Welcome to week 5 of PBA's blog series on the coming updates to the Michigan Energy Code! We're covering essential updates in the new Michigan Commercial Energy Code (based on ASHRAE 90.1-2019) before the adoption date on April 22, 2025. Click here if you've missed our previous posts!
This past weekend, Punxsutawney Phil saw his shadow and predicted six more weeks of dreary grey Michigan winter. Unexpectedly, we’ll use this as the backdrop to discuss solar panels. But, before we get there, we need to talk about the year-over-year improvements to the Energy Code.
As discussed in Week 1, ASHRAE updates Standard 90.1 every three years, improving the energy efficiency of a compliant building each time. How much the Standard reduces energy usage each revision varies each cycle, but each new version tends to result in about 5%-10% less energy used than the previous version. This approach of “let’s make improvements every cycle” was business as usual until 2023, when ASHRAE announced plans to transition Standard 90.1 to a Net Zero Energy standard by 2031. As a quick reminder, Net Zero Energy (generally) means that a building’s annual renewable energy production will exceed its annual energy consumption across all types of energy.
The first step of Net Zero is reducing energy usage – it’s far easier to reduce energy usage than to add more and more renewable generation sources. But, at some point, you do need to add those renewables. Solar Photovoltaic panels are most popular for deployment in urban and suburban areas, though wind turbines and hydropower tend to be more feasible at scale on the utility level within Michigan.
ASHRAE is walking the walk, repositioning Standard 90.1 to both reduce energy usage AND to start adding renewable energy generation on-site, with the goal of having those two numbers equal each other by edition 2031. See the graph below from the Pacific Northwest National Laboratory, showing that the forecast for 90.1 editions 2022, 2025, 2028, and 2031 will get us there.
https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-28605.pdf
Hang on, you just said “adding renewable energy generation on-site.” Does that mean I’m going to be REQUIRED to put solar panels on my roof? Short answer: not this time, but you need to pretend that you are.
ASHRAE 90.1-2022, for the first time ever in a model energy code, has a REQUIREMENT for on-site solar panels or other renewable energy generation in new buildings. However, we’re not adopting 2022 in Michigan, at least not yet. The new energy code come April 2025 (90.1-2019) is still solely focused on reducing energy usage. But in 3-6 years when Michigan next updates the Commercial Energy Code, solar panels may be become a requirement.
It is at this point that we look back to Week 1’s post and acknowledge that the Michigan Commercial Energy Code requires following both ASHRAE 90.1-2019 and IECC 2021. In 99.9% of matters, this just means we need to follow 90.1-2019. There is, however, one special part of IECC 2021 that is specifically adopted by the State of Michigan that is not covered by 90.1. Welcome to Appendix CB: The Solar Ready Rooftop Zone.
Your building won’t require solar panels, but starting April 22, 2025 any building five stories or less must reserve the space for them on the roof. The idea is that building owners are increasingly likely to want solar panels on the roof, and future model codes are going to require them anyway so we might as well start practicing. What does this space reservation look like?
However, both the current IECC 2021 “Solar Ready Roof” space reservation and the future ASHRAE 90.1-2022 “thou shalt put solar panels” rules have several exceptions. You’re not required to plan for solar if:
To summarize: your building won’t require solar panels today, but you will need to call out where you’d put them if you had to. In 3-6 years, those solar panels likely WILL be required on new buildings.
Next week, we'll talk about new requirements for building commissioning.
