In this day and age, energy efficiency is more important than ever. Building codes have grown stricter with the goal to reduce energy consumption, stimulate sustainability, and increase long-term savings. We needed a way to standardize these code requirements, which is why different energy efficiency ratings have been developed over recent years. But with so many ratings and certifications— like HERS, ENERGY STAR, DOE Zero Energy Ready Home, and the newer ENERGY STAR NextGen— understanding what each one means can get confusing! In this article, we will compare and contrast each of the primary energy ratings systems to help clear things up.

HERS Ratings

This is one of the flagship energy services that we offer at Scott Home Services. Developed by the Residential Energy Services Network (RESNET), the Home Energy Rating System (HERS) is a scoring system that measures the energy efficiency of a home. This is nationally recognized method to meet IECC energy code standards in many municipalities.

During the HERS rating process, the home is assessed based on a list of criteria including:

• Insulation Levels
• HVAC Systems
• Windows and Doors
• Ductwork
• Air leakage (Blower Door Test)
• Water heating
• Solar/renewable energy use (if applicable)

A certified home rater performs a full energy rating on the home by analyzing aspects listed above using a specialized software. The results of the data analysis are compared against a “reference home,” and a resulting HERS score is created.  A lower score means the home is more comfortable and energy-efficient. So the lower the score, the better.

ENERGY STAR

ENERGY STAR is a program implemented by the US Environmental Protection Agency (EPA) as an initiative to “protect the environment, improve air quality, and protect public health.”

In order to be branded with that recognizable blue logo, a home must be evaluated by a certified ENERGY STAR rater. A HERS evaluation is included as part of the qualification process. The home must meet a predetermined HERS score (based on several factors like climate zone, house size, etc.), and also meet strict standards for:

• High- performance insulation, doors and windows
• Efficient HVAC systems and ducts
• Proper air sealing and ventilation
• Energy Star-rated lighting and appliances

DOE Zero Energy Ready Home (DOE ZERH)

DOE ZERH, which was established by the US Department of Energy, is a type of certification that signifies an extremely high performance home. This is meant to build upon the already stringent ENERGY STAR rating.

The difference is that these homes must either have solar installed to meet net zero energy usage, or have solar-ready infrastructure installed to be able to reach net-zero energy usage. Additionally they must have a stricter focus on indoor air quality, utilizing the EPA’s Indoor airPLUS guidelines.

Indoor airPLUS is a program designed to “improve the quality of indoor air by outlining construction practices and product specifications that help minimize exposure to airborne pollutants and contaminants.” Learn more about it here.

With all of these sustainable features in place, the house should have the infrastructure in place to offset most, if not all, of its energy usage with photo-voltaic solar. If the homeowner opts to install the solar needed, the house can achieve net-zero energy usage (or close to it), hence the name of the certification.

ENERGY STAR NextGen

Just when you thought a home couldn’t get any more energy efficient, out rolls the ENERGY STAR NextGen program in 2024. This is the strictest of all the energy efficiency ratings. It incorporates all the standards of the ENERGY STAR, but also emphasizes a focus on electrification, decarbonization, and grid-interactive technologies. Requirements include:

• High-efficiency electric heating and cooling
• Electric water heating
• Wiring for electric vehicle charging
• Induction cooking technology
• High indoor air quality
• Solar readiness
• Smart grid capabilities (for demand-response and time-of-use optimization)

This process can certainly be costly for the homeowner and difficult for the contractors while building . However, the end product can prove to have multiple benefits such as significantly lower energy bills, smaller. carbon footprint, improved indoor air quality, reduced noise, and even increased resale value!

Check out the table below 👇 to see how each of the energy efficiency ratings differs.

Need Energy Services?

Whether you need to meet your local building minimum code requirements, or you are striving for an ENERGY STAR NextGen certification, you’ve come to the right place! Because all 4 of the energy efficiency ratings discussed above are structured on the HERS ratings – a service we offer!

We can help you with virtually every step in the process. We proudly offer a whole list of energy services – including HERS Testing (projected, mid-construction and final), Blower Door Testing, Insulation Inspections, Air Barrier Inspections and Duct Leakage Testing – to help you reach whatever energy goals you may have.

Furthermore, our Energy raters are also ENERGY STAR certified. So if you are striving to meet the ENERGY STAR, DOE ZERH, or ENERGY STAR NextGen qualifications, our specialists can aid in evaluation and verification.

Have Any Questions?  Feel free to give us a call to talk to one of our energy experts.

Want To Learn More? Visit us online to find out more about the services we offer.

Book Your Services Today! If you’re ready to get started, CLICK HERE.

Choosing the right in-home heating and cooling system is an important job. You need a product that will condition the living space safely, sufficiently and efficiently. There are a lot of different options out there, all with their own pros and cons. In this blog, we will shed light on the air source heat pump – a system with some unique features that make it stand out next to most of its HVAC competitors. So without further ado, let’s dive in!

What are Air Source Heat Pumps?

An air source heat pump (ASHP) is an energy efficient heating and cooling unit. It works differently from other combustion heating units because, instead of generating heat, it transfers the heat.

These devices generally consist of an outdoor unit and an indoor unit, which are connected by a refrigerant line. The heat pump works much like a refrigerator in reverse.

The outside unit extracts heat from the outside air. Then it pulls the air through a refrigerant coolant, which is then compressed to increase the temperature of the air. The warm air is then propelled into the home using a fan system.

The heat pump can also act as a cooling device. In this situation, the system pulls in warm from the home and sends it to the outside. Refrigerant is then circulated through the indoor unit, absorbing the heat in the air and redistributing cool and newly dehumidified air.

Different Types of ASHPs

There are several different varieties of air source heat pumps. You can have a single-zone or multi-zone system, which are fairly self explanatory. A single-zone system consists of one outdoor unit and one indoor unit, while a multi-zone will have one outdoor unit and two or more indoor units, installed in different locations within the residence.

ASHPs also can be ductless or ducted. Ductless systems consist of the traditional configuration – an indoor and outdoor unit, connected by a refrigerant line. These are commonly referred to as “mini-split” systems (shown below). These are generally meant to condition smaller spaces or single rooms.

As implied in their name, ducted ASHPs are configured with duct systems. They are set up the same way a normal HVAC duct system would be; and they can condition a whole home with heating and cooling.

ASHPs can also be installed as split or packaged systems. Split systems, which are the most common, involve one indoor unit with coils and one outdoor unit with coils (depicted in the above “Heating Cycle” diagram). In a packaged system, both coils are located in an outside unit.

The Benefits of Air Source Heat Pumps

Here are a few reasons why air sources heat pumps might be a great fit for you.

1. Energy efficient: ASHPs are much more efficient than traditional heating systems, such as boilers or furnaces. ASHPs deal with heat transfer, as opposed to heat production. As a result, they require less energy to produce the equivalent amount of heat.
2. Environmentally friendly: ASHPs are electric, non-combustion systems. So they emit much less carbon dioxide than traditional heating systems, making them a more environmentally friendly option.
3. Cost-effective: In addition to being more energy-efficient, ASHPs are also cost-effective in the long run, as they require less maintenance and have lower operating costs than traditional heating systems. Additionally, these units are usually only slightly more expensive than stand alone AC units. So if you plan to install an AC system anyway, it might be worth considering an ASHP for both cooling and heating.
4. Versatile: ASHPs can be used for heating, cooling, and hot water production, making them a versatile option for homes.
5. Solar-Compatible: Being that these units are electrical, they can be powered by solar panels. That way, if you are looking to convert completely to solar, this type of system is the right fit!

The Cons of Air Source Heat Pumps

While we love to talk about all the ASHP pros, we would be remiss not to mention the cons.

1. High Up-Front Costs: Although, in the long run, these systems could serve to save you some bucks, they tend to be a bit pricey in their upfront costs, compared to conventional HVAC products.
2. Higher Electric Bills: This is to be expected, but nonetheless, something to be aware of. If you convert from a gas-fueled system to an all electric heating/cooling system, your electric bills will increase.
3. Less Efficient at Low Temps: ASHP are unfortunately not very efficient at low temperatures. Joe Ophoff, our Director of Energy Services, states that “the drawback to [ASHP] systems is that you need an emergency backup of some kind. In our [Colorado] climate zone especially, when it’s super cold outside, a heat pump can’t do the job by itself.  So a mini split needs an electric baseboard unit to act as the emergency backup. Even ducted ASHP systems need an electric back up built into the air handlers. Basically, an electric furnace should get installed for the times that the heat pump can’t do the job.”

ASHPs and Energy Code

In this day and age, energy code has become such an important part of the building and remodeling process. One of the key steps in reaching energy code compliance is earning a satisfactory HERS rating.

The Home Energy Rating System (HERS) Index is the industry standard by which a home’s energy efficiency is measured.

Several different aspects contribute to the home’s overall HERS rating, including heating/cooling systems. If you are going the ASHP route, it will likely help your HERS rating. Due to their high efficiency design, air source heat pump systems generally yield better HERS performances over gas-fired equipment.

Speaking of HERS ratings…

Are you working on a new project or addition, and in need of HERS rating services? Well you came to the right place! At Scott Energy Services, we have a team of certified HERS raters, ready to help you with all of your energy code needs.

For more information about our energy services please visit us online and schedule your service today.

In today’s day and age, with expenses and bills around every corner, we’re all looking for ways to cut costs. If you are a homeowner, you know that your monthly bills to keep the house going have been steadily increasing over time. One of our biggest burdens are those costly heating and cooling bills.

One way to save significantly on these energy costs is to make efforts to increase the energy efficiency of your house. This can be done in many ways including upgrading insulation levels, increasing the efficiency of your mechanical systems (i.e your furnace and water heater), or reducing the air leakage in your home.

However, one of the best ways to do this is by updating your windows to meet higher energy-saving standards. This is especially true when your windows are older.

But in a world with seemingly endless window options, what qualifies a window as energy efficient? There are two main parameters that are measured in order to determine a window’s efficiency – U-Factor and Solar Heat Gain Coefficient. Having a better knowledge of these concepts can help you choose the windows that are right for your home.

What are U-Factors (U-Value)?

A U-Factor (also referred to as U-value) is a window’s rate of loss of non-solar heat. Similar to insulation R-Values (which we discussed in a past blog), U-Factors indicate the energy efficiency of a window. The lower the U-Factor, the more energy efficient the window is.

Conversely, windows with high U-Factors are less efficient. This form of measurement was created by the National Fenestration Rating Council (NFRC) as a way to have one, uniform method when determining window, door, and skylight efficiency.

A window’s U-Value can be determined by assessing three aspects of the window – the frame, the glazing (or glass), and the spacer. Each plays a key role in achieving an optimum window seal.

What is the Solar Heat Gain Coefficient?

The U-Factor works in conjunction with the Solar Heat Gain Coefficient (SHGC). The SHGC is the measurement of how much radiant heat, or heat produced by the sun, comes in through a window. Similar to U-Factor, the lower the SHGC, the lower the radiant heat transmitting through the window.

As indicated in the chart below, the EPA recommends different U-Factors and SHGCs depending on the region of the country. These calculations are based on the approximate number of days spent heating and/or cooling per region.

Generally, lower U-Values will be recommended in heating-dominated regions (i.e. colder climates).  In cooling-dominated regions with warmer climates, it is not as imperative to have windows that will keep the heat trapped in the home, however, better U-Values can help keep mechanically cooled temperatures inside the home.

Note that the SHGC has a direct relationship with the U-Value. For instance, in the southern regions (shown in red), the U-Factor can be less than or equal to 0.40, but their SHGC must not exceed 0.25.

Homes in northern regions (shown in blue) have several options that qualify for Energy Star certification. With each option, as the U-Factor increases, so does the Solar Heat Gain Coefficient. This essentially means that the heat gain caused by the sun must compensate for the heat loss from a window with a higher U-Factor. It is the tradeoff between these two measurements that helps to create the overall performance of a window.

The window orientation in the home is also important when considering U-Factors and SHGCs. For instance, in a cold climate, a window facing south should have a high SHGC. On the contrary, in a warm climate, a south-facing window should have a low SHGC.

The geographic features of your property must also be taken into consideration. For example, you may have a large tree creating significant shade on one side of the house. That may mean those particular windows should have a higher SHGC to allow for more solar heat, or a lower U-Factor to increase window insulation.

All of these factors are important to consider when choosing the right windows.

Energy Star Rated Windows

In efforts to promote sustainability and energy efficiency, the United States Environmental Protection Agency (EPA) established the Energy Star program. This program gives certain components of the home Energy Star ratings if these components can meet a number of pre-determined criteria. Windows are a key contributor to energy conservation (or lack thereof), and thus they are one of the components that can receive an Energy Star rating.

Windows must be manufactured to strict specifications in order to meet an Energy Star rated U-Factor and SHGC combination. They are often double or triple paned. And sometimes the panes are even filled with inert gases, such as argon. Because argon is denser than H2O, it helps to stop air from transmitting through the window, which in turn reduces its U-Value.

The window frame is built tightly around the glazing to enhance insulation, and a spacer is installed to further decrease heat flow and prevent condensation. Also, most modern window panes are constructed with film-coated, low emissivity (or “low E”) glass. Such materials help to reduce radiant heat and UV ray penetration.

All of these window characteristics cumulatively help to achieve an Energy Star rating and increase your home’s energy efficiency.

Benefits of Energy Efficient Windows

Even though high performance windows might be costly up front, they have the potential to save you a lot of money over time. In fact, according to the US Department of Energy, equipping your home with the proper Energy Star rated windows can save you from 7% – 15% on annual energy bills. Not to mention, the overall climate control and comfort of your home will be elevated as well.

As incentives to strive for sustainability, some regions offer benefits such as tax credits and rebates to those who install Energy Star rated windows. So in addition to saving money on those monthly energy bills, you may even get paid by the government!

Many Colorado regions have established rigid, residential energy codes for new construction projects. Places like Denver and Boulder County require new builds, remodels and additions to meet certain criteria established by the Home Energy Rating System (HERS).

When we conduct our HERS rating services, we are assessing multiple aspects of the home to give it an overall energy score. As you could probably guess, one of the main aspects we observe are windows. Simply put, a better U-Value and SHGC will get you a better HERS rating.

Similarly, we conduct RESchecks to help builders and contractors comply with IECC energy codes. And as we’ve discussed throughout this blog, when it comes energy conservation, it’s all about those U-Factors. Windows with optimal energy performance can help contractors meet IECC guidelines.

We hope that this excerpt has given you a better understanding of U-Factors, SHGCs, and the overall importance of good quality windows.

If you are interested in assessing the energy efficiency of your home, please feel free to reach out about our Scott Home Inspection Energy Services.

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.

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.

As we talked about in the earlier parts of this HERS rating guide, a HERS rating is a calculated score that quantifies the energy efficiency of a home. When a HERS rating is performed before a home is built, it can be used as a method to comply with energy efficiency code requirements instead of following the standard IECC pathway.

This is commonly referred to as prescriptive vs performance energy compliance. When building a home, using the prescriptive pathway requires following the code requirements line by line for each section of the home. Currently, this is more common but as the codes tighten it is becoming increasingly more difficult to meet every line item in the energy code.

The other option is the performance pathway. This includes using secondary reports such as HERS ratings or RESchecks to validate that a home is energy efficient enough to meet the current code standards.

It is called the performance path because you are measuring the physical energy performance of the building as opposed to following a set of guidelines.

This option gives builders the flexibility to alter sections of the home to be lower than the minimum required energy standards and make up for that deficiency elsewhere. This nets an equally energy efficient home as one built on the prescriptive codes but allows builders and architects to be more creative with their techniques and designs.

The above process is called a Trade-Off, and it is what we will be going through in this article.

Common Trade-Off Scenarios

There are endless scenarios where using a trade-off can help the building process but there are ones that come up frequently. A common trade-off trigger is window efficiency.

Trade-Offs: Window Efficiency

Say you are building a home with very large windows covering an entire wall. This is great to maximize your view, but energy efficient windows of this size that meet the prescriptive path U-value can be very expensive and difficult to find.

Because of this, many builders will opt for slightly less efficient windows and make up for it with a more efficient heating/cooling systems, for example.

You may lose more heat through the less expensive windows but it is now more efficient and less expensive to heat your home. This results in an energy neutral trade-off, and through the HERS model, the performance of the home should remain the same.

Trade-Offs: 2×4 Framed Exterior Walls

Occasionally, a builder or architect will want to use 2x4s to frame the exterior walls instead of the standard 2x6s. This typically cannot be done while following the prescriptive tables because the required exterior wall insulation is more than what can fit in 4 inches of space, or would require the use of more expensive closed-cell spray foam insulation.

However, this can be accomplished with a trade-off. The decrease in exterior wall insulation will cause your HERS score to increase. This can be offset by adding higher efficiency HVAC equipment, adding more insulation in other areas, or adding solar or other power generation techniques.

Rewards For Going Above and Beyond

Aside from trade-offs alone, going further than minimum expectations will decrease your HERS score as well. This means you get rewarded for being a great builder. If you have a duct leakage test performed, and the results are better than what was projected on the original HERS report, the HERS score will decrease.

This gives you extra room to make changes in the future if needed. A buffer zone in case you need to make an unforeseen trade-off. When building on the prescriptive path, you cannot capitalize on areas where you are more energy efficient than what is required.

The Trend Towards Performance

Because of the benefit of trade-offs, consumer understanding, and the demand for EnergySTAR homes, HERS ratings are becoming more and more popular and relevant in the building community.

To gain the maximum benefit from a HERS rating and the trade-off component, it is important to work with an experienced HERS rating company. A professional HERS rater will be able to identify where using trade-offs can save money and building time to ensure your project moves forward smoothly.

If you are interested in our HERS rating services, learn more here. We would be happy to talk to you about your project and answer any questions you may have.

You may have heard the term “HERS rating” used regarding home construction and energy efficiency.  You may have even seen and read through a HERS report, or you may have a HERS certificate for your own home. Or you may have read our first blog in this series, What Is A HERS Rating.  Many have heard the term, but might not fully understand how to decipher the final product: The HERS Score.

To review, HERS is an acronym that stands for Home Energy Rating System. The HERS index, also known as the HERS score, is the industry standard that is used to measure a home’s energy efficiency.

A HERS rating can be used to compare a home’s energy efficiency to another home of similar shape and size.  Because the HERS index compares efficiency on a relatively “apples to apples” basis, the HERS score can be used effectively to compare one home’s efficiency against other similar homes.

So what does the HERS Index look like?

The HERS rating process is well defined for the building community as a solution to meet specific building codes. But as a consumer, the HERS score is the official product of the rating that you can use to compare properties. So, how do you interpret the HERS Score Index?

With a HERS score, the lower the score, the more efficient the home is.  The HERS index uses a scale in which a HERS score of 100 indicates a standard new home score, and a HERS score of 0 indicates a home that uses zero energy.

The HERS Score can be useful when purchasing a home or when building a new home, as it can give you an easy-to-understand expectation of what your energy consumption, energy bills, and overall comfort will look like.

Many counties in Colorado are accepting or requiring a HERS Rating on new construction homes. Are you in need of a HERS rating? Learn more here. 

Here are a few examples of HERS scores, and what they mean:

• A home that scores a HERS  130 is 30% less efficient than a standard new home. You could expect that many existing homes older than 20 years old with minimal upgrades would score in this range.
• A home that scores a HERS 70 is 30% more efficient than a standard new home.  This is a big improvement, but is not as difficult to attain as many might think.  Many newer homes or retrofitted homes with good insulation levels, higher efficiency heating and cooling systems, and higher efficiency lighting will score in this range.
• A home that scores a HERS 50 is 50% more efficient than a standard new home.  This is where we’re really starting to see some extra effort put in toward green building.  This home will typically be designed with energy efficiency in mind, and will have above average insulation levels, high efficiency HVAC systems and water heating, and higher quality windows.
• A home that scores a HERS 0 is 100% more efficient than a standard new home, and is a net-zero energy home.  This is typically only attained when the home has an energy efficient design from top to bottom, along with renewable energy such as Photo-Voltaic solar installed on the home, to produce as much energy as the home uses.

These are rough examples, but many factors go into a HERS rating to determine the end score. An improved HERS score can be attained with numerous combinations of energy efficient measures.

RESNET has created an interactive tool to help consumers and builders understand a HERS score at every level. This breaks down the efficiency/health levels of the home, energy cost savings, and carbon emissions.

What construction changes affect a HERS Score?

A certified HERS rater models a home from top to bottom in HERS software. Each energy design change will slightly change the HERS Score as well. The following are some of the key factors that will affect the final HERS score of a home:

• The area and insulation levels of the thermal envelope, meaning all of the floors, walls, and ceilings of the conditioned space
• The windows, including window area,  orientation, shading, and the insulation quality of the windows
• The heating, cooling, and water heating equipment
• The lighting and standard appliances that will use energy in the home, such as all kitchen appliances and the clothes washer and dryer
• The overall air leakage rate of the home.  High air leakage results in more energy needed to keep the home heated or cooled.  Air leakage is measured on the finished home using a blower door test.

Changing one of the above items can have a range of effects on the outputted HERS Score. This is where an experienced HERS rater can help balance the inputs and help find ways to reach the desired HERS score on any type of property. This can also be used to a builder’s advantage as well by making trade-offs.

A trade-off is where a builder adds more of one energy efficient item to offset the lack of another. This is not used to bypass the energy codes, but it does help the builder when there are design issues that make energy compliance in certain areas more difficult to achieve. We will talk more about trade-offs in a later part of this guide.

You can see that having an efficiency score to assign to a home can be a very helpful tool.  We will explain in detail in upcoming posts how many municipalities are using the HERS index as the standard for meeting energy efficiency compliance in their building codes.  We will also show how a HERS rating on your home can be useful for resale or for determining the best ways to improve efficiency.

The HERS Rating Index, developed by RESNET:

More new homes are being built with a HERS Rating, particularly in Colorado.  The Home Energy Rating System (HERS) is a method used by architects, builders, and energy raters, to determine the overall energy use of a home.

RESNET, the Residential Energy Services Network, developed the HERS Index standard, which is a nationally recognized standard for measuring the energy efficiency of a home.  Many Colorado home builders use the HERS score to rate their homes, and several area municipalities use the HERS score to validate whether a home meets their energy codes, including the City and County of Boulder.

What does a HERS Rating say about a home?

The HERS rating measures a home’s energy efficiency and can tell you how efficiently it is operating and where you can make modifications for greater energy savings.  When you are selling a home, a low HERS Index Score can command a higher resale price.  And when buying a home you can anticipate the costs of energy bills and efficiency upgrades.

The video included in this post was published by RESNET to give an overview of the HERS Rating process. In the video, they mention a very important point about the HERS score. If a home has a lower HERS score, meaning it is more energy efficient, the price of the home should increase in value.

People want to buy more energy efficient homes. It reduces their monthly expenses, reduces their carbon footprint, and helps when they need to sell later. This shift has been reflected in many facets of the home buying industry. Just recently, the HERS score was added to many of the MLS providers so buyers can see a home’s efficiency when looking at the listing.

So what does a HERS Rating say about a home? A lot really. And because of that, it is becoming more and more popular among builders, building departments, and the general public.

Are you a Colorado Builder in need of a HERS Rating for your next building project? Learn more about our certified HERS Rating Services here. 

How does the HERS Index work?

To calculate the HERS Score, the rater performs a full energy rating on the home by analyzing information on the home’s energy aspects using a sophisticated software modeling tool. The results of the data analysis are compared against a “reference home” which is the same size and shape as the actual home, and from which a resulting HERS score is created.  The lower the score, the better. A lower score means the home is more comfortable and energy-efficient.

For example, a home with a HERS Index score of 70 is 30% more efficient than a standard new home, while a home with a score of 130 is 30% less efficient than a standard new home.  A HERS Index score of Zero would mean the home consumes net-zero energy and likely has renewable energy installed on the home, such as Photovoltaic (PV) Solar panels.

Field testing and verification is performed on all HERS ratings, including verification of insulation levels, window specifications, heating, cooling, water heating specifications, appliance and lighting specifications, in addition to performing blower door air leakage testing.

We will go into even deeper detail of the HERS score index in part 2.

What does it take to complete a HERS rating?

Obtaining a HERS rating is a multi-step process. There are steps to take before, during and after the construction process, but the 3 main stages are as follows.

Projected HERS Rating: Typically, before ground is broken on a new construction project, a projected HERS must be completed. This is where a certified HERS rater takes the plans for the project and uses them to project what the HERS rating will be if the plans are followed exactly.

Mid-Construction Verifications: During construction, the HERS rater will need to verify that the builder is following the plans and that the rating is on track to meet the projected rating. Some of these items cannot be seen or altered when construction is complete. Because of this the rater will go to the site and check these items. This includes insulation levels and duct leakage ratings.

Final HERS: The final HERS inspection occurs just as construction is coming to an end. At this point, the rater will go out to the site, verify that everything that was projected was installed, complete the final tests like blower door testing, and collect the final data for the rating. This completes the HERS Rating process.

Certified HERS Raters on staff:

If your new construction or remodel/addition project in Colorado requires a HERS Rating, or you simply want to understand the energy performance of your home, contact Scott Home Inspection.

We have Certified HERS Raters on-staff who can help with your project.  We have completed hundreds of HERS Ratings on homes throughout Colorado, and have extensive experience in the City and County of Boulder, meeting the city of Boulder’s Energy Conservation Code and Boulder County’s BuildSmart program requirements.

For more information visit the Energy-Service page of our website.

Also for more information about RESNET and the HERS Rating Index, visit the RESNET website.

Also, keep an eye out for our follow up blogs, that will dive even further into the HERS process.