Strategies for Designing Towards Net Zero Carbon

Posted by Alex Altieri on 2/17/22 3:25 PM  |  6 min read time
Alex Altieri
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Nate Kipnis, FAIA, is a leading activist in the realm of sustainability in architecture. Along with coining the term “High Design, Low Carbon,” Kipnis has taken the front seat in the journey towards carbon neutrality in architecture. Many of his projects with Kipnis Architecture + Planning demonstrate carbon reduction strategies as well as a decades-long commitment to environmental sustainability. This blog covers one of those projects.

In a webinar on Architectural Record, Kipnis discussed the overwhelming impact of the building industry’s rising embodied carbon levels. He made it clear that we’re nearing a crisis-level situation, and he outlined many steps we can take to address it.

Before we get into what architects can do to help, let’s first establish some definitions.

What Is Embodied Carbon?

Embodied carbon refers to the carbon emitted through the creation and transportation of a building’s materials and construction processes throughout the project’s entire lifecycle. Embodied carbon is responsible for about 11% of global CO2 emissions.

What Is Operational Carbon?

Operational carbon refers to the emissions during the buildings in-use phase of its lifecycle. This includes emissions from operations such as heating, cooling, lighting, and ventilation. Operational carbon is responsible for about 28% of global CO2 emissions.

Effects of Buildings on the Environment, by the Numbers

So, considering both sources, buildings are responsible for about 39% of global carbon emissions. It’s the single largest source, which may come as a surprise. Shouldn’t it be transportation?

In fact, according to the AIA’s Blueprint for Better campaign, transportation only accounts for about 23% of global carbon emissions, a shocking 16% less than buildings do.

Incorporating sustainable materials and building methodology has therefore never been more important if we’re to meet AIA’s 2030 commitment — and, more importantly, to meet the Paris Agreement, a multinational campaign that vows to keep Earth’s surface temperature from rising a total of 1.5 degrees Celsius since the industrial revolution.

And it’s already risen by 1 degree since then, leaving us with only half a degree Celsius before the environment is considered irreparable.

What Can Architects Do to Help?

imageStrategies for Designing Towards Net Zero Carbon

Net Zero residential project in Boulder County, Colorado. Image by ©2022 Kipnis Architecture + Planning.

Given the numbers, architects have the unique opportunity to shift the world toward a carbon-neutral future. Many would say it’s an obligation.

Kipnis articulates that embodied carbon is where the AEC industry needs to do the most work. This is because, even though it’s a smaller portion of the total than operational carbon, it requires a much larger commitment. You can’t simply reduce embodied carbon after a building is constructed. It must be done in the planning stages, indicating that we must evolve our methods of thinking about planning buildings.

“There are very few, if any, buildings with net zero carbon,” Kipnis said. “It’s challenging to do. Hopefully that changes in the coming years.”

Energy modeling helps Kipnis understand energy levels very early in the planning process, so he’s able to make more informed decisions throughout the project. Here are some of the tips he lays out in his webinar on Architectural Record.

Lake_Zurich_Kipnis_ABI_014 edited grass_tree

High performance home in Lake Zurich, IL. Photo by ©2022 A.J. Brown Imaging.

How to Design for Net Zero Energy – Tips from Nate Kipnis, FAIA
  • Design as efficiently as possible, i.e. simple design and smaller conditioned area.
  • Detail and build a tight shell.
  • Energy model early and often to test design strategy options to verify the efficiency of the design, working from a baseline energy use for the specific building type.
  • Specify extremely efficient appliances and lighting.
  • Design a very efficient, all-electric mechanical system and include mechanical ERV/HRV ventilation.
  • Design onsite renewable energy systems to cover the remaining energy load on an annual basis. A minor level of offsite renewable energy can be included, generally limited to less than 20% of the remaining required.

Before

DSC00428 HR II

Before/After of a Lake Bluff home. Embodied carbon was saved by keeping the existing building instead of tearing it down. Photo by 2022 Kipnis Architecture + Planning.

Four Steps to Net Zero Carbon  

ZeroEnergyProject.org lays out these steps:

  • Go all electric.
  • Reduce embodied carbon in the building.
  • Pay close attention to high embodied carbon materials (steel, iron, concrete, glass, insulation, etc.).
  • Integrate low carbon and carbon-sequestering materials. 

Some low carbon and carbon-sequestering materials are defined by Architecture2030.org:

  • Bamboo
  • Hempcrete
  • Sheep’s wool
  • Straw-bale
  • Wood 

Architecture 2030 has a webpage called Carbon Smart Materials Palette that offers tons of information on sustainable materials. One key takeaway is that insulation materials like extruded polystyrene and closed cell sprayfoam are incredibly carbon intensive. Insulating with straw bales, hempcrete, or other materials listed in the Carbon Smart Materials Palette is an effective way to reduce a project’s embodied carbon levels.

Concrete, similarly, is responsible for a large portion of carbon emissions in the building process.

“Some companies are starting to inject CO2 into concrete, which causes a chemical reaction that turns the CO2 into calcium carbonate, which is limestone,” Kipnis said. “It actually makes the concrete stronger and it reduces the amount of cement used. Cement is the key issue. It takes so much energy to make the material. So, optimizing the amount of concrete you use is a key step.”

Watch the full webinar and learn more about reducing the carbon impact of your building projects:

WATCH THE WEBINAR

Topics: Resources, BIM (Architecture)

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