Party Walls

What the Climate Mobilization Act Means for Developers, Designers, and Construction Teams


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The construction industry has been increasingly focused on meeting ever-tightening codes and achieving higher ratings in sustainability certification programs (e.g., LEED, Passive House, etc.). These standards do a good job of raising the bar, but there is a new bar in town and we’re not talking about whiskey.

Local Law 97

NYC’s Local Law 97 of 2019 establishes carbon emissions limits for buildings 25,000 square feet and larger. These emissions limits, which are based on current building performance data, will begin in 2024 and will rachet down in 2030 and beyond. While we continue to work with building owners and portfolio managers of existing buildings (“What Does the Climate Mobilization Act Mean for Building Owners?”), we need to make sure that new buildings and major renovations are set up for success. Developers, designers, and construction teams must take LL97 into account during design, construction and turnover to protect the value of these new assets.

A developer or asset manager’s least favorite word is probably uncertainty, and now there’s a whole new host of uncertainties to think about:

  • Just because you are code compliant or even certified to LEED platinum doesn’t mean you will receive good letter grades;
  • Achieving a good letter grade still does not guarantee that you will meet the carbon emission limits in the future;
  • Your modeled energy consumption may not match your actual energy consumption. This isn’t necessarily new, but it becomes a much more important factor with the new carbon limits. Current energy models may not predict performance precisely, due in part to the many variables, including occupancy and human behavior, that are difficult to foresee. For an example of a deeper dive into this performance gap, take a look at the recent studies by Sidewalk Labs on modeled vs actual energy consumption for multifamily residential new construction.
  • In certain locations, you may not have access to natural gas or will have limitations on gas supply. This is already happening in Westchester and Brooklyn.

So, What Do We Do?

No matter where you are in the concept, design, and construction process, we can act now to help the buildings we work on reduce their carbon emissions. Some changes now may help the project avoid necessary, yet costly, remediation in 2024, 2030, and beyond. Some important considerations:

Portfolio Analysis

The Motto: Sometimes you need to go backwards to go forward

  • What other buildings have you worked on? Go back and look at how those buildings are performing now. See what is working and what is not working. See how the buildings compare to the letter grades and emissions caps. Ask the operators what they wish was different.


The Motto: Get the core and shell right

The shell – The building enclosure will (hopefully) be there for a while. You do not want to reskin in 5-10 years:

  • Glass is the worst performing wall. I know, it’s pretty, but consider ways to reduce window to wall ratio without sacrificing daylighting and views. For more information about efficient building enclosures, listen to our podcast episode with SWA Senior VP and building enclosures expert, Bill Zoeller.
  • Get the details right. Design and specify properly air sealed and insulated construction details and then make sure they are implemented properly.
  • Good insulation. If you can achieve 20% better than code, there may be something extra in it for you.

The core – As an industry, we need to seriously consider the impact of infrastructure and build in the flexibility to adapt to new requirements in the future:

  • Get Smarter. Provide infrastructure for robust monitoring and control systems  (see ongoing monitoring below).
  • Consider electrification or incorporate design details that enable low-cost future electrification. There are still challenges facing electrification, particularly in cold climates, so be careful to review any new technology in depth.
  • Consider unitized systems or additional zoning and separate dedicated outdoor air systems where feasible. These items allow systems to operate only when needed.
  • Submeter everything. We have known that residential and commercial tenants who pay for their heating, cooling, hot water and baseload electricity use less energy, so individual meters are a no brainer. Submetering (rather than direct metering) may allow the building to take advantage of solar, carbon trading or renewable energy credits.

Plan for and maximize solar now:

  • Solar is financially viable now. Local policies and myriad incentive programs are encouraging PV installation in urban environments. Additionally, solar will be required in NYC via Local Law 94 (more on this in a future blog post).


The Motto: Watch it.

  • Verify
    • Minimally compliant energy code inspections are no longer sufficient.
  • Commissioning
    • Yes, energy code requires it, but dont just check the box. Commissioning can significantly reduce energy consumption by ensuring that heating, ventilation, and air-conditioning, domestic hot water, and lighting controls are functioning properly.

Prepare for Operation

Motto: Train and Track.

Design, development, and construction teams: it is your responsibility to aid the transition to operations.

  • Building operator training
    • The best equipment and smartest controls cannot function properly without well-trained building operators. Building energy consumption tends to increase year over year if systems aren’t well maintained and fine-tuned to specific building conditions. The building operator must understand the building systems and proper maintenance.
  • Ongoing monitoring
    • Use advanced metering and smart building controls to monitor the energy consumption of the building, and flag building system performance issues so they can be corrected as soon as possible. Don’t sit around waiting for your monthly bills or annual performance report.

Energy conservation and renewable energy production make sense now, but both have payback potential by avoiding penalties and taking advantage of carbon trading built into LL97.

Feeling overwhelmed? Give us a call to talk about what opportunities make the most sense for your project or portfolio.


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By Kelly Westby, Commissioning Director




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