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A net zero status is popularly in embodied emissions of the building depreciation, and residual costs.
understood as the gold standard in (Adams, Burrows, and Richardson Similarly, a life cycle carbon analysis
building energy efficiency. In typical 2019; Graham 2019; Schmidt, needs to include upfront carbon,
situations, a building achieves this Crawford, and Warren-myers 2020). annual emissions, and end-of-life
status based on an annual balance The annual performance evaluations processes. An LCA for a building
sheet of electricity. This balance do not consider the embodied requires the use of a metric that
sheet presents an environmental carbon released before the use of applies to all the phases of a building’s
evaluation for the building, annually, the building. With these additional lifespan. This metric must account
1
in terms of its Energy Performance provisions, the embodied emissions for GHG emissions, typically
Index (EPI). The key performance of a net zero building can be higher measured in terms of equivalent
indicator is the annual consumption than those of a typical building. The carbon dioxide (CO e). The metric
2
(EPI) with respect to the on-site annual savings may or may not be able should quantify the emissions from
generation (net-EPI). It is typically to compensate for these additional various GHGs based on their global
measured in kilowatt-hour (kWh) emissions, even across the lifespan warming potential (GWP). Once
and expressed as a function of the of the building. For the building the impact is quantified in terms of
2
building area (kWh/m /yr). The industry, a positive net-EPI is not CO2e, it can be normalized for the
common use of this metric is based good enough to ensure a significant factors of time, area, occupants,
on the idea that annual savings in reduction in emissions anymore. It is and cost. This normalized value can
electricity translate to reduction in now necessary to be able to quantify be used for comparative studies or
greenhouse gas (GHG) emissions. the total impact of a building on the benchmarking (Parkin, Herrera, and
However, recent research has environment across its life cycle. Coley 2020; Ürge-Vorsatz, Khosla,
suggested that may not be the case Bernhardt, et al. 2020).
(Bordass 2020). The total impact can be quantified Embodied carbon is projected to
through a life cycle analysis (LCA). account for 50% of the total carbon
A net zero status is achieved through When typically conducted for footprint of new construction
the provision of elements such as economic costs, an LCCA (life cycle until 2050 (Adams, Burrows, and
insulation, high-performance glazing, cost analysis) not only considers Richardson 2019). Data on embodied
on-site photovoltaics, etc. The the annual net sum but also looks carbon can be sourced from life cycle
provision of these systems increases at initial investments, inflation, databases and environmental product
declarations (EPDs) based on their
applicability to the project’s geography
and time. Contextualizing the data
sets for each project is necessary to
come close to the true impact. The
share of these emissions in the total life
of a building can vary so much that it is
not feasible to draw a simple, broadly
valid conclusion. The variations in
these shares are primarily due to
differences in construction materials
and technologies.

1 GHG emissions in buildings are typically
indirect, occurring due to the use of
electricity in the building. Absolute
emission numbers, therefore, largely depend
on emission factors considered during
calculation (Lucon, Ürge-Vorsatz, Ahmed,
et al. 2014). There is a need to include gases
other than CO because some construction
2
products and HVAC equipment emit
substantial amounts of GHGs, such as
methane, nitrous oxides, and HFCs.