Keeping Your Home Envelope in Good Shape
In the hot, humid climate around New Orleans and elsewhere in southern Louisiana, thorough sealing and insulation are two of your most powerful weapons against high energy bills.
These home improvements help reinforce your home envelope, the barrier between the interior of your home and the outdoors. An energy-efficient home envelope keeps your home at the temperature you want, reducing the load on the cooling and heating system and saving you money.
By optimizing the air sealing and insulation in your home, you could cut heating and cooling bills by as much as 20 percent, improve the indoor air quality and reduce airflow problems, such as drafts.
While these are some of the easiest and most budget-friendly improvements you can make, getting the most out of your effort takes some planning.
Little Air Leaks Cost You Big Money
Both sealing and insulation are equally important to your home’s energy efficiency, but air sealing is the job you’ll want to tackle first. Many of the common areas for air leaks will be covered if you add more insulation.
Air leaks are caused by cracks and gaps in the home envelope. In summer, they let out cool air produced by the air conditioner while letting in hot, humid outdoor air. In winter, they allow warm air to escape and create uncomfortable drafts from the cold air they let in. Year round, air leaks increase the load on your heating and cooling system, reduce comfort, and raise energy bills.
In addition, air leaks also worsen indoor air quality by letting in outdoor contaminants such as pollen, mold spores and smog.
In the average home, the amount of air lost through small leaks amounts to around the same that would be lost by having a hole the size of a basketball in the wall. These leaks are most common around:
- Doors and windows
- Penetrations for utility lines
- Appliance vents
- Baseboards and molding
- Electrical outlets and switches
- Fireplace and chimney
Many parts of the attic and basement or crawl space are also prone to air leaks. In the attic, the areas most likely to leak are the access hatch, plumbing vents, the spaces behind recessed lights and dropped soffits, and kneewalls. In the basement, the rim joints are the place to check for leaks.
Major air leaks are easy to find by yourself. All you’ll need is a lit incense stick or a smoke pen (puffer stick) available from home improvement supply stores. On a windy day, walk around your home and hold the incense stick or smoke pen up to areas you think may be leaky. Air leaking through will blow the smoke sideways.
How a Professional Can Help
Many of the leaks in your home may be too small to cause an obvious draft, but taken together, they can still add up to a lot of conditioned air lost and air contaminants let in.
To pinpoint all the wasteful air leaks in your home, call an HVAC professional. As part of a home energy audit, a professional can bring in a device known as a blower door, which increases air pressure to temporarily exaggerate small leaks so they’re easier to find.
Many older homes rely on a certain amount of air leakage for ventilation. Although it’s unlikely, too much sealing in such a home could lead to a buildup of air contaminants and carbon monoxide from fuel-burning appliances. If you’re concerned about making your home too airtight, consult a heating and cooling professional about improving the ventilation system before you air seal.
Seal the Leaks Yourself and Save on Energy
Of course, just knowing where your home requires sealing and insulation isn’t enough. The next step is to correctly seal the leaks you find with weatherstripping or caulk. Both these materials are easy to apply, but for effective sealing, you’ll need to know which type of each material to use where.
- Weatherstripping – This material comes in long, thin strips and is used for movable surfaces such as the top and side jambs of exterior doors or the inside tracks of windows. When the door or window is closed, the weatherstripping is compressed and seals any gaps.
The type you’ll need depends on the surface you’ll be applying it to, as well as your need for durability and easy application. Self-stick vinyl V-strip weatherstripping is durable, inconspicuous and works well with many surfaces, but it can be difficult to install. Foam tape is easier to install, but not as durable.
- Caulk – This substance is appropriate for semi-permanently sealing gaps between non-movable surfaces such as door or window frames. As with weatherstripping, the best type for your needs depends on the surface you’re sealing. Acrylic latex works well on many interior applications and is easy to apply. For outdoor uses such as sealing the chimney and metal flashing, however, butyl caulk a better choice.
Insulation Strengthens the Home Envelope
Sealing and insulation work together to maintain your home’s temperature. While sealing controls airflow, insulation controls the flow of radiant heat. In summer, your home absorbs radiant heat from the sun, meaning there’s more heat that the air conditioner has to remove. In winter, your warm home radiates heat to the cold outdoors, becoming colder as it does so. This heat loss forces your furnace to use more energy to keep your home warm.
Sufficient insulation in the attic, walls, floors, and basement slows the movement of radiant heat, keeping heat outdoors in summer and indoors in winter. That means less work for your air conditioner and furnace and lower energy bills for you.
This is another part of upgrading your sealing and insulation where a professional can help. An HVAC professional can bring in an infrared camera to take thermal images of your home that clearly show areas of heat loss. This allows the pro to find areas that lack insulation without having to open up your walls or floors. From there, you can add insulation as needed.
- Attic – The attic is one of the most important and easiest places to optimize insulation. Even on mild summer days, the attic temperature can rise to well over 100 degrees. Insulation holds this heat back so it doesn’t warm up your air conditioned home. In winter, attic insulation is critical for preventing rising warmth from escaping into your cold attic.
Take a look in the attic and check whether or not the insulation covers the floor joists. If it doesn’t, you’ll benefit from adding more. In southern Louisiana, if you already have a 3- or 4-inch layer of insulation, you’ll want to add an R-25 to R-38 layer. That’s around 10 to 12 inches of fiberglass batt or loose-fill cellulose insulation.
- Floors and walls – If you can access the area under the floor, check the insulation. For our climate, you should have an R-13 to R-19 layer of insulation. If you know the walls have been insulated, consider adding an R-5 layer of sheathing before you put on new siding.
- Basement – Insulating the basement walls and rim joists helps keep your whole home more comfortable and minimizes moisture problems, particularly if your basement is heated. After the rim joists have been air sealed, they can be insulated with a layer of rigid foam insulation.
Choosing the Best Insulation for the Job
Insulation is available in a number of different materials, including fiberglass, cellulose and eco-friendly materials such as cotton from recycled jeans. Several forms are also available.
- Batt insulation – Also called blanket or roll insulation, this material comes in long, flat strips cut to widths that easily fit between wall studs and floor joists.
- Loose-fill insulation – This insulation is made of small pieces of fiberglass or cellulose and is blown into place with a special machine. This form fills in small crevices better than batt insulation, helping it slow heat transfer more efficiently. It’s also a good choice for upgrading insulation in existing walls and floors because it can be added without the need to tear open the structures.
- Rigid foam board insulation – Although most often installed during a home’s construction, this material has some uses in existing constructions, such as insulating rim joists.
An Energy Audit Will Get You Started Right
Before upgrading your sealing and insulation yourself, consider hiring a heating and cooling professional to perform an energy audit on your home. During an energy audit, the technician will use diagnostic equipment such as blower door and infrared thermal imaging camera to pinpoint where you need sealing and insulation improvements. Your air ducts can also be inspected for wasteful leaks and poor insulation.
In addition, your technician can review the appliances, lighting and other sources of energy use to help you identify causes of energy loss that should be addressed.
If you’d like professional assistance with air sealing your home, adding insulation or otherwise improving your home envelope, contact us at Bryans United Air Conditioning. We proudly serve the Gretna, New Orleans, Metairie, Marrero and St. Rose areas.
Written by Zach Mouton
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