Productivity metrics in dynamic LCA for whole buildings: Using a post-occupancy evaluation of energy and indoor environmental quality tradeoffs

The IEQ + DLCA framework, which integrates indoor environmental quality (IEQ) and dynamic life cycle assessment (DLCA) at the whole-building level, was revised and expanded to consider non-chemical health impacts and productivity/performance impacts. The complete framework was evaluated for a case study of a LEED gold rated university building, supplemented with a post-occupancy evaluation (POE) designed to elicit qualitative feedback on IEQ and productivity impacts specific to the building. Most non-chemical health impacts (e.g. sick building syndrome (SBS), asthma) were not able to be included in the framework, due to potential overlaps with chemical-specific impacts already included in LCA. However, productivity impacts were able to be included in the framework for the purpose of comparing different design and operational choices for a given building. Occupants were also asked to evaluate the anticipated effects on their individual productivity due to IEQ changes associated with hypothetical energy-saving strategies. Results of the POE showed occupants were generally satisfied with IEQ, and considered that increasing summer cooling temperature set points would enhance productivity. Energy savings were calculated using an empirical energy and IEQ model calibrated with sensed data from the building. Evaluation of the full IEQ + DLCA framework suggested potentially significant energy savings potential and possible productivity enhancement, but indicated tradeoffs between internal chemical impact categories related to building ventilation, indoor pollutant generation and outdoor pollutant intake. The tradeoffs and overlaps between internal chemical impact categories themselves, as well as between chemical and non-chemical impact categories such as (SBS) are a challenge for LCA of whole buildings.