A Comparative Analysis of Conventional Buildings and Green Buildings: Energy Conservation Strategies and their Impact on Indoor and Ambient Air Quality

The building sector accounts for the largest total energy use in the United States (USDOE 2016), and adds about 110,000 new structures per year (EIA 2008). By 2035, an estimated seventy-five percent of the built environment... [ view full abstract ]

The building sector accounts for the largest total energy use in the United States (USDOE 2016), and adds about 110,000 new structures per year (EIA 2008). By 2035, an estimated seventy-five percent of the built environment will be new or renovated (Arch2030 2016); this continued growth posits a historic opportunity for the building sector to better target longitudinal energy conservation investments and efficiency programs. With climate change imminent, an increased interest in national energy conservation initiatives has emerged. Fourteen cities across the nation have joined the Architecture 2030 Districts Challenge to achieve a 50% reductions in water use, energy consumption, and transportation emissions by the year 2030. New buildings and major renovations goals include an aggressive immediate 50% reductions in water consumption and transportation emissions, with energy use in the design year reaching carbon neutrality by 2030 (Arch2030 2016). The Pittsburgh 2030 District established energy baselines in 2013; as of June 2016 the Green Building Alliance reports a 12.5%, 10.3%, and 24.2% reduction in energy use, water consumption, and carbon emissions, respectively.

While energy use reductions can have an indirect impact on upstream emissions produced during power generation, the impending challenge is further quantifying the effects energy conservation districts (ECD) have on indoor environmental quality (IEQ), considering Americans spend 90% of their time indoors (USEPA 2015). Unique to the Pittsburgh 2030 Districts is the inclusion of dynamic life cycle assessment (D-LCA) based models (Collinge et al. 2014) and real-time pollutant monitoring to develop urban GHG inventories from external and internal emission sources. Indoor air quality (IAQ) assessments have been conducted in seven representative buildings ranging from green certified (LEED Platinum, Living Building Challenge, etc.) to conventional buildings. Seasonal concentrations of ozone, carbon monoxide, carbon dioxide, temperature, relative humidity, formaldehyde, total volatile organic compounds, black carbon, and particulate matter, were collected over a 72-hour period in each building. Sampling results were compared to acceptable levels published in the ANSI/ASHRAE 62.2013 Ventilation for Acceptable Indoor Air Quality, ANSI/ASHRAE 55.2013 Thermal Environmental Conditions for Human Occupancy, and the EPA’s National Ambient Air Quality Standards (NAAQS). Results suggest significant difference in pollutant concentrations across ventilation functionality, showing a dominant effect on IEQ related to newer buildings being mechanically ventilated; however, the counterintuitive findings imply that some green and naturally ventilated buildings underperform when not optimized through controls and/or the proper use of building automated systems (BAS). Given the myriad of factors influencing IEQ, future work entails further uncovering statistical relationships between IAQ and building characteristics (occupant density, workspace type, anthropogenic patterns, and HVAC configuration). Although the inherent growth of the building sector is a formidable challenge when addressing climate change, the realistic evaluation of annual shifts in the regional energy mix (implementation and evolution of renewable sources) prove an even more daunting task. This transition is likely to coincide with variations in life cycle environmental impacts, therefore the inclusion of a dynamic-LCA approach is useful within the scope of our research.