Energy-efficient water heating system will not only provide enough hot water but also will do so energy efficiently, saving you money.

Ventilation is ineffective in hot, humid climates where temperature swings between day and night are small. In these climates, attic ventilation can help to reduce your use of air conditioning. Ventilating your attic greatly reduces the amount of accumulated heat, which eventually works its way into the main part of your house. Ventilated attics are about 30°F (16°C) cooler than unventilated attics. Properly sized and placed louvers and roof vents help prevent moisture buildup and overheating in your attic.

Source: EERE

The most common sizing mistake is in oversizing. This not only makes the new system more expensive to install, but also forces it to operate inefficiently, break down more often, and cost more to operate. Oversized heating equipment also often creates uncomfortable and large temperature swings in the house. Oversized air conditioners (and heat pumps) do not run long enough to dehumidify the air, which results in the “clammy” feeling and unhealthy mold growth in many air-conditioned houses.

Source: EERE, Department of Energy

• You have an older home and haven’t added insulation. Only 20% of homes built before 1980 are well insulated.
• You are uncomfortably cold in the winter or hot in the summer—adding insulation creates a more uniform temperature and increases comfort.
• You build a new home, addition, or install new siding or roofing.
• You pay high energy bills.
• You are bothered by noise from outside—insulation muffles sound.

Source: EERE, U.S. Department of Energy

When using masonry blocks for a foundation wall, filling the block cores with high-pressure foam works better than most poured-in insulations, like polystyrene beads or vermiculite or perlite pellets.

Note that even though filling the block cavities and special block designs improve a block wall’s thermal characteristics, it doesn’t reduce heat movement very much when compared to insulation installed over the surface of the blocks either on the exterior or interior of the foundation walls. Field studies and computer simulations have shown that core-filling of any type offers little fuel savings since the majority of heat is conducted through the solid parts of the walls such as block webs and mortar joints.

Source: U.S. Department of Energy – Energy Efficiency and Renewable Energy

Compared to insulating the basement ceiling, insulating basement walls has the following advantages:

• Requires less insulation (1,350 square feet of wall insulation for a 36 x 48-foot basement with 8-foot walls, compared with 1,725 ceiling)
• More easily achieves continuous thermal and air leakage boundaries because basement ceilings typically include electrical wiring, plumbing, and ductwork.
• Requires little, if any, increase in the size of the heating and cooling equipment. The heat loss and air leakage through the basement ceiling is similar to that through the exterior walls of the basement.

These are some other advantages of insulation on exterior basement walls:

• Minimizes thermal bridging and reducing heat loss through the foundation
• Protects the damp-proof coating from damage during backfilling
• Serves as a capillary break to moisture intrusion
• Protects the foundation from the effects of the freeze-thaw cycle in extreme climates
• Reduces the potential for condensation on surfaces in the basement
• Conserves room area, relative to installing insulation on the interior.

The disadvantages of basement wall insulation include the following:

• Costs may exceed those for insulating the basement ceiling, depending on materials and approach selected
• Installation is expensive for an existing building unless a perimeter drainage system is also being installed
• Many exterior insulation materials are susceptible to insect infestation
• Some contractors are unfamiliar with proper detailing procedures that are critical to performance
• If surrounding soil contains radon gas, the house will require a mitigation system underneath the basement floor.

Adding insulation to the interior of the foundation is often more cost effective for an existing building. Interior insulation has the following advantages and disadvantages.

Advantages:

• Interior insulation is much less expensive to install than exterior insulation for existing buildings
• Almost any insulation type can be used, giving a wider selection of materials
• The threat of insect infestation is eliminated
• The space is isolated from the colder earth more effectively than when using exterior methods

Disadvantages:

• Many insulation types require a fire-rated covering since they release toxic gases when ignited
• Interior insulation reduces usable interior space by a few inches
• It doesn’t protect the damp-proof coating like the exterior insulation
• If the perimeter drainage is poor, the insulation may become saturated by moisture weeping through the foundation walls
• Superior air-sealing details and vapor diffusion retarders are important for adequate performance

Source: Energy Efficiency and Renewable Energy, U.S. Department of Energy

In the United States, the most common types of foundations include the following:

* Basements
* Crawl spaces
* Slab-on-grade floors.

Some construction techniques lend themselves to both foundation structure and insulation, including these:

* Insulating concrete forms
* Insulating concrete blocks.

When insulating any type of foundation, it’s also important to take into account moisture control and air sealing.

Source: U.S. Department of Energy, Energy Efficiency and Renewable Energy

Use construction adhesive and screws to attach rigid foam insulation to the attic side of the door. Pay special attention to the clearance between the insulation and the door frame and air sealing details. Adjust insulation levels or R-values to meet those recommended for your area and climate. Also, insulate and air seal the knee walls themselves for maximum energy efficiency.

Source: Energy Efficiency and Renewable Energy, U.S. Department of Energy

Before insulating or deciding whether to add insulation to your attic, first see our information about adding insulation to an existing house or selecting insulation for new home construction if you haven’t already.

Warning: if you think you have vermiculite insulation in your attic, there’s a chance it could contain asbestos. Don’t disturb it. Only insulation contractors certified to handle and remove asbestos should deal with vermiculite insulation.
Attic Insulation Techniques

Loose-fill or batt insulation is typically installed in an attic. Although installation costs may vary, loose-fill insulation is usually less expensive to install than batt insulation. When installed properly, loose-fill insulation also usually provides better coverage.

Before installing any type of insulation in your attic, follow these steps:

* Seal all attic-to-home air leaks. Most insulation does not stop airflow.
o Duct exhaust fans to the outside. Use a tightly constructed box to cover fan housing on attic side. Seal around the duct where it exits the box. Seal the perimeter of the box to the drywall on attic side.
o Cover openings—such as dropped ceilings, soffits, and bulkheads—into attic area with plywood and seal to the attic side of the ceiling.
o Seal around chimney and framing with a high-temperature caulk or furnace cement.
o At the tops of interior walls, use long-life caulk to seal the smaller gaps and holes. Use expanding foam or strips of rigid foam board insulation for the larger gaps.

* Install blocking (metal flashing) to maintain fire-safety clearance requirements (usually 3 inches) for heat-producing equipment found in an attic, such as flues, chimneys, exhaust fans, and light housings/fixtures unless the light fixtures are IC (insulation contact) rated. IC-rated lights are airtight and can be covered with insulation.

* Make sure insulation doesn’t block soffit vents to allow for attic ventilation.

* Check the attic ceiling for water stains or marks. They indicate roof leaks or lack of ventilation. Make repairs before you insulate. Wet insulation is ineffective and can damage your home.

Also insulate and air seal your attic access if it’s located in a conditioned part of the house.

You’ll want to properly insulate and air seal any knee walls—vertical walls with attic space directly behind them—in your home as well.

Finally, if you’re constructing a new home or remodeling, make sure any attic decking, which provides additional storage space or a platform for an HVAC unit or hot water tank, is raised above the ceiling joists to ensure proper insulation depth. The decking then should be installed securely to the top of the raised lumber after the insulation has been installed.
Other Considerations

If you live in a hot or warm climate, you might consider installing a radiant barrier in your attic along with the insulation.

Source: U.S. Department of Energy