Building materials and sustainability

BUILDING MATERIALS AND SUSTAINABILITY

What really matters when selecting materials

DEAR READERS

The fact that this report has made it into your hands shows that you’re thinking about different material options for a building project – and clearly, you’re putting some thought into sustainability. That makes us happy!

If you’ll allow us to adopt a slightly different approach for the foreword of this report, we’d like to start with what not to expect. The pages that follow will not offer you recommendations on specific construction products. Nor will they recommend certain building methods. We will also not evaluate individual materials. The reason for this is that there are no catch-all solutions when it comes to the right building materials. Every building project is unique. Every building has to be considered differently. Thus choosing materials isn’t something you do when embarking on a construction or refurbishment project, it happens by itself while working out the best way to deliver a project.

What you can expect from this report is the topic broken down into different aspects relating to the overall issue of sustainability. You will also be introduced to different ways to solve problems, including methods that will help you work out what types of materials to use for individual projects. We’re convinced that as architects, planners, building owners or those responsible for projects, you will not be the only ones to benefit from this: looking at materials from different angles is the only way to transform the building sector to become sustainable.

We hope you enjoy the read!

With kindest regards

Dr Christine Lemaitre Johannes Kreißig Chief Executive Officer (CEO), DGNB e.V. Chief Executive Officer (CEO), DGNB e.V. Managing Director, DGNB GmbH

Building materials and sustainability

Let’s face the facts. The building sector is one of the largest producers of emissions that are harmful to the environment. It uses many different types of materials, consumes huge amounts of energy and results in large volumes of waste. Until now, political measures have focused on improving the energy efficiency of how buildings are used or operated. As a result, advances in energy efficiency and the expansion of renewable energy supplies now put us in a position to construct net-zero and energy-plus buildings. These generate their own renewable energy, which can be used by occupants to operate and manage their buildings. As a result, they produce very little in the way of carbon emissions. When buildings produce surplus energy – i.e. feed more power into the electricity grid than they take out – this is referred to as climate-positive operation.

Such measures will not be enough, however, if we want to achieve the climate protection targets of the Paris Agreement. We’re still not doing enough to consider the overall life cycle of buildings. This is not just about how buildings are operated; Greenhouse gas emissions are also released when we produce, replace, recycle or dispose of the building products needed for the structure. These carbon emissions hidden in the structure are also called embodied carbon. A study conducted by the DGNB found that on average, roughly one third of all carbon emissions produced by the buildings certified over the last ten years were embodied carbon [1]. So how can we ensure that in future, the way we use or operate buildings is climate-positive and the carbon footprint caused by constructing the building is also significantly lower (see Fig. 1)?

Discussion regarding climate change mitigation – in political circles, society in general and the (construction) business community – is therefore increasingly shifting towards building materials, how they’re made and the associated carbon emissions. The response of industry is to promote sustainable, climate-neutral materials. And now materials such as wood, which are made from plant-based sources and sequester carbon, are becoming fashionable. This is an important development and a first positive step when it comes to climate-friendly construction. But will it be enough to achieve transformation?

In 2021 the German government started subsidising buildings that produce small carbon footprints during their life cycle.

More: www.dgnb.de/beg-foerderung

(German)

A HOLISTIC APPROACH TO SELECTING MATERIALS FOR USE IN SUSTAINABLE BUILDINGS

The sustainable building movement has been around for many years. It’s based on the philosophy of holistic planning and construction, which not only means avoiding the negative environmental impacts outlined above, such as greenhouse gases, it’s also about doing things that have a positive impact on people and the environment. To do that, you have to consider all factors with a bearing on sustainability, i.e. the environment, socio-cultural aspects and the economy. It’s also important to consider the entire life cycle of a building. The goal should be to create buildings that perform as best as possible overall in terms of sustainability.

In line with this philosophy, choosing the right products is not just about carbon footprints. To save resources, it’s also important to think about reusing materials or whether they can be recycled. One should also consider whether the materials that go to make up products are harmful to health or the environment. In addition, it should be ascertained whether materials have been manufactured according to socially and environmentally acceptable standards. These are questions that require a rethink, not just in the building material industry but also among planners and architects, who should actively quiz the companies that make their materials.

But even if all this key data on products is available, it’s still up to the people who plan projects to understand how to make proper use of the information. That means selecting materials such that they play a positive role in making build -

The carbon emissions of buildings Present Future Past

Fig. | Embodied carbon (grey column) are rising as a proportion of operating emissions (blue). They must not be disregarded.

ings sustainable. It’s understood how the thermal properties of materials affect room climate. The required compressive strength of a material to perform a particular function is also understood. But what impact does the carbon footprint of a material have on the overall building? What should you consider when selecting materials to ensure buildings are as resource-efficient as possible in use? And how do you ensure the air in indoor areas is healthy?

This report shows how sustainability factors can be an integral part of the process of selecting products – and thus an integral part of planning culture. It outlines the information that planners need from the construction industry, the questions they should ask themselves when planning a project, and how they can use the right methods and tools to find answers to such questions. It also becomes clear where the most effective points of leverage are. If, from now on, the planners consider the best overall outcome of their sustainable building project when selecting products – and are less driven by trends and the marketing campaigns of the construction product industry – this report will have achieved an important goal.

Chapter 1 raises the question Where do we stand? , looking at the status quo in the construction industry and the planning culture (page 6).

Chapter 2 offers concrete decision-making tools for selecting materials . To highlight what to look out for, five overarching principles are explained. The topics – climate protection, resource conservation, health and environmental protection, and socially and environmentally compatible supply chains – are then examined individually (page 8).

Chapter 3 shows how planners can move from credo to concrete. We provide a synopsis in the form of a checklist for use with your next project, showing how building materials are dealt with by the DGNB certification process for sustainable buildings and giving tips on staff training (page 24).

To conclude our report, we offer a selection of building material alternatives: from the well-known to the innovative . Four pages of ideas are presented to provide inspiration and open people’s eyes to less conventional materials (page 28).

Tip: The terms marked in green are explained in the glossary at the end of this report.

Does a product have a major impact on the carbon footprint of a building?

Is the product recycled?

Do materials have any impact on indoor air quality?

Where does this product actually come from?

Can I remove materials after 50 years?

What aspects of sustainability does the product label really take into account?

Was this product made according to fair working conditions? Who ascertains this?

This report does not offer catch-all solutions. Instead, it helps you ask the right questions ...

... and find answers by specific project.

Where do we stand right now?

It would be nice if the only products that were available to us were manufactured in harmony with the needs of people and the environment. But even then, that would not be going far enough. A planning culture would still be needed that focuses on using materials in such way that we create holistically sustainable buildings. Ideally, people involved in the planning and design of buildings should be proactive and do something now by nudging the construction product industry into action and making demands. By challenging others, they will gain experience and learn to distinguish between the factors that really are relevant to materials and meaningless marketing claims. The situation

in the construction industry

The situation in the construction industry

An important principle of sustainability is consistent protection of the environment and our climate. This was signed off by the global community with the Paris Agreement in 2015. The school climate strike movement has been openly demanding that this happen for years, the European Union has its green deal and continues to draft laws, and numerous companies and organisations are in the course of changing their ways. To really achieve transformation, which until now has been decoupled from environmental and climate protection, a new way of thinking is required, one that integrates not only economic, but also ethical and environmental factors into corporate processes. Initial political measures are now in place in this area, in the form of the CSR Directive, ESG criteria and the EU Taxonomy Regulation. They require companies to offer transparency regarding sustainability measures, and are thus intended to bring about tangible changes in behaviour.

EVERY BUILDING MATERIAL HAS A LIFE CYCLE

More and more producers in the building sector are also now taking responsibility for their processes – ideally along the entire value and supply chain of their products. For example, they use life cycle assessments to gauge the environmental impact of processing raw materials and manufacturing their products. They also provide information on the durability or useful life of materials and identify different scenarios and the options to reuse, recycle or dispose of products at the end of life cycles. Companies now practise self-declaration and issue environmental product declarations (EPDs) in order to share such information. They also disclose information in their sustainability reports regarding corporate guidelines, targets and measures. Openly sharing this information is important for planners and architects, although they’re often still forced to actively request it.

The life cycle thinking referred to before is a cornerstone of sustainable building; indeed, this is one of the reasons why building materials are now attracting so much attention in the planning process. This broader thinking means that buildings and their environmental impacts are not only considered in terms of planning or completion, but thought is also given to raw material sourcing and ‘end of life’ factors. Conducting life cycle assessments on a building level makes it possible to estimate environmental impacts during the entire life cycle. This also avoids potential negative impacts on the environment being shifted into phases of the life

cycle that are not considered. Planning with the distant future in mind helps minimise unnecessary risk, thus ensuring buildings do not depreciate. It also allows you to consider whether a building can be repurposed or deconstructed to avoid being demolished early.

THE LIFE CYCLE: FROM LINEAR TO CIRCULAR THINKING

One promising economic model, particularly when it comes to making building materials, is the concept of the circular economy. This self-renewing system is an alternative to the imbalanced nature of the linear economy, which is also known as the throwaway economy due to the harmful practice of extracting raw materials at one end of the process and accumulating waste at the other. The circular economy has close overlaps with the cradle-to-cradle school of thought. The aim is to encourage firms to develop products in such a way that they remain within an unbroken cycle of production, use and reuse or recycling (see Fig. 2). This has given rise to the concept of circular building, thus transferring this line of thought to the planning, construction and use of buildings. This concept addresses two key questions. What can we already do today to reduce our use of resources and avoid creating waste? And how can we safeguard future value? To achieve a circular built environment, the mindset has to change among all stakeholders in the building industry.

The situation in planning and architecture

Looking at the life cycle of buildings and materials, including their environmental impact, requires a different approach to planning and the willingness to consider what materials are actually capable of. As well as design and technical issues, this also involves questions of an environmental and social nature. Instead of just thinking about the thermal conductivity of insulation materials, their carbon footprints also have to be considered. Rather than asking how many functions are possible for the same price, the question could be: is there anything we can leave out? And in addition to thinking about the load capacity of a material, its constituents should be considered, or its recycling options.

Until these sustainability issues become standard practice in production and planning, it’s up to planners to ask the right questions and understand the implications of specific projects. This, in turn, requires knowledge and time, and the latter should be invested in projects as soon as possible. The sooner it becomes clear which objectives apply and the performance of individual materials has been considered,

the easier it is to influence the design of a building with the aim of achieving a sustainable outcome.

Material decisions affecting climate protection and resource conservation should come at the beginning of the planning process. That way, planning stakeholders can run through design options and check their climate impact. Furthermore, this allows them to reduce the resources required for a design and avoid potentially harmful or hazardous materials

It’s important with bid invitations and the construction process to point specifically to sustainability factors, such as pollutant limits. It’s also crucial to check standards during the construction phase so that the right products are delivered – and that they’re installed correctly.

Adaptation based on: Fraunhofer Institute for Building Physics (IBP)

Fig. 2 | Keeping building materials within a cycle of use is the underlying idea of the circular economy.

Every building material has a life cycle

“We need clear facts when researching products, not misleading marketing.”

Antonino Vultaggio, Senior Partner, HPP Architects

Decision-making tools for selecting materials

The credo is: when you select materials, you should consider climate protection, resource conservation, health and environmental protection, and respect for socially and environmentally acceptable standards in the supply chain. Sorry, was that overload? Okay, one thing at a time. This section starts with a question: what really matters when selecting materials? It does this by looking at each issue individually. The idea is to offer help when making decisions relating to materials. As we will see, people involved in planning projects can make a big difference.

Before we jump to the next double page and delve deeper into these topics, let’s take a look at five principles. They provide a conceptual framework for everything that follows, showing why it doesn’t make sense to look for one-size-fitsall definitions of what makes a good or bad material.

Adopting a holistic approach shows that there will always be conflicting interests, which is actually all right – and is in fact quite important. Being candid and dealing systematically with these different interests – in keeping with the required outcome, in order to identify the best possible solution – is the key to sustainable building, and thus also to selecting sustainable materials.

Five principles of sustainable material selection

Climate protection

Resource conservation

Health and environmental protection

Sustainable supply chains

Five principles of sustainable material selection

These five principles act as a warm-up for choosing the right ma terials when it comes to sustainability. They can be kept in mind as a quick point of reference.

Strike the right balance (eco-sufficiency)

Eco-sufficiency is about making a positive sacrifice, logically q uestioning the complexity of modern construction and the over-sized nature of components and buildings. How much space do we really need? Is it absolutely necessary for materials to consist of different layers?

Consider the surrounding area

Every location is subject to its own particular conditions. Looking back in history, it used to be quite normal to build with what was possible or available locally. Are regional factors, the local climate, the surrounding area and nearby materials taken into account when selecting building materials?

Think about the context of the building

The impact and benefit of a construction product can only be understood within the context of the function it performs and how it interacts with other materials. Accordingly, products should never be selected out of context.

Plan in hierarchies

To ensure products are reused or recycled, it helps to consider the defined stages materials will be used in. As a rule, the core structure of an edifice is built to last for ever, façades should survive for 50 years and interior fittings are likely to be shorter-lived. To a large extent, whether materials can be used again depends on the absence of pollutants – or whether materials can be replaced or deconstructed at the end of their usable life.

Interpret product labels properly

Product labels mostly refer to a specific issue or only a small part of the overall value chain. They should therefore never be considered a reflection of the broader picture. It’s only when you examine label declarations in detail and you’re sure what they really mean that they can be used for guidance purposes.

Building methods that completely dispense with certain components or deliver the same benefit using less land save even more carbon dioxide than products manufactured in a climate-friendly manner.

Bricks from a nearby town could be a better option from a holistic standpoint than wood sourced from far-flung shores.

A paint may be judged to be unproblematic outdoors but it could still be hazardous to health indoors.

Even recyclable materials end up on landfill sites, often because they were not intended to be removed separately.

If building materials have been certified as ‘produced in an environmentally friendly manner’, that says nothing about whether they can be reused or whether they contain pollutants.

Climate protection

Decision-makers who take climate protection seriously when selecting products should not only consider declarations like ‘Climate-Neutral Product’. Instead, they should gain a clear understanding of carbon emissions and the life cycles of products and buildings. Just like thermal conductivity, greenhouse gas emissions should be considered a performance criterion of materials. To make the right decisions, it helps to envisage carbon footprints on both a material and a building level. This section shows how, covering four points.

Why choose climate-friendly materials?

Climate protection is not achieved by making promises. It requires immediate and actual reductions in greenhouse gas emissions. We’re already in a position to construct buildings that are climate-positive in use*. This squeezes fossil fuels out of the energy grid (see Fig. 3, right half). This positive approach to operating buildings is an obligation if we want to take the Paris Agreement seriously. To make a real difference, however, it’s important to look at all carbon emissions associated with buildings. Even before buildings enter use, materials generate carbon emissions when they’re produced, installed or fitted.

And of course products cause emissions when they’re maintained, replaced or removed (see Fig. 3, left half). It’s only when this embodied carbon has been offset retroactively – through climate-positive operation –that a building can be considered climate-positive for the entire life cycle. The aim with material selection and construction methods is thus to minimise embodied carbon. The first priority is therefore eco-sufficiency – and the most climate-friendly materials are those that can be dispensed with without abandoning function.

* climate-positive operation > line goes down

Fig. 3 | Climate-friendly construction (left half) is a significant point of leverage for cutting greenhouse gas emissions. The lower the embodied carbon, the faster they are retrospectively offset through climate-positive building use (right half) and the building is climate-positive for the overall life cycle.

Climate-positive building operation: producing renewable energy (e.g. using solar panels) allows more energy to be fed into the electricity grid than is required by the building. This squeezes the need for fossil fuels out of the power grid. To find out more about this concept, see the DGNB Framework for carbon neutral buildings and sites [2].

Climate-positive buildings over the entire life cycle: even embodied carbon caused by constructing, maintaining and dismantling a building is offset retrospectively over time by generating excess carbon-free energy.

1. Product level: gain an understanding of the carbon intensity of building materials

Which stages of the life cycle create carbon emissions?

It may sound obvious, but one way to construct buildings in a climate-friendly manner is to use materials that cause few carbon emissions in production. Such materials are produced by only using low levels of fossil energy and/or renewable energy (like clay). Or they’re actually made of renewable raw materials. Because plants sequester carbon while they grow, wood, bamboo or natural fibres such as straw and flax are regarded as carbon sinks and are thus particularly good when it comes to climate protection. It is, nonetheless, important to consider not only how building materials are produced, but also the entire life cycle, from production to disposal. After all, transportation and disposal can also produce significant carbon emissions. It makes sense to use materials from local sources or materials that can be reused.

Manufacturers provide data on the emissions generated by their products as part of environmental product declarations (EPDs), e.g. on the German official data platform Ökobaudat (see Fig. 4, right). Manufacturing emissions are based on actual data, unlike values for the phases of use or material disposal, which are based on different scenarios. Figure 4 uses the example of glued laminated timber (glulam) to show how to interpret data. Wood contains a certain amount of carbon (I). When glulam is produced, small amounts of carbon are released (II). The carbon value of production is thus negative (A). For disposal, the EPD scenario for wood is that it’s burnt to produce energy. This releases carbon again (C). Once the potential to produce energy is also taken into account, the result is a kind of environmental residual value (D). This is because generating energy from wood, e.g. electricity, ensures fossil fuels are replaced elsewhere. Depending on which life cycle phases are taken into account, this results in different carbon values.

2. Building components level: Carbon intensity in the context of the function

How much carbon emission is caused by my exterior wall?

To deliver meaningful values with which to compare materials, building materials are assessed according to the function they perform in a building. This can be an exterior wall subject to certain insulation or stability requirements. Once conditions have been defined, different types of walls can be compared in terms of carbon footprint. Figure 5 shows how this works, using the example of an exterior brick wall. The required volume of material per square metre of a wall is multiplied by the carbon values of the building materials.

Examples of how to deal with carbon emissions (Part 1)

Product level: what data is provided by the EPD on glued laminated timber (glulam)?

Building components level: how should the carbon emissions of a brickwork exterior wall be assessed?

Hollow T8-42,5 251kg 0,425 m3 brick

Thin-set mortar 6,5 kg

Clay plaster (interior) 15 kg

Lime plaster (exterior) 27 kg

Approx. 300 kg/m2 of wall

Calculation: mass x carbon emissions

= approx. 63 kg CO2/m2 wall

Result: there are few changes in carbon values over the life cycle. Emissions therefore stem from production (A).

These values can be compared with other types of wall construction.

Fig. 4 | Carbon emissions during the life cycle of glued laminated timber [3]

Fig. 5 | Carbon emissions during the life cycle of a brick wall

Examples of how to deal with carbon emissions (Part 2)

Building level: which building materials produce the most carbon dioxide in an apartment building adhering to energy-plus standards?

New building Reinforced concrete solid walls

3. Compare different building options

In total, how many embodied carbon is caused by production?

What causes most emissions?

Basing life cycle assessments not only on building materials, but on entire buildings instead, makes it possible to select materials with a view to achieving a holistic climate-friendly overall result. For example, it can be ascertained whether materials are particularly carbon-intensive for specific projects, or whether the carbon footprint changes if you use different materials. Figure 6 looks at the example of an apartmenet building to demonstrate a comparison between a building with reinforced concrete solid walls (1) and one based on wood post and beam construction (2). The third example (3) showcases how, compared to new buildings (reinforced concrete/timber frame), complete refurbishments result in the greatest carbon savings. This is because the shell of the building is already in place, including embodied emissions. Concrete, steel and sandstone bricks can be considered ‘credits’.

Reduction compared to solid-wall reinforced concrete, Shown without carbon storage in wood (37%)

Photovoltaics 17%

Foundation:

Concrete 9%

Reinforcing steel 3%

Insulation (cellulose) 7%

Mineral fibre boards 5%

Cement screed 4%

Wooden windows 4%

Plaster 3%

Other 11%

New building Wood post and beam

Diagram (4) uses the example of the apartment building to show to show which components are comparatively carbon-intensive. In this way, life cycle assessments help planners make optimisations where it matters most. Also, people waste much less time looking into components that will make little impact. In most cases, the biggest source of carbon emissions – and thus also the starting point for optimisations – are the materials used in the largest quantity [1].

Building level: which building components produce the most carbon dioxide in an apartment building adhering to energy-plus standards

Other 9%

Insulation 6%

Plaster 3%

Cement screed 5%

Windows 10%

‘Credit’ for complete renovation (50%) Renovation Reinforced concrete solid walls

Photovoltaics 17%

Concrete 34%

Reinforcing steel 12%

Sandstone 4%

Techn. equipment 22% (photovoltaics, heat pump, plumbing, underfloor heating, central heat recovery ventilation system)

Roofs 6 %

Ceilings 22 %

New building Reinforced concrete solid walls

Foundation 8 %

Exterior walls 23 %

Interior walls 19 %

Fig. 6 | Carbon emissions resulting from production based on the example of an apartment building comprising 20 flats on 4.5 storeys (equiv. standard ceiling height), energy-plus standard KfW 40, heat pump, photovoltaics and ventilation system with heat recovery [5]

4. The relationship between embodied carbon and emissions resulting from building operation

How many carbon emissions can be expected from operating a building?

How many years will it take me to retrospectively offset embodied carbon by operating a building in a climate-positive manner?

As mentioned at the beginning, it’s important with climate protection to aim to use building materials with small carbon footprints. That said, only focusing on this aspect and accepting that energy use will be high when using a building would be the wrong logic. Instead, it’s important to place equal emphasis on embodied carbon and the emissions resulting from the operation of a building. Ultimately, it’s important to establish what’s the best solution for the individual project. It’s entirely possible that a building that’s climate-positive to construct actually produces more carbon emissions than a standard building (see Fig. 7). Over time, however, carbon emissions can be offset retrospectively during operation by using the building to generate renewable energy. Adopting such a holistic view also shows that from a climate protection perspective, refurbishing a building to make it climate-positive in operation is still worthwhile, despite associated carbon emissions.

Important to remember: in addition to the carbon footprint of materials, there are other key areas where action can be taken when constructing climate-friendly buildings. These include good space sufficiency, circular design, adaptable use – so that buildings can be used for a long time – and low material use. For more information on this, see the chapter on resource conservation and the DGNB Framework for carbon neutral buildings and sites [2].

At a glance

What helps: life cycle assessments (LCAs), understanding climate-friendly construction methods

More information:

LCA data, environmental product declarations (EPDs), e.g. www.oekobaudat.de (German) www.dgnb-navigator.de/en/

Delve deeper:

Life Cycle Assessments – a guide on using the LCA www.dgnb.de/publications

Framework for carbon neutral buildings and sites: www.dgnb.de/publications

Standardbuilding

Renovation enabling carbon-neutral operation

climate-positiveRenovationenablingoperation

Fig. 7 | Carbon emissions of buildings with different energy standards over time. Illustrative example, DGNB.

Resource conservation

Focusing on resource conservation when selecting materials will mean you will need to think on two fronts. First, you have to consider the extent to which resources can really be conserved these days through sufficiency – and think about using and recovering building materials already in circulation. Second: you will need to think about the future to ensure materials in a building can also be used later on down the line. After all, the foundation of effective conservation is using all resources responsibly.

Why use materials that save resources?

As the global population expands and demand for building materials intensifies, raw materials are becoming increasingly scarce. The burden this places on the planet is causing major environmental problems, such as a loss of biodiversity, a decline in soil quality, and climate change. The resources we use in buildings are valuable, scarce and often carbon-intensive. They demand responsible approaches that avoid wasteful behaviour. One concept that has become established within the context of sustainable building is circular building.

‘Circular’ in this context means circulate building materials in order to preserve their value for as long as possible and avoid waste. The idea is to encourage all building industry stakeholders to base their actions on circular thinking. Accordingly, planning and selecting products with a focus on resource conservation is partly about acknowledging the value of what has already been built – and may thus be available as a secondary raw material . But it is also about preventative action and preserving the value of materials.

Fig. 8 | How do you conserve resources in a building project? By looking at what can be preserved and focusing on essentials . By prioritising what is available in good quantity . And by planning for the future so that resources can be used for as long as possible

The DGNB website provides access to a circular building toolbox offering strategies and recommended actions that can be applied to a actual building projects. More: www.dgnb.de/en/circular-building.

Consider the situation today

1. If possible, doing without materials and using fewer resources

Do I really need this material?

Could the same function be fulfilled with fewer resources?

Aiming for eco-sufficiency should always involve asking which building materials are really necessary, or which add-on functions are really needed. Optimising materials so that fewer resources are required to deliver the same function is also in the interest of resource conservation. An example: using hollow or ribbed ceilings instead of flat ceilings (see Fig. 9). If the amount of technology used in a building can be minimised, it’s called low-tech. A classic example of this is passive cooling. The idea behind a research project called Einfach Bauen (simple construction) is to fundamentally reduce the complexity of a building and thus achieve major savings in resources. It’s worthwhile looking into these concepts.

Recommended reading: the Einfach Bauen (simple construction) project won the 2022 German Sustainability Award for Architecture.

More: www.einfach-bauen.net (German)

2. Use existing components again and make use of recycled materials

Is the material available through a material exchange platform?

Does the product contain secondary raw materials?

It’s important when selecting materials to use materials that will not require new raw materials to be mined. Such secondary raw materials should, for example, be recovered from existing buildings. It is still difficult to access the raw material stock of existing buildings and there’s a gap in the circular system between recovery and new buildings. Despite this, so-called urban mining is gathering pace on an EU level. As part of its action plan for the circular economy, the EU is planning to promote a market for secondary materials. It’s already possible to reuse* entire building components, without needing to change them – such as windows, doors or even façades – as well as building materials like bricks. Material trading is still a niche market, but exchange systems are on the rise and they’re becoming more user-friendly and increasingly well-connected. With regard to reuse, standards are required for the future that make it possible to easily dismantle components. In addition to reusing existing components, there are also products that partly or completely comprise reprocessed secondary materials.

One goal of resource conservation is to minimise the use of resources while achieving the same standards.

Definitions and examples:

Reuse (product remains intact)

Bricks are used again as bricks for a wall

‘Further use’ (materials are repurposed)

Bricks are used to lay a path

Recycle (original product does not remain intact)

· Metal beam is melted down and used again as a beam

· Waste glass is processed into glass wool

Fig. 9 | With hollow or ribbed ceilings, optimising components makes it possible to use fewer resources. An even more efficient solution is to reduce areas.

5. Ensure materials are easy to recover

Can building materials be removed in such a way that they still fulfil their function?

Has the number of different materials and layers been kept to a minimum?

Building materials and components should be used in such a way that they can be removed and reused separately. Not only must they be accessible, but if possible it should be ensured that all layers are detachable by avoiding connected materials that cannot be separated or composites that cannot be broken down. It also helps to focus on materials that consist of a small number of different layers or constituents. Examples of applications that are suitable for such approaches are ventilated façades (instead of composite structures), click-lock floating parquet floors, self-adhesive carpet tiles, dry screed, soluble basement wall insulation and basement walls that are impermeable to water, and thus do not require additional waterproofing.

6. Use locally available raw materials that are renewable

Could a renewable material be used?

Is it available in the nearby area?

Because vegetable materials can be composted, they are already part of the natural cycle and renewable. This makes such materials an appealing resource for sustainable building. Despite this, a number of points will still need considering if they are to be used as building materials. First, just because something is renewable, that doesn’t mean it should be used lavishly. It should first be checked whether it’s possible to use secondary raw materials. Second, it’s also important to consider how long it takes for vegetable materials to grow back again; we need ecosystems that are managed sustainably. Third, resources should be used that are available locally in order to minimise the distance materials are transported.

At a glance

What helps: Circular building know-how

More information:

To find out more about secondary raw material content, refer to EPDs and self-declarations

www.oekobaudat.de (German) or product endorsements such as natureplus

Dig deeper:

Report on the circular economy in the construction sector: www.dgnb.de/publications

Circular building toolbox: www.dgnb.de/en/circular-building

Changing perspective: starting at the end and thinking backwards

The three pictures below show how waste can be avoided and how to save resources. A good rule of thumb: the less effort (or fewer resources) needed to retain the value of a material, the better. For this to work, a shift in mindset is needed among all building sector stakeholders.

Reduce quantities and extend usage Material remains intact

■ Avoid anything that is unnecessary

■ Use things more intensively; share

■ Reduce material use through effectiveness and efficiency

■ Reuse on a 1:1 basis

Conservation of resources and value retention

Resources that would normally go to waste can be used again Material remains intact

■ Repair

■ Renovate to reflect the current status of technology

■ Overhaul

■ Put to alternative use

Conservation of resources and value retention

Process resources and make them usable again (recyclates) Material is taken apart

■ Reprocess into high-quality recycled materials

■ Reprocess into recycled materials of an inferior quality

■ Convert to compost

Conservation of resources and value retention

Fig. 12 | Conservation of resources and value retention in keeping with the concept of circular building [8, 9,10].

Health and environmental protection

The market for building materials includes a large number of products that contain pollutants and hazardous materials. If you’re serious about protecting people’s health and the environment, then you should be realistic about this when selecting materials. Better still, develop an understanding of the typical substances that cause problems. To avoid using them altogether, help is available in the form of the DGNB System, product labels and specific building solutions. This section offers guidance in thi s area under five points.

Why think about harmful substances when choosing materials?

In Europe, there are European chemical laws and ordinances such as the European Chemicals Regulation (REACH)* aimed at ensuring products do not contain hazardous materials. Nonetheless, it’s important to understand that legislation refers to healthy adults. Children and people with pre-existing conditions or allergies may also suffer negative reactions to materials, even if products adhere to safety limits.

90 per cent of the population of industrialised countries spend 90 per cent of their time indoors. It’s often underestimated to what extent our well-being is influenced by lighting conditions, the room climate and air quality. Certain components of building materials have a detrimental impact on indoor air. This can be the result of material evaporation or combination with other substances. One objective of positive design is to create uncontaminated living environments and a healthy indoor climate. Also, for environmental reasons pollutants and hazardous substances should be avoided throughout the life cycle of materials. Instead, alternative solutions should be found, or materials should be replaced by harmless and non-hazardous substances.

It’s therefore not enough to rely on regulations. Of course this makes choosing products quite complicated, so additional information on ingredients will be required – and if this is available, you will also need to understand what to do with that information. This is because the way materials affect people depends not only on the material itself, but also where it’s used and how the pollutants in different materials interact with others. They may mitigate the effects of a substance, but also amplify them. Therein lies the problem. But it’s still entirely possible to find materials that are not harmful to human health, and there are already materials on the market that meet the strictest health requirements, with more entering the market every day. There are also expert building ecologists, who have been working in this area for many years, and the DGNB offers assistance with such issues.

Industrial chemicals and biocidal active substances contained in building materials are governed by the European Chemicals Regulation (REACH), the European Biocidal Products Regulation (BPR), the POPs Regulation and the EU Decopaint Directive. Monitoring of the REACH process is the responsibility of the European Chemicals Agency, or ECHA [11].

Materials classified as substances of very high concern (SVHC) b y the ECHA should be avoided at all cost. Nevertheless, they may be present in products that are currently available. By law, they may be used until they’re banned, albeit with mandatory labelling. With mixtures such as paints, this means a product safety data sheet , with materials such as insulation, information is only provided on demand.

Note: The following steps refer to current guidelines and standards. What’s still permitted today may be prohibited at a later date. This also means that a large number of pollutants that were banned a long time ago may still be encountered during refurbishments. If in doubt, the safest strategy is to gain a pollutant certificate!

1. Understand product categories and problematic constituents

What kinds of pollutants exist?

Which product categories do they affect?

Gaining a general understanding of contaminants and where they’re encountered in typical product categories will help you make sensible material choices. Some emissions are released from solvents contained in materials and they can be detected in the air. These are volatile organic compounds (VOCs). That’s why it’s important to take measurements of indoor air after completing a building project. But there are also pollutants that make their way into house dust, the environment or drinking water. These include for example heavy metals such as cadmium, lead or zinc, as well as plasticisers, which are added to materials. And then there are biocides, which are used to control pests, bacteria and fungi, or hazardous substances that come from flame retardants, other protective agents or halogen-containing blowing agents, which are used for things like foaming. For a general overview of pollutant types, refer to Figure 13.

2. Use DGNB Quality Level 4 as a point of reference

Is it possible to ensure materials meet the requirements of the DGNB’s highest quality level –Level 4?

Under legal requirements such as Construction Product Regulations (BauPV) or REACH regulations, materials must come with various (safety) data sheets . Many companies are already offering greater transparency and posting such details online through building material databases such as the DGNB Navigator. They are also submitting materials for certification with product labels. For non-experts, however, it’s virtually impossible to know what to do with this information without understanding chemistry. There’s also no time for such exercises. This explains why, ever since its foundation, the DGNB has been working with experts to create an overview of the complex issue of pollutants and hazardous materials. Under its certification system (see p. 26/27), the DGNB has developed a system for pollutants and hazardous substances as part of criterion ENV 1.2 (Local environmental impact), which is regularly reviewed and updated [12].

Pollutants and hazardous substances are typically encountered in certain product categories.

PRODUCT CATEGORIES

Materials used on floors: primers, fillers VOCs containing solvents, flame retardants

Coatings such as paints, varnishes, glazes, wallpapers VOCs containing solvents, flame retardants, heavy metals, plasticisers, biocides

Plasters and anti-mildew paint Biocides, plasticisers

Chemical wood preservatives Biocides

Sealants and adhesives VOCs containing solvents, plasticisers/flame retardants, biocides

Mounting foams Blowing agents with or without halogens, plasticizers/flame retardants

Materials made of plastics such as PVC films Plasticizers, flame retardants

Metal cladding Heavy metals

Flooring

Elastic: VOCs, plasticisers/flame retardants, heavy metals

· Wood surfaces: VOCs containing solvents

· Textiles: VOCs, backing also with plasticisers/flame retardants, biocides (e.g. against moths)

Insulation materials made from synthetic foam

Halogen-containing blowing agents, flame retardants

Binders for wood-based materials Formaldehyde

Concrete release agents (formwork oil) VOCs containing solvents

Refrigerants for cooling systems Halogen-containing refrigerants

Corrosion and fire protection for metal components VOCs containing solvents, halogens

Fig. 13 | Selection of product categories and potential pollutants considered by the DGNB in the certification process.

To raise awareness of these issues among market stakeholders and establish a standard on an industry level, the DGNB has also developed four quality levels. The highest one, Quality Level 4, defines the strictest conditions for materials. More and more producers of building materials want to operate sustainably, using these DGNB levels as a point of reference and identifying their products accordingly. If planners consistently use products adhering to Quality Level 4, it can be assumed that the overall outcome will be positive. There are two ways to find such products. First: our building material platform, the DGNB Navigator, allows you to filter products by quality level. Second: ask producers directly. If planners are conscious of the standards they want to achieve, they should include their requirements in invitations to tender. It’s not necessarily the case that products on Quality Level 4 come with a bigger price tag, because there are always at least three products on the market that meet DGNB requirements.

The DGNB Navigator allows manufacturers to provide data sheets detailing the constituents of their materials and indicate which DGNB Quality Level they meet. More: www.dgnb-navigator.de/en/

3. Make use of DGNB pollutant lists

Are products included in categories on the pollutant lists complied by Wissensstiftung?

Do they show details of the required eco-labels, declarations or testing procedures?

Further help with selecting building materials is provided by Wissensstiftung, a ‘knowledge foundation’ co-founded by the DGNB offering quick access to expert know-how. DGNB criterion ENV 1.2 (Local Environment Impact) includes a

system for pollutants and hazardous materials. This can also be found in comprehensible wording on the German platform www.norocketscience.earth. The website contains lists, sorted by categories such as roofs or floors, with a directory of products itemised by intended use, plus links to product requirements. An example of how the lists work is shown in Figure 14. For instance, with wood coatings (third line), care must be taken to ensure materials use no VOCs containing solvents. The DGNB recommends evidence based on certification issued under the Blue Angel scheme for low-pollutant varnishes. Incidentally, as well as including relevant products when it comes to pollutants and hazardous substances, the lists also detail non-relevant products to save planners doing unnecessary work.

Indoor air measurements are required after project completion for quality assurance purposes. These prove whether declarations were actually true!

4. Follow building material labels carefully

Can product labels match key requirements?

Some building material labels specifically address the issue of pollutants and hazardous materials in an effort to offer healthy materials. These can also provide guidance. However, it’s important to read the small print and check which pollutants are mentioned, at which stage of the supply chain. To create transparency with this issue, the DGNB has introduced label approvals. Product labels can apply to the DGNB to be reviewed by DGNB experts. This process offers transparency by comparing the details of product certification with the requirements of the DGNB. Figure 15 provides a list of the labels we recognise.

Wall cladding, indoors: wall paint and primer

Indoors: skirting boards, door rails, column adhesives

Coatings on non-mineral substrates e.g. wood, metals, plastics

Coatings, primers and fillers

Sealing compounds, sealants, adhesives for interior building components

Glazes, varnishes with primer coatings

VOCs containing solvents, plasticisers

VOCs containing solvents

VOCs containing solvents

Solvent-free and plasticizer-free

GISCODE PU20* and EMICODE EC1, EC1PLUS, EC1-R or EC1PLUS-R*

Blue Angel eco-label DE-UZ 12a

Abb.

14 |

Supported by the DGNB and Building Material Scout, pollutant lists are available at www.norocketscience.earth (German) The website offers recommendations for complying with specific requirements by key building product category.

*GISCODE evaluates the potential hazard posed by materials during processing (occupational health and safety). The EMICODE eco-label conducts tests on emissions. If products mention any of the seal categories (EC1...), they can easily be checked to see if they have been approved by the DGNB.

5. Building with the right materials and avoiding potentially harmful substances by design

Are there building solutions or simple ways to make problematic materials superfluous?

There are basically two ways to minimise the use of pollutants. One: look for pollutant-free alternatives, as explained under the previous points. Two: use building techniques that make certain products unnecessary. For examples of this, see below.

A positive side-effect of avoiding such materials is that materials used can be recycled. What everyone needs is a philosophy of building with the right materials, by considering what can be achieved with a material and how to use it sensibly, without having to include chemical additives that cause problems during production, processing, use or recycling.

A small selection of building ideas:

Use mechanical fixings, e.g. bracing door frames instead of adhesive foams

Clamp, jam or lay objects, e.g. carpeting, carpet tiles, click-and-fit floor coverings, dry screed

Seal objects, e.g. hemp sealant in joints

Adapt construction methods to preserve wood rather than use wood preservatives, e.g. use wood that’s suitable for surfaces more exposed to the elements, eaves, wood on floors raised on metal

Natural fire protection for insulation, e.g. rock wool, foam glass

Product labels offering guidance on the listed materials

Blue Angel: coatings, resilient and textile floor coverings, wood-based materials, flooring installation materials and auxiliaries

Indoor air comfort: resilient and textile floor coverings, flooring installation materials and auxiliaries, sealants, assembly adhesives, epoxy resin coatings, wood-based materials, furniture

At a glance

What helps: basic understanding of pollutants and hazardous substances – if in doubt ask a pollutant expert

More:

Pollutant list on the Wissensstiftung website: www.norocketscience.earth (German)

DGNB Quality Levels and data sheets: www.dgnb-navigator.de/en/

DGNB label recognition: www.dgnb.de/labelanerkennung (German)

Delve deeper: Training on pollutants and hazardous substances

EMICODE: flooring installation materials and auxiliaries, sealants, installation adhesives, installation foams

GUT-Label: textile floor coverings

nature plus: wood-based materials, e.g. chipboard, fibreboards, OSB boards

eco INSTITUT label: flooring installation materials and auxiliaries, sealants, assembly adhesives, sealants, wood-based materials, furniture

TÜV PROFiCERT products for interiors: resilient and textile floor coverings, sealants, epoxy resin coatings, wood-based materials

Fig. 15 | Labels recognised by the DGNB as evidence in each of the product categories mentioned. This list is continuously maintained and expanded.

Sustainable supply chains

If you want a building project to come with an endorsement that it’s based on socially and environmentally responsible manufacturing, you will need to consider a number of points when selecting materials. Yes, of course planners are dependent on producers to take care of certain standards in their supply chains. But they can also do something themselves by actively giving thought to this issue and, at the same time, motivate the construction product industry to do things differently. Corporate guidelines and voluntary declarations ensure transparency. But the most effective strategy is to consciously ask.

Why pay attention to socially and environmentally responsible supply chains?

Even today, many raw materials rely on the exploitation of workers and nature during harvesting and processing. Extreme exploitation – such as child labour, forced labour or predatory mining – are forbidden by law, at least for materials that originate from or are produced in Europe. But in many cases, supply chains can hardly be called socially responsible. Also, little is known about environmental impacts, such as water pollution or threats to biodiversity and soil quality. To make things better, it’s essential to gain more transparency when it comes to the origin, extraction and processing of raw materials. The best way to gradually change the system is to demand evidence. A fundamental principle when selecting materials is thus to only use products that adhere to the required environmental and social standards – at all stages of the supply chain.

16 | Our economies are linked internationally and the legal situation varies. It’s up to manufacturing companies to take care of their supply chains.

A supply chain is a process, from extraction of raw materials to mining and the manufacture of building materials. Products often go through a journey with many stops along the way, in all corners of the globe. And it’s often the supply chain that causes the biggest environmental impact of a company. It’s not easy keeping track of everything, but if companies don’t bother to make the effort, who will?

Laws and regulations: in Germany, starting in 2023, the Supply Chain Act will enshrine companies’ due diligence obligations in the supply chain. The European Convention on Human Rights makes general violations of human rights punishable before the International Court of Justice. OECD Guidelines offer recommendations on responsible government action.

Fig.

Production of end product

Product 1

Product 2

Extraction

1. Ask about corporate social responsibility

Is the company committed to preventing violations of human rights when it comes to the extraction and processing of raw materials?

Is it doing anything to avoid negative environmental impacts?

Some aspects of the supply chain are now governed by laws and regulations. Corporate guidelines and sustainability reports also reflect the extent to which companies are now committed to certain standards, such as the OECD Responsible Business Conduct or the European Convention on Human Rights. If a supplier is only offering limited information, ask for more.

2. Ask about certified resource extraction

Is the producer offering certification that confirms resources are being extracted sustainably?

Product labels help companies demonstrate that they are acting responsibly. They also create transparency. Bodies such as the FSC, the PEFC or the Holz von Hier timber initiative in Germany prove that wood is being sourced from sustainable forestry. There is the Fair Stone initiative for stone imports, CSC for concrete production, and natureplus, which covers the production of various types of building materials. Despite these programmes, it’s still important to check carefully. Often, certificates are only awarded for extraction or material processing, but it’s better if they apply to the whole supply chain.

3. Aim for DGNB standards

What standards does the DGNB recommend and how can they be attained?

To provide guidance, the DGNB has been working with experts to define three quality standards, offering environmental and social requirements in the supply chain that go far beyond legal requirements (see table on the right). Criterion ENV1.3 of the DGNB certification system (Sustainable resource extraction) shows how different aspects on the right can be checked based on defined sources of information [12]. Some product labels are also recognised by the DGNB for specific requirements. These include the FSC, PEFC, natureplus, CSC, Holz von Hier and Fair Stone.

At a glance

More information:

Voluntary declarations, sustainability reports provided directly by producers, or www.dgnb-navigator.de/en

Labels recognised by the DGNB: www.dgnb.de/labelanerkennung (German)

DGNB standard environmental requirements

1. Protection and preservation of biodiversity e.g. diversified cultivation, use of untreated seeds, organic natural fibres

2. Protection of natural habitat diversity. Nature should be restored to its original state.

3. Preservation of the protective functioning of ecosystems e.g. flood protection, drinking water, avalanches

4. Soil and landscape conservation by minimising land use

5. Preservation of soil quality by avoiding biological, chemical and physical soil degradation

6. Preservation of the natural water cycle e.g. avoidance of wide-scale land cover

7. Reduction of water consumption and avoidance of quality degradation by managing water and energy

8. Avoidance of water pollution e.g. recycling, waste water, no environmentally harmful fertilisers or pesticides

9. Avoidance of waste, especially toxic waste e.g. no heavy metals in paints

10. Preservation of air quality by avoiding harmful emissions

11. Reduction of environmental impacts resulting from transportation, e.g. use of local raw materials

DGNB Standard social requirements

1. Prohibition of child labour and forced labour in accordance with the International Labour Organization (ILO)

2. Preservation of core labour standards and occupational health and safety measures protection of workers at all stages of the supply and value chain

3. Compliance with working rights e.g. guaranteed employment contracts in keeping with legal requirements

4. Respect for the right to freedom of association protection of freedom of association and collective bargaining

5. No discrimination in the workplace e.g. equal pay

6. Preservation of cultural values and respect for the rights of the indigenous population e.g. by avoiding conflicts of use and the endangerment of livelihoods

7. Implementation of ethical business practices e.g. prevention of corruption, implementation of fair trading practices, compliance with legislation

All requirements detailed under DGNB criterion ENV1.3, as well as information on how to ask about them, can be found at www.dgnb.de/en/label-recognition-env13.

From credo to concrete

There’s so much to take in! So what now needs doing in practical terms? If your head’s buzzing, maybe try the checklist on the right. To help you, here are the essential questions from Section 2 again. You might want to see which ones you already know, what you can do next and which areas you could use some training in.

Choosing materials sustainably is also one of the specific areas captured in DGNB certification. The knowhow pooled in our certification system also went into this report. If you’re interested in more detail on how building materials are are reflected in the DGNB criteria, the next two pages will help you.

We’ve also summarised all offerings of the DGNB, which might be quite useful when selecting materials. There’s only one thing left to do after that: get started.

Checklist for sustainable material selection

Material selection and DGNB certification

The issues highlighted in this report are not yet reflected in current standards. But some planners and project managers are already doing a successful job selecting and planning building materials with sustainability in mind. With a bit of practice, important questions pop up by themselves, almost automatically, as you take each step through the process. The following checklist was drafted with the support of experts in this area. It highlights the most effective points of leverage when selecting materials to achieve a sustainable outcome.

Checklist for sustainable material selection

Asking the following questions will help you think more about climate protection, resource conservation, health and environmental protection, and supply chains when selecting materials.

Climate protection

Have I reduced the carbon emissions of high-volume materials?

Use fewer materials and focus on suitable construction techniques, e.g. use panels or hollow construction with wooden structures instead of solid timbers; prioritise lightweight and dry screeds; exploit the (often big) potential to save materials on ceilings (e.g. flat concrete ceilings are resource-intensive); use suitable material spans

Are low-carbon building materials a good solution?

e.g. use building materials made from renewable raw materials; only use carbon-intensive materials such as steel, aluminium and concrete when absolutely necessary for a long service life and/or the structural design

Could the size of a building be reduced to what’s really necessary?

Quality of living comes from the usefulness of rooms, not the size of rooms.

Is there any way to cut transportation emissions?

Transporting heavy and bulky materials causes high carbon emissions.

Resource conservation

Have I thought about the above climate protection factors (and thus saved resources)?

Am I focusing on aspects of the circular economy that can actually be achieved right now?

e.g. by reusing existing materials and making use of recycled building materials

Are combined components and materials reversible and easy to take apart in the future?

Am I planning a building that can be used or operated by using resources efficiently?

e.g. how often do materials need updating or removing; floor plans that can be adapted to different uses

Health and environmental protection

Am I thinking about healthy interiors, and am I selecting pollutant-free materials?

Can my design do without potentially harmful substances?

e.g. constructions that preserve wood rather than use chemicals

Am I remembering to ask for samples of materials early and planning to ask for tenders properly?

Are materials checked on the building site?

Have my recycled materials also been assessed for pollutants?

Am I in a position to provide building users with care and maintenance instructions?

Sustainable supply chains

Have I asked about the origins of bulk or high-volume materials? Do they travel short distances?

e.g. wood, stone, masonry, concrete, steel, insulation materials, roof tiles

Are my building materials – such as wood, concrete and stone – certified for sustainable supply chains?

The material selection has a significant influence on the overall impact of sustainable buildings.

Material selection and DGNB certification

Building materials and their impact on sustainability are also central to the DGNB certification system. The idea behind the DGNB System was to create a planning and optimisation tool for assessing sustainable buildings, interiors and urban districts, and the resulting system offers tangible help in improving the actual sustainability of building projects. The DGNB System is based on the concept of holistic sustainability, placing equal emphasis on the environment, people and economic viability. Quality requirements look at the big picture by considering the overall life cycle of buildings, with explicit reference to building materials.

ENVIRONMENTAL QUALITY

ENV1.1 Building life cycle assessment

ENV1.2 Local environment impact

ENV1.3 Sustainable resource extraction

ENV2.2 Potable water demand and waste water volume

ENV2.4 Biodiversity at the site

ECONOMIC QUALITY

ECO1.1 Life cycle cost

ECO2.1 Flexibility and adaptability

TECHNICAL QUALITY

TEC1.3 Quality of the building envelope

TEC1.5 Ease of cleaning building components

TEC1.6 Ease of recovery and recycling

TEC1.7 Immissions control

TEC1.4 Use and integration of building technology

PROCESS QUALITY

PRO 1.4 Sustainability aspects in tender phase

PRO 1.5 Documentation for sustainable management

PRO 2.1 Construction site/construction process

SOCIOCULTURAL AND FUNCTIONAL QUALITY

SOC1.1 Thermal comfort

SOC1.2 Indoor air quality

SOC1.3 Acoustic comfort

SOC1.4 Visual comfort

SOC1.5 User control

SOC1.6 Quality of indoor and outdoor spaces

SOC1.7 Safety and security

SOC2.1 Design for all

Fig. 17 | Criteria used by the DGNB System for new buildings, focusing on those pertinent to building materials and their influence on assessments

Apart from looking at environmental, economic and socio-cultural factors, the criteria used by the DGNB System are designed to evaluate planning, building processes, site quality and technical standards. The overall rating of a building is based on meeting the individual criteria.

Figure 17 shows how the criteria fall under five different aspects of quality, and how specific material requirements directly or indirectly impact the overall rating of a building. Technically speaking, building materials potentially influence more than 55 % of the certification outcome for a new building. The coloured areas of the diagram show the scores that can be achieved under each DGNB criterion by selecting certain materials, based on the share of the overall score.

Direct influence : qualitative and quantitative characteristics of a specific material used for a building

Indirect influence : planning tasks affecting building materials (e.g. highlighting environmental requirements for materials in invitations to tender); solutions applied to the planning process and the specific choice of materials (e.g. reducing drinking water consumption by using fittings that save water)

The DGNB has written a criteria catalogue for both new buildings and the operation, renovation and deconstruction of buildings used for all kinds of purposes, as well as a catalogue for entire urban districts. All DGNB catalogues are available free of charge at www.dgnb.de/en/criteria

BUILDING MATERIALS AND THE DGNB CRITERIA

It is clear by now that the specific characteristics of materials play an important role in some criteria. However, the requirements outlined in the previous section mainly focus on just five criteria, because they’re particularly relevant to planning. These fall under the four overarching topics:

Climate protection: ENV1.1 Building life cycle assessment

Resource conservation: ENV1.3 Sustainable resource extraction/TEC1.6 Ease of recovery and recycling

Health and environmental protection: ENV1.2 Local environment impact

Sustainable supply chains: ENV1.3 Sustainable resource extraction

These pick up on the aforementioned issues and describe different approaches to decision-making.

The criteria list thus achieves something that’s often not reflected in current planning practice: It provides us with reminders of all material issues requiring consideration.

It defines which evidence is required for building materials, and when this evidence is needed. It describes methods that help with choices. It ensures that standards are maintained until buildings enter use and that they’re checked.

During certification, DGNB auditors work with planning teams and take on the task not only of asking all questions with a bearing on sustainability, but also answering them alongside the building owners. The goal in the long term, however, is for sustainability goals to become the norm in planning practice. The certification system can thus also be seen as an instrument of change for the industry.

If you want to delve deeper into these topics, the DGNB network offers plenty of options.

The training arm of the DGNB offers workshops and seminars to anyone interested in the topics covered by this report: www.dgnb-academy.de

Our product database creates transparency when it comes to material requirements in keeping with DGNB certification. It also offers guidance on selecting building materials, regardless of certification:

www.dgnb-navigator.de/en/

Wissensstiftung offers ideas and inspiration that can be immediately applied to projects. These are provided in a concise format as building blocks, each curated by industry experts: www.norocketscience.earth (German)

Initiated by the DGNB and the German Federal Chamber of Architects (BAK), Phase Sustainability is an association of planners driven by a desire to make their planning methods more sustainable. The initiative also deals with the selection of materials. It costs nothing to participate in the project:

www.phase-sustainability.today

A number of reports and guidelines offer detailed information on sustainable construction, all free of charge: www.dgnb.de/publications

Fig. 18 | Staff training options and other DGNB services offering help with material selection

Most multi-storey buildings in Germany still rely on reinforced concrete or bricks and mortar. Manufacturing such materials produces much too much carbon dioxide, however. Some people feel that wood will save our climate and it’s experiencing a renaissance. But even wood is a limited resource, as some noticed to their expense in 2021 when there were material shortages hand in hand with price inflation. At the same time, there has been a steady rise in the number of alternative building materials, all compatible with market needs. Many ideas are yet to make it out of the research lab and there are limitations to the areas they can be used in. A number of major obstacles still need to be overcome, many stemming from a lack of regulation and production methods. But the move to more comprehensive, end-to-end systems will come. A number of pioneers in the building sector are already ensuring this will happen, in the knowledge that they’ll be one step ahead when the true environmental costs are understood – supply chain standards will be tightened and resources will become increasingly scarce. It’s high time we all consider the alternatives – also so that niche products become the new normal. Allow us to introduce some of those alternatives now.*

WOOD

Areas of use

Supporting structures

Exterior and interior cladding

Drywall areas

Regulatory factors

Regulated building materials Standards exist

*This report focuses on the situation (and available materials) in Germany, list is not exhaustive Wood stores carbon, it grows back again, it creates a pleasant atmosphere. In addition, thanks to the possibilities it offers to prefabricate parts in quick cycles, wood lends itself to serial production. Not without reason, wood is an essential alternative to conventional materials. The growing number of timber-frame and solid timber buildings show that technically, many things are possible these days. Hybrid building methods involving timber, which make use of the best possible combination of material properties, as well as new timber products and production methods are now opening the door to wooden architecture. But it’s also important to consider whether it always makes sense to use wood – it’s not necessarily the best choice. It’s equally important to think very carefully about technical and structural requirements, as well as availability and transportation. From a global perspective, the forests are shrinking and climate change calls for a new approach to forestry. It’s not without reason that there’s conflict between climate activists and the timber industry. In summary: consider carefully whether or how to use wood – and don’t put all your eggs in one basket!

Market situation

Increasingly used in multi-storey buildings (e.g. hybrid wood/ concrete construction)

Used on a small scale

Multi-storey buildings still stand out as beacon projects

Growing demand

More:

Timber construction in Germany: www.holzbau-deutschland.de (German)

An example from practice: Skaio, a multi-storey timber building in Heilbronn, Germany

DGNB position paper on timber construction: www.dgnb.de/stellungnahmen (German)

“The demand for bio-based building materials is picking up, but current technical standards, and often a lack of economic incentives, are inhibiting more wide-scale use in construction. What’s needed are scalable solutions that combine products from different manufacturers and are adapted to the requirements of customers and market segments.”

Jan Wurm, Professor of Regenerative Design and Biofabrication at KU Leuven

Building material alternatives: from the well-known to the innovative

Areas of use

Drywall areas

(Blow-in) insulation

Straw bale construction

Regulatory factors

Approvals available

Straw bale construction:

European Technical Assessment, Straw Building Guideline 2019

Market situation

Still a niche product, but suitable for mass use

It’s been under our feet for ever and is available in abundance as a by-product of brickmaking and lignite mining. Clay offers a multitude of benefits when it comes to circular processes in the building industry. Unlike other building materials, it’s not processed irreversibly; it can be reused and fits in well with the concept of using locally available materials. It’s also appealing in terms of material properties: not only is clay permeable to air, it also absorbs moisture and can be used for indoor climate control. With the right planning, it even allows you to do away with ventilation systems. For a long time, clay was not a priority due to its poor image and the focus on building ‘higher, faster and further’. Clay first enjoyed a renaissance in the 1980s and it’s currently coming back into fashion thanks to new processes and building methods. In 2013, a specific DIN standard was introduced for this mixture consisting of clay, sand and silt for use in bricks, plaster and mortar. More recently, in 2018 standards were extended to incorporate clay panels, now bringing the material to drywalls. Clay is most commonly found in thin-layer coatings and plaster. It’s also used in a solid format as rammed clay, clay bricks and in compressed clay-straw blocks, primarily for renovations.

More:

Dachverband Lehm e.V.: www.dachverband-lehm.de (German)

Examples from practice: Ricola Herb Center, Laufen (Switzerland), Alnatura Campus, Darmstadt, international example: Shibam (Yemen)

STRAW

Given the properties of straw, it’s not surprising it has been making inroads into the market for building materials in recent times. The dried stalks of straw are available worldwide, they sequester carbon as they grow and they deliver good insulating properties. Because straw is harvested as a dry material, it also involves little carbon dio xide in production. Roughly 20 per cent of the straw produced annually through farming in Germany is not actually needed [13]. This is an important factor in view of raw material shortages. Traditional construction methods involving bales of straw date back to the 19th century and have witnessed a revival in this country since the turn of the millennium [14]. New to the fold are a number of straw-based developments, which are good enough to compete with conventional building materials. For example, there are now straw panels for use in drywall construction and straw blow-in insulation for use in new and existing buildings. Development is also underway on footstep sound insulation, thermal insulation panels and reinforcing structural panels. It’s worth keeping an eye out for straw, because it can be used in an increasing number of areas.

More:

Straw bale construction: www.fasba.de (German)

Straw construction panels, e.g.: www.oekologisch-bauen.info (German)

Harvesting in Germany produces enough straw residues to insulate 350,000 family homes [14].

Building material alternatives: from the well-known to the innovative

MUSHROOMS

Areas of use

Sound insulation

Anticipated use: insulation, support structures

Regulatory factors

Still few approvals

Market situation

Niche product

Still being researched

Mushrooms, a building material?! This still raises eyebrows in industrial practice, but research in this area is advancing in leaps and bounds. Labs in Germany are also growing mushrooms on organic waste, producing a dense web of root-like threads called mycelium. Growing this culture in formwork and baking it at 70°C kills off the organism, leaving behind mycelium biocomposites (MBs). The highly porous nature of cultivated MB gives it strong insulation and sound-absorption properties, making it a low-carbon and environmentally friendly alternative to many conventional interior materials. One Italian firm has ev en launched acoustic and interior linings made of mycelium. This material still requires improvements to its mechanical properties for load-bearing applications, and corresponding standards are also needed.

More:

Karlsruhe Institute of Technology (KIT) Chair of Sustainable Construction: nb.ieb.kit.edu

Examples from practice: KIT MycoTree, Hy-Fi Tower at the MoMa Young Architecture Program New York, acoustic panels made of mushrooms

HEMP

Areas of use

Insulation

Wall bricks

Regulatory factors

Individual cases of approval

Market situation

Niche product

Although the share of renewables used for insulation purposes is still rising, around 90 per cent of all insulation materials in Germany are still based on mineral and fossil resources [15]. From an environmental perspective, it’s difficult to better the advantages of natural fibres such as hemp or flax. Construction hemp is low-maintenance, requires no pesticides and grows 50 times faster than wood. The short fibres required to produce insulation and acoustic panels are waste materials from the textile industry. Shives extracted from the hard core of hemp can be compressed with lime using cold air to produce bricks. The thermal properties of hemp bricks make them useful as two-in-one wall and insulation materials. Hemp fibres can also be used in load-bearing materials to replace non-renewable fibres and deliver tensile strength. For many years, growing hemp was prohibited, but now the number of (strictly regulated) fields is rising again. France, Italy and the Netherlands are ahead of Germany in this respect [16]. Local farming will be decisive. Supply is driven by demand – so ask more about hemp!

More:

The ‘Hemp Engineers’: www.hanfingenieur.de (German)

The European Industrial Hemp Association: www.eiha.org

FNR agency for renewable materials: www.fnr.de (German)

China dominates the global hemp textiles market with a share of just under 80% [17].

Areas of use

Supporting structures

Regulatory factors

Approvals only available for certain recyclate content

Market situation

Recycled concrete is still a niche product in Germany

Carbon concrete and gradient concrete are still under development

Things are also happening in the concrete and cement industry. Issues surrounding the high levels of carbon emissions caused by cement production, in combination with strong demand for primary raw materials, are an opportunity to make things better. The biggest point of leverage for producing less carbon-intensive materials lies in low-carbon cements and optimized concrete formulations. This involves replacing cement constituents by other materials. In many cases, granulated blast furnace slag (GGBS) is used as a cement substitute, and research is being carried out into further alternatives. Some companies are also using alternative fuels in cement production.

In addition, the industry offers recycled concrete in the interests of saving resources. This is based on recycled aggregate, which can be used to replace a certain proportion of gravel or ground stone. The amount of material substituted depends on the demands placed on the concrete and recyclate properties. As much as 45% of materials can be replaced. A prerequisite for producing recycled concrete is that recyclates have been processed and quality-checked (as far as possible locally). In Germany, little use is made of recycled concrete in buildings. For the most part, this is undoubtedly due to ignorance regarding guidelines, mistrust in recycled products and the fact that conventional concrete is still inexpensive to source. In addition, although more than 90% of mineral-based materials are currently put to further use, this is mainly for civil engineering projects and road construction [18].

Under the current guidelines of the German Committee for Reinforced Concrete (DAStB), depending on the type of recyclate and where it is used in a building, it is permitted to use between 25 and 45 per cent of recycled aggregates in concrete. There is no prospect of this share rising in Germany. A planned update of the directive should also include approvals for recycled sand.

More: www.dafstb.de (German).

Other approaches to resource efficiency include carbon concrete and material-saving components. With pre-stressed carbon concrete, structural steel is replaced by high-tensile carbon fibres offering material savings as high as 75%. Carbon concrete is a new arrival to the market and has received its first general building approvals. One option that still needs research in this area is recycling materials for further use. One important lever, that is very much in the hands of (structural) designers, is introducing components that make the best possible use of material properties in order to deliver important savings. Examples of this include optimised precast concrete elements and hollow ceilings, as well as timber hybrid construction methods. In summary, plan buildings that save materials and ask about low-carbon concrete that conserves resources [19].

More:

Example of a recycling plant in Germany: www.feess.de (German)

Recycled concrete: www.baunetzwissen.de (German)

Project C3 – Carbon Concrete Composite: www.bauen-neu-denken.de (German)

Reuse of undamaged precast concrete components

– ReCreate: www.recreate-project.eu

Carbon emissions directly caused by cement production

CONCRETE EVEN WITH CONCRETE, THERE ARE ALTERNATIVES...

“We have a major responsibility as structural engineers, because we bear a major responsibility for the type and quantity of the materials that are used. So we should make more use of renewable resources in the spirit of a circular economy – and we should strive to reuse materials, components and entire structures.”

Prof. Patrick Teuffel, Managing Director of Teuffel Engineering Consultants and Circular Structural Design

Glossary

The following definitions offer an explanation of the terms highlighted in green in this report.

Carbon emissions

Carbon dioxide accounts for a major share of the man-made greenhouse effect, which is why in the context of climate change, instead of saying greenhouse gases , the term is simplified instead to carbon emissions. The term ‘carbon emissions’ is often used to mean carbon dioxide emissions. See also Greenhouse gases . The simplified term used in figures in this report for kg CO 2 equivalents

Carbon footprint/CO 2 footprint

The total of all carbon emissions caused by an individual or company, but also processes, products and buildings, measured over a certain timeframe. In the case of products, the term often only refers to the manufacturing phase and not to the entire life cycle.

Carbon sink

A building material that temporarily absorbs and stores carbon from the atmosphere.

Climate-neutrality

When the natural balance between carbon emissions and Carbon sinks is restored. In its framework for climateneutral buildings and sites, the DGNB defines when a building is considered climate-neutral in operation and when it is climate-neutral over its entire life cycle [2].

CO 2 equivalents

see Global warming potential

Eco-label

A distinction is made in Germany between three types of eco-labels. Type I labels according to ISO 14024 are Environmental labels , Type II according to ISO 14021 are Self-declarations made by manufacturers and Type III according to ISO 14025 are Environmental product declarations [26]

Embodied energy

The energy-related expense of production, storage, transportation, processing, use and the end of life of a product.

Embodied emissions

Carbon emissions caused by the consumption of Embodied energy resulting from the use of fossil fuels.

Environmental labels

Recognition from an independent body or auditing agency of special environmental qualities. Such labels are particularly suitable for products that can be compared between different manufacturers but less so for materials that only have an impact when they are part of a building. Examples: the German Blue Angel label or FSC. Environmental labels count as Type I Eco-labels . Synonymous with: Product labels

Environmental Product Declaration (EPD)

A document capturing the specific features of a product with a bearing on environmental factors, reflected in neutral and objective information. In addition to LCA information, some EPDs also provide details of material constituents or recycling options. Ideally, they take the entire life cycle of a product into account. Whereas environmental labels focus more on the commissioners or owners of buildings, EPDs are used by architects and project planners. EPDs are not a reflection of the environmental friendliness of a product, even if they have been independently verified. Nonetheless, architects can assess EPDs in the context of buildings [25]. More in the DGNB Navigator or the Ökobaudat website. EPDs count as Type III Eco-labels

Global warming potential (GWP)

A measure of the relative contribution of a chemical compound to the greenhouse effect, i.e. to global warming. This indicates how much a certain volume of a Greenhouse gas contributes to the greenhouse effect over a period of 100 years compared to the same volume of carbon dioxide. This is why it is also referred to as CO2 equivalents [24]. Synonymous with: CO 2 equivalents.

Greenhouse gases/emissions

lead to rises in global temperatures due to the greenhouse effect. According to the Kyoto Protocol, this includes carbon dioxide (CO 2), methane (CH4), nitrous oxide (N2O) and fluorinated greenhouse gases (F-gases) [23]. With the term ‘greenhouse gas emissions’, the focus lies in emissions released into the atmosphere.

Life cycle assessment (LCA)

The systematic procedure of analysing the entire life cycle of a project/product, capturing and evaluating the different impacts a building or product has on the environment. Key environmental problems are captured and linked in functional terms over the entire life cycle of a building, looking at issues such as carbon emissions, energy consumption, required resources and the use of water.

Life cycle thinking

An expanded view of construction that includes the entire lifetime of a product or building in the design process, from manufacture to the end of life of a building.

Natural resources

All resources that make life on earth possible: primary raw materials, air, the soil, ecosystem output, energy, water, biodiversity [22].

Ökobaudat

Data platform of the Federal Ministry of Housing, Urban Development and Building (BMWSB) and the official database for conducting life cycle assessments on buildings. A distinction must be made between general data and manufacturer-specific information contained in EPDs. Both are subject to verification before inclusion in the database.

Primary raw materials Unprocessed and sourced through primary extraction

Product labels

see Environmental labels

Pollutants and hazardous materials

In a building context, this refers to constituent materials, additives or chemical substances in building materials that cause harm or have the potential to do harm to people or the environment.

Recyclate

see Secondary raw materials

Safety data sheet

A document that provides information on the properties of substances and required protective measures for anyone dealing with chemical substances. With certain product groups, there are obligations from the REACH chemicals agency to provide such declarations; with others this is voluntarily. Available on request from manufacturers. Synonymous with: Technical data sheet

Secondary raw materials are obtained by processing waste materials. Synonymous with:

Recyclate

Self-declaration

An explanation provided by a producer of the environmental properties of its products. Such information may

not have been verified independently. In Germany, certain fixed terms such as ‘compostable’, ‘designed to be taken apart’ and ‘recyclable’ are protected by DIN standards. One example of self-declaration is the three-arrow symbol for certified recycled products. Self-declarations count as Type II of the Eco-labels

Sustainability data sheet

Certification systems such as the DGNB System lay down a variety of sustainability requirements affecting building materials. As a result, more and more manufacturers now provide sustainability data sheets capturing all relevant data. For the DGNB System, such information is made available in the DGNB Navigator.

Technical data sheet

see Safety data sheet

1 German Sustainable Building Council – DGNB e.V. (2021). Benchmarks for greenhouse gas emissions from building construction. Stuttgart.

2 Deutsche Gesellschaft für Nachhaltiges Bauen – DGNB e.V. (2020). Framework for climate-neutral buildings and sites.

3 Institut Bauen und Umwelt e.V. (2018). Umweltproduktdeklaration: Brettschichtholz (BS-Holz) (Environmental product declarations: glued laminated timber/glulam)

4 Institut Bauen und Umwelt e.V. (2021). 4 Institut Bauen und Umwelt e.V. (2021). Umweltproduktdeklaration: Mauerziegel (ungefüllt). (Environmental product declarations: Bricks (hollow))

5 Mahler B, Idler S, Nusser T & Gantner J. (2019). Energieaufwand für Gebäudekonzepte im gesamten Lebenszyklus (Energy expenditure for building concepts throughout the life cycle). Final report. Dessau-Rosslau.

6 Brand S. (1995). How Buildings Learn: What Happens After They’re Built. London. Graphic based on edited version, Technical University of Munich. In Einfach bauen: Ein Leitfaden (Build simply – a guide). Munich.

7 The Story of Stuff. (2022). From www.storyofstuff.org // Based on an adaptation by Jörg Finkbeiner, Partner und Partner Architects

8 European Union. 2018. Directive (EU) 2018/851 of the European Parliament and the Council on 30 May 2018 amending Directive 2008/98/EC on waste. From eur-lex. europa.eu/legal-content/EN/TXT/?qid=153002898.

9 German Federal Ministry of Justice. (2012). Act for Promoting Closed Substance Cycle Waste Management and Ensuring Environmentally Compatible Waste Disposal (Closed Substance Cycle Waste Management act, KrWG).

10 Potting J, Worrell E & Hekkert M P. (2017). Circular Economy: Measuring innovation in the product chain. The Hague: PBL Netherlands Environmental Assessment Agency.

11 European Chemicals Agency. (2022). ECHA European Chemicals Agency. From Understanding Reach: www.echa. europa.eu/de/regulations/reach/understanding-reach.

12 German Sustainable Building Council – DGNB e.V. (2018). DGNB System Criteria catalogue for new buildings. Stuttgart.

13 Fasba (German Trade Association for Straw Bale Construction). (2019). Strohbaurichtlinie 2019 (Straw Construction Guidelines 2019). From www.baustroh.de.

14 FNR (Agency for Renewable Materials). (2021). Strohgedämmte Gebäude (straw insulated buildings). From www. fnr.de/broschuren/nachwachsende-rohstoffe/bauen.html

15 FNR (Agency for Renewable Materials). (2021). Press release: Marktanteil von Nawaro-Dämmstoffen (Market share of renewable insulation materials). From www.fnr.de/

presse/pressemitteilungen/aktuelle-mitteilungen/aktuellenachricht/marktanteil-von-nawaro-daemmstoffen-waechst.

16 European Commission. (2022). Hemp production in the EU. From https://ec.europa.eu/info/food-farming-fisheries/ plants-and-plant-products/plant-products/hemp_en.

17 Statista, Inc. (13 January 2022). Global market share of hemp consumer textiles in 2018, by country. From www.statista.com/statistics/980467/hemp-based-productsmarket-share-by-country-global/.

18 bbs (German Federal Association for Building Materials – Stones and Soil). (2022). Kreislaufwirtschaft Bau: Mineralische Bau- und Abbruchabfälle, Monitoring (The circular economy and construction: mineral building and demolition waste, monitoring). From www.kreislaufwirtschaft-bau.de.

19 VDZ (Association of German Cement Works). (2020). Dekarbonisierung von Zement und Beton – Minderungspfade und Handlungsstrategien (Decarbonization of cement and concrete – mitigation pathways and action strategies. From www.vdz-online.de/wissensportal/publikationen/dekarbonisierung-von-zement-und-beton-minderungspfade-und-handlungsstrategien.

20 European Union. (2011). Regulation (EU) No 305/2011 of the European Parliament and of the Council defining harmonised conditions for the marketing of construction products, repealing Council Directive 89/106/EEC. FromFrom eur-lex.europa.eu/legal-content/DE/ LSU/?uri=CELEX:32011R0305.

21 German Federal Environmental Agency. (17 October 2018). Ökobilanz (Eco-balance). From Federal Environmental Agency: www.umweltbundesamt.de/themen/wirtschaftkonsum/produkte/oekobilanz.

22 German Federal Environmental Agency. (1 August 2019). Resource use and its consequences. From https://www. umweltbundesamt.de/en/topics/waste-resources/resourceuse-its-consequences.

23 Umweltbundesamt. (5 July 2021). Die Treibhausgase (Greenhouse gases). From www.umweltbundesamt.de/ themen/klima-energie/klima-schutz-energiepolitik-indeutschland/treibhausgas-emissionen/die-treibhausgase#undefined.

24 Baunetz_Wissen. (5 July 2021). Treibhauspotenzial (Global warming potential). From www.baunetzwissen.de/glossar/t/treibhauspotenzial-6305134.

25 Institut Bauen und Umwelt e.V. (2020). Was ist eine EPD? (What is an EPD?). From ibu-epd.com/was-ist-eine-epd.

26 Baunetz_Wissen (2022). Umweltzeichen, Labels und Umweltproduktdeklarationen (Ecolabels, other labels and environmental product declarations). From www.baunetzwissen.de/daemmstoffe/fachwissen/richtlinien-verordnungen/ umweltzeichen-labels-und-umweltproduktdeklarationen-152368.

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Authors and contributors (DGNB): Pia Hettinger, Mieke Schleife, Johannes Kreißig, Dr. Christine Lemaitre, Felix Jansen, Dr. Anna Braune, Jürgen Utz, Christine Ruiz Duran, René Traunspurger

© DGNB September 2022

All rights reserved. All information has been prepared and compiled with the utmost care. The DGNB cannot accept responsibility for the correctness or thoroughness of content, nor for any subsequent changes to content.

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