Tackling Greenhouse Gas Emissions in the Built Environment

Filed in Sustainability and Green Building by on July 2, 2020 5 Comments

In designing and planning for long-lasting communities, how can the home-building industry move forward while also limiting greenhouse gas emissions from carbon and methane?

As municipalities and states start enacting climate goals, builders and remodelers will need to think about what strategies work best for them to achieve set targets. Defining how buildings contribute to global carbon emissions can be a critical step in understanding how we can utilize various approaches for decreasing the environmental impact of buildings.

Direct emissions from the building sector involve combusting fossil fuels (i.e., coal, natural gas, petroleum) for heating and cooking purposes. Indirect building emissions include fossil fuels used to generate electricity off site, which is then used by buildings to power lights and appliances. There is also the concept of embodied carbon, or “cradle to gate” emissions from the extraction, manufacturing and transportation of building materials. For instance, building materials such as steel, concrete and aluminum contributed approximately 23% to global carbon dioxide emissions in 2017 (IEA, Global ABC, Architecture 2030).

Ed Mazria, architect and founder of Architecture 2030, expressed hope for the future of the built environment while addressing NAHB’s Sustainability & Green Subcommittee during the 2020 Spring Leadership Meetings. Mazria noted that between 2005 and 2019, building energy use decreased 1.7% despite the addition of 47 billion square feet of floor space. This “de-coupling” of carbon-dioxide emissions and activity growth can be attributed to careful planning and thoughtful design of new buildings that relies on building science principles, provides energy-efficiency improvements and incorporates renewable energy technologies.

Just as the industry can intentionally design new buildings with tighter building envelopes to reduce thermal losses, use passive heating and cooling techniques with mechanical ventilation, and incorporate daylighting strategies to reduce the lighting load, builders and remodelers can also plan for reduced greenhouse gas emissions from existing buildings. An assortment of strategies could work together to encourage the incorporation of renewable energy systems, use of carbon-storing building materials, and completion of deep energy retrofits, including but not limited to:

  • Financial incentives, such as low-interest loans, rebates, tax abatements and fast-track permitting for green projects; and
  • Incentives and education for contractors to reuse materials from buildings that are being de-constructed.

If you are looking to learn more about how you can can incorporate green building best practices to give your company a competitive edge, consider using design ideas and strategies for new and existing, single- and multifamily homes from the ICC 700-2020 National Green Building Standard® (NGBS), which is now available to download for free. To learn more about embodied carbon and potential paths for how the building sector can reduce greenhouse gas emissions, register for the CARBON POSITIVE RESET! virtual event in September 2020.

For more information about NAHB’s sustainable and green building programs, visit nahb.org. To stay current on the high-performance residential building sector, follow NAHB’s Sustainability and Green Building team on Twitter.

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Comments (5)

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  1. Phil Crone says:

    Has NAHB ever thought about updating the prior studies done on greenhouse gas emissions? As the green mandate movement was gaining steam, NAHB was able to separate residential construction and specifically new residential construction from the larger charge that buildings in general are a significant overall source of greenhouse gas emissions. Stats like the one listed above that decouple added space from addition emissions could help prove the one of the most effective ways to address climate change is to replace aging housing stock with new homes that are built to today’s already-efficient energy codes.

    • NAHB Now says:

      Phil: As of now, NAHB has no set date, but at some point, the Economics and Housing Policy Group will produce an updated study on greenhouse gas emissions. When it does, separating residential from nonresidential and new from old residential construction will certainly be a key feature of it.

  2. The emmissions produced by gas-powered electrical generation plants are less than half of those produced at the house, when you couple a modern heat pump in the house with a modern power plant in the field, as compared to simply burning the gas in the house, either for space heating or for water heating. If we just stop burning fossil fuels (natural gas and others) in the new homes today, and replace all gas and oil-fired furnaces and water heaters as they fail and need replacing ove the next 20 years, we will have reduces the total emissions from homes to below 1960 levels by the year 2031. No more changes to the energy codes woud be required.

    • Mark Mahan says:

      The efficiency of burning natural gas in the home is a far better use of the natural gas. 68% of the natural gas is wasted in the conversion process to electricity. When you look at source to site efficiency there is far more carbon and methane emitted in the electrification process (power plant) as opposed to 92% of the natural gas extracted being used at the site. Only an 8% loss in that process of the source energy. I do agree with you Ted that more modern efficient appliances are part of the solution but not doing away with natural gas use in the home. We can’t keep adding load to the grid as a solution which is what eliminating natural gas appliances will do.

  3. Tim Gnojek says:

    It’s incredible to see the results of our home and building construction practices. As they were, and as we update requirements. We’ve seen a ton of changes over recent years in the electrical industry as well. Thank you for sharing

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