Importance of Weatherizing

Insulating and air sealing your home, also known as weatherizing, is one of the most important things you can do to your home to reduce carbon emissions. Not only does it reduce energy loss from your home, but it also makes your home feel more comfortable and saves you on your energy bill. It also is an important first step in upgrading other aspects of your home, such as installing heat pumps, to make sure they run efficiently. With Mass Save covering 75-100% of insulation and 100% of air sealing costs, weatherizing your home is the biggest bang for your buck when it comes to taking climate action.

Mass Save

How to Get Started

If your home feels drafty or you’re getting ready to make other upgrades, it’s a good time to start thinking about insulation. The very first thing to do is schedule a free Home Energy Assessment. Massachusetts residents are eligible to receive one every two years, and there are two options:

  1. Schedule an assessment directly with Mass Save by calling 1-866-527-SAVE (7283)
  2. Schedule an assessment with a Home Performance Contractor

After your home energy assessment, you’ll be sent a report with recommended work and costs. Mass Save sets the pricing for this work for all participating installers, which means that there is no need to worry about being overcharged and no need to shop around for different quotes.

If it is discovered that your home has Knob and Tube wiring, non-IC rated lights, or vermiculite (which are all potential fire hazards), you may have to have them remedied before any work can take place.

All About Insulation

There are many different kinds of insulation materials, but Mass Save installers primarily use blown-in cellulose for attics and walls, and fiberglass batts and foam boards for crawl spaces and knee joints. Blown-in cellulose is made from recycled paper and is considered one of the “greenest” insulation options.

Blown-in cellulose

Fiberglass batts

Polyiso foam board






While Mass Save does not cover spray foam insulation (aside from using it to air seal), it may be the right choice for your home, particularly if you have a non-ventilated attic, or an attic with HVAC equipment. If you need advice about which type of insulation might be best for your home, you can make an appointment with one of Newton’s Energy Coaches here.


Installation Process

Blower door test

A blower door test being performed.

The first thing a Mass Save approved installer will do is perform a blower door test. This simple diagnostic test will show how ‘leaky’ your home is, and will be repeated after your weatherization work is complete. 

If you are having insulation blown into your ventilated attic, they will seal up any gaps or holes in your attic floor and bring a hose up into your attic to spray enough cellulose to cover the attic floor completely. It’s possible they might cover any recessed lights with foam boxes that will further prevent any energy loss up into the attic, and install baffles, or chutes, that go from your soffit vents up to the ridge cap of your roof to ensure adequate attic ventilation and prevent insulation from covering the vents. 

If you are having insulation blown into your walls, your installer will advise whether it is best done from the inside or outside depending on the characteristics of your home. Holes will be drilled in between each wall stud to allow every cavity to be filled, and will be patched up afterwards. This may require a visit from a handyman or painter after the job is complete to smooth and repaint, but will be well worth the added comfort and energy savings achieved by insulating your home.

Insulation being installed on exterior of home

Insulation being blown in through the exterior of a home with shingle siding. Holes are drilled beneath the shingles, patched up, and shingles put back in place.

Blown-in cellulose may also be added to your garage ceiling, and polyiso foam boards and fiberglass batts might be added in additional places such as knee joints or crawl spaces. Mass Save will typically not come to a property just to air seal, but if they are performing insulation work, they will air seal your home at no cost while there. Air sealing may include new weatherstripping around doors and sealing leaky ductwork, for example.


Incentives & Financing

There are a number of financial incentives that make insulating and air sealing your home one of the more affordable energy-efficiency projects. See below to learn more about current incentives, financing, and tax credits for weatherization.

The financial incentives offered by Mass Save make weatherizing your home one of the most affordable, effective upgrades you can make to your home. As of January, 2023, Mass Save will cover:

-75% of insulation costs (and up to 100% for income eligible homes)
-100% of air sealing costs
FinancingYou can apply for a 0% HEAT loan through the Mass Save program (which we recommend to do alongside other HVAC and energy efficiency projects, as you can only have one).
Tax CreditsThrough 2032, you can deduct 30% of the cost of insulation products with the Energy Efficient Home Improvement Tax Credit (up to $1,200 yearly). This tax credit is also applicable for exterior doors, exterior windows, and energy efficient heating and cooling equipment. Learn more here.

Further Resources

For more information, please contact Green Newton at or schedule an appointment with one of Newton’s Energy Coaches. The Energy Coaches have a wealth of knowledge about insulation and air sealing, and can help answer any additional questions you might have. To schedule an appointment, visit



What if I rent?

Renters and condo owners can still sign up for a home energy assessment, as long as you have an electric or gas bill.  You’ll need your landlord’s permission before adding insulation.

What else can I do?

  1. Convert to an electric heat pump heating and cooling
  2. Convert to an electric heat pump water heater
  3. Replace upper level recessed light fixtures with insulated ones.
  4. Install a draft stopper for your chimney
  5. Use insulation products not covered by the MassSave program
  6. Change to electric induction cooking
  7. Carry out advanced air sealing through blower door directed air sealing
  8. Weather strip or replace drafty windows
  9. Add heat recovery ventilation to improve air quality and preheat fresh air entering your home