Reduction of operational carbon in existing buildings through energy efficiency

Our Motivation:

According to the International Energy Agency (IEA), over 85% of buildings worldwide must become "zero-carbon-ready" by 2050. 

The IEA defines “zero-carbon-ready” buildings as “highly energy-efficient and resilient buildings that either use renewable energy directly or rely on a source of energy supply that can be fully decarbonized, such as electricity or district energy” [1]. The definition also explicitly states that the “zero-carbon-ready” concept includes operational as well as embodied carbon emissions [1], thereby highlighting the importance of addressing both categories of emissions in building decarbonization efforts. This is a major challenge, as we need to take into consideration each building’s unique set of characteristics. Meanwhile, solutions must be simple to execute, affordable, and scalable.

Research Contribution

Achieving the IEA goal requires existing buildings in the US to undergo energy-efficiency retrofits. The purpose of the current research is to contribute to the building decarbonization knowledge base by (1) concurring with the increasing number of studies showcasing the advantages of full building electrification from a financial and whole-life carbon emissions perspective, (2) exploring the trade-offs between operational carbon savings and embodied carbon in the context of energy efficiency retrofits, for which limited studies have been conducted to date, (3) highlighting the need for a more comprehensive set of parameters that should be assessed in the energy efficiency retrofitting process, such as the possible electrical grid decarbonization pathways for each US state, and (4) helping simplify the workflow of energy efficiency retrofit analysis.

Problem

Solution

A data-driven methodology to determine retrofitting solutions that maximize whole-life carbon emissions savings in a 30-year timeframe at a minimum upfront financial cost.

Added Value For The Industry

The developed methodology will help AEC professionals make faster and more informed decisions in the context of residential energy efficiency retrofits. Additionally, the methodology will consider the implementation of mature heat pump technologies that have been proven to be efficient and scalable solutions in the context of retrofitting. Finally, insights from the developed methodology could be integrated into existing design toolkits.

Cooperation Partner

 Timeline

Project Summary

The current research aimed at developing a comprehensive and simple-to-execute workflow for analyzing energy retrofit scenarios for existing buildings through a whole-life carbon lens.

The purpose of the research project was therefore to contribute to the building decarbonization knowledge base by (1) concurring with the increasing number of studies showcasing the advantages of full building electrification from a financial and whole-life carbon emissions perspective, (2) exploring the trade-offs between operational carbon savings and embodied carbon in the context of energy efficiency retrofits, for which limited studies have been conducted to date, (3) highlighting the need for a more comprehensive set of parameters that should be assessed in the energy efficiency retrofitting process, such as the possible electrical grid decarbonization pathways for each US state, and (4) helping simplify the workflow of energy efficiency retrofit analysis. 

Key outcomes of the case study implementing the proposed workflow on a multifamily housing complex located in climate zones 1A, 4A, and 3C in the US and constructed to the ASHRAE 90.1-2010 standard include:

• Building envelope upgrades are a poor investment from an energy savings as well as a financial cost perspective, while electrification measures, primarily using heat pumps for HVAC and DHW needs, can lead to annual energy load reductions of 60%, 50%, and 40% in each climate zone respectively;

• The trade-off between long-term operational carbon savings and the embodied carbon associated with energy efficiency and electrification measures is not intuitive and is highly dependent upon the % reduction in annual energy consumption caused by each measure, the embodied carbon intensity of the materials used, and the local grid decarbonization pathways.

Contact Person

If you want to participate in the project please reach out to Eleni Alexandraki.

Sources

[1] https://www.iea.org/energy-system/buildings

[2] Walker, I. S., Less, B. D.,Casquero-Modrego, N.(2022). Pathways to Home Decarbonization in the US. Proceedings of the 2022 Summer Study on Energy Efficiency in Buildings.American Council for an Energy Efficient Economy (ACEEE), 21-26 August, Pacific Grove, CA