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Make Your Attic Energy Efficient by Christopher Foos
Making your attic energy efficient is extremely important
to the proper heating and cooling of your home. It also
helps increase the longevity of the materials your home
was constructed of. Read below to find out what needs to
be addressed.
to the proper heating and cooling of your home. It also
helps increase the longevity of the materials your home
was constructed of. Read below to find out what needs to
be addressed.
I, Chris Foos, have over 12 years experience in roofing,
framing, and insulation installation. With this experience, I
have come to be an expert on how to make your attic
energy efficient and how to save you money on
electricity. So grab a pen and notepad, and get started on
your attic today!
framing, and insulation installation. With this experience, I
have come to be an expert on how to make your attic
energy efficient and how to save you money on
electricity. So grab a pen and notepad, and get started on
your attic today!
Insulation:
First, we need to check the insulation in your attic, ceilings, exterior and basement walls, floors,
and crawl spaces to see if it meets the levels recommended for your area. Insulation is measured in
R-values—the higher the R-value, the better your walls and roof will resist the transfer of heat. DOE
recommends ranges of R-values based on local heating and cooling costs and climate conditions in
different areas of the nation. State and local code minimum insulation requirements may be less
than the DOE recommendations, which are based on cost effectiveness. For more customized
insulation recommendations, check out the Zip Code Insulation Calculator. This tool provides
insulation levels for your new or existing home based on your zip code and other basic information
about your home. Although insulation can be made from a variety of materials, it usually comes in
four types; each type has different characteristics.
and crawl spaces to see if it meets the levels recommended for your area. Insulation is measured in
R-values—the higher the R-value, the better your walls and roof will resist the transfer of heat. DOE
recommends ranges of R-values based on local heating and cooling costs and climate conditions in
different areas of the nation. State and local code minimum insulation requirements may be less
than the DOE recommendations, which are based on cost effectiveness. For more customized
insulation recommendations, check out the Zip Code Insulation Calculator. This tool provides
insulation levels for your new or existing home based on your zip code and other basic information
about your home. Although insulation can be made from a variety of materials, it usually comes in
four types; each type has different characteristics.
Rolls and Batts—or blankets—are flexible products made from mineral fibers, such as fiberglass and rock wool. They are available in widths suited to standard spacings of wall studs and attic or
floor joists: 2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.
Loose-fill insulation—usually made of fiberglass, rock wool, or cellulose in the form of loose fibers or fiber pellets, it should be blown into spaces using special pneumatic equipment. The blown-
in material conforms readily to building cavities and attics. Therefore, loose-fill insulation is well suited for places where it is difficult to install other types of insulation.
Rigid foam insulation—foam insulation typically is more expensive than fiber insulation. But it's very effective in buildings with space limitations and where higher R-values are needed. Foam
insulation R-values range from R-4 to R-6.5 per inch of thickness, which is up to 2 times greater than most other insulating materials of the same thickness.
Foam-in-place insulation—this type can be blown into walls and reduces air leakage, if blown into cracks, such as around window and door frames.
Insulation Tips
**NOTE-Recessed light fixtures can be a major source of heat loss, but you need to be careful how close you place insulation next to a fixture unless it is marked IC—designed for direct insulation
contact. Check your local building codes for recommendations. See Lighting for more about recessed cans.
One of the most cost-effective ways to make your home more comfortable year-round is to add insulation to your attic. Adding insulation to the attic is relatively easy and very cost effective.
floor joists: 2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.
Loose-fill insulation—usually made of fiberglass, rock wool, or cellulose in the form of loose fibers or fiber pellets, it should be blown into spaces using special pneumatic equipment. The blown-
in material conforms readily to building cavities and attics. Therefore, loose-fill insulation is well suited for places where it is difficult to install other types of insulation.
Rigid foam insulation—foam insulation typically is more expensive than fiber insulation. But it's very effective in buildings with space limitations and where higher R-values are needed. Foam
insulation R-values range from R-4 to R-6.5 per inch of thickness, which is up to 2 times greater than most other insulating materials of the same thickness.
Foam-in-place insulation—this type can be blown into walls and reduces air leakage, if blown into cracks, such as around window and door frames.
Insulation Tips
**NOTE-Recessed light fixtures can be a major source of heat loss, but you need to be careful how close you place insulation next to a fixture unless it is marked IC—designed for direct insulation
contact. Check your local building codes for recommendations. See Lighting for more about recessed cans.
One of the most cost-effective ways to make your home more comfortable year-round is to add insulation to your attic. Adding insulation to the attic is relatively easy and very cost effective.
Radiant Barrier:
Radiant barriers are installed in homes—most commonly in attics—to reduce summer heat gain and winter
heat loss, which helps lower heating and cooling costs. The barriers consist of a highly reflective material that
reflects radiant heat rather than absorbing it. They don't, however, reduce heat conduction like thermal
insulation materials.
heat loss, which helps lower heating and cooling costs. The barriers consist of a highly reflective material that
reflects radiant heat rather than absorbing it. They don't, however, reduce heat conduction like thermal
insulation materials.
How They Work
Heat travels from a warm area to a cool area by a combination of conduction, convection, and radiation. Heat
flows by conduction from a hotter location within a material or assembly to a colder location. Heat transfer by
convection occurs when a liquid or gas is heated by a surface, becomes less dense, and rises (natural
convection), or when a moving stream of air absorbs heat from a warmer surface (forced convection). Radiant
heat travels in a straight line away from any surface and heats anything solid that absorbs the incident
energy. Radiant heat transfer occurs because warmer surfaces emit more radiation than cooler surfaces.
Heat travels from a warm area to a cool area by a combination of conduction, convection, and radiation. Heat
flows by conduction from a hotter location within a material or assembly to a colder location. Heat transfer by
convection occurs when a liquid or gas is heated by a surface, becomes less dense, and rises (natural
convection), or when a moving stream of air absorbs heat from a warmer surface (forced convection). Radiant
heat travels in a straight line away from any surface and heats anything solid that absorbs the incident
energy. Radiant heat transfer occurs because warmer surfaces emit more radiation than cooler surfaces.
When the sun heats a roof, it's primarily the sun's radiant energy that makes the roof hot. A large portion of this heat travels by conduction through the roofing materials
to the attic side of the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor. A radiant
barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.
to the attic side of the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor. A radiant
barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.
A radiant barrier's performance is determined by three factors:
1. Emissivity (or emittance) – the ratio of the radiant energy (heat) leaving (being emitted by) a surface to that of a black body at the same temperature and with the same area. It's expressed as
a number a between 0 and 1. The higher the number, the greater the emitted radiation.
2. Reflectivity (or reflectance) – a measure of how much radiant heat is reflected by a material. It's also expressed as a number between 0 and 1 (sometimes, it is given as a percentage between 0
and 100%). The higher the number, the greater the reflectivity.
3. The angle the incident radiation strikes the surface—a right angle (perpendicular) usually works best.
All radiant barriers must have a low emissivity (0.1 or less) and high reflectivity (0.9 or more). From one brand of radiant barrier to another, the reflectivity and emissivity are usually so similar that
it makes little difference as far as thermal performance. (Most products have emissivities of 0.03–0.05, which generally corresponds to a reflectivity of 95%–97%.) Also, the greater the temperature
difference between the sides of the radiant barrier material, the greater the benefits a radiant barrier can offer.
Radiant barriers are more effective in hot climates than in cool climates, especially when cooling air ducts are located in the attic. Some studies show that radiant barriers can lower cooling
costs between 5%–10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. But in cool climates, it's usually more cost effective to
install more than the minimum recommended level of insulation rather than a radiant barrier.
Types of Radiant Barriers:
Radiant barriers come in a variety of forms, including reflective foil, reflective metal roof shingles, reflective laminated roof sheathing, and even reflective chips, which can be applied over loose-
fill insulation. The reflective material, usually aluminum, is applied to one or both sides of a number of substrate materials. Substrate materials include kraft paper, plastic films, cardboard,
oriented strand board, and air infiltration barrier material. Some products are fiber-reinforced to increase the durability and ease of handling.
Also, radiant barriers—which don't provide a significant amount of thermal insulation—can be combined with many types of insulation materials. These combinations are called reflective insulation
systems. In these combinations, radiant barriers can also act as the insulation's facing material.
1. Emissivity (or emittance) – the ratio of the radiant energy (heat) leaving (being emitted by) a surface to that of a black body at the same temperature and with the same area. It's expressed as
a number a between 0 and 1. The higher the number, the greater the emitted radiation.
2. Reflectivity (or reflectance) – a measure of how much radiant heat is reflected by a material. It's also expressed as a number between 0 and 1 (sometimes, it is given as a percentage between 0
and 100%). The higher the number, the greater the reflectivity.
3. The angle the incident radiation strikes the surface—a right angle (perpendicular) usually works best.
All radiant barriers must have a low emissivity (0.1 or less) and high reflectivity (0.9 or more). From one brand of radiant barrier to another, the reflectivity and emissivity are usually so similar that
it makes little difference as far as thermal performance. (Most products have emissivities of 0.03–0.05, which generally corresponds to a reflectivity of 95%–97%.) Also, the greater the temperature
difference between the sides of the radiant barrier material, the greater the benefits a radiant barrier can offer.
Radiant barriers are more effective in hot climates than in cool climates, especially when cooling air ducts are located in the attic. Some studies show that radiant barriers can lower cooling
costs between 5%–10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. But in cool climates, it's usually more cost effective to
install more than the minimum recommended level of insulation rather than a radiant barrier.
Types of Radiant Barriers:
Radiant barriers come in a variety of forms, including reflective foil, reflective metal roof shingles, reflective laminated roof sheathing, and even reflective chips, which can be applied over loose-
fill insulation. The reflective material, usually aluminum, is applied to one or both sides of a number of substrate materials. Substrate materials include kraft paper, plastic films, cardboard,
oriented strand board, and air infiltration barrier material. Some products are fiber-reinforced to increase the durability and ease of handling.
Also, radiant barriers—which don't provide a significant amount of thermal insulation—can be combined with many types of insulation materials. These combinations are called reflective insulation
systems. In these combinations, radiant barriers can also act as the insulation's facing material.
Ventilation:
If your attic is not properly vented, attic temperatures can reach 140 degrees or higher in the summer. These high
temperatures penetrate into the rooms below, increasing demand on your cooling system, and ultimately increasing energy
bills.
Attic ventilation helps cool your home and reduce air conditioning costs. It can also help extend the life of your roof
shingles because excess attic heat may cause roof shingles to deteriorate and require repair or replacement. With proper
attic ventilation, you can avoid unnecessary costs and keep your home cooler in hot summer months. Proper Ventilation
Cools Your Attic Naturally. An attic ventilation system provides a steady flow of air that carries heat out of the attic
before the heat radiates to the inside of your home. With natural ventilation, the flow of air through the attic is balanced
between intake and exhaust vents.
temperatures penetrate into the rooms below, increasing demand on your cooling system, and ultimately increasing energy
bills.
Attic ventilation helps cool your home and reduce air conditioning costs. It can also help extend the life of your roof
shingles because excess attic heat may cause roof shingles to deteriorate and require repair or replacement. With proper
attic ventilation, you can avoid unnecessary costs and keep your home cooler in hot summer months. Proper Ventilation
Cools Your Attic Naturally. An attic ventilation system provides a steady flow of air that carries heat out of the attic
before the heat radiates to the inside of your home. With natural ventilation, the flow of air through the attic is balanced
between intake and exhaust vents.
Positioning of Vents – Intake vents, where cooler air enters the attic, should be placed lower than exhaust vents, where warmer air exits the attic. Vents should be located and designed to
prevent rain from leaking into the attic.
The most common types are:
Ridge Vents – These are installed along the roof ridge.
Roof Vents – These are metal vent housings installed in the roof.
Gable Vents – These are louvered vents installed in the high part of the roof gable.
Eave or Soffit Vents – These are installed in the roof eaves or overhang.
To make a complete venting system, you should have properly sized roof, ridge or gable vents installed at the high points of the roof, and eave vents installed at the low points in the eaves or
overhangs.
*Note- Avoid any electric powered attic fan. These defeat the purpose of saving on energy costs! Why use electricity to save electricity? I prefer the use of good old-fashioned "whirly birds"
to allow hot air to escape, and they are a fraction of the cost of powered fans!
prevent rain from leaking into the attic.
The most common types are:
Ridge Vents – These are installed along the roof ridge.
Roof Vents – These are metal vent housings installed in the roof.
Gable Vents – These are louvered vents installed in the high part of the roof gable.
Eave or Soffit Vents – These are installed in the roof eaves or overhang.
To make a complete venting system, you should have properly sized roof, ridge or gable vents installed at the high points of the roof, and eave vents installed at the low points in the eaves or
overhangs.
*Note- Avoid any electric powered attic fan. These defeat the purpose of saving on energy costs! Why use electricity to save electricity? I prefer the use of good old-fashioned "whirly birds"
to allow hot air to escape, and they are a fraction of the cost of powered fans!
| If you do none of the above in your attic, at least explore it and check if all of your duct work is sealed properly. Even the slightest leak can cost you a bunch of money in the long-term. |
There is no question that adding insulation, a radiant barrier, and proper attic ventilation can cost anywhere from a couple of hundred to a couple thousand dollars upfront,
but an efficient attic, if paid for by credit card, could save you at least what that credit card's minimum amount due is every month! Also, look into the tax rebates. Doing all
of these changes in December could easily be paid for by February and then save you money each month! Win! Win! Win!
but an efficient attic, if paid for by credit card, could save you at least what that credit card's minimum amount due is every month! Also, look into the tax rebates. Doing all
of these changes in December could easily be paid for by February and then save you money each month! Win! Win! Win!