CAMBRIDGE, Mass., Nov. 24, 2021 /PRNewswire/ — The Harvard Center for Green Buildings and Cities (CGBC) at the Graduate School of Design has just published “Zero-carbon Balance: The Case of HouseZero,” the first full accounting of the structure’s embodied carbon and a detailed methodology behind calculating its zero-carbon balance in the peer-reviewed journal Building and Environment. In tandem, the CGBC has also released a summary of the lab’s full-year performance results.
Prof. Ali Malkawi, Founding Director of the CBGC, said the research in the paper, as well as the summary of results, reflect a “positively promising performance” by HouseZero with potentially far-reaching implications amid a deepening, intertwined climate and energy crisis.
HouseZero’s research team evaluated the building’s performance based on its entire lifecycle of CO2e emitted. This included operational and embodied emissions as well grid-energy offsets from onsite sources. These results highlight important lessons about buildings’ net zero carbon balance.
- The calculations for balancing carbon emissions over the lifetime of a building are sensitive to future technology development and cleaner energy supply.
- More transparent and consistent accounting of carbon emissions is needed for all building life cycle stages, such as product replacement occurrence and the building’s end-of-life stage.
- Accounting for carbon emissions of the entire building is important and should include embodied carbon emissions associated with heating and cooling; onsite renewables; and other mechanical, electrical and plumbing systems.
HouseZero, the residential-to-institutional retrofit project and laboratory, which also serves as the headquarters of the Harvard CGBC, is located in the Mid Cambridge Neighborhood Conservation District in Cambridge, MA.A perfect example of a building that aims to be completely net-zero in carbon emissions. The majority of HouseZero operating systems were completed in May 2020, but the building opened its doors earlier.
Prof. Malkawi said, “The CGBC, along with our architectural and engineering partners, is very encouraged by the project’s progress to date. We all believe, and our research supports it, that transparency is an essential component of a zero-carbon balanced.
Dean Sarah M. Whiting, of Harvard Graduate School of Design, and an operation board member of the CGBC, added, “HouseZero not only promises to be a core contributor to Harvard’sTransition to a net-zero-carbon future. But also an important and clarifying voice in defining the meaning of common terms like “embodied carbon” and “carbon balance”.
Jonathan Grinham, CGBC Senior Research Associate and co-author of the paper, explained, “there are robust standards for whole building lifecycle assessment (LCA), but there is little conformity on what is actually reported and there is a serious need for a universal definition of zero-carbon emissions buildings.” The new published research details the life cycle assessment methods used. It includes system boundaries, data availability and scenarios. It also reports on the uncertainties and the details of the result.
Also, the newly-released FY 2021 HouseZeroPerformance Summary provides one year of actual operational data (a period during which the building was not occupied due to the pandemic). Based on data starting in June 2020May 2021HouseZero (see below) shows that excess onsite renewable energy can offset emissions associated to the primary building structure (which doesn’t include emissions from technical equipment). Provided that the photovoltaic production can achieve optimal efficiency (as designed), and that the building performance is maintained, HouseZero can demonstrate that this can be done. Using existing standards, calculations were conducted by the CGBC based on total load without IT (e.g., data servers) and plug loads and the interpolation of some unavailable data.
As reflected in the Performance Summary, while the building has been able to provide excess generated energy to the local power grid, researchers recognize that adding more PVs, while being mindful of the additional embodied carbon emissions, will offset the added energy demand from onsite data servers used for research. As part of ongoing experiments, the CGBC continues to explore strategies and technologies to further reduce electricity consumption in HouseZero.
SOURCE Harvard Center for Green Buildings and Cities