EPISODE: 038 - APPROVED DOCUMENT Z - WHOLE LIFE CARBON

BYTNAR - TALKS

EPISODE: 038 - APPROVED DOCUMENT Z - WHOLE LIFE CARBON

This episode is for people who want to know more about the proposal of Approved Document Z

You should like this episode if you ask yourself questions like:

• What is the impact of construction materials on UK greenhouse gas emissions?

• How do whole-life carbon requirements affect construction projects in the UK?

• What is the difference between embodied carbon and operational carbon in buildings?

• What are the A1-A5, B1-B7, C1-C4, and D lifecycle modules in BS EN 15978?

• What are the proposed requirements Z1 and Z2 for carbon assessment and carbon intensity?

• When will the whole-life carbon regulations (Z1 and Z2) come into effect in the UK?

• How does the RICS Professional Standard define whole-life carbon assessment?

• What is the role of biogenic carbon in whole-life carbon assessments?

• How will the UK government enforce carbon reporting for construction projects?

LET'S TALK ABOUT YOUR PROJECT

---

This is Bytnar Talks – The Engineer Takes on Construction, Episode 38.

Hi, I'm Piotr Bytnar. Each day, I help my clients plan and design building projects through Bytnar Limited – a consulting Chartered Structural Engineers practice.

My biggest passion, and the cornerstone on which I've built my business, is finding clever solutions for construction projects.

I am a Chartered Structural Engineer and a budding software developer, so you can rest assured that I will strive to talk about best practices and the use of new technologies in the industry.

And if you're embarking on a construction project or are involved in planning, designing, and building the world around us, you'll find this podcast useful.

Approved Document Z – Whole Life Carbon

Hi guys, and welcome to Bytnar Talks, your favorite podcast on all matters of architecture, engineering, and construction.

It is Thursday, the 5th of December, 2024, and I'm here, back with you, with the 38th episode and information on Approved Document Z – Whole Life Carbon.

Who doesn't love the period towards the Christmas break? We are all working at full throttle, delivering designs and solutions to sites all over the place, just so everything is nicely tied up before the curtain falls and most of us go for a well-deserved break.

I'm planning to close the year with 40 episodes of this podcast and restart recording the second week of January.

So, let's start with the delivery of this one. But before I move forward to the new material, let's recap the past episode.

In the last episode, I talked about the Approved Document 7 – Materials and Workmanship, which is covered in two sections.

Section One deals with materials, where building regulations tell us we need to use materials that are fit for purpose. No brainer there, really, is there?

We are flexible on the use of the material, though, as long as we meet performance and functional requirements. Compliance can be demonstrated through the use of CE marking, British Standards, international standards (with proper justification of their appropriateness—if there is such a word—for the British market), independent certifications, or historical performance evidence of the material in use.

Authorities may inspect materials under Regulation 46 or impose conditions to ensure safety for the use of more perishable materials that need to be accessible for maintenance, replacement, and repair whenever needed.

Some further restrictions are applicable to combustible materials in tall residential buildings – but we well know about this one. We’re talking buildings over 11m and, obviously, 18m.

Section Two – Workmanship – deals with, guess what? Well, workmanship, right?

Which basically needs to be of good and proper standard to ensure safety and functionality. This can be fulfilled by following the guidance of CE marking standards or following the British Standard 8000 series.

Independent or proprietary certification schemes are also a very good starting point. Quality can be further verified through robust management systems, past performance, and regulatory tests like sound insulation testing, ventilation, or pressure testing.

The British Standard 8000 series outlines detailed workmanship standards across various construction tasks, covering things like principles and specifications of masonry, roofing, glazing, drainage, and so on.

In this episode, I will move to the possible future Approved Document – the Approved Document Z: Whole Life Carbon.

So without further ado, let’s dive straight into this.

The world is changing, dear friends. We’ve reached the apex of growth, and now we look into making things better for us all.

You know, most of us can buy a car, a home – or at least rent one, right? Or have an avocado and egg?

Once you get to this level of development, it doesn't really make sense to just keep on going the old ways. And when you have global information exchange and most know about things having a global impact, a global discussion follows straight after – about things of daily occurrence, and things like big disasters are very quickly spread throughout the land.

Now, on the topic of global warming, or perhaps cutting ourselves away from the dictatorship world of OPEC, hydrocarbon dependencies, and whether building more when there is enough is a good idea – you will find many opinions.

And the proposed Approved Document Z is such an opinion with a difference.

It actually drives a solution. Whether the solution is good or bad – there is still time to see. But for certain: if we do not measure what we do, we will have no clue where we are heading.

Several European countries do it already. But hey, the European Union likes to formalize everything, don’t they?

But on this front, I trust they are right.

The information on the proposed document, as well as the actual document proposal, can be found on the Part Z website. You can head to this space to endorse the initiative. I have already.

Frankly, without this legislation, we will maintain the status quo of wasters and—well—inconsiderate monkeys, just because we can. As long as the investments will pay with dividends, we will continue to build wastefully.

In my over 10-year career in the construction industry, I have learned that finance and legislation are the only forces that matter—and we can certainly influence legislation to make that change.

All right, so let’s have a look into the nitty-gritty of this proposal.

So what is the fuss all about?

It’s about the not-so-clever use of materials. According to information provided by the Institution of Structural Engineers, 10% of the UK’s total greenhouse gas emissions is due to the creation and use of construction materials—giving an impressive 64 million tons of CO₂ equivalent per year, which is quite a substantial number, nearly on par with agriculture and electricity supply, according to government data from 2023.

The rate of reduction of emissions is also lagging behind the electricity and the industrial sectors.

So, the idea is to drive that downward with a positive trend—even further than we are doing right now—and to do so through legislation.

The proposal is rather short and sweet, as it should be, and I’m reviewing its proposal revision number two of the 31st of January of this year—the godly year 2024.

The proposal proposes—right, proposal proposes, blah blah blah—dealing with the matter in two requirements:

• Requirement Z1, treating carbon assessment

• Requirement Z2, dealing with carbon intensity

The idea is to give meaning to the whole life carbon requirements for projects with a gross internal area of 1,000 square metres or more, or such that create more than 10 dwellings.

It is being proposed to contain this within three sections:

• Section One is to set out the relevant legislation and shows us steps to demonstrate compliance.

• Section Two informs us of the considerations to apply to the whole life carbon assessment, using the life cycle module nomenclature of BS EN 15978 – Sustainability of Construction Works: Assessment of Environmental Performance of Buildings – Calculation Method.

The modules are:

• A1 to A5,

• B1 to B7,

• C1 to C4, and

• D

I will finish this episode by expanding slightly on each and every single one of them.

It is envisaged that Requirement Z1 will kick in from 1st January 2026, and Requirement Z2 two years later.

The actual writing of the requirement does seem to be a little too little. I would rather like to see an implementation of minimum digital information for all buildings, applied at certain intervals—say, every 5 years—no matter the size and type of building.

In addition, and perhaps a provision of showing an alternative minimized embodied carbon version of that building, as this will help us track the actual feasibility of construction.

Anyhow, I will read you the proposal so you make your own judgment.

The proposal as laid down to be put into legislation:

Requirement Z1 – Carbon Assessment

Whole life carbon emissions shall be assessed and reported for the building and any other part of the project where building regulations apply.

Requirement Z2 – Carbon Intensity

Reasonable provision shall be made for the minimization of carbon emissions.

The intention behind the document is to level the playing field when it comes to the assessment of buildings by using the same standards in evaluation and reporting—to drive the change by decreasing the upfront embodied carbon intensity of the building to reasonably achievable levels.

In Section One, we are asked to fill in the form with the whole life carbon data, as defined in BS EN 15978—so, A's, B's, C's, and D's information.

We are told that A should not exceed the set limit.

Section Two treats the whole life carbon assessment. We are given a handy table to fill in, and we are sent to the RICS Professional Standards for Whole Life Carbon Assessment for the Built Environment – Second Edition, for how information is handled, with a slight tweak to the method described in module B6, where the energy usage should be evaluated to Approved Document L.

We are reminded that sequestration should not form part of the upfront carbon calculation.

The builder is made responsible for reporting on as-designed and as-built whole life carbon, using standard factors for the upfront determination and actual Environmental Product Declarations for the as-built report, which should be submitted digitally to a governmental portal.

Section Three sets limits for the upfront embodied carbon emissions—that is, Modules A1–A5.

The assessment should be made against the nationally set performance levels. These levels are not yet set and will require data from the industry for the initial assessment.

The period for gathering the initial data is envisaged to be 2 years, and then revisited every 3 years to allow improvement, but also to control the level to a reasonable standard for most of the industry—while stopping the worst offenders in their tracks.

The idea is to extend the limits across most modules with time, but starting with the A modules will do for now.

Okay, what are the modules about then?

According to RICS (or “Rick” as cleverly put), they made several distinctions and created a nomenclature of their own.

I’ll go with it bit by bit, breaking the whole thing down.

We start with whole life carbon assessment information, which simply means all the information.

That grouping is then divided into:

• Whole life carbon (aka System Boundary), and

• Information beyond the construction works life cycle (aka Benefits and Loads Beyond the System Boundary / Life Cycle D)

There are four life cycles: A, B, C, and D.

Within all of them, the biogenic carbon—you know, the stuff sequestered within the material—is reported on separately.

Life Cycle D is further divided into:

• Module D1 – net output flows from reusing the physical elements in any way, shape, or form possible

• Module D2 – resource generation of that building throughout its use

The whole life carbon assessment information consists of two parts:

1. The whole life carbon assessment, and

2. Life Cycle D (treated separately)

In other words:

• The actual stuff that is used by the creation, operation, and—comm… communion… bloody hell—commissioning of a building,

• And the stuff that can be reused, and the good stuff the building produces.

The whole life carbon section makes a distinction between:

• Embodied Carbon,

• Operational Carbon, and

• User Carbon

Breaking down Embodied Carbon (aka life cycle embodied carbon)—it is covered by:

• Life Cycle A – Upfront Carbon

• Life Cycle B – In-Use Carbon

• Life Cycle C – End-of-Life Carbon

Life Cycle A:

Further divided into:

• Pre-construction Stage A0 – preliminaries and design

• Product Stage A1–A3 – raw material supply, transport, and manufacturing

In-Use Stage B1–B5:

• Use of the building, maintenance, repair, replacement, refurbishment

Life Cycle C1–C4:

• Deconstruction and demolition, transport, waste processing, and disposal

Operational Carbon is treated separately from embodied carbon and is contained in:

• Modules B6 and B7 – operational energy and operational water

User Carbon is covered in:

• Module B8 – activities not covered in modules B1–B7 (e.g., commuting, service vehicles, and other ancillary stuff associated with building use)

So, this is it, folks—the potentials of Approved Document Z – Whole Life Carbon.

Let’s sum it up:

The proposal addresses the significant contribution of construction materials to the UK’s greenhouse gas emissions, aiming to drive reductions through a standardized approach and legislation.

It introduces:

• Requirement Z1, which mandates whole life carbon assessments for buildings over 1,000 m² or developments with more than 10 dwellings, hopefully starting January 2026

• Requirement Z2, focusing on minimizing carbon intensity, hopefully effective from 2028

The standard leverages the BS EN 15978 framework, requiring life cycle carbon data from:

• Modules A1–A5, B1–B7, C1–C4, and D1 & D2,

  
  

  and emphasizes upfront embodied carbon limits in early phases (Modules A1–A5).

Builders must report both designed and actual carbon data digitally.

The framework used is the RICS Professional Standard, which guides the assessment and separates:

• Embodied carbon,

• Operational carbon, and

• User-related carbon impacts

Modules are grouped by life cycle:

• Life Cycle A – Upfront Embodied Carbon (production and construction)

• Life Cycle B – In-Use Carbon (operation and maintenance)

• Life Cycle C – End-of-Life Carbon (demolition and disposal)

• Life Cycle D – Reuse and resource generation benefits

Operational energy and water are treated as separate entities in Modules B6 and B7, and user activities are in Module B8.

Initial performance levels will be set after 2 years of data collection, with reviews every 3 years thereafter to refine benchmarks.

This standardized, iterative approach aims to curb the worst practices while enabling industry-wide progress toward sustainability.

So undoubtedly, we need to visit the RICS Whole Life Carbon Assessment for the Built Environment published standard to get a little more acquainted with it.

And also have a look into the Building Environment Carbon Database 2, which is available for free online.

I will leave you with a perhaps different frame of mind than the one you had before.

As some will say:

“The grid becomes greener and greener, so operational carbon becomes.”

And less important, so will the production of materials become less carbon-heavy?

But if that’s the case, should we not still push for better buildings?

Sure we should.

Just because something is more environmentally neutral does not mean we should abuse it use.

In the next episode, I will talk about the Building Safety Act.

I hope you enjoyed this episode.

Making sure buildings are considered wholesomely, and adding some limits to the use of materials, makes sense, does it not?

In a future episode, I will go through the carbon assessment of a building, so you have a better appreciation of this also.

If you have any questions, reach out to me on LinkedIn or send me an email—I’m more than happy to help you out.

At Bytnar, we deal with planning, designing, and managing your projects, and we are always glad to facilitate a free initial consultation to steer you in the right direction.

Visit www.bytnar.co.uk and reach out to us—whether your question is:

“Can you help with my project?”Or“What should I do?”

We will be able to give you a piece of no-obligation advice.

At Bytnar, we help our clients design and execute their dream homes or investments.

And if your building is falling apart—we can also help investigate the reasons behind it and provide you with an appropriate strategy, design, and specifications for the repair.

Thank you again for listening.

Please voice your opinions—I’m waiting for you on LinkedIn, and I want to hear from you.

See you next week.

Bytnar Designs the World Around You.Toodloo!

---

Piotr Bytnar BEng (Hons) MSc CEng MIStructE

Chartered Structural Engineer who deals with the Architecture of buildings. His Master's Studies led him to an in-depth understanding of risk and contract arrangements in construction as well as specialist knowledge in soil mechanics.

He and his team help homeowners and property developers to design and deliver construction projects reducing waste in time and the cost. He believes that the construction project is an iterative process that can be well managed and it is best managed if all the aspects of the project definition and management are dealt with in-house or coordinated by one organisation. His team works to all stages of RIBA and ISTRUCTE stages of work and enables contractors to deliver projects on-site providing risk evaluations, methodologies for execution of works and temporary works designs.

---