Abstract
The concept of (net) zero greenhouse gas (GHG) emission(s) buildings is gaining wide international attention and is considered to be the main pathway for achieving climate neutrality targets in the built environment. However, there is an increasing plethora of differing terms, definitions, and approaches emerging worldwide. To understand the current progress of the ongoing discussion, this study provides an overview of terms, definitions, and key features from a review of 35 building assessment approaches. The investigation identified that 13 voluntary frameworks from 11 countries are particularly characterised by net zero-carbon/GHG emissions performance targets, which are then subject to a more detailed analysis. The review was organised in the context of the project IEA EBC Annex 72 on “Assessing Life Cycle Related Environmental Impacts Caused by Buildings”, which involves researchers from over 25 countries worldwide.In the current dynamic political surroundings and ongoing scientific debate, only an initial overview of this topic can be presented. However, providing typologies and fostering transparency would be instrumental in delivering clarity, limiting misunderstanding, and avoiding potential greenwashing. To this end, this article categorises the most critical methodological options—i.e., system boundaries for both operational and embodied GHG emissions, the type of GHG emission factor for electricity use, the approach to the “time” aspect, and the possibilities of GHG emission compensation—into a comprehensive framework for clarifying or setting (net) zero GHG emission building definitions in a more systematic way.The article concludes that although variations in the existing approaches will continue to exist, certain minimum directions should be considered for the future development of harmonised (net) zero GHG emissions building frameworks. As a minimum, it is recommended to extend the usual scope of the operational energy use balance. At the same time, minimum requirements must also be set for embodied GHG emissions even if they are not considered in the carbon/GHG emissions balance.
Highlights
Despite the high variation in key factors among the analysed building assessment approaches, the general findings are as follows: (1) The system boundaries recognised among analysed data focus mostly on the operational life cycle stage, excluding the embodied life cycle impacts
(3) Primary energy is the most common assessment metric, observed in most European countries, where the implementation of nearly zero energy building performance target is applied in national policy
(5) Most of the reviewed building assessment approaches are titled “zero carbon”, even though their frameworks cover carbon dioxide (CO2) emissions and a set of other gases whose emissions contribute to global warming
Summary
As part of the way forward for sustainable development, actors in the built environment, including the related upstream and downstream economic sectors, strive to protect their traditional business interests, along with fulfilling their responsibility towards society and the envi ronment. Regional, and national standards exist to guide the description of the environmental and health-related charac teristics and properties of construction products—e.g., ISO 21930 [5] and EN 15804 + A2 [6]—as well as the determination and assessment of the environmental performance of buildings—e.g., ISO 21931–1 [7] and EN 15978 [8] They contain information on the specification of the respective object of assessment, including the system boundaries, and on the calculation rules. These are indispensable for supporting actors in the built environment in their decision-making
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