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It happens to countless homeowners around the end of the year - you make the annual visit to your attic to collect the holiday decorations and what do you find? Spots and blotches covering the bottom of the roof sheathing.

Worse yet - it turns out to be attic mold!

What does energy conservation have to do with mold in the attic? Well if you take a step back and consider how the house behaves as system, they are often directly related.

Building science experts have long been using the “house as a system” approach to diagnose the cause and origin of building defects.

For example, ice dams. These are often caused by warm air seeping into the attic which causes the snow and ice on the roof to melt. The water drains to the edge of the roof (which is colder than the rest of the roof because it is an overhang and not warmed by the attic), freezes and creates an ice dam. As this process is repeated daily, the ice dam grows larger. Eventually water is forced under a shingle where it can seep into the house.

Understanding how the house behaves as a system and the various causes and effects is necessary to diagnose most building related problems.

But how about that attic mold? How did it get there?

Mold requires chronic moisture to form and to thrive, so source(s) of moisture must be present. Possibly the moisture came from outdoors. The roof is newer and a quick check of the roof shows no obvious damage or leaks.

Possibly the moisture came from indoors. During the heating season, the interior of the house frequently has high moisture levels, especially bathrooms and kitchens. A quick check shows that all bathroom fans, kitchen vents, etc. are properly ducted completely outdoors and not into the attic. The amount of insulation looks good and the attic is well ventilated.

Don’t give up - you are almost there! Remember the house as a system? You know that warm, moist air is in the house, but how is it getting into the attic?

By air leaks! Air leaks are the leading source of energy loss in most houses, and a frequent source of chronic moisture that can cause attic mold.

Most homeowners are well aware of air leaks around windows and doors (especially old ones), but many overlook the numerous gaps leading directly into the attic!

Have a look around the attic and you may find large gaps around recessed lights and fans, holes where wires or pipes are installed, even large gaps around the chimney.

And don’t overlook the whole house fan and especially the folding attic stair - a big, uninsulated hole in your ceiling that is often overlooked!

These gaps can add up to a large hole that allows warm, moist air from the house to flow right into the cold attic. The warm moist air condenses on the cold roof sheathing, creating chronically damp conditions that can lead to attic mold growth. And the energy loss - it can be like leaving a window open all winter long!

Seal these air leaks and you stop a significant moisture source. And just think of all the energy you can save and the cold drafts you can stop!

Mark D. Tyrol is a Professional Engineer specializing in cause and origin of construction defects. He developed several residential energy conservation products including an attic stair cover and a fireplace draftstopper. To learn more visit http://www.batticdoor.com

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If you would like to make your existing home more energy efficient and get some help paying for the improvements, you need to know about the Energy Tax Incentives Act of 2005. The new law provides a $500 lifetime credit against your federal income tax for the cost of certain energy-saving home improvements that you make to your home after December 31, 2005 and before January 1, 2008. Up to $200 of the tax credit may be applied to windows.

As you may know, a tax credit is far more favorable than a deduction of the same amount. Deductions only reduce the amount of income that is subject to tax. A tax credit, on the other hand, is a dollar for dollar reduction of the tax due when you file your income tax return. So, if you are in the 28% income tax bracket, the new $500 credit is equivalent to a tax deduction of nearly $1800!

Here are highlights of the new provisions:

There is an overall lifetime cap on the credit of $500, and a maximum of $200 of the credit may be applied to qualified window expenditures. Subject to those limitations, you may receive a credit for the sum of the following:

Building Envelope Components. Ten (10%) percent of your expenditures for so called “building envelope components” will qualify for the tax credit. Building envelope components include the following:

• any insulation material or system which is specifically and primarily designed to reduce the heat loss or gain of a dwelling unit when installed in or on such dwelling unit,
• exterior windows (including skylights),
• exterior doors, and
• any metal roof installed on a dwelling unit, but only if such roof has appropriate pigmented coatings which are specifically and primarily designed to reduce the heat gain of such dwelling unit.

To qualify for the credit, the building envelope components must be installed in or on a dwelling unit (including a manufactured home) located in the United States that is owned by you and used by you as your principal residence. Installation of envelope components in a second or vacation home or rental property therefore will not qualify for the new tax break.

Only new components are eligible for the credit and the components must reasonably be expected to remain in use for at least 5 years.

Energy efficient property expenditures. Amounts paid for “residential energy property expenditures” will also qualify for the credit up to the following specific limits:

• Up to $50 for any advanced main air circulating fan;
• Up to $150 for any qualified natural gas, propane or oil furnace or hot water boiler;
• Up to $300 for any item of “energy-efficient building property.” This includes certain qualifying electrical heat water pumps, electric heat pumps, geothermal heat pumps, central air conditioners and natural gas, propane or oil water heaters.

Expenditures for labor costs for onsite preparation, assembly or original installation may be included. Improvements must be installed in or in connection with a dwelling unit located in the United States that is owned by you and used by you as your principal residence.

There are energy efficiency standards described in the new law that your home improvements must meet, so some investigation on your part will be necessary to be sure that the improvements will qualify for the credit. For this reason, if you hire a third party to do the work, your written agreement with the contractor should include the contractor’s guaranty that the installed property will meet the energy efficiency standards of the new law.

There is one potential trade-off, if you use the credit. Many improvements to your home will increase your “tax basis” in the property, and this increased tax basis may, in turn, reduce the amount of capital gain that is realized if you sell your home at a profit. The increase in tax basis that would otherwise result from energy efficient improvements that qualify for the credit will be reduced by the amount of the allowed credit. Since the tax credit decreases your tax basis, you are likely to have more capital gain at the time of sale. This will not affect you if all of the capital gain realized at the time of sale is protected by the $250,000 exclusion ($500,000 for married couples) for gains realized on the sale of your principal residence. But even if there is an increase in the taxable capital gain realized when you sell your home, it will almost certainly be outweighed by the advantage of using the new income tax credit currently.

Like so much of the Internal Revenue Code, the new provisions encouraging energy efficient home improvements seem unnecessarily complicated, but we have to consider the source - Congress! However, a bit of patience and careful planning will bring you some very real tax savings and help the environment to boot!