Tackling Greenhouse Gas Emissions in the Built Environment
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.