Embodied Carbon and the Nuances in Office-to-Residential Conversions

Abstract

Reducing carbon emissions associated with buildings is a top priority for mitigating the human impacts from climate change. Reducing carbon emissions resulting from the manufacturing, designing, constructing, investing, owning, operating, occupying, renovating, and demolishing of buildings is essential to safeguard the environment from negative consequences. This paper relates to the environment and human influence on the climate and addresses the different amounts of embedded carbon for building activities ranging from new buildings to major renovations to minor renovations, using a methodology termed the “whole-life carbon measurement”. The data from the case studies indicate that refurbished or renovated buildings exhibit the least carbon footprint compared to other alternatives. This outcome can be attributed to the sustainable practice of reusing materials, coupled with the positive effects of retrofitting. The expectation that refurbished buildings would demonstrate a lower carbon footprint aligns with the principles of sustainability, emphasizing the environmental benefits of repurposing existing structures. While embedded carbon is currently not priced, it is important that it be accurately measured over the entire life cycle of buildings if the real estate industry is to meet sustainability goals.

1. Introduction

Reducing carbon emissions associated with buildings is a top priority for mitigating the human impacts on climate change. Reducing carbon emissions resulting from the manufacturing, designing, constructing, investing, owning, operating, occupying, renovating, and demolishing of buildings is essential to safeguard the environment from negative consequences. The buildings and infrastructure that define our cities contribute approximately 38 percent of greenhouse emissions [1,2]. Rising temperatures, wildfires, shifting rainfall patterns, and sea level rises are changing the ecosystem that has defined the built environment. The increase in greenhouse gas emissions, consisting primarily of carbon dioxide, is associated with global warming, which poses a dire threat to the environment and results from the negative impacts of human activity. A necessary step to reducing the devastating negative impacts of climate change is the global clarion commitment by countries to significantly reduce carbon emissions by reaching net zero (carbon neutrality) by 2050. Although this is a daunting task, countries need to demonstrate adaptation and resiliency measures to reach this target while aligning actions across the entire building value chain to deliver a net-zero built environment.

Large steps are required to reach this target if any meaningful results are to be expected in the next decades [3,4,5]. Some of these include powering economies with clean energy (renewable energy sources—i.e., wind, solar farms, electric vehicles), nature-based solutions (improving farming techniques, restoring natural habitats and forests to bolster biodiversity and ecological resilience—flora and fauna), making lifestyle changes during construction, and renovating and repurposing existing buildings to perform the same or new functions [6,7].

Amidst the COVID-19 pandemic, global economies experienced a deceleration that produced an unexpected silver lining. Office buildings, once bustling hubs of activity, have had to grapple with significantly reduced occupancy rates due to the widespread adoption of remote or hybrid work models [8,9,10]. Consequently, the office market has undergone a structural transformation, marked by diminished space demand and soaring vacancy rates, reaching an unprecedented 17.3% according to CBRE’s report [11]. There is a slow but steady return to the office, with office occupancy at around 50% of pre-pandemic levels as of March 2023 [11,12]. Post pandemic recovery could provide an important turning point in transitioning to net zero emissions by 2050 through renewable energy investments, smart buildings, green transportation, and interventions meant to slow down the impacts of climate change.

Reducing carbon from building activities is a priority for achieving net zero emissions by 2050. Renovating existing office buildings and converting them to residential uses rather than building new ones from the ground up, is one of the best ways to reduce carbon emissions. Repurposing existing structures saves the embodied carbon that was used to build them in the first place. However, it is important to understand the concept of the full life cycle of buildings and how much carbon is used at each stage of the building’s life—from construction to operations, to end-of-life, and beyond. The focus of this paper is to address the different amounts of embedded carbon for building activities under different regimes—ranging from new buildings to major renovations to minor renovations. Our data are taken with permission from ARUP, who have analyzed a series of building typologies across their full life cycle [13].

The embodied carbon of a building is the amount of harmful greenhouse gas (carbon dioxide emission associated with the manufacture, transport, maintenance, and disposal of building materials and components) stored during the construction process and the materials used in the building during retrofitting or renovation [1]. This differs from operational carbon that defines greenhouse gas emissions due to building energy consumption. Embodied carbon contributes at least 21% of global emissions during construction [14] but is rarely reported as part of reducing emission strategies. Many references to net zero emissions only refer to reduction in operational carbon (i.e., reductions in fossil fuel use, water usage, energy consumption, and waste) and not emissions during the construction processes [15,16].

In general, repurposing an office building into a residential space tends to result in lower embodied carbon emissions compared to constructing a new residential building from the ground up, primarily because the building foundation and structural framing already exist. To the extent that curtain walls, windows, and HVAC systems can be saved, the reduction in carbon emissions can be very substantial. Nevertheless, the conversion process itself can either augment or diminish the embodied carbon footprint, which is contingent upon the construction methods employed during renovation. Various factors such as the extent of structural modifications, the materials used, and the energy efficiency enhancements implemented during the conversion or retrofitting phase can significantly influence the overall carbon impact of the project. Therefore, meticulous planning and sustainable construction practices are imperative to mitigate environmental repercussions and optimize the carbon efficiency of the transformation process. For example, while implementing improvements such as new triple-glazed windows, partition walls, and upgraded bathroom fixtures can enhance the functionality and appeal of the residential space, it is essential to acknowledge that these enhancements may contribute to significant carbon emissions during their production and installation phases. Thus, striking a balance between renovation objectives and carbon reduction strategies is essential to ensure a sustainable and environmentally conscious conversion process.

With many people still working from home, employers are encouraging employees to return to physical office spaces. If companies continue to give up leases and the demand for office space continues its downward trend, landlords will not be able to generate enough rent to pay off commercial loans. Without more rent, building owners will not be able to refinance their debts in the post COVID-19 era with its much higher interest rates than before COVID-19. To cut down on losses, the focus now has been on how to transform traditional single-purpose business districts to mixed-use centers because of obvious resource reallocation challenges.

It is essential to recognize that hybrid work arrangements have become a permanent fixture in the modern workforce [8,9,10]. With this shift in how people work, the question of how to transition building stock to mixed-use development becomes a paramount priority. A significant debate surrounds the extent to which existing office spaces can feasibly be converted into residential units, with estimates varying between 15% and 30% of the current office building inventory.

This transition towards hybrid work models has fundamentally altered the dynamics of traditional office environments, prompting a reassessment of the utilization and functionality of commercial real estate assets. As organizations continue to embrace flexible work arrangements, the imperative to optimize office spaces and address rising vacancy rates has become increasingly apparent. Consequently, there is growing interest in exploring the potential of repurposing underutilized office buildings to meet the evolving needs of urban communities [17,18], with a particular focus on accommodating residential demand. However, the feasibility and economic viability of such conversions remain subjects of ongoing discussion, highlighting the complexities inherent in adapting existing infrastructure to align with changing societal and economic trends.

Converting existing buildings into alternative uses presents numerous challenges, particularly when confronted with issues such as oversized floor plates or inadequate street exposure. Anecdotal evidence suggests that low-to-mid-rise structures, typically spanning up to five stories, emerge as the favored choice for conversion projects due to their inherent flexibility and adaptability. The surge in conversion activities has been notably pronounced since the onset of the pandemic, driven by a concerted effort to mitigate financial losses incurred by office space managers. This trend is expected to persist as stakeholders seek innovative solutions to optimize underutilized real estate assets.

From a sustainability perspective, the renovation or retrofitting of existing buildings represents a more environmentally responsible approach compared to new development. By repurposing structures that already exist, the construction of new infrastructure and associated carbon emissions can be minimized, thereby reducing the environmental footprint of urban development initiatives. Moreover, refurbishment projects offer the opportunity to incorporate energy-efficient technologies and sustainable design principles, further enhancing the long-term environmental performance of these repurposed buildings. As the imperative to address climate change intensifies, the emphasis on sustainable building practices underscores the importance of prioritizing adaptive reuse strategies in urban planning and development efforts.

Post pandemic recovery, occupancy trends and decarbonization strategies have provided ample fuel to consider office conversion to residential as an option in the wake of discussions to reduce emissions to meet global targets—net zero carbon strategies [4,11,15,17]. The shifting priorities of commercial real estate decision makers as well as corporate occupiers impacts the management, investment, and future of office buildings. Renovation projects are seen as providing new life to existing structures of steel and concrete, as well as reuses for door frames and light fixtures. For climate analysts, embodied carbon represents an enormous potential savings in carbon production that needs to be addressed as part of reducing global carbon emissions. Past efforts to reduce emissions have focused on increasing energy efficiency in building operations. However, recent research on greenhouse gas emissions across the full life cycle of buildings highlights the enormous impact of embodied carbon during construction that requires urgent attention [19].

2. Materials and Methods

The data for the paper were obtained from the World Business Council for Sustainable Development [13]. To provide an in-depth exploration of complex phenomena in their real-life natural setting, a case study approach was used. The case studies examined embodied carbon at the specific stages of development, operations, and end of life, including selective demolition of all or certain components of the building, for various projects across Europe. The case studies analyzed carbon emissions at different stages throughout the entire life cycle of the project.

The authors focused on comparing emission trends across six projects by redacting the essential details of the case studies from the ARUP report. This process involved carefully extracting and summarizing pertinent information, allowing for a comprehensive and accessible analysis of the carbon footprints associated with each project. By focusing on these important factors, we aim to facilitate a more detailed understanding of the environmental impact of different initiatives. This will enable stakeholders to make informed decisions based on a comprehensive comparison of carbon emissions within the specific projects outlined in the report.

The whole-life-cycle assessment (WLCA) methodology was used to extract the carbon footprint used in the case studies. The idea was to benchmark the results in a recognized and standardized way. For the results to be internationally representative, the Building System Carbon Framework (BSCF) was adopted. The BSCF integrates different carbon assessment frameworks including (i) the ISO 14040: 2006 Environmental Management—Life-Cycle Assessment; (ii) 2011 European Standard EN15978, Sustainability of Construction Works—Assessment of Environmental Performance of Buildings—Calculation Method; (iii) the 2017 Royal Institution of Chartered Surveyors (RICS) Whole-Life Carbon Assessment for the Built Environment; and the (iv) the 2020 WBCSD, Building System Carbon Framework.

The WLCA splits the building life cycle stages into modules and assesses each stage’s carbon emissions separately. Four building stages are identified—construction, in-use, end-of-life, and beyond-life stages. These steps are explained in the next sections.

The authors adopted calculations used in the case studies as reported from the WBCSD report [13]. For a detailed methodology on how embodied carbon can be measured, refer to the Institution of Structural Engineers’ guidance notes on calculating embodied carbon (see https://www.istructe.org/IStructE/media/Public/Resources/istructehow-to-calculate-embodiedcarbon.pdf (accessed on 25 January 2024)).

3. Embodied Carbon and Current Strategies

The whole-life carbon measurement, mitigation, and impact of buildings is not fully developed, as the industry is still growing. There seems to be an attempt on the one hand to present a picture of reduced emissions, while in fact, this is not the entire picture. It must be noted that it takes more time and effort to collect and report data on embodied and operational carbon (Figure 1) [19]. Figure 1 shows a schema of carbon sequestered during a building’s lifetime and allows users to identify the best emission-reduction strategies for that part of the value chain. This utilizes a full life-cycle approach instead of other approaches that only measure individual building stages and ignore others completely. Carbon analysts argue that carbon emissions are quantitative with measurable effects, and as such, should not be subject to manipulations and inflated statements. Total carbon emissions of renovated or retrofitted buildings must, in effect, be calculated using figures for both embodied and operational carbon footprints. There does not seem to be an agreed definition of what net zero means, and this lends itself to different interpretations [1,6,15,16]. The Buildings Performance Institute Europe [20] asserts that the measurement and mitigation of embodied carbon at the building level is typically voluntary, as there is no existing regulatory or statutory mechanism in place that provides a consistent framework and reporting trajectory for many countries. Some voluntary reporting is currently undertaken, but this is not uniform and does not cut across the industry.

Significant capital expenditures involved in reducing emissions during renovation or retrofitting are a matter of major concern to investors. Are investors willing to invest in a “green premium” to ensure that global emissions targets are reached? Are customers willing to pay up to ensure sufficient investment returns? Are these interventions worth the additional time, implementation, and reporting in order to meet global carbon targets? It is reported that financial institutions have stopped providing loans to unsustainable building projects [22,23]. The hesitancy might be understandable, as lenders may soon be required to report on how sustainable their loan portfolios are. In periods of uncertainty, investors generally tend to be risk-averse. Considering the evolving regulatory environment, it is not surprising that equity investors will prefer to adopt less risky options to safeguard their investments. Owners and investors are skeptical as to whether the sum effect of “green interventions” are reducing global emissions or if there is something still missing in the equation considering data requirements and reporting standards to be met.

Another important consideration is the lack of verifiable self-reported data and/or statements presented by entities reporting on their carbon emissions. Considering the different certification regimes that exist to self-report carbon emissions, these figures may, in some cases, represent misleading, dishonest, and questionable judgments. There is the need to examine the metrics that are used to support these emission claims, as the best practices are still emerging. Organizations must institutionalize Key Performance Indicators (KPIs) and competency by setting up teams to implement suitable measuring and simple reporting systems that can be verified independently. An objective outcome that emanates from this process will trigger change in the right direction. Embodied emissions are the first emissions a building generates. Disregarding embodied emissions can result in several negative outcomes. It may not contribute significantly to reducing emissions during the use phase. Furthermore, it could lead to adverse long-term consequences such as environmental degradation or increased carbon footprint over time.

Ways to identify structures that produce less atmospheric carbon are two-fold. First, renovation and reuse projects are considered to save between 50 to 70% of embodied carbon. Salvaged materials typically have less of an embodied carbon footprint than using new materials in the construction process. This option is environmentally sustainable and rewarding in the long term. Second, designs that limit carbon-intensive materials (i.e., low-carbon concrete mixes) and incorporate natural and renewable materials (like timber, bamboo, straw, and hemp insulation) that sequester carbon dioxide over their life cycle will reduce embodied carbon. A case example is the Wood Hotel in Skelleftea, Sweden—a nearly all-timber structure. Research shows that timber continues to store carbon sequestered throughout its growth in perpetuity—and even after it has been cut—accounting for a significantly smaller embodied carbon footprint. Advances in the use of biomaterials such as bamboo in place of steel [24] and bacteria growth as a bonding agent present alternate innovations to replace traditional construction materials. Until these breakthrough materials can be viable on a commercial scale, renovating existing buildings will be more sustainable than building from the ground up. Architects and allied professionals must consider ways to achieve maximum structural efficiency. Construction techniques and designs should use appropriate methods that minimize material use but maximize efficiency in all forms of the building life cycle. One way to achieve this is to consider the use of structural materials as a finish for walls, floors, and ceilings, among others. Another is to consider, for example, designing wooden-framed projects in standard sizes that minimize waste (i.e., using standard sizes for common materials). In summary, embodied emissions can be partly minimized through reused, reusable, recycled, and recyclable materials.

Another way to neutralize embodied carbon emissions is through carbon offset credit projects, either onsite or offsite. The idea is that the conversion process will necessarily produce unavoidable emissions, which need to be offset by a verifiable project. This is more like a double-edged sword intended to lead to zero carbon emissions on account of the offset for a sustainable future. However, opponents are of the view that this policy loophole simply shifts the goal posts of emissions to another project in order to meet emission requirements. Minimizing emissions performance is required to ensure that the quality of building is improved, and carbon offsetting substitutions are avoided. The main objective of reducing emissions is to fully decarbonize along the entire building life cycle and avoid the need for offsets.

Measuring embodied carbon in a building can be a complex venture. Two common methods are generally used to derive an estimate—the product stage method (PSM) and the whole-building life-cycle assessment (WBLCA). The WBLCA method accounts for all carbon emissions through the duration of a building’s life cycle and relies on data from many life-cycle stages. The PSM focuses on the up-front carbon emissions emitted during the product stage of the whole-building life cycle and can be utilized for any building material or specific product. With the PSM, the embodied carbon is estimated by multiplying material quantity by the global warming potential, indicated as follows:

Material Quantity × Global Warming Potential = Embodied Carbon.

(1)

4. Case Studies

Table 1. Carbon emissions for new versus refurbished office buildings.

	Emissions at Building Stages (kgCO2e/m2)
	Products	Construction	Use	End of Life	Total	Beyond Life
New office building—London, the UK GIA—29,819 m2; AEC—222 kWh/m2/year	503	40	1900	6	2449	−227
New office building (all electric)—London, the UK GIA—40,065 m2; AEC—109 kWh/m2/year	623	44	972	8	1647	−208
Office building (complete transformation)—London, the UK GIA—42,776 m2; AEC—118 kWh/m2/year	516	37	1024	4	1582	−145
Office building (refurbishment)—London, the UK GIA—47,264 m2; AEC—149 kWh/m2/year	289	24	1197	5	1515	−155
Mixed-use building—Copenhagen, Denmark GIA—26,366 m2; AEC—117 kWh/m2/year	842	36	1168	33	2079	−336
Residential timber tower—Amsterdam, the Netherlands GIA—14,544 m2; AEC—74 kWh/m2/year	377	41	1005	17	1440	−158

Note: GIA—gross internal area. AEC—annual energy consumption. Source: [13].

presents six case studies from the World Business Council for Sustainable Development [13]. The case studies examine embodied carbon at specific stages of the development, operations, and end of life (including selective demolition of all or certain components of the building) for various projects across Europe. The case studies compare the amount of carbon emissions at various stages across the entire life cycle of each project.

The authors of the ARUP Report on page 3 [13] state, “The case studies also help us to better understand the key levers that will drive the built environment decarbonization, for example, in new building projects more than 50% of emissions may be from the embodied carbon associated with the construction, and 70% of this comes from six materials. As much as 20% of life-cycle emissions come from the maintenance and refurbishment of installations during the lifetime of a building. Hence it is paramount that we tackle these emissions alongside a continued focus on driving down emissions from the energy used to operate buildings”. In Table 1, we have redacted and synthesized the essential details of the case studies from the ARUP report, focusing on key parameters crucial for comparing carbon emissions across diverse projects. This process involves carefully extracting and summarizing pertinent information, thus allowing for a comprehensive and accessible analysis of the carbon footprints associated with each phase of each project. By honing in on these crucial factors, we aim to facilitate a more nuanced understanding of the environmental impact of various initiatives, enabling stakeholders to make informed decisions based on a thorough comparison of carbon emissions within the context of the specified projects outlined in the report.

In Table 1, the columns are defined as follows:

Products account for carbon emissions associated with the manufacturing of all materials used in construction, including material supply, transportation of raw materials, and the manufacture of the finished products.

The Construction stage accounts for emissions relating to the transportation of materials to site and construction (including material wastes, construction plant, and machines).

Use relates to emissions associated with the maintenance, repair, replacement, and refurbishment of the built asset over its lifetime. This also includes operational energy (water and energy). The structural frame and foundation are supposed to last for about 60 years (operational life of the building with good maintenance) ([13], p. 13).

End of life is related to the demolition and waste processing of construction materials. This usually has little impact on the environment, depending on the biogenic materials used.

Total represents the sum of the four stages of the full life cycle.

The Beyond life stage accounts for repurposing building elements, e.g., discarded materials from the built asset or energy recovered from beyond the project’s life cycle. This stage presents a wider impact of the future potential of materials and the building through the lens of circular economy principles (reusing existing material and designing new buildings to be environmentally sustainable, resource-efficient, and resilient to change).

The ranking of carbon production from most to least for the different conversion alternatives based on the case studies is as follows:

• New office building, London, the UK—2449 kgCO₂e/m² (most carbon use);
• Mixed-use building, Copenhagen, Denmark—2079 kgCO₂e/m²;
• New office building (all electric) London, the UK—1647 kgCO₂e/m²;
• Office building (complete transformation): exterior steel frame with concrete columns retained, precast frames largely retained with minor strengthening, roof cladding with laminated zinc—1582 kgCO₂e/m²;
• Office building (refurbishment), London, the UK: foundation raft and piles strengthened, composite floors introduced, lightweight steel frame for some parts of the exterior—1515 kgCO₂e/m² (least carbon use).

The case studies indicate that construction for refurbishment/renovation sequesters less carbon in terms of total and per-square meter emissions than ground-up construction. Emissions per square meter are the lowest for the refurbished office building (0.0321 kgCO₂e/m²). Moreover, the annual energy consumption is the lowest for construction that incorporates natural and renewable materials such as timber.

The data gleaned from the case studies highlight a clear trend: refurbished or renovated buildings tend to exhibit the lowest carbon footprint among the examined options. This outcome underscores the sustainability benefits derived from the practice of reusing materials and implementing retrofitting techniques. By leveraging these sustainable approaches, refurbished buildings contribute significantly to reducing environmental impact, aligning with broader sustainability principles aimed at minimizing resource consumption and waste generation.

The expectation that refurbished buildings would exhibit a lower carbon footprint aligns seamlessly with sustainability principles, emphasizing the environmental advantages of repurposing existing structures over constructing new ones. This approach not only conserves valuable resources but also mitigates the environmental burdens associated with new construction, including raw material extraction, manufacturing processes, and transportation emissions. Ultimately, the data from the case studies reinforce the importance of prioritizing refurbishment and renovation strategies as integral components of sustainable building practices in the pursuit of environmental stewardship and carbon reduction objectives.

Interestingly, the data also reveal that new office buildings equipped with all-electric components compare favorably to their refurbished counterparts. This finding suggests that advancements in design, technology, and energy efficiency in new construction contribute significantly to reducing the carbon footprint. The favorable comparison indicates that the implementation of all-electric components in new buildings is an effective strategy for achieving sustainability goals.

The case studies underscore the importance of considering both refurbishment and new construction approaches in sustainable building practices. While refurbishing existing structures is commendable for its resource efficiency, the positive environmental impact of incorporating advanced technologies in new construction cannot be overlooked. The nuanced findings highlight the need for a comprehensive and balanced approach to sustainable building design and construction, taking into account both renovation strategies and innovative features in new developments.

It is important to note the potential challenges associated with new construction. The process of constructing entirely new buildings, in spite of incorporating energy-efficient components, most likely contributes to increased carbon emissions during the initial stages. This phenomenon, often referred to as the “carbon lock-in” effect, stems from the carbon-intensive nature of manufacturing building materials, transportation, and the construction process itself. Balancing the benefits of technology in new buildings with environmental impacts remains a crucial part of achieving comprehensive sustainability within the built environment.

5. Limitations

Undoubtedly, a study of this nature focusing on embedded carbon and whole-life cycle assessments demands substantial amounts of data, which can pose challenges in achieving representation across various jurisdictions. Given the complexities involved, we recognize the inherent limitations in obtaining a comprehensive sample that adequately reflects diverse geographic contexts. Considering these constraints, we opted to utilize readily available secondary data provided by the WBSCD [13] to inform our findings. While this approach allowed us to glean valuable insights, it is important to acknowledge the inherent constraints of relying on existing data sources and the potential implications for the generalizability of our results. Also, a case study approach is, by definition, a small sample, and the buildings selected for the case studies are not necessarily comparable. Ideally, one would have identical buildings that represent the full range of alternatives from modest to extensive renovation to new construction. Measuring carbon emissions across the full life cycle of buildings is still in its infancy. Future research will require data on carbon emissions from a broad cross section of buildings, representing different geographies and building typologies.

6. Policy Recommendations

The lessons learned from the case studies provide valuable guidance for governments, regulators, and industry stakeholders seeking to promote sustainable building practices. The clear trend that refurbished or renovated buildings tend to have the lowest carbon footprint underlines the importance of prioritizing reuse and retrofit techniques in building design and construction. Policymakers can use this information to develop and implement policies that encourage the refurbishment and renovation of existing buildings over new construction. By providing financial incentives, tax breaks or streamlined permitting processes for refurbishment projects, governments can encourage the adoption of sustainable practices in the built environment.

In addition, the data highlight the environmental benefits of reusing existing structures, in line with broader sustainability principles aimed at minimizing resource consumption and waste generation. Regulators can use this evidence to advocate for green building certification programs that prioritize refurbishment and retrofit efforts. By establishing standards and benchmarks for sustainable building practices, regulators can encourage an industry-wide adoption of green building practices.

The findings also highlight the importance of considering both retrofit and new construction approaches to sustainable building practices. While the refurbishment of existing structures is commendable for its resource efficiency, the positive environmental impact of incorporating advanced technologies in new construction cannot be overlooked. Industry stakeholders can use this insight to adopt a holistic approach to building design and construction, integrating both refurbishment strategies and innovative features in new developments. By investing in research and development initiatives focused on energy efficient building materials and technologies, industry stakeholders can further improve the sustainability of new construction projects.

However, it is crucial to recognize the potential challenges associated with new construction—in particular, the “carbon lock-in” effect resulting from the carbon-intensive nature of the production of building materials and the construction process itself. Policy makers and industry stakeholders need to work together to address these challenges by promoting the use of low-carbon building materials, implementing carbon-offsetting schemes and investing in renewable energy solutions for construction.

The problem today is that embodied carbon is not monetized; therefore, there is little if any investment incentive to renovate buildings rather than demolish them and build from the ground up. Unless the embodied carbon savings from renovation is monetized, it is often cheaper to build new buildings than to renovate and repurpose existing buildings. Carbon emission taxation is one way to achieve this, but such taxation is widely opposed in most countries today.

Taken together, the case studies offer valuable insights into the environmental impact of various building practices and highlight the significance of implementing sustainable approaches in the built environment. Governments, regulatory bodies, and industry stakeholders can advance sustainability in building design and construction by incorporating these findings into policy development, regulatory frameworks, and industry practices. This will pave the way for a more environmentally-conscious and resilient built environment.

7. Conclusions

The obsolescence of a significant part of the office building stock in the wake of the COVID-19 pandemic creates both a problem concerning what to do with them and an opportunity to repurpose many of them to residential or other suitable uses. The conversion of office to residential use, however, presents many difficulties. Only 15 to 30 percent of office buildings are considered good candidates for conversion. Low-carbon design techniques are the industry-accepted standard that need to be incorporated in construction projects to ensure a sustainable future for all.

Relatively few buildings can transform seamlessly without significant retrofitting and expensive reconstruction. In order to ensure that global sustainability standards are maintained, there is a need to establish common standards, methodologies, and a reporting framework with a clear understanding of what is to be reported, as well as how much sustainable renovation will cost compared to investment returns. This will prove to be important information as the industry strives to achieve uniform emission reporting standards.

In delivering these targets, major emitters in developed countries must deliver on their commitment to provide USD 100 billion a year for mitigation, adaptation, and resilience strategies in developing countries if a coordinated effect is envisaged.

The future of how office spaces will be reconfigured and function is not possible to predict, as owners and property managers need to adapt to the changing needs of occupiers based on well-aligned policy measures. Whole-life carbon reporting is a necessary step to ensure data collection and benchmarking and to allow the construction sector to develop necessary skills and capacity for effective mitigation strategies.

The implementation of a common reporting framework is pivotal in facilitating the creation of a harmonized open-source database accessible to all stakeholders involved in the building sector. This database would serve as a centralized repository, consolidating data that are currently fragmented across various stages of the building value chain and life cycle. By streamlining access to comprehensive data sets, stakeholders can make more informed decisions regarding carbon emissions and sustainability practices.

The case studies presented in this article underscore the significance of adopting a whole-life carbon reporting approach. By considering carbon emissions throughout the entire lifespan of buildings, from construction to end-of-life processes, stakeholders can better understand the environmental impact of repurposing obsolete structures. This holistic perspective enables stakeholders to identify opportunities for carbon reduction and align building practices with sustainability goals more effectively.