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Residential Energy Code and Energy Efficiency

Program Overview

Residential Construction Energy Code Requirements

Planning to Purchase or Build a New Home in Montana? Montana has a state-wide energy code that governs all new home construction.

  • Use the Energy Code Guide to help ensure your new home is comfortable, healthy, and energy code compliant. These codes are for the homeowner's protection.
  • Talk with your builder and look for the blue Energy Code Compliance Label on the electrical panel of your recently completed new home.

Energy Conservation

The Department of Environmental Quality (DEQ) can help homeowners and business owners save money and energy right now. By taking energy-saving measures, you will save energy and money. Some measures are simple and inexpensive. Others will take some investment. Money spent today to improve energy efficiency will reduce energy bills in the future.

When looking at any specific energy-saving ideas, its helpful to know how your home or business uses energy. Energy equals dollars and we pay a certain amount of money for every unit of energy used.

Energy code & Efficiency Contacts

Section Supervisor
John Dendy (406) 444-6439

Energy Resource Professional
Bonnie Rouse (406) 444-4956

Energy Resource Professional
Paul Tschida (406) 444-6464

What the energy code means for you:

It makes sense to include energy-efficiency features in a house as it is built, rather than renovating later. Key features such as high performance windows, high efficiency heating systems, extra insulation, and proper air sealing are much cheaper and easier to build into a new house than to add to an existing one. And all new homes built in Montana must meet the current energy codes.


The new Montana Statewide Energy Code came into effect on June 10, 2022. Local code jurisdictions had up to 90 days to adopt the new code.  Outside of code jurisdictions, provisions of the Energy Code became effective as of June 10, 2022.

This updated Energy Code essentially is the state's adoption of the 2021 International Energy Conservation Code (IECC) with amendments specific to our region and climate. As in the past, the code continues to provide minimum requirements for the efficient design and construction of new and renovated homes. The Montana Residential Energy Code Handbook is a guide to complying with the statewide energy code or visit the Montana Residential Energy Code Summary Booklet  or the Residential Energy Code Handbook.

What's New for Builders

Blower door equipment are available to builders through local building industry associations.

Builders and contractors are encouraged to contact their local association to learn the details of using these blower door testing devices. Some associations may require training in the use of the test kits before they can be checked out for specific projects. This manufacturer's video is a good introduction to blower doors with a second part that offers data interpretation.

List of blower door providers

Contact information for the local associations is available at the Montana Building Industry Association (MBIA) website.

Within code jurisdictions, testing may be required to be performed by an approved third party.

Builders and contractors who self-certify:

The building tightness standard is targeted at 4 air changes per hour (measured at 50 Pascals pressure control), or 4 ACH50. This is a Montana amendment to the 2021 IECC, which recommended 3 ACH50.

In certain instances, builders must perform ductwork sealing tests.

When part of the heating ductwork is located in unheated/unconditioned space, such as in a garage or attic, the entire ducting system must be tested for tightness. Further, the new code requires that all ducts be sealed with code-accepted mastic or UL listed tapes. Manufacturer recommendation for mastic application is 1/16th-inch thick, about the thickness of a nickel. Testing, when required, may be at rough-in, or at post-construction.

Ductwork does not have to be seal-tested when the ducts and air handler are entirely within the building thermal envelope. A Montana amendment to the code allows building cavities to serve as return ductwork. Supply ductwork must be a discrete system separate from the building cavity.

Whole-house mechanical ventilation constitutes one of the more significant home features in the Energy Code.

Functionally, efficient exhaust ventilation is required at a rate appropriate to dwelling square footage. For example, a 2,500-square foot, 3-bedroom home would require 60 cubic feet per minute (CFM) of continuous ventilation. Homes that rely on intermittent ventilation must feature greater ventilation capacity.

Other significant changes with the new energy code (2021 IECC) include:

  • Mechanical ventilation systems (bath and kitchen exhaust fans) are required to pass an air flow test.
  • All permanent light fixtures must be high-efficacy lighting sources.
  • Bathrooms, hallways, exterior and security lights are exempt.
  • Blower door test has a new option making it easier for small houses to pass the blower door test.
  • One additional energy efficiency feature is required.

Minimum local exhaust capability in kitchens and bathrooms is also called for in the new code. A balanced ventilation system that neither positively pressurizes nor negatively pressurizes the living space is most preferable, since such systems may recover some heat from exhausted air. These centralized heat recovery systems are more costly, however.

While this is a brief summary of major code changes, it should be noted that heating and cooling equipment must be sized according to a code-acceptable procedure. While not a code change, proper mechanical sizing is an important consideration in residential construction. Consult the ACCA Manual J Brochure for more details on heating plant efficiency.

Montana adopted the 2021 International Energy Conservation Code (2021 IECC) with Montana amendments on June 10, 2022.  Certified jurisdictions were allowed up to 90 days from their notification date to adopt the code.  For a listing of certified jurisdictions go to the Montana Department of Labor and Industry.

The information is divided into a residential and commercial energy code section.   The links should help your department with energy code compliance.

The Administrative Rule authorization of the energy code for Montana: 24.301.161 - Incorporation by Reference of International Energy Conservation Code

Other significant changes with the new energy code (2021 IECC) include:

  • Mechanical ventilation systems (bath and kitchen exhaust fans) are required to pass an air flow test.
  • All permanent light fixtures must be high-efficacy lighting sources.
  • Bathrooms, hallways, exterior and security lights are exempt.
  • Blower door test has a new option making it easier for small houses to pass the blower door test.
  • One additional energy efficiency feature is required.

Energy Code Resources

Blower Door Resources

Best Practices

Energy Code Guides & Newsletter

Energy Efficiency

How We Use Energy in Our Homes

Energy use is divided into two areas; base load and heating. Heating is the biggest utility expense for most Montana families. Baseload consumption is year-round energy uses like water heating, refrigeration and lighting. Small changes in baseload consumption add up over the entire year. The EPA offers a measurement tool called the Home Energy Yardstick to calculate home energy use. All you need is a single power bill, which ordinarily shows electricity and natural gas usage over a year's time. Enter your usage and see how you compare to similar sized homes nationally. Another excellent resource to use is DEQ's Montana Energy Saver's Guidebook which helps you identify and implement energy savings in your home. 

Energy Saver Guide 2017 -

  • Space Heating in your Home - Heating your home uses more energy and drains more energy dollars than any other system in your home. Typically, 49 percent of your utility bill goes for heating. No matter what kind of heating system you have in your house, you can save money and increase your comfort by properly maintaining and upgrading your equipment.
  • Heating Tips - Your heating system, like your car, needs regular maintenance to run at peak efficiency. That means scheduling a yearly maintenance visit with a heating contractor to tune-up the system. A licensed contractor will make sure your heating system is operating efficiently and safely. A regular maintenance schedule can also help in identifying problems early.
  • Select Energy-Efficient Products When You Buy New Heating Equipment - Your contractor should be able to give you energy fact sheets for different types, models, and designs to help you compare energy usage. For furnaces, look for high Annual Fuel Utilization Efficiency (AFUE) ratings. The national minimum is 78 percent AFUE, but certain ENERGY STAR models on the market that are rated 95 AFUE and above. ENERGY STAR-qualified models are eligible for the $500 Montana energy conservation credit.
  • Install an Energy Star Programmable Thermostat - Inexpensive and easy to install, programmable thermostats automatically turn down the heat during the weekdays and at night so you do not pay to heat your home or business when no one is around. Programmable thermostats are easy to operate and allow for your different workday and weekend schedules. 
  • Thermostat Replacement Warning - Many older homes have room temperature thermostats that contain mercury. To identify, remove the front plate and look for one or more small glass bulbs, known as tilt switches. These contain mercury. Each tilt switch contains roughly three grams of mercury, though there may be as much as six grams. Never dispose of this type of thermostat in the trash or local landfill, because mercury is toxic and can leak out to contaminate our air, water, and soil. To assist home-owners with proper disposal of mercury-containing thermostats, a no-cost collection/recycling program is available to all Montana residents. To determine a drop off location in your area, contact your local county sanitarian

Quick Tips to Save Energy

Most of these actions focus on changing daily habits around the home, are cost-free and result in savings that quickly add up. Other actions require modest investments to reap the benefits of more efficient lighting technology or improvements in appliance efficiency. The more measures you adopt, the more you will save. Focus first on space heating and then on water heating, lighting, refrigeration and clothes drying for maximum benefits.

  • Start Strong and Simple
    • Install a programmable or setback thermostat to automatically turn down heat when people are not at  home, and during sleeping hours.
    • Set thermostats to 68oF or lower for winter heating and 78oF or higher for summer cooling.
    • Turn off lights, computers and entertainment devices when not in use.
    • Install compact fluorescent light bulbs in lamps and fixtures you use the most. This measure alone can save you $35 a year or more if you change out five 100-watt incandescent lamp bulbs.
    • Look for savings available by unplugging infrequently used televisions, VCRs and other electronic games. These devices always consume small amounts of electricity, even when turned off, to power internal clocks or 'instant-on' features. To really shut these devices 'off' you need to unplug them. Putting them all on a power strip can make the task easier.
  • Appliances Matter
    • Switch to the 'energy-saver' settings on your washing machine, clothes dryer and dishwasher.
    • Check the temperature of your refrigerator and set it between 37 and 40 degrees F.
    • Check and clean your refrigerator’s condenser coils once a year.
    • Unplug that second refrigerator in the garage or basement. Older refrigerators are very inefficient and can easily cost you $125 - $150 a year in electricity bills.
  • Watch your Water
    • Make it a habit to run only full loads in your dishwasher or clothes washer.
    • Repair those dripping hot water faucets that send money down the drain 24 hours a day.
    • Install low-flow showerheads and cut your hot water consumption for showering by 30 – 40 percent.
    • If your water heater is more than 10 years old, wrap it with an insulated blanket and save $10 - $15 per year in energy costs.
  • A Sealed Home is an Efficient Home
    • Examine your basement or crawl space.  Heat will try to move to the coldest area of  your home. Often this is the basement, or an unheated crawl space.  Check to be sure that there is insulation in the basement or crawl space walls.
    • Also check the insulation levels in your ceilings and walls. The most recent recommendations call for ceilings to be insulated to R-49 and above ground walls to at least R-19. Crawlspace walls should be insulated to R-19 and basement walls insulated to R-11 or greater.  Windows should have two layers of glass, either a thermopane or a window and a storm window.
    • Air sealing the openings around plumbing pipes, wires, chimney and other gaps is recommended before adding insulation.
    • Change your furnace air filter at least twice each winter.
    • Seal and insulate heating system ductwork in unheated parts of the house.
  • Go the Distance
    • Get a home energy audit. Call the utility that provides your heating fuel and ask if energy audits are offered. Or, conduct a do-it-yourself audit.

For more complete information the Department of Environmental Quality has published the Montana Energy Savers Guide.

Energy Efficient Lighting

Light emitting diodes (LEDs) are the newest type of lighting. Commonly available LED lamps produce more lumens per watt then incandescent or CFLs and these efficiencies continue to improve. Common incandescent light bulbs use 90 percent of their energy for producing heat instead of light. LEDs on the other hand produce very little heat. LED use almost all their energy to produce light.

LEDs provide a higher value since you don’t have to replace them as often. LEDs last 15-25 years compared to 10 years for a typical CFL and 5 years or less for incandescent bulbs. LED’s are also durable. They do not have a filament that can burn out like incandescent bulbs, they don’t contain mercury like CFLs, and they aren’t typically made of glass, so they don’t break easily.

LED lamps come in variety of styles, lumen outputs, and color temperatures. Install bulbs, fixtures, and controls designed for their intended application (for example: enclosed, dimmable, indoor, outdoor, etc.).

Replace incandescent or CFL bulbs in a recessed light fixture use an LED assembly intended for this purpose. The replacement LED should have the correct retainers or clips to match the recessed light fixture assembly. The LED will replace the trim ring of the existing recessed fixture. Choose a LED replacement that has an air sealing gasket on its trim ring. This will help to seal the LED fixture against the ceiling which could potentially save some energy if the existing trim ring isn’t air tight.

Be sure to look for the ENERGY STAR® label when shopping for LED lamps. Not all LED bulbs are ENERGY STAR, which certifies the rated efficiency of the lamps, but also that the lamps are designed correctly for their purpose. The more LEDs that Montanans installs, the more energy savings we will achieve from lighting retrofits.

Lighting Tips
  • Replace light bulbs in the highest use fixtures with energy-efficient light emitting diodes (LEDs).Good candidates to replace are fixtures that are in use for at least two hours or more per day. Replace incandescent bulbs that are in the 60 - 100 watt range.
  • The highest use fixtures are typically the kitchen ceiling light, living room table and floor lamps and bathroom vanity. ENERGY STAR qualified lighting products are available to meet all these lighting needs. Switching to ENERGY STAR products in all these applications can save you up to $60 each year in energy costs.
  • Take advantage the 25 percent Montana energy conservation tax credit when you purchase new ENERGY STAR qualified light fixtures to reduce both your tax bill and lighting bill.
Change a Light, Change the World Campaign

The ENERGY STAR Change a Light, Change the World campaign is a national challenge sponsored by the U.S. Environmental Protection Agency and U.S. Department of Energy to encourage Americans to consider the energy they use and help change the world one light, one step, at a time. Save time, energy and money while helping to protect the environment by switching to light bulbs and fixtures that have earned the ENERGY STAR.

Visit to learn more about this year’s campaign.

For more helpful information check out ENERGY STAR and Lighting Design Lab. For a lighting guide from the Clean Energy Resource teams please click here.

Check out the Lighting Buyers Guide, sponsored by the EPA. DOE provides good technical information on compact fluorescent bulbs.

Energy Efficient Appliances

Many improvements in the energy efficiency of refrigerators and freezers and other appliances have been made in the past 10 years.  New refrigerators, for example, use as little as 1/3 of the energy of older models thus reducing the cost of operation from $120 - $180 per year to $40 - $60 per year.

When shopping for energy efficient appliances, look for the energy use label to compare costs. An ENERGY STAR designation is a quick way to know that an appliance is efficient and will result in low energy consumption and costs. For more information see the Montana Energy Savers Guidebook, Chapter 7.

Here are some other sources for appliance information:
Water Heating

Water heating makes up the second largest energy usage in most homes, after heating. A few simple home fixes can reduce your water heating cost. 

  • Make sure the temperature on the hot water tank is set to 120 degrees F
  • Fix any leaks in the plumbing system 
  • You can also install water-saving shower heads to reduce the biggest hot-water user.
  •  Insulate your water heater if it is more than 10 years old.  

For more information see Montana Energy Savers Guidebook, Chapter 6

How to Read the Energy Guide Label

The Energy Guide label gives you two important pieces of information you can use to compare different brands and models when shopping for a new appliance. Test results are printed on yellow Energy Guide labels, which manufacturers are required to display on many appliances. This label estimates how much energy the appliance uses, compares energy use of similar products, and lists approximate annual operating costs.

Energy Guide Label

Building the Shell of Your Home

The building shell of your home is the area that stands between you and the outdoors.  That includes the ceilings, walls, windows, floors, and foundation of your home.  The building shell insulates you from the outside temperatures.  The right amount and type of insulation in the building shell and limiting the amount of air leakage in the building shell will help keep heating and cooling costs low.

Energy Code Minimum Insulation & Recommended Levels
  • Ceilings R-49
  • Walls R-21
  • Crawlspace wall R-19 or crawlspace floor R-30
  • Basements R-19
  • Window U-value U-.30
  • Furnace AFUE rating 95%
First Steps

First, check the insulation levels in your ceilings, exterior walls, basement and crawlspace to see if it meets the levels recommended above for Montana. In an existing home it may be difficult and expensive to meet these guidelines in all cases. Some measures, such as adding additional ceiling insulation can be done easily in many homes. If your ceiling is insulated with vermiculite insulation it is best not to disturb the insulation due to the potential of exposure to asbestos fibers contained in the vermiculite. Hire only trained professionals if you want to safely remove this material from your attic. is the U.S. Department of Energy’s website for specific steps on how to conserve energy and save money at home. It has extensive links to a broad range of informational resources on saving energy at home, work or school.

ENERGY STAR: visit their home improvement page.  Energy Star is sponsored by US EPA.

Home Energy Yardstick allows you to compare your home's energy performance to other homes and estimate the potential for improvement. The tool will compare your home to others after adjusting for size, age, location, and the number of people living in it. This tool is part of the ENERGY STAR site.

EnergyIdeas Their Q and A on energy questions, on the Solutions page, is particularly good.  Energy Ideas is sponsored by the Northwest Energy Efficiency Alliance and the Washington State University Cooperative Extension Service Energy Program.

DOE EERE Information Center has all sorts of technical information and publications.

Building Envelope

  • DOE Energy Efficiency and Renewable Energy Clearinghouse provides a good overview of why and how to set up an energy program.
  • EnergyStar programs are sponsored by the Environmental Protection Agency (EPA).
  • EnergyIdeas - This site's Q and A on energy questions, on the Solutions page, is good for most topics.  Energy Ideas is sponsored by the Northwest Energy Efficiency Alliance (NEEA) and the Washington State University Cooperative Extension Service Energy Program.
  • The Building Commissioning Association is a Pacific Northwest professional association. They don’t have many Montana members yet, but they can tell you about commissioning a building, a process that can tell you how efficiently or inefficiently your building is operating. HVAC systems can be out of balance, or energy controls out of adjustment, but these problems may not be obvious. Commissioning evaluates how well a building’s systems work together, then recommends improvements. Commissioning can reduce energy use, lower repair and replacement costs, and improve air quality, lighting and comfort.
  • Energy analysts, and anybody wanting to compare their usage to national figures, might be interested in the Energy Information Administration’s (EIA) Commercial Buildings Energy Consumption Survey.
  • News and information pertinent to facility operators and managers is available at FacilitiesNet .
  • Federal agencies can obtain technical and financial assistance from the Federal Energy Management Program. There is very useful information to all government agencies.
  • These sites offer information on performance contracting, one way to evaluate possibilities for energy improvements in buildings and to finance the ones that will save money:


Experts say that proper daylighting can improve employee performance, but improper window design can lead to higher energy bills in warm and cold climates. New window designs should weigh beneficial daylighting with heat control and heat loss. Here are some links to sites that help evaluate window design and energy efficient windows.

Appliances and Light Bulbs

Help on motors and compressed air systems is available from the US Department of Energy's site. These are good places to look for energy savings in large government and school buildings.

Montana Combined Heat and Power

Combined Heat and Power (CHP) is an established technology sometimes referred to as cogeneration. In the process, electricity is generated very close to a site where the power is used. Residual heat from the generation is also used at the site, oftentimes for heating, cooling or for industrial or manufacturing processes.

Many industries across the country employ CHP. In fact, about 10 percent of energy use in the U.S. is derived from CHP. Nonetheless, a great deal of energy is lost as unrecovered, or waste heat. The federal Department of Energy would like to advance these efficient technologies


The Environmental Protection Agency (EPA) issued a Catalog of CHP Technologies in 2015. That publication notes that traditional industrial energy sources offer

efficiencies in the 45 to 50 percent range, while CHP applications can boost efficiencies up to 75 percent or more. Also, visit the EPA Combined Heat and Power Partnership web page for more information on CHP. 

The  U.S. Department of Energy offers a website devoted to "distributed energy" with an emphasis on CHP.  

Accelerated Combined Power and Heating

Accelerated CHP has proven its effectiveness and holds promise for the future — as an environmental solution significantly reducing carbon dioxide emissions through greater energy efficiency; as a competitive business solution that increases efficiency, reduces business costs, and creates green-collar jobs; and as a technology deployable throughout the United States. CHP also holds promise as an infrastructure modernization solution that may help grid congestion and improve energy security.


In Montana, interest in CHP has grown along with the millions of acres of beetle-killed woodlands. Lumber mills are good candidates for CHP installations in our region due to the large quantities of available biomass feed stock, high on-site energy use, and heat-using industrial processes. Excess generated electricity can be distributed over the grid where it is eligible for Renewable Energy Credits (RECs). Regional associations such as the Northwest Clean Energy Application Center have emerged to promote CHP. 

Recently, the Montana Department of Commerce, NorthWestern Energy (NWE) and others supported a business feasibility study into sustainable biomass for the western portion of the state. The report examined the feasibility of developing CHP at lumber plants and sawmills in western Montana. These facilities are envisioned to reduce energy load at the mills while providing excess generation capacity to NWE's mandated renewable energy portfolio. 


Energy Code Guide for New Home Construction