One question that we are asked frequently is when and where is a HERS rating required in Colorado? A HERS rating can be an alternative solution to following the building codes when building a Colorado home. We covered many of the benefits of performing a HERS rating in our earlier blog about performance vs prescriptive pathways.

However, that does not necessarily mean that a HERS rating is required or preferred. It is typically just an alternative solution to meeting the requirements. As energy codes are updated and tightened up, they can phase out specific design options on homes that can only be achieved by using trade-offs, which are easier to achieve with a HERS rating.

A HERS rating can be a great option to meet the energy requirements, but in some cases can be overkill. In an effort to substantiate the HERS rating system, however, and give consumers more insight into how good a home’s energy performance will be, some counties and cities in Colorado have required or “incentivized” the HERS rating system.

In this part of HERS rating guide, we will cover where and when a HERS rating is more than just an alternative.

When is A HERS Rating Required In Colorado

Where is a HERS Rating Required In Colorado? One place. Boulder.

Boulder has always been a community bullish on energy efficiency. They are continually pushing the boundaries and have emerged as a leader in this area. They have become a role model for the state of Colorado and the nation between their SmartRegs program to their goals of reducing carbon emissions by 80% by 2050.

Both the City of Boulder and Boulder County building departments require a HERS rating in most instances, but they differ on their specific requirements. In general, the city has more stringent requirements as listed below.



City Of Boulder HERS Rating Requirements:

The city of Boulder requires a HERS rating on most larger projects. A HERS rating will need to be performed on new construction projects over 500 sqft, additions where the floor area of the addition is over 1000 sqft, or interior remodels where the square footage of the project is greater than 50% of the area of the current home. When a HERS rating is required, it must meet the required HERS Score represented in the below table. These requirements are outlined in the cities code documents.

The city has created its own internal building code called the City of Boulder Energy Conservation Code (COBECC). This code is based on the IECC energy code, but with many additions to make homes even more efficient. This code will be updated in 2020 and will include even smaller building projects and remodel projects that do not add additional square footage. More information can be found about this update here.

The HERS score of a home needs to meet a certain level based on the proposed square footage. The larger the home, the more energy efficient it must be, meaning the HERS score needs to be lower as well. The table below represents the HERS scores needed per square footage. As you can see, all homes built over 5000 sqft need to have a HERS score of 0. This means the home is net zero.

Boulder County HERS Rating Requirements:

The county follows a similar path as the city does. However, they are slightly less stringent as to when a HERS rating actually needs to be done vs following the prescriptive tables. Most dramatically, they raise the square footage caps.

Currently, a HERS rating will need to be performed on new construction projects over 3500 sqft or additions where the floor area of the addition is over 1000 sqft. You can see these requirement changes in the county’s easy to use BuildSmart Checklist.

You have many options in the county to defer to an Energy Smart Assessment over a HERS rating when the project is smaller. This consists of an energy audit being performed prior to construction. But the table also shows that you can use a HERS rating instead, which in some cases, can end up being easier in the long run. Read the full set of building energy requirements here.

These codes are always changing, but this gives a brief overview of what Boulder is looking for. If you have questions on HERS ratings or a Boulder code requirement feel free to contact us.

Denver’s Energy Rating Index system

The City of Denver has overhauled its energy requirement system in the last few years. From switching to IECC 2015 building codes, to requiring blower door testing, to creating many code amendments, the city clearly sees the value in energy efficient building.

While a HERS rating is not required in the City of Denver, it is one of the few places that outlines what they want to see when choosing a HERS rating over the traditional prescriptive pathway. A copy of the code requirements can be found here.

Their residential provision documents state that if you do decide to go with a HERS rating for a new construction home, you will need to meet a HERS score of 55 or less.



If you are building an addition, and it is difficult to isolate what section of the home will need to meet the energy codes and what will not, it may be beneficial to use a HERS rating. In this case, the City of Denver has made it very simple. You will need to have a certified HERS rater model the home before construction to get an initial HERS score. Then the post construction HERS score just needs to beat the initial score showing that there was an efficiency improvement. This should be a very easy way to gain compliance on complex additions.

On top of these 2 simple requirements, the city has also added one incentive to use a HERS rating. When submitting your HERS rating for a permit, they offer a $150 discount to offset the cost of the rating. This will help level the cost playing field between prescriptive and performance and give builders more flexibility on the route they choose to take.

Energy Star Certified Homes

One wild card to throw into the mix is when builders are looking to build an Energy Star Certified home. Energy Star has its own set of requirements that a home must meet in order to obtain the familiar blue seal on your project.

These requirements are slightly more difficult than the standard energy codes, which ensures buyers that they are purchasing an efficient and comfortable home.

One of the requirements of Energy Star is to work with a HERS rater that is trained in the Energy Star program to determine a target HERS score. This number will then need to be met during the planning and construction process.

So even if the county does not require an energy rating, if you are planning on building an Energy Star Certified home, you will be needing one anyway. Our HERS raters are certified with the Energy Star program as well and can help with your HERS rating and planning. Learn more about our HERS rating services here.

On The Horizon

Above are the current HERS Rating Requirements in Colorado. However, things are changing rapidly in this state. As the construction boom roars on, we are continuously hearing more information from building officials about upcoming changes.

HERS ratings have been a nationwide success in many states, aiding builders with complex building codes, and bringing energy efficiency into the marketplace. We predict that the demand for these services will continue to rise, and city building departments will begin to adopt the rating system.

Until then, we hope this article helps. If you are interested in talking to us about your next project please visit our HERS rating service page.