Graphic of a modern house with the U.S. DOE ZERH logo and Energy Star logo above it; ZERH and Energy Star Certified homes need specific levels of insulation.

A world with fewer carbon emissions would mean a higher standard of living for all people. And so, people and governments everywhere are making a huge push toward more energy-efficient housing.

To build energy-saving homes, you must use building materials that are also energy-saving. One of the most important is insulation.

The best types of insulation for Energy Star or ZERH homes are those that match the R-value for the area in which you live.

Energy Star divides the U.S. into eight climate zones by required R-value, with colder zones needing a higher rating, while ZERH only uses three general climate zones.

If you want your home to meet these requirements, it is first important to know what they are and the best ways to achieve them.

There are a variety of factors that go into Energy Star and ZERH houses, from the appliances you use to the cooling system you have installed. But we want to look specifically at the type of insulation needed to keep the inside air in and keep the outside air out.

Energy Star Homes & R-Values

Energy Star is a program funded by the U.S. Environmental Protection Agency and the U.S. Department of Energy.

This program promotes the proper use of energy, meaning that it encourages people everywhere to be sure they are saving what energy they can through lower usage and also through the materials they use in their homes.

energy star logo

A home that has earned the energy star is a home that has met all the requirements of the program. By doing this, they raise their energy efficiency, in part by using proper insulation and heating and cooling systems.

“Certified homes are at least 10% more efficient than homes built to code.”

energystar.gov

Some of the codes that must be followed to achieve the star are below, and you can also find more through the above link:

  • All-encompassing Air Sealing
  • Proper Insulation
  • Quieter Heating and Cooling Systems
  • Best Building Practices and Materials
  • Certified Lighting and Appliances
  • High-performance windows
  • Better moisture control
  • A complete water management system

To tie all of this together, Energy Star homes are great at using energy effectively! In the insulation world, that means proper R-values.

An R-value measures how good the insulation is at preventing heat from flowing into and out of a home.

The higher the R-value, the more the temperature of the house will be consistent.

Home Depot has made a chart for different areas and the thickness of insulation needed. See the video and chart below to learn more:

ZoneAtticsWalls (2×4)Walls (2×6)FloorsCrawlspace
1R30 to R49R13 to R15R19 to R21R13R13
2R30 to R60R13 to R15R19 to R21R13R13 to R19
3R30 to R60R13 to R15R19 to R21R25R19 to R25
4R38 to R60R13 to R15R19 to R21R25 to R30R25 to R30
5R49 to R60R13 to R15R19 to R21R25 to R30R25 to R30
6R49 to R60R13 to R15R19 to R21R25 to R30R25 to R30
7R49 to R60R13 to R15R19 to R21R25 to R30R25 to R30
8R49 to R60R13 to R15R19 to R21R25 to R30R25 to R30
Energy Star Required insulation R-values by climate zone

As the video and chart above mention, suggested R-values can depend on where a home is located.

A map on energystar.gov shows the different R-values that are needed in each location. Cooler locations have a higher required rating, whereas states such as Florida and Hawaii have the lowest need for insulation.

It’s worth mentioning that you can enhance the ratings above by adding more insulation layers. You can also mix the different types of insulations.

For instance, if you want to improve the R-value rating in your attic insulated by fiberglass blankets, you can add blown-in cellulose insulation on top. This way, the R-values will accumulate.

Besides the home areas covered in the chart above, other locations you want to insulate include:

  • Basements since they have the potential for heat transfer
  • Garages to ensure excellent temperature control for better storage
  • Water pipes and heaters to lower stand-by heat loss by between 25 and 40 percent
  • Ceilings to ensure excellent floor-to-floor climate control

To ensure that Energy Star Homes have EPA-approved insulation, Energy Star only works with insulation manufacturers that allow their products to be tested to strict codes and regulations.

The different EPA-approved insulations include:

  • Blow-in and loose-fill
  • Blanket insulation: batts and rolls
  • Spray foam
  • Rigid fibrous or fiber insulation
  • Foamboard
A map of the USA with different colored climate zones, with a chart below it showing the recommended insulation R values for each zone throughout the country.
Courtesy of EnergyStar.gov

Each of these types of insulation requires different installation practices. Some call for a specific certification to install, with spray foam being the most rigorous.

Most of the other types of insulation can be installed by homeowners and do not require certification.

An easy first step toward Energy Star certification is taking a look at their Home Advisor. This is an interactive tool to help you assess your home’s current energy efficiency and find the most important areas to improve.

Energy Star Building Strategies

Modern builders are already using ENERGY STAR strategies to make homes more efficient. As a homeowner looking to have a home that meets ENERGY STAR requirements, here are some building strategies to pay attention to:

  • The slab must be insulated and the crawlspace must be sealed perfectly
  • Designed and built to attain a HERS rating in the lows of 60s
  • The kitchen range should exhaust to the outside
  • Fresh air ventilation system installed
  • Use of advanced framing like ladder blocking and California corners

Luckily, you can make upgrades in these regions to ensure they meet stipulated standards. Some common upgrades to undertake include:

  • Building envelope: Ensure that the insulation is installed effectively without gaps. You can also install advanced framing with continuous insulation on exterior walls and ensure drywalls have been sealed to the top plate.
  • HVAC system: Use an ENERGY STAR-certified HVAC contractor and ensure that fresh air ventilation adheres to ASHRAE 62.2 standards. If you have full baths, ensure bath fans are rated 80 cfm or higher.
  • Performance: Ensure the HERS score ranges from the mid-50s to the low 60s. Also, duct leakage must not exceed 8% total and 4% outside conditioned spaces.

ZERH Homes

U.S. Department of Energy Zero Energy Ready Home logo

ZERH is also a term coined by the U.S. Department of Energy (DOE). It stands for Zero Energy Ready Homes. Here’s one definition of a fully zero-energy home:

“They are regular grid-tied homes that are so air-tight, well insulated, and energy efficient that they produce as much renewable energy as they consume over the course of a year, leaving the occupants with a net zero energy bill, and a carbon-free home.”

Source

In essence, ZERH homes are homes which meet or exceed the standards for an Energy Star home, but aren’t yet producing their own energy.

What makes them zero-energy “ready” is that they are already set up to be able to use alternative on-site energy sources, such as solar panels.

According to the DOE, certain requirements must be met to label a house as a Zero Energy Home.

Those requirements include but are not limited to:

  • Certified by Energy Star
  • Ceiling, walls, floors, and slabs must meet or exceed 2012 and 2015 IECC requirements
  • Indoor air quality must be approved by EPA
  • Fenestration must meet or exceed ENERGy STAR standards
  • Hot water systems must meet efficient design requirements
  • 80% of lighting fixtures must be ENERGY STAR certified
  • HVAC systems must use high-efficiency heating and cooling technologies
  • Advanced technology components like ENERGY STAR-certified smart appliances, solar-ready design and wiring, and electric vehicle charging may also be incorporated in the design

According to the U.S. Inflation Reduction Act Tax Credit, homes built between 2023 and 2033 with ZERH certification qualify for $5,000. Therefore, it’s a good move to qualify for the federal government tax incentives.

To learn more about the requirements of a ZERH home, the DOE has created a PDF that lists all the necessary requirements at this link.

Zero Energy Homes are gaining popularity in the U.S., with more builders getting on board all the time.

To find ZERH partners nearby, the U.S. Department of Energy’s website has an interactive map that allows users to find builders, verifiers, and architects in their area.

Conclusion

If your home doesn’t already have an Energy Star or ZERH rating, it might be a good idea to try and get that done.

Insulation can be expensive to purchase and install, but having the proper insulation can save you a lot of money over time. Not only that, but it can also provide benefits for the environment around you.

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