The role of engineering in the push for net-zero

Going back to basics: efficient design can deliver huge reductions in embodied carbon

When it comes to the push for net-zero, the odds couldn’t be higher. With global temperature rises rapidly ticking upwards, governments are scrambling to decarbonise their economies. Without firm climate action, global temperatures will continue to rise, leading to cataclysmic weather events and a catastrophic loss of human life.

Our industry more than most others has a big role to play. A whopping 39% of emissions come from construction, with 28% coming from operational costs and 11% coming from the construction process. If global climate emissions are to be curbed to any meaningful degree, we’ll need a complete step change in construction and the built environment.

It’s tempting to think that we need to wait around for some cutting-edge material that’s carbon negative while still providing all the same structural benefits as concrete and steel. But this is a lazy approach and one that we cannot afford to take.

With structural frames accounting for around 60% of a building’s embodied carbon, the engineer’s role is large when it comes to reaching carbon targets. In this blog, we’re going to examine the lay of the carbon landscape, highlighting what we, as structural engineers can be doing in the here and now to help our industry lay the foundations for a brighter future.

An industry finding its feet

If our efforts to decarbonise our industry were to be personified as a human, they’d be a well-meaning though slightly disorganised adolescent. Certainly no child, but not a sensible well-adjusted adult either. To put it simply, we’ve got a lot to learn and a lot of growing up to do.

That’s not an invitation to discredit some of the laudable work being done to transform our industry, but it’s all very preliminary and in many cases, not market ready.

The thing with construction is it’s slow to change. With time not on our side, we can’t afford to go through a protracted period of change. Developers and contractors like to stick to what they know. The proven methods they’re used to, to deliver predictable costs, time frames and safety standards.

While it might be tempting to stick to what you know, a refusal to evolve will do more damage to the environment and jeopardise your businesses in the long run.

As we move further and further towards the drop-dead dates for achieving carbon targets, carbon efficient buildings (not just operationally carbon efficient) will become more and more desirable. Alongside consumer behaviour, government aspirations will likewise also become regulations forcing the hands of those businesses yet to commit to change.

A period of change

Our industry is set for a period of rapid change similar to that which occurred during the 19th century. From 1815 to 1915, there was a sea change in the built environment with countless new structural technologies replacing old ones.

Timber gave way to cast iron, cast iron gave way to wrought iron and wrought iron gave way to Bessemer steel. Likewise, flooring systems went through several different technological incarnations from 1870 onwards, including some that were considered unsafe.

This period of evolution we find ourselves in here in the 21st century will need to be quicker than the last great built environment revolution (and thankfully more considered and safer). Hopefully, the external pressure of the climate crisis will be enough to motivate the industry to adapt in double time.

If that isn’t enough, the government will need to step in and lead with stringent policy enforcement.

Dragging carbon stragglers kicking and screaming into the future

There have been guidelines and nebulous ambitions floating around from the UK government regarding carbon in the built environment for years now. What’s lacking are policies and legislation with enough teeth to enforce action in the here and now and it’s hoped that the Part Z regulations will take force in 2025. The London plan – while great in principle – offers weak ambition on carbon strategy.

What this means is that the push to net zero is being left to the conscientiousness of the market. While in a perfect world this would be adequate, we all know that conscientiousness is often in competition with profit and profit seldom loses.

Thankfully, there is some positive movement in this regard, with developers becoming more and more open to carbon-efficient options because of their desirability from a building occupier’s perspective. It also helps that carbon efficiency can sometimes lead to lower costs (as we’ll explore later). However, there are still many stragglers who aren’t doing enough to tackle the carbon crisis in our industry. It’s for these unscrupulous outfits that decisive government legislation is required. When it arrives, they’ll have no option but to adapt or die.

What tools do we have at our disposal to decarbonise construction?

Climate change is occurring right this minute, so it stands to reason we have to change in step with it. That means we can’t hang around waiting for the perfect solution. We have to start the process of decarbonising our industry today. For the remainder of the blog, we’re going to look at the options in front of us.

“Wait!” I hear you say. “Don’t zero carbon buildings exist already?”

In operational terms, yes. That means there are buildings in existence that don’t generate carbon in their operational day-to-day functions. It doesn’t mean that the construction of those buildings is completely carbon-free.

So how do we relieve that carbon burden?

Do we need to build at all?

There’s no carbon burden where there’s no building. An honest question to ask is whether we need to build a development.

While this method delivers a 100% reduction in embodied carbon, it isn’t practical nor realistic.

It would be an exceedingly hard sell to say to a developer that they shouldn’t build anything. Further complications arise when we consider we’re in the middle of a global housing crisis. The UK has consistently missed its quota of 300,000 new homes a year and the country’s record of delivering affordable housing is already dire.

We need to build. But we also need to build smarter to reduce our carbon burden.

Making use of new tools, materials and methods

Surely there has to be some holy grail material that can deliver all the structural gusto we need without the carbon intensity of steel and concrete?

Unfortunately, we’re not quite there yet.

Granted there have been a few impressive prototypes delivered, using everything from straw to bamboo (perhaps the three little pigs were onto something…). But these are just that, prototypes for bespoke buildings and not necessarily suitable for mass production. These materials and methods are nowhere near market readiness or financial viability.

Even timber, a material consistently touted as a replacement for steel frames fails to deliver a carbon-free build. While it may have a part to play in the future, there is a supply issue to convert worldwide builds towards a timber-only model. Even if that weren’t an issue, the carbon is only sequestered for as long as the building is in use. As soon as those timber frames are disposed of, the carbon sequestered in them is released.

Can we just offset our carbon?

A relatively new model, carbon off-setting exists to allow developers and contractors to offset their carbon contributions by investing in initiatives that remove carbon from the atmosphere – like tree planting. Under this model, there can still be a carbon-intensive element to the delivery of a new building, as long as the off-setting gobbles up more carbon comparatively.

Sounds good right? While there are certainly positives to offsetting, it’s a controversial practice. Less carbon is a good thing. The issue is in its practicality. It works when a few companies do it, not when everyone does. There simply isn’t enough offsetting to go around for everyone.

For example, many offsetting initiatives include the planting of new trees, but this requires land. There are already concerns over big corporations buying farming land for offsetting purposes. When too much viable farming land is converted for carbon offsetting, we get stuck with food shortages and an agricultural sector on its backside.

How efficient engineering can lead the way in the fight for carbon reductions

While the progress of science and the advent of new materials will give us exciting new methods of decarbonising our industry, we needn’t wait on its progress to get started. While the problem of how we relieve our carbon burden is a complicated issue, the solution needn’t be.

Give or take a few flowery words, Occam’s razor states that the simplest solution is normally the best and that rings true when it comes to the push for carbon reductions in construction.

We stated earlier that engineers are in a unique position to have a considerable effect on the carbon cost of a project, primarily because a large portion of a building’s carbon burden is in the frame.

If we can design buildings more efficiently, we can deliver huge carbon savings and considerable cost savings for the client.

An industry where waste is endemic

Construction is a £100 billion industry with a £25 billion problem.

25% of all construction output is wasted because of errors and overdesign.

That’s not just monetary waste, that’s material and carbon waste. Simply by reducing that waste we can remove huge swathes of carbon from the construction process.

So how do we remove needless carbon from the process?

Set expectations at the outset and challenge inefficiency

At the outset of a project, an engineering consultancy should understand the expectations clearly, removing any doubt and uncertainty while opening up strong channels of communication with the client, architect and contractor. Once the specifics of the project have been gleaned, there is an opportunity to challenge inefficiency and offer improvements.

While it might seem a tough ask to encourage a client to dispense with treasured elements of a design, the prospect of improved viability is often a considerable carrot you dangle in front of their nose. The truth is, improving efficiency and removing waste delivers considerable savings in terms of materials and importantly for the client, costs.

Beginning a project with total clarity of what’s required considerably cuts down on site errors and enables engineers to completely remove structural overdesign and inefficient framing solutions.

Design for unity and leave nothing on the table

When we truly design for unity, we leave zero waste on the table and operate at 100% efficiency. Everything is delivered just as needed. Overdesign often occurs because of a desire to leave something in the back pocket just to be safe, but the building safety codes already have a bit in the back pocket, so compromising on maximum efficiency makes no sense.

Designing to unity removes profligate material usage and cuts down on site errors because the design is less convoluted.

Complexity = waste and inefficiency

When a solution gets convoluted, it’s nearly always inefficient. It’s all too easy to start designing wasteful and complex proposals. Designing to unity is difficult, but its the mark of a good engineer. Truly efficient designs require careful thought, high levels of engineering expertise and a willingness to go above and beyond to find the right solution.

Crunching the numbers of designing for efficiency

While efficient design isn’t going to completely remove the carbon burden from our industry, it will provide us with the tools to make a pronounced dent in our carbon output. As new methods and materials become available, this will deliver bigger and better carbon savings as the years go on until we reach total decarbonisation.

Simply aiming to be 10% more efficient each year will put us well on track to deliver carbon targets by the 2030 and 2050 deadlines. Until we have market-ready technology available to deliver net-zero builds, we mustn’t fall into the trap of thinking in too binary a fashion. It’s not a matter of choosing between carbon positive and no carbon net-zero activities. We have to be pragmatic and strive to use less carbon where we aren’t able to eliminate it completely. Any effort to reduce carbon will help us deliver better projects and lay the foundations for further carbon reductions down the line.

Consider the effect of the carbon savings that come simply from prioritising efficiency and designing for unity. Renaissance recently delivered a design for the frame of a 22-story residential tower. The design in place by previous engineers had the embodied carbon value at about 550 kg of carbon per m2.

Through working closely with the client, asking the right questions and challenging inefficient design decisions, we managed to deliver a beautifully lean and efficient design that reduced that burden down to below 300 kg of carbon per m2.

With consistent and ongoing effort, this number can be brought down further in the future. This can be achieved by:

  • Designing an efficient column grid
  • Designing the core and stability systems optimally
  • Specifying the concrete cycle times on floors
  • Considering the best construction technique for the building. For example, do you slip or jump the core, etc.

With amenable clients and willing architects, we’re finding that we can start to bring the embodied carbon number down to below 200 kg per m2. If we can get down to that number on a 22-storey residential development, that starts to get us close to carbon targets without too much industry upheaval.

When ameliorated by new technologies as they become available, we start to achieve genuine decarbonisation.

Embracing the future

Renaissance is an engineering consultancy driven by efficiency in design and delivery. This philosophy not only allows us to deliver more carbon-friendly engineering designs but in many cases allows us to deliver considerable cost savings to our clients.

Because efficiency is all about making more out of less material it doesn’t require any fancy new materials or methods that cost the earth. Just good, old-fashioned engineering know-how.

Our industry is in the middle of a step-change that will define the future direction of not just the built environment, but the entire human race.

Adaptation and change are coming whether we like it or not.

If we’re to live in a world in which everyone can thrive, we need to take our responsibility seriously and put efficiency at the top of the agenda.

This piece was co-authored by Helen Gribbon and Kevin Gilsenan