Zero-over-time means taking action now. What’s your plan?

Example graph illustrating how zero-over-time plans can strategically stay ahead of emissions targets.

Boston’s Building Emissions Reduction Disclosure Ordinance—or BERDO—is the City’s requirement for buildings of a certain square footage in size to decarbonize. The ultimate objective is for Boston buildings to achieve zero emissions by 2050. One approach is a zero-over-time (ZOT) plan, which helps building owners achieve interim BERDO targets with that long-term goal in mind.

First things first, what’s a zero-over-time plan?

A zero-over-time plan is a strategic roadmap for gradually achieving net-zero carbon emissions over a period of time. Creating these plans entails identifying necessary decarbonization measures and determining the most strategic timeline for implementation.

For example, if a building’s gas-fired boiler is going to reach the end of its life in ten years, it may be advantageous to prioritize a different decarbonization measure first and plan to replace the boiler with an electric heat pump once it’s due for replacement. This spreads out the capital investment necessary for decarbonization and takes advantage of capital expenditures that are already in the budget.

Looking to develop a strategic approach to decarbonization? GreenerU is here to help.

GreenerU is an authorized provider for Boston’s Building Decarbonization Advisor Program (BDAP), which provides support for underserved building owners facing the challenge of meeting BERDO’s requirements. The program offers qualified applicants a no-cost zero-over-time planning process that helps them identify steps they can take to reduce emissions and comply with BERDO requirements. 

While the ultimate net-zero target year of 2050 seems like a long way off, creating a zero-over-time plan now allows for more strategic thinking and flexibility. BERDO also allows for gradual reductions, meaning that there are emissions thresholds buildings need to meet those targets in five-year increments (see blue shaded area in above graph). This means that if a building doesn’t gradually lower their emissions, they will have to make alternative compliance payments of $234 per metric ton of carbon dioxide equivalent.

Some view the regulations as an added financial burden, but with the right plan, decarbonization actually saves money, increases property value, and decreases the total cost of ownership. Zero-over-time plans are therefore beneficial beyond meeting BERDO standards.

For Boston building owners: the deadline to apply for the Building Disclosure Advisory Program was April 18, 2025, but applications are still accepted on a rolling basis.

Zero-over-time plans outside of Boston

We know from experience that building decarbonization cannot happen overnight, but creating strategic and deliberate pathways toward long-term objectives is a proven method of making progress in the right direction. Zero-over-time plans, whether they are based on local emissions reduction targets or to provide other benefits, take a holistic and strategic approach to decarbonization. They help building owners identify and model:

• Emissions baseline, targets and projections. The first step of a zero-over-time planning process is to establish an emissions baseline based on current and historical energy consumption. Once the emissions baseline is complete, the next step is to identify and map out self-imposed emissions reduction goals and/or regulatory requirements. These can be in absolute emissions or intensity level (emissions per square foot of building area). Using this information, emissions can be projected into the future to compare estimates with targets, accounting for known facilities and operations plans and changing electric grid emissions factors.  
• Project phasing and timing. Zero-over-time plans identify emissions-reducing projects such as energy conservation measures, building envelope improvements, system upgrades, and electrification. They also consider timing of project implementation with respect to other planned projects and activities, identifying contingent and enabling tasks (e.g., electrical system upgrades prior to heat pump installation).
• Cashflow and cost of ownership. As part of a zero-over-time plan, a cashflow analysis is performed, which includes all relevant capital and operating costs. This information can also be used to calculate the total cost of ownership, accounting for cost escalation and discount rates.
• Scenario analysis. Comparing scenarios to find the most advantageous course of action is the last part of this planning process. The base case cost of ownership, the zero-over-time plan scenario, and any alternatives under consideration are usually included in this analysis. These scenarios are also evaluated against the emissions reduction targets identified earlier in the project. The goal is to optimize the total value by implementing the most cost-effective strategies that meet targets and reduce cost of ownership.

Meeting BERDO requirements can seem overwhelming. But using a zero-over-time approach can be an excellent way for some organizations to pace their changes to achieve decarbonization within their budgets.

Zero-over-time plans are powerful tools that can be used to map out the best path to a decarbonized building. Contact GreenerU to learn more about strategic decarbonization.

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