Insulation
For optimal energy efficiency, your home should be insulated from the roof down to two feet below ground level. Insulation’s ability to reduce heat transfer is rated in terms of its R-value, with a higher R-value making the home more efficient and comfortable. Efficiency Maine recommends that the entire building envelope be insulated: attics, cathedral ceilings, all wall cavities, rim joists, basement walls, and crawl spaces.
Increasing the amount of insulation in your home can have the following advantages:
- Lower Heating and Cooling Costs – Effective insulation means that it takes less energy to make your home comfortable and reduces your costs.
- Increased Year-Round Comfort – Insulation helps keep rooms warmer in the winter and cooler in the summer.
- Reduced Outside Noise – Increased insulation levels may also make your home quieter by reducing the amount of outside noise that comes in.
Types of Insulation
There are many different types of materials used for insulation, each with their own costs, advantages, and disadvantages. A Residential Registered Vendor will be able to recommend appropriate insulation levels, tell you which insulation materials might work best in certain locations, and perform insulation work.
Here are some of the common types of insulation:
| Material | R-Value Per Inch | Advantages | Disadvantages | |
| 1 | Fiberglass (loose blown) | 3.6 to 4.4 | Low cost | Performs poorly where there’s moving air, settles over time, can be irritating/itchy to install |
| 2 | Fiberglass (batt) | 2.6 to 4.3 | Low cost | Performs poorly where there’s moving air, settles over time, can be irritating/itchy to install |
| 3 | Cellulose (loose blown) | 3.2 to 3.6 | Low cost, reduces drafts | Absorbs water, can be heavy, settles over time, may corrode metal if wet |
| 4 | Cellulose (dense pack) | 3.0 to 3.4 | Low cost, reduces drafts | Absorbs water, can be heavy, may corrode metal if wet |
| 5 | Spray Foam (open cell) | 3.5 to 3.8 | Reduces drafts, lower price than closed cell foam | Not a moisture barrier, may require fire barrier |
| 6 | Spray Foam (closed cell) | 6.0 to 7.0 | Reduces drafts, serves as a moisture barrier | Highest upfront cost, may require fire barrier |
| 7 | Foam (board) | 3.6 to 7.6 | Reduces drafts, moisture resistant | May require fire barrier |
| 8 | Mineral Wool (batt) | 3.0 to 3.6 | Non-combustible, minimal off-gassing | Heavy, more compressible than fiberglass, fibers can be irritating |
| 9 | Mineral Wool (board) | 4.0 to 4.4 | Non-combustible, minimal off-gassing | Heavy, fibers can be irritating |
Source: Residential Energy: Cost Savings and Comfort for Existing Buildings
Radon is an indoor air quality issue commonly found in Maine homes. Click here for more information.
Financial Example: Any Income
| Insulation Cost | $5,000 |
| Air Sealing with Energy Assessment Cost | +$600 |
| Total Project Cost | $5,600 |
| Insulation Rebate | -$2,500 |
| Air Sealing with Energy Assessment Rebate | -$500 |
| Net Project Cost | $2,600 |
| Annual Savings | $479/year |
| Payback Period | 6 years |
Note: If $2,600 project is financed over 10 years at 4.99% APR, monthly savings ($40) would exceed monthly payments ($28).
Financial Example: Low Income
| Insulation Cost | $5,000 |
| Air Sealing with Energy Assessment Cost | +$600 |
| Total Project Cost | $5,600 |
| Insulation Rebate | -$4,500 |
| Air Sealing with Energy Assessment Rebate | -$600 |
| Net Project Cost | $500 |
| Annual Savings | $479/year |
| Payback Period | 1.5 years |