Green from the Ground Up Best Practices
- Treat insulation recommendations from the Department of Energy as minimums. Aim for insulation levels that are 50% better.
- Use insulation that completely fills walls and ceiling cavities and reduces or eliminates air leaks - structural insulated panels, spray-in foam, or spray-in cellulose or fiberglass are the best products for this.
- Avoid fiberglass batt insulation that contains formaldehyde and cellulose that contains ammonium sulfate.
- Avoid fiberglass batts if possible; if they must be used, make sure the installer knows what he's doing. Supplement batts with a layer of rigid foam insulation on the exterior of the building.
- Do not use light-gauge steel framing on exterior walls without a layer of exterior insulation to counteract thermal bridging.
- When calculating the desired thermal performance of a wall or ceiling, don't forget to include the effects of doors, windows, and other materials that penetrate the building envelope. In general, real performance will be lower than the nominal R-value of the insulation you're using. Plan accordingly.
- Don't confuse a thermal barrier with an air barrier. One retards the flow of heat, the other prevents air infiltration and the migration of water vapor into wall and ceiling cavities. Both are important.
Want to know more about Insulation and Green Building Practices
Green from the Ground Up - Upcoming Training
Intensive 2-Day Classroom Program
In this two-day course, David Johnston teaches participants how to approach a home from the green building mindset.
Green Training Information & Course Details
More About Insulation
Green Insulator Resource
Sustainable building starts with reducing the heating and cooling loads of the home as much as possible and insulation is the key to energy conservation, a cornerstone of green building. Well-insulated houses not only save energy, thus lowering operating costs, but also keep people more comfortable.
Appropriate Type and Amount of Insulation
Because different types of insulation have different insulating values (R-values), what you choose determines how the house is framed and detailed on the outside. Your exact route will probably take a variety of factors into account:
- the appropriate level of insulation for the region where you build. See a the climate zones around the country and their recommended insulation levels in Chapter 11 on Insulation in the Green from the Ground Up book for more details.
- your experience with alternative building practices
- the availability of different kinds of insulation
- how much experience your insulation contractor has
- the design of the house
- local cost comparisons for different types of insulation
Green Insulator's Transition Guide
Conduct a Home energy audit, how much insulation is there?
- An audit will indicate how a house is performing and where it is loosing heat.
- A blower door test and infrared camera will outline the problem areas.
- Contact a licensed HERS energy auditor in your area, or look into become certified yourself
Seal all wall penetrations such as wires or pipes or electrical outlets
- Even a small air leak can have a huge impact on heat loss over the life of the building
- Use expansion foam
- Canned expansion foam. Look for products that use HFC rather than HCFC or CFC as propellants.
Add additional insulation to the attic
- An attic is a great place to pile on the insulation. A large quantity of a home’s heat is lost through the attic
- Lay R-38 batts perpendicular to each other or blow at least 10 inches of cellulose in most climates.
- Use insulation with 75% recycled content and doesn't emit formaldehyde or other VOC’s. loose fill cellulose, fiberglass or spray urethane foam.
Remove window trim and seal around windows
- Incorrectly installed windows are a major source of air infiltration.
- Remove window trim and drywall from the inside or exterior trim to expose the window framing. Insulate any cavities between the frame and studs.
- Canned expansion foam. Look for products that use HFC rather than HCFC or CFC as propellants. Choose foam designed for windows so that the pressure from the foam doesn't warp the windows.
Insulate the crawl space and between floor joists
- The crawl space helps compose a significant part of the thermal envelope. It should be insulated to prevent heat loss in the home and to keep feet warmer in winter.
- Install batt insulation between joists to at least R=19 or higher depending on climate.
- Rigid closed cell foam works well on the walls, preferably on the exterior. The floor joists should also be insulated to help prevent heat loss.
Go through the drywall and re-insulate all walls
- Depending on climate and existing construction, blowing insulation into walls increases comfort and reduces energy bills
- Small holes are drilled into drywall and insulation is blown in to fill the cavity
- Poorly done, or a house without an adequate drainage plane on the exterior, blowing wall insulation can lead to mold damage and compromise the house.
Re-insulate wall cavities from the exterior
- Wall insulation provides increased comfort and lowers utility bills
- The best approach is to apply rigid foam to the entire exterior of the home. This both reduces heat loss and thermal bridging through studs. It can also help reduce infiltration
- To be done when siding is being replaced or over traditional plywood siding. Closed cell foam should be used to not absorb moisture
Green Building Training & Certification
Find out when the next Green Building Training is and learn more about Green Building Practices.
Read more on the Federal Tax Credits for Insulation
Insulation Meets 2009 IECC & Amendments
- 30% of cost, up to $1,500
- For insulation to qualify, its primary purpose must be to insulate. (example: vapor retarders are covered, siding does not qualify).
- Must be expected to last 5 years OR have a 2 year warranty