Making the Transition From Zero Energy to Zero Carbon Building Policies

As the building industry transitions into a new era — one focused on delivering carbon-neutral buildings — building codes will continue to play a critical role. This is the third in a series of blog posts about the transformation occurring within the building industry away from programs and policies that deliver energy savings toward programs and policies that deliver carbon neutrality and overall carbon reductions.

The first blog (Efficiency and Carbon Reduction Goals Converge at the Built Environment) focuses on the forces driving the building industry to look beyond kilowatt-hour (kWh) savings to a carbon metric, and examines some of the big questions around how we define zero carbon buildings. The second blog (Decarbonizing Buildings: A Changing Lexicon) focuses on the emerging lexicon of low-energy buildings and why it’s important to get clarity around the terms as well as defining metrics associated with decarbonization. In this current post, we’ll share some of the tools available to jurisdictions that want to pursue carbon neutral building policies and programs as a way to achieve climate goals.

Four Foundations of Zero Carbon Building Policies

For new construction and major retrofits, achieving climate policy goals in the built environment relies on developing policies that are soundly built on four foundations, or fundamentals.

Foundation 1: Energy Efficiency

Energy efficiency still offers many of the least-cost actions to achieve carbon reductions in buildings. By ensuring that policies capture energy efficiency savings, each of the other three foundations becomes easier to meet. And many jurisdictions have decades of experience writing codes that lead to energy savings, including zero energy building codes. Seattle’s commercial and residential energy codes are some of the most advanced in the country. In 2015, Seattle aligned with the Washington State Energy Code, which under state law:

  • Residential and Nonresidential construction permitted under the 2031 state energy code must achieve a 70% reduction in annual net energy consumption (compared to the 2006 state energy code) (RCW 19.27A.160), and
  • Construct increasingly efficient homes and buildings that help achieve the broader goal of building zero fossil‐fuel greenhouse gas emission homes and buildings by the year 2031 (RCW 19.27A.020)

Foundation 2: Renewable Energy Resources

Promoting zero carbon and zero carbon-ready buildings requires the understanding that not all building types and locations will have access to enough onsite renewable energy to achieve an annual zero energy balance. Building owners are turning to purchase renewable energy from off-site locations as a way to meet their renewable energy requirement.

Code writers must be mindful of this and write code in a way that ensures appropriate and verifiable crediting of off-site renewable energy sources. Programs such as community solar, power purchase agreements, and offsite shared corporate facilities are all viable options. A leading example is the California Department of General Services (DGS), which manages a portfolio of 69 state-owned buildings totaling 18.5 million square feet across the state. DGS entered into two 20-year community solar agreements with the Sacramento Municipal Utility District (SMUD), the city’s community-owned nonprofit electric service, to generate 39 megawatts of renewable energy at an offsite solar farm. This agreement is the largest community solar project of its kind in the nation—creating enough energy to power about 8,200 homes per year (about 74 gigawatt hours), according to SMUD.

Foundation 3: Building-Grid Integration

Codes that encourage buildings to generate enough energy to offset their entire annual energy consumption can actually create problems by putting extra burdens on the grid. How? When a building’s demand for electricity during a day, week or year differs from the time when energy is being supplied by onsite or grid-supplied renewable energy, it can create unaligned electricity demand load and generation curves. Codes should encourage building designs that address the variable patterns of generation and consumption on the electricity (T24-2019 residential).

Foundation 4: Building Decarbonization Framework

Decarbonization, which implies the prohibition of onsite combustion, is not a necessary condition for a zero carbon code. However, a growing number of jurisdictions have these decarbonization objectives in the shorter term. Best practice decarbonization policies should:

  1. address the transition away from onsite fossil fuel combustion as the electricity grid becomes cleaner,
  2. have strict standards for what qualifies as a renewable fuel for onsite combustion, and
  3. ensure that onsite combustion for buildings is not permitted to exacerbate local or indoor air quality problems.

As we approach a Presidential election year, climate change is surfacing as a key issue. All Democrats in the race support recommitting to the Paris Climate Agreement. And most Democratic candidates view achieving net-zero carbon emissions as the pathway to meeting the goals of the Paris Climate Agreement.

Many local and state jurisdictions are already on that path, having already committed to meeting the goals of the Paris Climate Agreement. NBI is working with many of them to incorporate these four foundations into their zero carbon building policies. However, these forward-thinking policies typically address new construction only. In the fourth and final blog in this series about decarbonizing the built environment, we’ll focus on policies that address zero carbon existing buildings.

by Jim Edelson, NBI Director of Codes and Policy