Building LCA and Carbon Footprint (GWP)

INTRODUCTION

The following guide aims to address some practical aspects related to the life cycle of buildings. An overview is given at a European level and then insights are developed on the Italian case and the voluntary BREEAM and LEED protocols.

The subject of LCA has existed for many years, but is now the focus of attention due to the increasingly stringent environmental demands linked to the subject of climate change.

Unfortunately, it is still a little known topic, especially in the translation and practical application of the literature. It is also often applied in an ‘unsustainable’ way.

STATE OF THE ART IN EUROPE

The current European situation is quite diverse. Some member states have guidelines on the use of LCA for buildings.

Some actually have numerical limits for carbon footprint and are included in local regulations, either as guidelines or as an obligation.

Others have no indication or refer to general guidance (such as the Level(s) framework).

What is being done is to inform as much as possible and to unify requirements, so as to facilitate comparisons and the achievement of targets on a large scale.

With the recent EPBD (Energy Performance of Buildings Directive), there is a shift from the concept of
energy to that of emissions. If before we talked about nZEB as ‘Nearly Zero Energy Building’, or ‘Net
Zero Energy Building’, or ‘Zero Energy Building’, now the focus has shifted and we talk about ‘Zero
Emission Building’.

If you think about it, in the end if one produces a lot of energy from renewable sources (so, simplifying,
let's say one produces it without polluting), why shouldn't one be able to consume it all?
If in a balance sheet we only look at energy consumption without seeing where it comes from and
without having a balance sheet on emissions as well, we might think that a large consumption might
represent something negative.

The subject is complex and there would be many considerations to make. To simplify, let us say that
when planning, one should reduce energy demand as much as possible and that this energy should
then come from on-site renewable sources. If more energy is then produced than consumed, we enter
into a Microgrid or Energy Community discourse, where the objective is to optimise consumption and
reduce waste.

Level(s) is a European framework that is becoming more and more established and widespread as a
guideline. In fact, in the new versions of the voluntary BREEAM and LEED protocols, the reference to
the three-level structure (concept, final design and as-built) is evident in the credits and issues related
to LCA. This makes us realise its enormous influence not only in Europe, but also globally.

For now, in many cases, what is done is to carry out an LCA as an end in itself.
This means having a report that indicates environmental impacts at the building level, for better or
worse.

Having an LCA does not mean reducing impacts, it simply means declaring them (e.g. the carbon
footprint is declared).

Doing the analysis is already a first step compared to not doing it. Let's face it, the analysis also serves
as a reference on building types, so as to create databases to compare the impact of my building with
another of the same type (as is done for energy classes).

But the real purpose of an LCA is to make people think, to make comparisons. It is a design tool if you
like. I have to show that I have done some thinking and that I have chosen materials that have reduced
the impact of the building. That is what we must aim for.

In Italy, Life Cycle Assessment (LCA) is not a compulsory aspect and is not yet standardised.
We find it as a rewarding criterion in public tenders, i.e. in projects requiring compliance with the
Building CAM and the DNSH (Do No Significant Harm) criterion.

The LCA remains rewarding due to the lack of experience among engineers and professionals in the
construction sector.

One must first have the specific theoretical knowledge and then also practical experience. LCA also
requires the use and thus knowledge of software.

These represent huge stumbling blocks, which is why one relies on consultants who are experts in the
field.

Referring to the application of what comes from the European Union, in Italy there is talk of adding to
the energy label of buildings, also a label indicating the carbon footprint, thus relating to GWP (Global
Warming Potential).

This for now is just an idea that will perhaps be made compulsory in a few years' time (now it is not
feasible, precisely for the reasons given so far). Together with energy modelling, we could have LCA
modelling. In addition to having the energy consumption information in kWh/m2 we will also have the
carbon footprint in kgCO2 eq/m2.

Lately, even in the protocols, more weight and importance has been given to the LCA of the building. In
fact, especially in the latest versions of LEED (v5) and BREEAM (v7), the credits and issues relating to
LCA have been calibrated, referring to the Level(s) framework.

There is still the possibility, for example, in LEED to get one point if one does an LCA analysis (thus
without comparisons and improvements). But it only stops at one point.

If you want to obtain more points, you have to demonstrate an improvement of a certain percentage
with respect to at least three indicators, including GWP.

The comparison is made against a baseline that is created, keeping the boundary conditions the same
(building and its characteristics). Only the materials or elements of interest are changed.

In BREEAM, precisely the division into three levels is taken up and therefore the possibility is given to
do a single analysis (corresponding to only one level), or several levels. If the LCA is considered at all
stages and we end up with three di>erent analyses, we can obtain a higher score.

Also in protocols, LCA analysis can be (and should be) understood as a Building Optioneering tool.

When you want to reduce the environmental impacts of your building, you have to stop for a moment
and ask yourself a few questions:

• Are there environmental indicators that are more important than others to consider for this
  project?
  For example, if you are in the middle of fields and there are natural elements to be protected,
  you can consider biodiversity indicators in addition to the classic GWP.
  This will make the comparisons and choices contextualised to the specific case.
• Based on my experience, can I already identify elements or materials with greater impact? If
  yes, I could already make some improvement design assumptions.
  For example, if I am building logistics, I can say with certainty that one of the highest impact
  elements will be concrete, as it is well known that the cement sector has one of the highest
  impacts. Furthermore, in the case of logistics, the use of concrete is massive (just think of
  industrial flooring).
• Before thinking about materials, did you put into practice all design strategies to reduce
  consumption and impacts, also thinking about the long term (use and end of life)?
  For example, working on the orientation and shape of the building, the position and type of
  openings, the e>iciency of installations, etc.

It is essential to have a project that first optimises all these aspects, before thinking about comparing
materials (those who have had experience with Passivhaus-type protocols know these aspects very
well).

With this image I would like to highlight this aspect, that of the focus almost exclusively on carbon
emissions.

I am not saying that they are not important; on the contrary, they are crucial. The GWP indicator is
always to be taken into account, but surrounded by other indicators as well.

Maybe not necessarily all of them (there are more than forty...), but depending on the context and the
project, some should be selected and compared. There are also regional priorities, where some areas
may be very important and therefore to be considered, such as reduction of water consumption,
biodiversity, human health.

Talking about cement means entering the world of embodied emissions (embodied carbon) and
biocements made from microalgaeront carbon, i.e. those emissions that are released into the atmosphere
before the building is occupied.

Decarbonisation and circular economy strategies in the cement sector are:

• Use of alternative fuels;
• Substitution of natural raw materials (with blast furnace slag, fly ash, natural pozzolans,
  calcined clays);
• Reduction of waste sent for disposal;
• Selection of suppliers who declare the use of raw materials with
  recycled/recycled/underproduced content.

A combination of interventions and strategies can help reduce embodied carbon.

The cement sector has defined decarbonisation pathways to reach the net-zero target in 2050. Despite
the fact that cement is one of the most carbon-intensive materials (high GWP), it remains and will still
be crucial for future construction.

A necessary short-term step on the path to net-zero is to increase the e>iciency of building design and
material utilisation to minimise the overall volume of concrete required. On the production side, the
main means of reducing the carbon intensity of concrete at present is to reduce the cement content,
which accounts for up to 90 per cent of the carbon embedded in concrete.

In addition to cement substitution, further methods are available to reduce the carbon intensity of
concrete, including the use of recycled aggregates, decarbonisation of the electricity grid and savings
in clinker production processes (increasing thermal e>iciency and using alternative fuels).
Emerging technologies that have the potential to make carbon-neutral concrete include on-site
carbon capture technologies and CO2 re-carbonisation.

There is more and more talk of innovation in the construction sector and in particular in materials. The
need to reduce the carbon footprint of materials requires investment in research and an increasing
reliance on innovative materials.

As far as cement is concerned, some examples are cements that reduce the amount of clinker,
biocements made from microalgae and carbon capture.

With regard to the LCA analysis and the reduction of impacts of a logistics building, we can first
identify the most impactful elements:

• Concrete (precast structure, industrial floor, external yards and foundation castings);
• Trapezoidal sheet metal and roof insulation (due to the large areas to be covered);
• Substrates;
• HVAC.

With regard to installations, it is currently not easy to make specific analyses, as there are still few
EPDs within the market. Therefore, real impacts cannot be simulated.
What is done for installations is to select local impacts and to include the building surface in the
simulation.

On the other hand, some materials on which one can act directly are the others listed. Let us see them
in detail below:

• In-situ concrete → search for concrete plants that are close to the construction site and
  possibly have strategies to reduce impacts.
  It may be useful to ask for documentation, such as EPD (Environmental Product Declaration),
  CSC (Concrete Sustainability Council) certification, mix-design and recycled content.
• Precast concrete structure → search for manufacturers with impact reduction strategies.
  Many companies are working on mix-design using recycled materials (such as industrial slag)
  and favouring cements with lower clinker content.
• Trapezoidal sheet metal and roof insulation (because of the large areas to be covered) →
  especially the choice of insulation is important because there is a big di>erence in terms of
  environmental impacts. For example, a PIR can impact about twice as much as an EPS in
  terms of GWP (comparing them with the same performance).
• Sub-bases → Due to the large amount of sub-bases for both the exterior and the entire
  warehouse part, it is appropriate to use crushed stone from other demolitions instead of virgin
  aggregate.

In general, for a medium to large logistics building, if all the above strategies implemented are taken
into account, a 10% improvement on GWP can be achieved compared to a baseline (defined as ‘builtas-
usual’).