared audit is that for best results, there needs to be a temperature differential (delta T) between indoors and outdoors. Recommendations as to precise numbers differ, but you should talk to your auditor about an ideal differential for your region, climate and house.

Homes burn through a mortifying 21% of the energy used in the United States. A lot of that energy is spent heating and cooling your house. And even worse, a whole lot of that energy is spent heating and cooling your backyard and front porch, through leaks and holes in your building envelope.

Although some of the air leaks in your home are visible to the untrained eye — around old and untreated doors and windows, for example — much of the average home's air leakage takes place in areas you don't see. A lot of it takes place because of something called the stack effect, or chimney effect, which works like this: cold air infiltrates your cellar through leaks and cracks in the foundation and walls, and begins rising. It works its way up through the floors and/or walls, then up into your attic through structural defects, holes in your ceiling, recessed lighting, leaky duct work, the furnace flue, the plumbing stack, or a poorly sealed attic floor. A home performance contractor doing air sealing work in your home will generally focus on the basement and the attic floor in order to minimize the stack effect, and thus minimize unwanted air movement throughout your home.

Perhaps equally important, air sealing is crucial for maximizing the performance of insulation, the other major component of your home's building envelope. The R-Value of insulation is determined under the assumption that there will be no air infiltration throughout the insulation — it assumes that there will be adequate air sealing around the insulation. Once insulation is left exposed to air movement (air moving up through your attic floor, for example), R-Value decreases.

If you do some serious air sealing work, you can expect to net about $600.00 in annual energy savings. To boot, because the materials are relatively inexpensive, and because much of the most important work takes place in the attic and basement (where you don't have to worry about fancy trim or replacing drywall), the upfront cost is usually pretty low.

Sometime during your crusade to seal those energy robbing cracks and holes in your home, you're bound to start asking yourself, "Isn't air flow important for a healthy home? Can I take this whole thing to the extreme?"

The answer is yes, and probably not.

While it's true that air flow prevents pollutants like dust and mold from reaching unhealthy levels, a leaky home provides no assurance that indoor air pollutants are properly eradicated: during periods of calm weather with no wind, for example, air can sit stagnant in a leaky home for days. On the other hand, during a windy day in the winter, a leaky home effectually needs to be re-heated from scratch every few hours, which is a waste of both energy and money. So the best way to ensure that a home is both healthy, safe, and energy efficient is to air seal the home as well as possible, and to pair air sealing efforts with increased mechanical ventilation to make sure that air cycles in and out of the house at a healthy and consistent rate.

That said, if you happen to live in an old, leaky home, and aren't ready to install a whole house ventilation system or heat-exchange ventilation system (which captures the heat from outgoing air and transfers it to incoming air to minimize heat loss during the heating season, and vice versa during the cooling system), the truth is that your home probably has a long way to go before its tightness is in any way a health hazard.

Ventilation standards like ASHRAE 62.2 are largely designed for newer, very energy efficient buildings that have very little air leakage. Chances are, even after significant air sealing efforts, an older, leakier home will have enough natural ventilation (which we recommend supplementing with basic mechanical ventilation systems like bathroom fans and range hoods for those stagnant, windless days) to keep the air in your home healthy. The EPA recommends a rate of .35 ACH (natural air changes per hour — that is, just over 1/3 of the air in your home being replaced every hour; or 3 hours for a full air change) for healthy indoor air quality. The average home has a much higher rate of natural air infiltration than this.

The best thing you can do as a homeowner to ensure that your home is as energy efficient and as healthy as possible is to talk to your home energy auditor about where you should focus your home improvement efforts. But as a basic premise, as the mantra goes, "seal tight, and ventilate right."

Your utility bill may be shocking, but it offers few helpful details: it doesn't tell you when your energy use peaks, doesn't explain how best to reduce power consumption, and doesn't tell you how your home is spending your money.

We think it’s worth finding out. A home energy audit is one of the first steps to understanding your home's energy usage, as well its overall health and performance. Using a combination of high tech tests and common sense evaluations, a good auditor provides homeowners with a list of energy and money saving steps, explains how and why your house is costing you money, then prioritizes steps to take to knock down those costs over the long haul.

A typical audit is comprised of several steps:

1) A thorough visual inspection of the home's building envelope.

2) An insulation check, generally involving infrared thermography, to pinpoint spots where insulation may have settled, been improperly installed, or where it may be missing altogether.

3) An air leakage test using a blower door, to measure the cumulative effect of all the air leaks in the home.

4) A ventilation check: healthy houses have appropriate ventilation, and an auditor will test ventilation systems to ensure that they conform to safety standards.

5) All visible gas lines, the gas stove, and gas powered water heater will be examined to insure that there are no leaks.

6) The auditor will evaluate if your central heating system needs cleaning or a tune-up.

7) Finally, expect a few suspect appliances, including old driers or refrigerators to be tested with an electricity monitor. There are times when one terrifically inefficient appliance throws an entire house's energy use out of whack.

We believe that whole house energy audits by certified professionals are worth every penny, so long as you act on what the audit turns up.

Last off, bear in mind that what turns up might surprise you: homeowners are often shocked to discover that all the little air leaks throughout their house add up to the equivalent of a window (or two, or more) being left open year round! Just remember that what you don't know can cost you: it's better to know!