What is Title 24 Energy Efficiency?
Author: Napa Sonoma ADU Guest Blogger Adrian Osgood, CEA, HERS, ACCA, CALGreen | Delta T Energy Consulting
If you’re here, you are most likely weighing your options for adding an accessory dwelling unit to your property. That prospect comes with several code requirements that are mandatory for an ADU permit submittal such as structural engineering calculations, electrical diagrams, and site grading/paving plans.
Another, perhaps less known component, is Title 24 energy efficiency documentation, commonly referred to in the building industry as Title 24. We’re going to do a deep dive here into what Title 24 means for your ADU project!
Overview of Title 24 Energy Efficiency
Title 24 documentation will be one of the primary design documents in your plan set and will play a large role in the selection of the following items for your ADU: Furnace/AC/heat pumps, water heaters, windows, insulation types/R-value, Solar/PV, and testing requirements. It is the blueprint for how your home will operate and how efficient it will be when finished. Once these items are selected and included in the plans your home must be built to that standard, so it is important for you to think about how you want your home to function once completed.
So what is Title 24 more specifically, and why do you need it? Well, depending on how old you are you may or may not remember some hot summers in California where everyone and their mother was blasting the fans and AC in their homes. You may also remember sometimes when suddenly, during those hot afternoons, the power went out. The fans and AC stopped, your refrigerator shut off, and the lights dimmed or turned off completely. Basically, you could not get electricity when you needed it. These periods of energy insecurity became known as the “brownouts.” Title 24 Buildings Energy Efficiency Standards (AKA BEES) are designed to help mitigate those insecurities by establishing energy efficient design criteria in the construction and building industry. Essentially, the State recognized that our demand for power was outgrowing our ability to produce the energy we needed, resulting in stress and imbalance in the power grid. By establishing the BEES, the State could set guidelines on how energy efficient buildings must be.
How does this all work?
The BEES sets an energy efficiency standard for a building’s design. You will need to find someone well versed in the BEES -- and that is an energy consultant. When designing a new home or ADU an energy consultant takes the floorplan of the home and develops a digital representation of it which is then run through an energy algorithm. In the calculation the new home’s design is compared to the state standard using units known as Time Dependent Variables (basically, how much energy is used per square foot per year in the designed home).
To model the home an energy consultant must work with the architect and yourself, the homeowner, to establish the different systems, assemblies, and envelope features (the building’s outer shell) that will be incorporated into the design.
This includes things like insulation types/R-values, window solar/thermal properties, water heaters, etc. By establishing these key features your energy consultant can make a detailed analysis of how much energy your new home is going to use.
It also gives us an excellent opportunity to value-engineer your home with you. Modern construction can be expensive. Might as well get the most bang for your buck, right? A good energy consultant can custom design your home to meet your build-budget while also addressing your long-term comfort and energy goals, saving you money in the long run.
Another cool component of Title 24 energy analysis is it can help you establish the correct sizing for things like HVAC systems, solar/PV systems, etc. That way you only install what you need for your home to operate optimally -- and not more.
One more benefit that should not go unmentioned is the quality assurance that comes with Title 24 through the process of HERS testing (Home Energy Rating Systems). When an HVAC or hot water heating system is installed in a home it must then pass a documented inspection process to ensure that you the homeowner are receiving exactly what you paid for -- a system operating as effectively and efficiently as it was designed. We will touch more on this subject below!
The Process
First off, you will want to shop around to find yourself a reputable and reasonably priced energy consultant during the design phase of your new ADU. The nonprofit Napa Sonoma ADU Center has a Vendor Registry with local lists of Title 24 consultants that can serve as a great starting point.
From there, you will want to have your architect or designer coordinate getting a PDF copy of your plan set over to your energy consultant. After that the consultant will design the model and ask for your input and goals. After a draft or two is completed with your review they will then likely have a final version of the energy certificate for your home.
At that point, the document is included within your plan set and is submitted for your plan review at the building department. That Title 24 document then becomes the road map for exactly how the home must be constructed to meet the Building Energy Efficiency Standards (BEES).
Final Steps -HERS Testing
One of the last components of the Title 24 and construction process is a suite of inspections known as HERS testing which stands for Home Energy Rating Systems. HERS testing is a form of quality assurance to make sure that all homes are built to the design specifications within Title 24.
A certified HERS rater will come out to the home to take sample measurements from several systems. It involves things like duct leakage testing, building envelope leakage testing, insulation inspections, and more. Depending on the required tests these can be performed either at the “rough-in” stage of construction before the drywall goes in or after the home is completed.
It’s important to understand that it is possible to fail HERS tests. That is why an integrated design approach is so important. You as the owner want the peace of mind knowing that the systems installed in your new ADU are functioning as they were designed -- eliminating cost/efficiency issues and ensuring that you receive the finished product you paid for. The required HERS tests vary from project to project, however, all new homes and ADUs have a mandatory ventilation testing requirement in which the HERS rater confirms the minimum ventilation needed for your home.
HERS tests can assist in “value engineering” because credits can be earned in one area of the build which will enable you to save money in other areas such as insulation, windows, or even equipment costs. A knowledgeable energy consultant will help you work through the HERS testing requirements to determine which are the best choice for your wallet and your home. Once the HERS testing is completed and filed with the state, your documents will be handed over to the building department and you will get your final occupancy permit.
ADU Specifics for Title 24
- Solar is required for all newly constructed, detached ADUs. This means that if your ADU is a ground-up build that is separate from your home you will be required by code to install solar for the ADU. If however the ADU is attached to your home or a conversion of a separate garage you will not be required to install solar -- although you may want to anyway.
- Solar + Battery systems are always recommended if feasible in your budget. As previously mentioned, only brand new ground-up ADUs will require solar; however, a solar system and battery backup can be a life saver when the utility company shuts down the power so you may wish to consider it for other ADU types as well.
- Framing size is another component that is especially important because it determines how much insulation we can fit in the walls and roof. Newly constructed walls now have a minimum mandatory standard of R-21 in 2x6 framing, however, if you are building within an existing structure (e.g., garage or barn conversion) you can keep the framing at the existing size as long as you install R-15 insulation.
- Furnace/Heat pump selection is important. I always recommend going with ductless heat pump units for ADUs. This is because they are compact, high efficiency, and do not require any propane or natural gas connection as they run on electricity. They do not have ducting that a traditional furnace requires. This saves time and money when installing. Another added benefit of the units being mounted directly in the conditioned space of the home is that you do not have rodent or energy loss issues that are common with ducted units.
- Heat pump and gas tankless water heaters are excellent for energy conservation when it comes to water heating, but each unit has caveats that go along with it. Heat pump water heaters have a small condenser built into them like a refrigerator only larger. As the compressor works to heat your water it does create some noise and vibration. While the units can be installed inside a home or garage, I highly recommend having them installed in an exterior insulated closet mounted away from bedrooms. This will reduce any noise or humming that some may find annoying.
- Hot water distance to fixtures is important. When discussing hot water heater locations, you should aim to have the heater located as closely to the sinks and showers as possible. This reduces water waste when turning on the hot water and reduces energy use by reducing the length of hot water piping that can give off heat as the water passes through it.
- Windows are especially important when it comes to home design as they allow energy to pass through easily. We recommend staying under 20% window-to-floor ratio -- ergo, if you have a 750 square foot ADU you will want less than 150 square feet of windows. If you go beyond the 20% the efficiency of the home will begin to drop, and operational costs will increase. You will also want to select high efficiency windows. U-factor and SHGC are the primary units used to measure window efficiency. The state standard is .30 U-value and .23 SHGC. In this case the smaller the number, the better. Basically, lower U and SHGC values translates into less energy loss.
- Insulation is important. You will want to think over what types of insulation you want to install. Fiberglass batts are affordable but do not work quite as well as rockwool, blown-in blanket (AKA Bibs), or spray foam. Personally, I like rockwool. It is made from inert stone dust which is kiln fired into insulation. It is pest and rodent resistant (fiberglass is not), has high insulation R-value, and does not have any chemicals (spray foams are a liquid applied chemical based insulation).
- Radiant Barrier is a reflective coating that can be applied inside attics and roofs during construction. We highly recommend having one of these installed as they will dramatically reduce how much thermal energy passes from your hot attic down into your home during summer and how much heat you lose during the winter.
- Different jurisdictions have different requirements for energy code and building code. This means that you may be required to select equipment, windows, and other energy features that meet your local jurisdiction requirements. In some cases, cities will have “reach codes,” which mean that the local code is more stringent than the state standard. Make sure you are informed about the selections you are making for your ADU before you make a final decision. At the following link you can find if any reach codes apply to your area: https://localenergycodes.com/. Scroll to the bottom and select “View Adopted Ordinances.” If your city or county is not listed there currently are no reach codes that you need to be aware of.
This is a TON of information to digest, and rest assured that if you select a high-quality professional team, they will be aware of these details and able to help guide you to make the best decisions for your particular accessory dwelling unit project. It’s always best however to be an empowered consumer -- and so I hope that this information is helpful to you along your ADU journey!
You can learn more about Green Building Strategies for ADUs in general from another guest blog post right here!
Adrian Osgood is the founder of Delta T Energy to help homeowners, architects, and contractors in achieving their green energy design goals. Learn more about Delta T Energy at https://www.deltatenergyconsulting.com/. Connect with them at (707) 827-0233 or Base@DeltaTEnergyConsulting.com.