If you're planning to build a new single-family home in Massachusetts, one of the first things you'll need to understand is the energy code requirements. This article is an overview of how the July 1st 2024 energy code update for single family homes is going to effect you, the design of your home, and the planning with the professionals needed to complete any project.
Section 1: Overview
"When is it affective, and what does it mean?"
Starting July 1st 2024: The base energy code for residential construction in Massachusetts is the 2021 International Energy Conservation Code (IECC), which is a national model code. However, Massachusetts has adopted its own amendments to the IECC, known as 225 CMR 23 and 225 CMR 22. These amendments modify certain provisions of the IECC to better suit the state's climate and energy goals. Primarily, all homes will need to get a qualified Home Energy Rating by a certified HERS professional. The score every home own must achieve is changing from 52 to 42, which is basically a 10% increase in the demand in energy efficiency of new construction homes. At a high level, this is the largest item in the code update that will affect budget and planning.
The code now demands a certain decision-making tree. Herin is what we believe to be a perfect example. The second primary focus for homeowners is the decision to do an all-electric or mixed-fuel home. The code largely favors all-electric buildings and can be a potential cost-savings avenue at the expense of some lifestyle changes. For example, electric clothes dryers. You can choose an all electric home, with an all electric dryer. Should it be a direct current dryer (traditional) or a heat pump dryer (slow and 50% more energy efficient). The heat pump dryer will take a lot longer when doing comforters, sheets, and towels. Based on our experience with homeowners, usually in the ballpark of an all-day process. The energy consumption of a standard electric dryer will need to be paid for via extra solar panels as a trade-off. So the job of the homeowner is multi-part in deciding where the budget goes, and how it effects their lifestyle.
Time to get more specific.
Section 2: Basic, Stretch, and Specialized Code
The requirements for these categories differ based on whether your town has voted to 'opt-in' to either the base code, the stretch code, or the specialized code. Each is more strict than the previous. For some reason, the majority of towns in MA have voted to be in the stretch code at this time, which means any new construction must have this higher level of coordination and cost.
The Massachusetts "Stretch Code" requires higher insulation levels, more efficient windows and doors, and stricter air sealing measures compared to the base code.
Lastly, the specialized code, or 225 CMR 22 for low rise construction, is adopted by towns for single family buildings as the specialized energy code. It can be found on the Massachusetts State website here. And the PDF of the code itself is here. Let's compare some of the requirements for the strictest energy codes to our most basic:
"So how do I do it?"
The short answer is time, money, and additional planning and coordination. We will start by explaining at a high level the areas of construction that are controlled by the Energy Code. Foremost the energy dictates the thermal performance of the building envelope (walls, ceilings, windows, etc.), enhancing air sealing requirements, and increasing the efficiency of heating, cooling, and ventilation systems. The idea is to reduce energy waste and make your home as energy efficient as possible.
Building Envelope Insulation:
Base energy code (IECC 2021 with MA Amendments): Requires a minimum ceiling R-value of R-49, wall R-value of R-20+5 or R-13+10, and basement wall R-value of R-15/19 (continuous/cavity) for Climate Zone 5.
Specialized code (MA 2020 Specialized Code): Requires a minimum ceiling R-value of R-60, wall R-value of R-20+5 or R-13+10, and basement wall R-value of R-20/13+10 (continuous/cavity) for Climate Zone 5.
Air Leakage:
Base energy code: Requires a maximum air leakage rate of 3.0 ACH50 (air changes per hour at 50 Pascals) for single-family homes and 0.30 CFM50/sq.ft. (cubic feet per minute at 50 Pascals per square foot) for low-rise multifamily buildings.
Specialized code: Requires a maximum air leakage rate of 2.0 ACH50 for single-family homes and 0.23 CFM50/sq.ft. for low-rise multifamily buildings.
Duct Leakage:
Base energy code: Requires duct leakage testing only for ducts outside the conditioned space, with a maximum leakage rate of 4.0 CFM25/100 sq.ft. (cubic feet per minute at 25 Pascals per 100 square feet) of conditioned floor area.
Specialized code: Requires duct leakage testing for all ducts, regardless of location, with a maximum leakage rate of 3.0 CFM25/100 sq.ft. of conditioned floor area.
Lighting:
Base energy code: Requires a minimum of 90% high-efficacy lighting in permanently installed fixtures.
Specialized code: Requires a minimum of 100% high-efficacy lighting in permanently installed fixtures and requires occupancy sensors or automatic shut-off controls in certain spaces.
Mechanical Systems:
Base energy code: Requires minimum efficiency ratings for heating, cooling, and water heating equipment based on federal standards.
Specialized code: Requires higher minimum efficiency ratings for heating, cooling, and water heating equipment, often exceeding federal standards. For example, the specialized code requires a minimum AFUE (Annual Fuel Utilization Efficiency) of 95% for gas furnaces, compared to the federal minimum of 90%.
This is just scratching the surface.
Section 3: Reviewing the different 'paths' offered by the Code
Not unlike those children's books, Energy Code has you pick between different confusing ways to become compliant. This is true in both the stretch code requirements and the specialized code requirements. Each has different 'choose your path' options. We can largely categorize these confusing multi-branch choices into a few groups; Net Zero Homes (using less grid energy than they create), Passivehouse Homes (homes with a particular ratio of efficiency by focusing on using less windows and highly calibrated HVAC equipment, limited occupant control over comfort by manually opening windows, and ), and All-Electric Homes vs. Highly Calibrated Mixed Fuel Homes with Solar Power.
Let's review where the choices begin, with the 2021 IECC Stretch Code, which says:
"Residential buildings shall comply with Section R401.2.5 and either Sections R401.2.2, R401.2.3 or R401.2.4. The different sections (paths) are as follows; R401.2.1 Prescriptive Compliance Option, R401.2.2 Passive House Building Certification Option, R401.2.3 Energy Rating Index Option., R401.2.4 Apendix RC"
The worst part about this is that the last option is yet another 'choose your path' type section of the code. If you're feeling overwhelmed, we get it. The code is complicated. Hopefully you find our breakdown relatable and helpful. Here is an overview of these first few sections. Keep in mind that the question of going all-electric is going to be requested at multiple layers of every path option. In general, the code intends to push people away from using fossil fuels unless they can compensate the grid with an equal amount of on-site renewables.
Choice 1:
Option 1 : Prescriptive Compliance means that a designer or builder must demonstrate that each component of the building meets or exceeds the prescribed requirements outlined in the energy code. This can be done through the use of checklists. For example; windows must have a heat transfer rating (u value) of .3 or lower. Your standard Marvin double hung fiberglass window is .3, and we would have that specification from Marvin stating this as well as having the information on a checklist. In total, there are about a hundred items on the checklist. The secondary choice branch for this option is covered in Section R408, a checklist of 'additional energy efficiency options'. The choices are based on the homeowners choice to do a mixed fuel or all-electric building.
Option 2: Passive House Compliance. The key principles of Passive House design include a highly insulated and airtight building envelope, high-performance windows and doors, strategic placement of windows to optimize solar gains, thermal bridge-free construction, and a mechanical ventilation system with heat recovery. By carefully balancing these elements, Passive House buildings are able to maintain a stable and comfortable indoor environment with minimal active heating and cooling, resulting in significant reductions in energy consumption and carbon emissions compared to conventional buildings.
Option 3: The Energy Rating Index (ERI) Option offers a more flexible and performance-based approach to achieving energy efficiency in residential buildings compared to the Prescriptive Compliance Option. Rather than adhering to a set of prescribed requirements for individual building components, the ERI Option allows for trade-offs between various energy efficiency measures, as long as the overall energy performance of the building meets a specified ERI score. This approach enables designers and builders to prioritize investments in the most cost-effective and impactful energy efficiency strategies, while also accommodating innovative design solutions and technologies. The ERI Option relies on energy modeling to assess the building's performance
Choice 2:
According to the obligations of section R401.2.5 Additional Energy Efficiency paths, home-owners must pick one additional path below.
Option 1: Two of the additional efficiency package options shall be installed according to Section R408.2. (Right? It's just a branch of choices. It's ok, you can use this article to sort through them).
A. Enhanced Envelope Performance Option
B. More Efficient HVAC Equipment Performance Option
C. Reduced Energy Use in Service Water-Heating Option
D. More Efficient Duct Thermal Distribution System Option
Option 2: All electric building that complies with R408.2.2 and R408.2.3 shall apply for primary space heating and domestic hot water supply.
Each path has their own particularly enhanced strictness that creates some level of unique efficiency for the home. For homeowners and design professionals, this process is the most confusing and requires the most planning and coordination. Since most homes have very strict budgets, this area is the largest question mark as designers and future home owners try to figure out how each path affects the budget of their home. Unfortunately, there is no easy answer. In addition to this, each code type (stretch, or specialized) has their own path types. Let's review.
Specialized Pathways:
We now know some general requirements of the 2021 IECC, with the state's amendments (225 CMR 23 and 225 CMR 22). The 'pathways' generally take the qualities we discussed so far and make them even more strict.
Code Excerpt (225 CMR 22):
RC101.1 Compliance. Existing residential buildings shall comply with Chapter 5 of the stretch energy code. New residential buildings shall be Net Zero Buildings and comply with Section R404.4 (EV wiring) and either Section R405 (Passivehouse) or Section R406 (HERS) in accordance with RC101.2, as well as one of the following Specialized code pathways: 1. Section RC102 Zero Energy pathway 2. Section RC103 All-Electric pathway 3. Sections RC104 and RC105 Mixed-Fuel pathway. RC101.2 Application. New dwelling units over 4,000 square feet in conditioned floor area shall comply with either RC101.1 option 1. Zero Energy Pathway or option 2. All-Electric Pathway, and follow either Section RC102 or Section RC103.
In order to achieve net zero, the total energy generated on-site from renewable sources must equal or exceed the total energy consumed by the building over the course of a year. In a mixed fuel building, this involves accounting for energy consumption from various fuel sources, such as electricity, natural gas, propane, or oil. We describe achieving this as a 'best of both worlds' approach. If you truly want to maintain a fuel option, it's wise to plan for heat pumps to be both the cooling as well as the primary heating option. The fuel option as a backup is more reasonable than home-owners may be expecting. Because the homes are sealed and insulated so carefully, the heat pumps are often more than capable of heating rooms beyond typical comfortable indoor temperatures.
Section 4: What is a HERS rating and how do we achieve the right score? What is energy modeling?
A Home Energy Rating System (HERS) Index is a nationally recognized measure of a home's energy efficiency. A HERS Rater is a certified professional who assesses the energy performance of a home using specialized software and diagnostic tools. The HERS Rater evaluates factors such as insulation, air leakage, heating and cooling systems, windows, and lighting to generate a HERS Index score, which provides a standardized way to compare the energy efficiency of different homes. In many cases, hiring a HERS Rater is an obligation for demonstrating compliance with energy codes or qualifying for certain energy efficiency incentives and programs. The HERS Rater's expertise starts at the construction documentation phase of a project with energy modeling done through their software, based on the Homeowners path choices. The HERS rater is later involved with the testing of the home to meet the proposed standards in the building permit, as well as commissioning at various stages of pre and post occupancy.
The HERS software calculates the estimated annual energy consumption of the home and compares it to the annual energy consumption of the reference home (built to the 2006 IECC code) to determine the HERS rating.
Heating and Cooling Loads: The software calculates the heating and cooling loads of the home based on factors such as the home's size, orientation, insulation levels, air leakage, window performance, and local climate data. The output includes the peak heating and cooling loads in BTU/hour for the design conditions (e.g., extreme winter and summer temperatures).
Equipment Sizing: Using the calculated peak heating and cooling loads, along with other factors like system type and efficiency, the software can recommend the appropriate size (capacity) for the heating and cooling equipment. This helps ensure that the equipment is not significantly oversized or undersized, which can lead to inefficiencies and higher energy consumption.
Energy Consumption: The software also estimates the annual energy consumption of the heating and cooling system based on the equipment size, efficiency, and the home's loads throughout the year. This information can be used to compare different system types and sizes to identify the most energy-efficient option.
"So how do I get a lower (better) score?"
For example, using heat pumps for not just cooling but heating. The HERS rating calculation does provide incentives (lower scores) for using more efficient heating systems like heat pumps. Here's a general idea of how heat pumps can affect the HERS rating:
Air-Source Heat Pumps: Using an air-source heat pump instead of a conventional furnace or electric resistance heating can typically improve the HERS rating by several points, depending on the climate and the efficiency of the heat pump.
Ground-Source (Geothermal) Heat Pumps: Ground-source heat pumps are even more efficient than air-source heat pumps and can further improve the HERS rating, often by 10 points or more compared to a typical furnace or electric resistance heating.
Another example is choosing insulation and exterior sheathing. The use of continuous insulation on exterior walls and the roof can have a significant impact on a home's HERS rating, as it helps to reduce heat loss and improve the overall thermal performance of the building envelope. The actual point reduction in the HERS Index score will depend on various factors, such as the climate zone, the thickness and type of insulation used, and the efficiency of other building components. However, as a general example, adding continuous insulation with an R-value of R-5 to the exterior walls and roof of a typical home could potentially reduce the HERS Index score by around 10-20 points compared to a home without continuous insulation. This improvement in the HERS score translates to substantial energy savings and increased comfort for the occupants, as the home will require less heating and cooling to maintain a stable indoor environment. It's important to note that the impact of continuous insulation on the HERS rating should be evaluated in the context of the specific project, and a qualified HERS Rater can provide a more accurate assessment based on the unique characteristics of the home.
Section 5: Solar Ready? Yes.
In the context of the Massachusetts Stretch Energy Code and the Massachusetts Specialized Code, there are specific requirements for solar readiness and the use of solar panels in residential and commercial buildings. The Stretch Energy Code requires new residential buildings to be "solar-ready," meaning that they must be designed and constructed to accommodate the future installation of solar photovoltaic (PV) or solar thermal systems. This includes providing adequate roof space, structural support, and electrical conduit for future solar installations. The Massachusetts Specialized Code does not yet require solar panels for the July 1 2024 update.
Homeowners should consider State and Federal subsidies and do a cost analysis comparison to installing solar panels and how this will offset requirements, and cost, of other systems of Solar is not installed.
Conclusions:
As a homeowner, you should get more familiar with the building code to understand the details of where cost savings could be made, either upfront or over the lifetime of ownership.
Hire a HERS professional at the right time, to better understand specifications, rebates, project planning, and scheduling.
Discuss you options with your local building inspector. Use our article as a checklist to familiarize yourself. Bring in the checklist of options you are considering to your local code enforcer and get their opinion.