When is ‘sustainable’ actually sustainable?
A brief explanation of the German Sustainable Building Council DGNB (Deutsche Gesellschaft für Nachhaltiges Bauen eV) and the Sustainable Building Quality Seal QNG (Qualitätssiegel Nachhaltiges Gebäude)
Germany wishes to promote sustainable construction. But when is a building actually considered sustainable? The answer isn’t quite as simple as it may seem at first glance.
For example: Is a mud-brick house with a tiled roof and sheep’s wool insulation the only sustainable option? Or can a concrete building actually be sustainable?
Ultimately, concrete consists mainly of natural raw materials such as sand, gravel, water and cement. However, its sustainability is assessed throughout its entire life cycle, rather than solely on the basis of the origin of the raw materials.
DGNB: How sustainability is assessed
Assessment systems for sustainable construction have been developed to ensure that developers, planners and funding bodies do not make decisions based on instinct alone.
The DGNB is one of the leading providers of sustainability certifications. Other recognised assessment schemes and certification bodies also exist. The DGNB assesses buildings according to a fixed set of criteria. Points are awarded for each criterion. A building may be awarded one of the certification levels: Bronze, Silver, Gold or Platinum, depending on the level of compliance achieved.
And not just based on the construction method; the assessment also takes into account the building materials used. In addition, social, organisational, technical and location-related aspects are considered. DGNB has therefore developed a comprehensive set of criteria against which numerous building materials can be assessed and classified.
QNG: Why the assessment is important for funding
This is not just theory. In many cases, the assessment determines whether a building project is eligible for funding.
This is where the QNG comes in. This is a government quality mark and is required, in particular, for certain funding schemes such as the KfW’s ‘Climate-Friendly New Build’ (Klimafreundlichen Neubau - KFN) programme. KfW (Kreditanstalt für Wiederaufbau) is Germany’s state-owned development bank. It provides low-interest loans and grants – e.g. for housing construction, energy-efficiency upgrades and sustainable new-build projects. Proof of sustainability is also often required for public construction projects.
Independent certification bodies determine whether a building fulfils the standards required. One of the best-known is the DGNB.
Moreover, other organisations such as NaWoh (Nachhaltiger Wohnungsbau - Sustainable Housing Construction) and BiRN (Bau-Institut für Ressourceneffizientes und Nachhaltiges Bauen GmbH - Building Institute for Resource Efficiency and Sustainable Construction) / BNK (Bewertungssystem Nachhaltiger Kleinwohnhausbau - Assessment System for Sustainable Small Residential Buildings), are also authorised to issue certifications that comply with QNG.
PU (polyurethane) foam in DGNB and QNG
Sustainable construction does not mean you cannot use PU foam. Both the DGNB and the QNG take PU foams into account in their assessment systems. However, the product used must meet the relevant standards.
PU foams are listed in the DGNB set of criteria. The DGNB Navigator, contains product-specific sustainability information and supporting documentation for planners to help them satisfy the relevant DGNB criteria.
The QNG also stipulates the standards required for the building materials used. QNG criterion 4.5 is particularly relevant for PU foams. The next section describes these standards, and which products fulfil them.
QNG Criterion 4.5: Important factors concerning PU foam
The QNG also stipulates the standards required for the building materials used. QNG criterion 4.5 is particularly relevant for PU foams; it specifies the standards that installation foams must meet to be used in QNG-certified buildings. Among others, this relates to certain constituents and substances that may be released into the indoor air after processing (emissions).
The good news is that there are many PU foams available here too that fulfil these standards. Whether DGNB or QNG: Suitable PU foams are available for both systems.
FAQs about DGNB, QNG and PU foam
Is PU foam suitable for sustainable construction?
Yes. PU foam can be used in sustainable construction projects. However, the product used must fulfil the standards of the respective assessment system.
Can PU foam be used in a DGNB certification?
Yes. The DGNB lists suitable PU foams in its set of criteria and in the DGNB-Navigator. Here, planners can find product-related sustainability information and documentation to ensure compliance with the relevant DGNB criteria.
What role does QNG play in PU foam?
The QNG details the standards required for the building materials used. The QNG criterion 4.5 is particularly relevant for PU foams.
Where can I find suitable PU foams for DGNB or QNG projects?
A good place to start is theDGNB-Navigator. Here, planners can find product-related sustainability information and documentation to ensure compliance with the relevant DGNB criteria.
Does sustainable construction rule out the use of PU foam?
No. Sustainable construction does not rule out the use of PU foam. However, the product used must fulfil the standards required by the DGNB or the QNG.
What is the difference between DGNB and QNG?
The DGNB is a certification body that assesses buildings according to a set of criteria. The QNG is a government quality mark which may be required, among others, for various KfW funding programmes.
What is the DGNB Navigator?
The DGNB Navigator is a product database. This is where planners, architects, tradespeople and building owners can find building materials suitable for sustainable construction projects.
