7.15 Building Design: Retrofit vs New

Author: Rennie Taylor

ABSTRACT: What is better for the environment, retrofitting old structures or starting from scratch with new construction? This paper explores the issue of carbon emissions within buildings, which account for 30% of all carbon emissions in the world, and how to decarbonize structures both new and old. The difference between embodied carbon in a building’s materials, transportation or assembly is compared with the energy cost of running a building, in operational carbon. Operational carbon is consistently being reduced through energy saving design practices and regulations and embodied carbon will remain as the major source of building’s carbon footprint. The conclusive evidence is that retrofitting is an important option knowing that 80% of the structures existing today will still be in use in fifty years. Reuse and adaptation with retrofitting will be a necessity.

(Image Credit: Rennie Taylor)


With worldwide existential urgency to stay within the Paris Agreement Accord (2015), limiting global warming to under 2 degrees Celsius by 2030 (United Nations), a significant focus has turned to buildings and the energy they consume in construction and operation. Buildings emit a significant amount of carbon and therefore the need to enforce stricter carbon-efficient measures for new construction while also upgrading or “retrofitting” current existing buildings is significant to help combat climate change at this immediate moment in time. The reason to address this issue is that the global building sector is responsible for 30% of our world’s carbon emissions (Embodied Carbon 101). Additionally, a survey from the Energy Information Administration from 2015 showed that 40% of the energy consumed in the U.S. was spent on the operating of buildings (Strain). Another 10% was from new construction. New constructions emit what is termed “embodied carbon”. Embodied carbon refers to greenhouse gas emissions, or GHG, that come from the production, travel, installation, maintenance and removal of a building’s materials. This is in contrast to operational carbon which is an emission due to a structure’s energy use (Embodied Carbon 101). Extending the lifespan of older, and possibly historic, structures through new improvements in innovation and technology can be considered a more ethical lower carbon direction (Leiper). With the necessity to rapidly reduce carbon in our present moment, retrofit projects can save up to 50-75% of embodied carbon compared to new construction projects (Leiper). “As buildings become more energy efficient and building energy supplies decarbonize, the importance of embodied carbon grows; it can even become the dominant source of carbon emissions associated with our buildings in the future (Ebrahimi).

Why are retrofit projects critical right now? It is because “80% of today’s buildings will still be in use in 2050 and 75% of this stock is energy inefficient” (Wade). With the knowledge that a significant amount of carbon is produced by pre-existing buildings, architects, city planners and homeowners have an ethical responsibility, when possible, to preserve and adapt existing structures. Additionally, due to the fact that a building’s embodied carbon is taken into account by its base and structure, it is more viable to reuse these parts rather than demolishing them because more carbon is produced in the rebuilding process (Duncan). But, what exactly is retrofitting? A retrofit refers to the inclusion of a new technology into a pre-existing structure, such as thermal insulation or an upgraded heating system for cost and building efficiency and carbon reduction (Leiper). One way that retrofitting is used within the parameters of the design industry is by the choice of energy efficiency materials.

In addition to planning and reuse, a positive way to “commit to a low-carbon retro is the choice of insulation material, for example, using insulating materials like straw bale, hempcrete, and wool store to neutralize and even negate carbon” (Ebrahimi). Also, minimizing manufacturing through upfront planning, such as prefabricated design, are low-carbon options (Strain). Reusing existing construction materials within a retrofit project, such as salvaged concrete, brick or wood is a way to neutralize the construction carbon footprint since the carbon used to manufacture these items have already been used (Strain). An example of a retrofit, done by the architectural firm ERA, is the University of Toronto campus building, The Gemini House, a “Second Empire” style building built in 1880. This retrofitting, an on-going experiment that was started in 2013, based on the “Passive House” model, transformed the structure into a low-energy performing building. Specifically, a new box construction was incorporated in the house to minimize heat loss resulting in energy use being reduced by over 90% (Gemini House). This experimental example shows how sometimes difficult structures can be modified for carbon-positive uses.

What is the relationship between retrofitting and new constructions and which is the better option for our environment? One downside to retrofitting is the upfront costs. “New construction can be more cost-effective in some scenarios, especially if a retrofitting project is going to cover several different types of utilities, such as completely upgrading a building’s lighting design, HVAC, or plumbing” (New Construction vs. Retrofit). Additionally, if a structure is too old, and with too many aspects being out of date, it may require a lot of expensive repairs and improvements in order to make the structure low-carbon and energy efficient (New Construction vs. Retrofit). Another aspect in a project reuse that would bring difficulties are the limitations brought by the space, which may prove difficult, or impossible, if the building was not up to code from the start (New Construction vs. Retrofit). In contrast, a positive aspect for new buildings is that they are already following new codes and typically have energy efficiency built into them. “[H]owever, the energy, water, and related carbon savings achieved once a new building is occupied can take a long time to overcome the embodied carbon that was emitted during construction” (Duncan). What this does is that when buildings become more efficient, the majority of carbon emissions no longer come from operational energy but by the embodied carbon of construction (Duncan). With this in mind, it is more ethical to reuse and adapt existing structures than to start again from scratch.

With the existential charge to limit global warming to 1.5 degrees by the end of this decade, the need to address embodied carbon in new construction through carbon efficient materials and retrofitting older historic buildings is a necessity. By reusing foundations, structural frameworks, building materials while at the same time replacing heating systems and adding new insulation can significantly reduce the carbon, both embodied and operational, within a structure’s footprint. As embodied carbon becomes more of a significant carbon expenditure, than operational carbon, then many of the existing structures need to be adapted rather than torn down for new construction. Everyone needs a home and a shelter. We must transform the buildings we have right now, through adaptation and reusables, into the future community buildings, offices and homes.


“1 – Embodied Carbon 101.” Carbon Leadership Forum, 17 Nov. 2021, https://carbonleadershipforum.org/embodied-carbon-101/.

Duncan, Jake. “Should I Stay or Should I Go: The Embodied Carbon of Buildings.” Institute for Market Transformation, 20 Oct. 2021, https://www.imt.org/should-i-stay-or-should-i-go-the-embodied-carbon-of-new-and-existing-buildings/.

Ebrahimi, Ghazal. “Embodied Carbon and Deep Retrofits.” Pembina Institute, 21 July 2020, https://www.pembina.org/pub/embodied-carbon-retrofits.

“Gemini House.” Building Resilience, Sept. 2020, https://buildingresilience.ca/case-study/gemini-house/#.

Leiper, Andrew. “Retrofit or New Build?” Net Zero Carbon Guide, https://www.netzerocarbonguide.co.uk/guide/early-decisions/retrofit-or-new-build/summary.

“New Construction vs. Retrofit: What You Need to Know.” CESnews, 18 Sept. 2019, https://blog.cityelectricsupply.com/new-construction-vs-retrofit-what-you-need-to-know/#:~:text=Retrofitting%20an%20%20old%20.

Strain, Larry. “10 Steps to Reducing Embodied Carbon.” The American Institute of Architects, 2021, https://www.aia.org/articles/70446-ten-steps-to-reducing-embodied-carbon.

“The Paris Agreement.” United Nations Climate Change, https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement.

Wade, Faye. “Retrofitting Buildings to Support the Recovery.” Buildings and Cities, 8 July 2020, https://www.buildingsandcities.org/insights/commentaries/retrofit-buildings-recovery.html.


Rennie Taylor is an artist who engages in the practices of photography, filmmaking and collage while exploring themes of consumerism, the handmade and obsolescence. He is currently in his fourth year of Photography at Ryerson University.

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