Case study

Carbon Expert - Gilbert Lennox-King

Carbon Expert - Gilbert Lennox-King

Source: Pexels

A recap of the conversation with guest expert Gilbert Lennox-King, from our Carbon Experts Live series

An Introduction to Gilbert Lennox-King

Meet Gilbert Lennox-King, a visionary and passionate leader in sustainable construction. His spark was lit in 2007 when the movie “An Inconvenient Truth” awakened his curiosity about climate change and set him on the path of promoting energy efficiency. More recently, he has been delving into the world of embodied carbon and realizing the pressing need to reduce the impact of thiscarbon-expert_gilbert-lennox-king-cel-66016f5af2099 “upfront” carbon. Gilbert conceived and co-founded Construction Carbon, a leading global energy efficiency business, where he’s worked with blue-chip clients on energy optimization and carbon efficiency. He also co-chairs the Innovative Startup committee at the UK Green Building Council. Most of all, he’s deeply committed to reducing barriers to decarbonizing construction.

I sat down with Gilbert to understand how we can reduce the barriers to decarbonizing construction and speed up our progress. In this interview, I wanted to understand how he thinks we can achieve our 2050 goals. I wanted to find out if he thought that policy was the main driver of decarbonization, learn what is working in his region, and find solutions that could be applied across regional and cultural divides. 


Net Zero for All: Unlocking Achievable Low Carbon Construction

A Common Definition Of Net Zero

I love challenging my guests with tougher questions, so I asked Gilbert how he defines Net Zero. Without a common understanding of Net Zero, it’s difficult for companies to set targets and make meaningful progress.

Gilbert pointed out that as we create a definition, it needs to be a collaborative effort. We need to get together as a globe and come to a common understanding. The world trying to adopt the standards of just one country isn’t working. He also pointed out that the solution needs to be as simple as possible, and mentioned NABERS (National Australian Built Environment Rating System) as a successful scheme to model after. NABERS’ success is partly due to its simplicity and ease.

Ultimately, we landed on the fact that Net Zero should be a thorough accounting system where we calculate all the CO2 added and removed from the atmosphere. It’s a big ask, as the global economy is a very complex system with many inputs and outputs. It’s going to be a monumental task to accurately track and forecast these numbers. But just like a household budget, we can’t plan for the future without accurately measuring today – and Net Zero accounting is no different.

The Map To Net Zero: Assess, Reduce, Offset, Report

Roadmaps can be great ways to untangle the noise and simplify a process. Gilbert shared his thoughts on a roadmap to reduce construction carbon emissions:


The first step is to assess or measure how much carbon emissions are produced during construction projects. This includes mining, manufacturing, transportation, and energy used during the building process.


Once we know how much carbon emissions are generated, the next step is to find ways to reduce them. We can do this by using lower-carbon materials and implementing sustainable building practices. For example, retrofitting an existing building can significantly reduce carbon emissions compared to new construction.


Despite our efforts to reduce emissions, it may not be possible to eliminate them. Offsetting is compensating for carbon emissions by supporting activities that reduce an equal amount of greenhouse gases. For example, reforestation or carbon capture technologies.

Gilbert also highlighted the importance of transparency in offsetting environmental impacts locally. Insetting, (offsetting within a company’s supply chain), helps companies take responsibility for their emissions.


Finally, it’s key to keep track of the progress made. Reporting includes recording the data, analyzing the results, and sharing the findings with relevant stakeholders.

This transparency allows everyone involved in projects to be aware of their environmental impact and find ways to work together to improve.

Closing the Gap for Smaller-Medium Companies:

Gilbert is aware that small to medium-sized companies contribute a large share of the industry’s carbon emissions. Large corporations often have more resources, visibility and ability to address environmental impacts. Smaller companies struggle to access sustainability resources, knowledge, and financing.

This is something that gets both of us excited. It’s my goal through One Click LCA to equip small companies with the tools they need to assess their environmental impacts. It’s also my passion to make it easier for these companies to understand sustainability. As Gilbert put it, nobody wants to read and decipher an 18-page report on construction carbon.

So, how do we close this gap for small to medium-sized companies? Gilbert prescribes training, benchmarks, and a global carbon price.


We need training in this industry to be accessible. Gilbert emphasized the importance of training to achieve this common understanding. Accessible and digestible training can help everyone in construction gain the knowledge needed to reduce their carbon footprint.

I’m eager about training as well. It’s why we provide free training through One Click LCA. If you want clear guidance in the noise of sustainability, access our huge library of resources through our academy.

Global Carbon Price

Gilbert feels a huge opportunity lies in creating a global carbon price. I see this as a real-world cost that’s historically been externalized. The consumer of a product should bear the environmental costs of that product, rather than insurance companies, governments, or at worst, individuals whose lives or businesses are effected by manufacturing processes or natural disasters that result from climate change. A universal carbon price would add future costs to the purchase price of the product (like a core charge on a recyclable product), this money to be funneled into adaptive technologies and processes to help us in the future.

A universal carbon price would also help level the playing field. It would encourage companies to prioritize sustainability in their operations. It could financially incentivize developers to adopt “greener” construction practices. Financial incentives could be a game-changer for smaller companies, especially those that struggle to invest in sustainable initiatives.

A global carbon price would undoubtedly simplify decision-making and incentivize sustainable practices. That said, Gilbert acknowledged that its implementation might take time. In the meantime, he advocated for collective action based on the existing landscape.


Developers could be incentivized to embrace “green construction” through financial incentives. For example, offering rebates on loans based on sustainability goals. Banks and financial institutions can play a pivotal role in driving change in the construction industry. This could encourage hesitant developers to commit to sustainable practices.


Establishing benchmarks is another essential aspect to close the gap. With clear guidelines, companies of all sizes can measure their progress. This would allow stakeholders to speak the same language about emission reduction strategies.

Data Landscape Challenges

Gilbert expressed that the incomplete and inconsistent data landscape is a major hurdle in setting benchmarks. There are varying data sources, methodologies, and interpretations, which makes it  difficult to establish standards for carbon emissions in construction projects.

One of the areas where data inconsistency poses a challenge is in Life Cycle Assessment, or LCA. LCA evaluates a building’s environmental impact throughout its life cycle. From raw material extraction to construction, operation, and demolition. The lack of harmonization in LCA methods makes it difficult to compare data, thus making it almost impossible to draw concrete conclusions from different assessments.

To address this issue, Gilbert emphasized the need to establish a common set of parameters for conducting LCA. Working with the same datasets would provide more accurate and comparable assessments. Organizations like One Click LCA are making significant efforts in this direction. One Click LCA offers valuable training and tools to aid in understanding and implementing LCA practices.

Gilbert emphasized the importance of not waiting for the perfect dataset to act. The urgency of the climate crisis demands action now, and waiting for a flawless system would hinder progress. Instead, he encouraged the industry to make use of the available data and improve the methodologies over time.

Driving Sustainable Retrofitting

Retrofitting existing buildings holds immense potential in the journey towards sustainability. Gilbert emphasized that by reusing existing structures, we can make a huge dent on embodied carbon. Retrofitting allows us to forgo the extraction and manufacturing of many new materials.

Retrofitting also presents an opportunity to integrate cutting-edge technologies and innovations. Gilbert encouraged the exploration of energy-efficient systems and materials during the retrofitting process.

Accurate LCA reports help decision-makers make informed choices during the retrofitting process. It helps them find areas for improvement to achieve the most carbon reduction. Understanding the implications of materials can guide the selection of sustainable alternatives.

However, to harness the full benefits of retrofitting, transparency and accuracy are essential. Gilbert stressed the importance of clearly stating assumptions in LCA reports. Documenting assumptions made ensures that the data used is credible and allows others to verify the findings, both today and in the future.

Insetting vs. Offsetting

As I continued the conversation with Gilbert, I asked him about the challenges of offsetting. He pointed out that while there are options for local credits in the UK, they can be limited and expensive. Instead, he advocated striving for absolute reductions rather than relying on offsetting. He encourages “insetting” within your supply chain rather than, for example, planting trees in other countries.

So much can be done through absolute reductions and insetting. The serendipity is the incredible insight that comes from learning the details of your business’s supply chain. You discover surprising financial inefficiencies when looking for ways to reduce carbon emissions, so that building “greener” can oftentimes be more cost effective than continuing the status quo.

Lessons from the UK

I’ve noticed that the UK has pioneered construction carbon reduction. I was curious if the rest of the world could take a few lessons. The UK’s successful adoption of LCA has been driven by schemes like BREEAM, which have become a standard for many developments. Gilbert emphasized the power of collaboration and a common vision. The UK Net Zero Carbon Building Standard involved nine organizations crafting rules for what “zero” means.

The United Kingdom has been at the forefront of sustainable construction practices. Gilbert highlighted some valuable lessons that can be drawn from their success. One of the key factors contributing to the UK’s sustainability leadership is the adoption of LCA methodologies. This is facilitated by schemes like BREEAM (Building Research Establishment Environmental Assessment Method).

BREEAM has become a widely recognized standard for sustainable building certification. It encourages developers to meet high environmental performance targets. The scheme evaluates various aspects of a building’s sustainability, including energy and water usage, materials, and waste management. By incentivizing the use of LCA in its assessment process, BREEAM has forged the path for LCA adoption in the UK.

Gilbert reminded us that collaboration is a huge part of the UK’s sustainability journey. The UK Net Zero Carbon Building Standard is a great example. They brought nine organizations together to define what “zero” means for building carbon emissions. This collaborative effort brought together diverse perspectives and expertise. By setting a common vision, the UK has paved the way for consistent and unified efforts toward decarbonization.

Another valuable lesson from the UK is its proactive approach to regulation and policy. Initiatives like the Greater London Authority’s requirement for large sites to conduct LCA demonstrate the government’s commitment to promoting sustainable practices. By integrating sustainability goals into regulations, the UK has incentivized developers to embrace greener construction methods and prioritize carbon reduction.

As the world grapples with the urgency of climate change, the UK’s success story offers a blueprint for other countries and regions to follow. 

If You Could Change One Thing…

When asked if he could change one thing about construction carbon, Gilbert expressed his desire for a global carbon price. He believes it would be a game-changer, driving decisions and encouraging developers to prioritize sustainability. More than that was his urge for countries to make decisions together. 

Question From Our Last Guest

In our last Carbon Experts Live interview, Helen Cheng asked Gilbert about steps to mainstream whole-life carbon calculation for the construction industry. He emphasized the importance of training and creating a common understanding of the rules and benchmarks. Gilbert suggests EN 19578 (an LCA calculation method) could be a suitable candidate for standardization. Organizations like One Click LCA actively work toward these initiatives and offer valuable training. The key lies in establishing a shared understanding of benchmarks and the strategies to achieve them. Shared objectives will foster greater adoption of whole-life carbon calculation practices in the construction sector.

Unlocking Achievable Low-Carbon Construction

Gilbert’s parting message was powerful and inspiring. “We’re only scratching the surface of what’s possible,” he said. He encouraged us not to be paralyzed by the pursuit of perfection but to take the first steps toward sustainability. “Don’t let perfection get in the way of good,” he emphasized, urging us to get started, learn, and continuously improve.

My Takeaways

After the interview, I found myself reflecting on the insights shared by Gilbert. His knowledge of the space is invaluable. His commitment to reducing emissions in construction was evident, and his vision for a sustainable future was infectious. It reminded me that we all have a role in creating a greener world.

One of the most significant takeaways from our conversation was the need for collaboration and consensus. Gilbert emphasized that to tackle the challenge of reducing carbon in construction, we must all come together as an industry. By setting benchmarks, clearly defining net zero, and sharing best practices, we can create a powerful ripple effect to drive positive change.

Another aspect that resonated deeply with me was his approach to embracing imperfection. He encouraged us not to be paralyzed by perfection but to take action, even if it means starting with imperfect solutions. The journey toward sustainability may have its challenges, but the most critical step is getting started and improving along the way.  

Gilbert’s passion and optimism left me feeling hopeful about the future. If we all come together and take action we can make an impact that will shape the world for generations. The challenges of climate change are immense, but as Gilbert reminded us, “We’re only scratching the surface of what’s possible.” So, let’s not be discouraged by the enormity of the task ahead. Let’s be inspired by Gilbert’s call to action, not letting perfection get in the way of good, and simply getting started.


About ‘Carbon Expert of the Month’

Carbon Expert of the Month is One Click LCA’s way to showcase the expertise, inspiration and best practices of One Click LCA users. Each month, we feature experts who are passionate about reducing carbon in general and from materials in particular, who seek to push projects beyond the boundaries of common practice, and who wish to share from their personal experience.

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