Montana Homes Collaborative
The Montana Homes Collaborative (MHC) is a group of residential construction stakeholders, including designers, builders, educators, and government officials who meet regularly to discuss energy efficiency building codes, construction best practices, and new developments in the construction industry. The focus of our discussions is based upon the application of best building science principles in energy efficiency, with an eye toward economic efficiency and housing affordability. We aim to compile our discussions into practical educational materials to help designers and builders build Montana’s next generation of energy-efficient and affordable homes.
Montana Roadmap to Home Energy Efficiency and Affordability
10 Recommendations of the Montana Homes Collaborative
This page identifies and explains the Collaborative’s 10 initial recommendations and proven techniques that are integral to building homes that are both affordable and sustainable by prioritizing energy-efficiency measures that will, in turn, allow homeowners to enjoy affordability and comfort over the life of their homes.
Energy Code Resources
Montana Residential Code Handbook
This 2021 Montana Residential Energy Code Handbook aims to assist builders and designers in complying with the residential provisions of the new 2021 International Energy Conservation Code (IECC). This handbook emphasizes the major changes, but it is not a substitute for the full text of the 2021 IECC or the Montana Amendments, Administrative Rules of Montana (ARM) 24.301.161. As before, the IECC includes provisions for both residential and commercial new construction.
Montana Residential Code Quick Reference
The Montana Residential Code Quick Reference outlines the requirements for building codes in Montana, focusing on energy efficiency standards. It specifies compliance criteria for different types of energy codes and provides guidelines for installing and maintaining building materials.
MHC Newsletters
Helena Habitat for Humanity Adopts Double Studded Walls
A double stud wall is a construction method where two separate stud-framed walls—one for the interior and one for the exterior—are built in parallel. This approach creates a deeper wall cavity, offering significant energy efficiency benefits. By increasing the overall wall thickness, a double stud wall can accommodate much more insulation, resulting in a higher R-value. It also helps minimize thermal bridging, especially when the studs are offset or separated by an air gap, enhancing the building’s thermal performance. Click the title above to learn more!
Previously Published Newsletters
2024
- Winter 2024: Weather-Resistant Barriers
The Winter 2024 Newsletter discusses best practices for building materials, specifically weather-resistant barriers, to prevent moisture issues. It explains that water vapor entering a building envelope can cause moisture to seep into the wall assembly, leading to degradation of materials and potential structural damage. - Spring 2024: Energy Saving Appliances
The Spring 2024 Newsletter outlines best practices for energy-saving appliances in homes, focusing on water heating, lighting, and clothes washers/dryers. It highlights the advantages of heat pump water heaters and tankless water heaters, offering cost savings and energy efficiency. - Summer 2024: Windows and Doors
The Summer 2024 Newsletter outlines best practices for installing windows and doors in new construction to ensure energy efficiency. It emphasizes proper window installation, careful window opening preparation, and proper glazing to minimize energy loss and improve indoor air quality. - Fall 2024: Heating, Venting, and Air Conditioning
The Fall 2024 Newsletter discusses how heating, ventilation, and air conditioning (HVAC) are the largest energy users in a typical home. In past newsletters, the focus has been on building practices and techniques that will help ensure an energy-efficient envelope, which will minimize the amount of energy the home’s HVAC system will use. However, the efficiencies gained from building an airtight, well-insulated home can be lost if the HVAC system is not designed properly.
2023
- Fall 2023: Montana Accessory Dwelling Units
The Fall 2023 Newsletter outlines Montana’s plan to improve housing access for small, independent units. It also introduces new regulations for ADUs and other housing solutions, aiming to address housing shortages and ease housing regulations. - Summer 2023: Zero Energy Homes in Montana
The Summer 2023 Newsletter outlines Montana’s new energy code standards for zero-energy homes, offering features like zero-energy systems, energy recovery ventilation, and energy conservation measures. It also provides federal tax credits for net-zero energy homes. - Spring 2023: Post-Frame Construction and Foundation Types
The Spring 2023 Newsletter outlines a new post-frame construction method called post-frame construction for Montana, which uses large wooden posts or columns instead of traditional frames. It also discusses the benefits of this construction method, including better energy efficiency and faster construction times.
2022
- Winter 2022: Montana Building Codes Edcation Conference and Cold Climate Heat Pumps
The Winter 2022 Newsletter outlines the Montana Department of Labor’s Building Codes Education Conference in March 2023, focusing on cold-climate heat pumps. It highlights the need for next-generation heat pumps to meet consumer comfort and efficiency needs in cold climates, with a focus on Montana’s unique climate. - Fall 2022: Radon Mitigation for New Homes
The Fall 2022 Newsletter outlines best practices for radon mitigation in new homes, emphasizing passive systems and radon-resistant techniques. It also recommends installing a radon-mitigation system in all new homes, with a radon-resistant vent system to minimize energy use and noise. - Summer 2022: Solar Ready Provisions – Appendix RB Summary Information
The Summer 2022 Newsletter outlines Montana’s best practices for solar-ready housing, including solar-ready zones, roof orientation, and structural design. It also covers solar-ready provisions for new and retrofitted buildings, including specific requirements for solar systems and roof configurations. - Spring 2022: Exploring No-Concrete Slabs
The Spring 2022 Newsletter explores no-concrete slab construction, highlighting its benefits and challenges. It emphasizes the need for well-planned assembly and consideration of moisture protection during the building process.
2021
- Winter 2021: Best Practices Newsletter
The Winter 2021 Newsletter discusses the adoption of new building codes for Montana, focusing on the 2021 International Energy Conservation Code (IECC). It also mentions a meeting where the Council of Decks (Montana) discussed the adoption of the IECC, with public comments and a decision to adopt it as an appendix. - Summer 2021: Structural Insulated Panels
The Summer 2021 Newsletter outlines Montana’s plan to adopt the 2021 IECC, introducing structural insulated panels (SIPS) to improve energy efficiency and reduce construction time. It also highlights the benefits of SIPS, such as stronger structural systems and energy-efficient performance. - Spring 2021: Blower Doors
The Spring 2021 Newsletter outlines Montana’s best practices for building tighter, more effective homes. It explains the blower door test as a simple tool to ensure air leakage, moisture, and health issues are addressed.
2020
- Winter 2020: Rooms Containing Fuel-Burning Appliances
A fundamental axiom of building science is that air will move from higher pressure to lower pressure. Anytime a condition creates a low-pressure condition inside a home’s thermal envelope, replacement air must enter the thermal envelope. A combustion appliance—such as a gas water heater or furnace—will draw in air to supply oxygen for combustion and send flue gases out of the building, and create a low-pressure area. Without a mechanism to supply replacement combustion air, one of two conditions could result. - Spring 2020: Air Barriers, Vapor Retarders, and the Perfect Wall
Controlling building envelope air leakage is critical in an energy-efficient house or dwelling unit. In common construction parlance, this is known as “building tight.” A house built tight will bring a number of benefits to its occupants, including lower heating bills, fewer drafts, greater comfort, reduced chance of mold and rot, and smaller heating and cooling systems, to name just a few. To minimize air leakage, the Montana energy code requires that a “continuous air barrier shall be installed in the building envelope.” An amendment to the International Energy Conservation Code (IECC) definition of an air barrier adds a requirement that the air barrier be installed on the warm side of the wall, ceiling, or floor assembly. - Summer 2020: Whole House Mechanical Ventilation
Prior to the 2012 IRC, mechanical ventilation in homes was limited to localized exhaust fans — in kitchens and bathrooms, for example — e.g., to control moisture and odors. Typical residential building envelopes were generally leaky enough that whole-house systems were considered unnecessary. Since its introduction in the 2012 International Residential Code (IRC) and 2012 IECC, whole-house mechanical ventilation is now required for Montana residential buildings.
2019
- Winter 2019: Common Walls and Air Tightness in Townhouses
The 2012 International Energy Conservation Code (IECC) requires that all residential buildings, which includes detached one- and two-family dwellings and multiple single-family dwellings (townhouses) as well as Group R-2 (apartment dwellings), R-3, and R-4 buildings three stories or less in height above-grade plane comply with a specific building tightness limit. In Montana that limit is four air changes per hour at 50 Pascals of pressure difference (ACH50). This air leakage rate requirement is important to achieving an efficient building thermal envelope but, currently the IECC does not address differences between single-family and multifamily buildings. - Spring 2019: Residential Energy Code Field Study Results
In 2018 a field study of Montana residential energy code compliance was carried out with funding from the U.S. Department of Energy and the Northwest Energy Efficiency Alliance. The research identified opportunities to reduce homeowner utility bills in residential single-family new construction by increasing compliance with the state energy code. Public and private entities within the state can use this information to justify and
catalyze future investments in energy code training and related energy efficiency programs. - Summer 2019: Radon and New Homes
Some states and local jurisdictions have adopted Appendix F of the International Residential Code (IRC). Montana has not adopted Appendix F despite the high incidence of radon in Montana homes. In Montana, builders are not required to test a home, nor to guarantee that a home will meet a specified radon level. But by installing radon-resistant features, a builder is proactively offering features designed to reduce radon levels. - Fall 2019: Frost protected Shallow Foundations
A frost protected shallow foundation (FPSF) is a practical alternative to a deeper, more-costly foundation in cold regions with seasonal ground freezing and the potential for frost heave. FPSF results in a shallower frost penetration depth around the building due to soil that has been warmed by both building and geothermal heat. The insulation around the foundation perimeter conserves and redirects heat loss through the slab toward the soil below the foundation.
2018
- Spring 2018: Proposed Energy Codes
This newsletter reviews the most significant differences between the current state energy code and the 2018 IECC. Key Montana amendments to the
residential provisions of the 2012 IECC are also discussed.
2017
- Winter 2017: Duct Tightness
Tightly sealed ducts can reduce utility bills. Tight ducts improve indoor air quality because leaky ducts in attics, unfinished basements, crawl spaces, and garages can allow dirt, dust, moisture, pollen, pests, and fumes to enter the home. When ducts are leaky, the heating and cooling system has to work harder to condition the home. Duct sealing, along with proper insulation, allows the installation of a smaller, less costly heating and cooling system. - Fall 2017: Tightness Testing
Prior to the 2012 edition of the International Energy Conservation Code (IECC) there was more trust than verification regarding building tightness. But with greater use of blower doors, testing building tightness has become commonplace. Since November 2015, blower door testing has been mandatory for all new residential construction, both within and outside local code enforcement jurisdictions. - Summer 2017: Mechanical Ventilation”
The key to realizing the full benefits associated with building energy codes is through compliance. Energy code compliance and verification are performed from different perspectives, but share the same end goal. Architects, designers, engineers, contractors, builders, and other construction-industry stakeholders have a professional responsibility to design and comply with the energy code on behalf of the building owner/developer. Code officials, on the other hand, as well as others who may be involved in compliance verification, must make sure what is built actually complies with the energy code. - Spring 2017: Introducing the Energy Code Newsletter
Natural ventilation using windows and other operable openings can provide adequate ventilation if they are used (which is more likely when the climate is more temperate than in Montana). However, there are many reasons why occupants may choose not to open the windows, including security, outdoor air quality, dust, or noise. Good ventilation in homes is important because it helps protect both occupant health and the house itself.
Previously produced newsletters can also be found on the Montana Department of Environmental Quality – Energy page.
Residential Energy Code and Energy Efficiency | Montana DEQ (mt.gov)
Join our List Serve
The MHC meets virtually through Microsoft Teams every two months. Please feel free to send us your email and join the conversation and submit questions and comments for the next discussion.
MHC Meeting Minutes & Links
Next MHC Meeting: To Be Determined
June 26th: NCAT Building Science Workshop. Thank you to the speakers and attendees!
- Mark Leland (Helena Habitat for Humanity) and Paul Tschide (MT DEQ), Building Simple, Decent, Affordable, Energy Efficient Homes
- Andrea Michael (Love Schack Architecture), Retrofitting Homes for Greater Energy Efficiency
- Matthew Skuntz, Ph.D. (MSU), Cold-Climate Heat Pump Systems
- Jaya Mukhopadhyay, Ph.D. (MSU), Ventilation Requirements for Residential Buildings in Cold Climates
- Carl Berntsen (NCAT), ENERGY STAR Requirements and Checklist for Designers and Builders
May 21st: Discussion of NCAT Building Science Workshop, 2024 IECC, NCAT Energy Star
March 12th: In-person during lunch at the 19th Annual Building Codes Education Conference.
February 12th: MHC Meeting Minutes
During this MHC Meeting we discussed Heat Pump Water Heaters (HPWH). Here is a link to an excellent article on HPWHs installed in the Northwest.
Cold Climate Demonstration Installation & Water Heater Installer Focus Group Research (NEEA)
