The amount of heat gain through the home envelope is proportionate to the amount of cooling needed to keep your Tallahassee home comfortable. To maximize cooling efficiency and comfort, sealing and insulating the home envelope may be in order. Here’s the scoop.
What Exactly Is a Home’s Envelope?
A home’s envelope is comprised of the structure, systems and components that separate the air conditioned living spaces from the non-conditioned spaces of the home, such as the attic, crawl space and garage. The envelope may also be referred to as the shell or insulation barrier of a home.
The typical home envelope includes ceilings, floors, exterior walls, windows, doors and, depending on design, the air ducts. That's a large envelope to seal and plenty of opportunity for insulation deficiencies and air leaks to develop, perhaps unnoticed, which drive heat gain, outside air infiltration and moisture issues.
Home Energy Assessment
The sensible route to take for sealing and insulating the home envelope begins with a home energy assessment by a qualified HVAC expert. Working with the right HVAC contractor puts control of home efficiency in your hands for positively identifying envelope heat gain issues, moisture and indoor air quality issues -- all affecting comfort, energy bills and indoor air quality.
Air Sealing for Comfort and Savings
Before air leaks can be sealed, they must be found. If you notice drafts and hot or cold spots in your home, or rooms which are more difficult to keep comfortable than others, air leaks, insulation deficiencies and heat gain issues are the likely culprits.
Your HVAC contractor uses professional equipment to find and measure the amount of air leakage through the envelope. The primary tool is the blower door test. This involves connecting a large fan to an exterior door of the home, sealing the home and then de-pressurizing (or pressurizing) the home to force airflow through cracks and leaks in the envelope.
The tools and basic materials used for sealing air leaks include caulk, weatherstripping, spray foam and door sweeps.
- Caulk is available in a variety of colors and application methods, such as the standard caulk gun, caulk rope and squeeze tubes. Caulk may be used around windows and at baseboard and flooring junctions where cracks exist.
- Weatherstripping is available in many different materials (e.g. plastic, foam and silicon) which are used for different types of sealing applications. For instance, V-strip tension weatherstripping is excellent for double-hung windows. Door sweeps are used for the bottom of access doors, while foam weatherstripping is used around the door frame.
- Expandable foam spray is perfect for larger holes and gaps that are present at the home’s exterior wall, perhaps from piping entering the shell.
Make sure your HVAC contractor pays special attention to sealing attic access doors, and the shared walls, ceilings and doors to attached garages, for health and home safety reasons, as well as supporting energy efficiency.
Insulation: What’s in the Attic?
Once your home is tightly sealed, you can tackle insulation issues. Insulation should be installed to Energy Star recommended R-values (indicating resistance to heat) for the attic, walls and floor. Insulation must also be in good condition with no mold or wet spots.
Fiberglass rolls are popular in the attic and inside walls, particularly during home construction. For existing walls lacking adequate insulation and for supplementing attic insulation, loose fill fiberglass and cellulose are often the most practical and cost-effective solutions. Following are the basic pros and cons of fiberglass and cellulose:
- Fiberglass is lightweight, relatively inexpensive, resistant to rodents and fire, and maintains its R-value for life barring any external damage.
- Cellulose is often used for wall cavities. It has excellent sound dampening properties, is resistant to rodents, is chemically treated with fire retardants and is long lasting. Cellulose is heavier than fiberglass.
Note that basements and crawl spaces are generally too wet and damp in homes in the greater Tallahassee region to install fiberglass or cellulose insulation. Rigid foam board is the insulation of choice for these spaces.
Lastly, ask your HVAC contractor to inspect the air ducts for leakage and insulation deficiencies, too. By design, air ducts are typically part of the conditioned spaces and occasionally non-conditioned spaces as well. Leaks and insulation deficiencies waste substantial energy and make the A/C or heat pump work harder.
Please contact us at Air Control Heating & Cooling for more information about sealing and insulating the home envelope. We've proudly served Tallahassee area for 50 years.
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