Construction of a timber frame. Image by Josh Olalde.

Climate Cleanup Sprint Diaries: Sprint 2 — Development

Developing the building material impact tool

Tijn Tjoelker
Climate Cleanup
Published in
7 min readApr 15, 2021


We’ve created a decision making tool to easily compare the impact of building materials on CO2 and nitrogen emissions, carbon storage, biodiversity, wellbeing and the weight of the house. This tool shows that bio-based materials can transform buildings into carbon sinks. In this Sprint Diaries Series we share how we did it.

The building material impact assessment tool we developed.

The goals of Sprint 2

  • Collect data for each material based on impact categories outlined in Sprint 1
  • Redefine model houses from Sprint 1.
  • Create an open-data api to serve data to the tool
  • Design and build an interface for the tool based on insights gained in Sprint 1
  • Communicate outcomes of Sprint 0 & 1 on the LifeLab

Data Collection

In week 1 of sprint 2 the team defined the requirements for the dataset on bio-based building materials. The dataset was filled with existing data from NIBE and Holland Houtland and expanded to include new materials and new impact categories. In the absence of nationally recognized frameworks for specific materials, desk-research was used to ascertain which data source is most appropriate, also considering EU (EN-norm based) data. All data sources were recorded and entered into the database for reference. The Open Data bio-based, hybrid & conventional materials are stored and structured in a google sheet that will be available for public use.

Creating a dataset on bio-based building materials.

Impact categories and indicators

The current assessment model is based on 5 impact categories divided into two groups, social and ecological. Each category has one or more impact indicators. The main task of sprint 2 was to ensure that each indicator is assigned a unit of measurement and a value based on a reliable source. These sources need to be defendable in the face of scrutiny as the credibility of the tool will be based on the rigour of the dataset.

The main challenge was to find datasets which represent each of the impact categories for each of the materials. As there are no existing datasets, we needed to find creative ways to fill this knowledge gap. This task becomes much more approachable when we take inspiration from the drawdown method of meta-analysis which takes into account the lack of data sometimes available. It is important to bear in mind that this database will evolve over many iterations and become more precise and detailed over time.

Stored Carbon

Stored carbon reflects the total CO2 equivalent that remains stored in bio-based materials on site after construction. It remains stored (out of the atmosphere) for as long as the building stands and the material exists.

Sequestered Carbon

Carbon taken out of the atmosphere by biological or technological processes. Once a reasonable duration of storage is expected (IPCC standards prescribe 100 years or more), sequestered carbon can be considered stored.

Life Cycle CO2

The Life Cycle Carbon dioxide embodied carbon dioxide reflects the total CO2 equivalent emitted from cradle to gate. This data is included in the Life Cycle Assessment (LCA) of each individual product. Many analysts use the term embodied carbon, however this is becoming increasingly confusing as actual carbon storage is considered, because ‘embodied’ sounds like the carbon that is in the actual ‘body’ of the material.

Embodied Carbon

Now increasingly confusing term used by LCA analysts to describe all energy and other emissions that went into the production of a product or material. See ‘Life Cycle CO2’.

Nitrogen Transport Emissions

The nitrogen emissions for each material are based on the total weight of the material and the distance travelled.

Biodiversity Impact

Biodiversity impact is measured in kg 1,4 dichlorobenzene (1,4-DB) eq. This is based on the ReCipe approach developed by RIVM, but is a lighter implementation due to data gaps across materials databases. We use the ReCiPe method to create a compound score to be derived from LCA impact categories. This lightweight approach allows us to create a basic preliminary assessment based on existing EPD and LCA assessments. Indicators used are land toxicity, freshwater toxicity and saltwater toxicity. Data is obtained from product LCA’s.

Recipe impact assessment module. From ASN bank.

Further reading:


In this case we consider wellbeing as a psychosocial indicator based on consumer preferences towards climate positive goods and services. Empirical evidence indicates that practices linked to reducing the environmental impact are compatible with high levels of wellbeing. A positive score is given when negative carbon emissions for the whole house are reached.

Further reading:


Alternative building materials come at a higher monetary cost than traditional materials due to market demand and scalability. Due to the fluctuation of building material prices per project we have omitted affordability as an impact category in this version. Initial research suggests that alternative building materials carry a premium of around 8% above average.

Open Data API

In week one of sprint #2 the team defined which information technologies should be used to create the biobased building materials database. This choice was made based on the expected size of the database, data-structure, expected database queries load vs cost per query, future proofing for python integration etc. The choice was between SQL vs noSQL approaches to structured and unstructured data. In the end we made the choice for the Firebase Realtime Database. This is a cloud-hosted NoSQL database that lets you store and sync data between users in realtime and remains available when the app goes offline.

Assessment model visualisation

We incorporate the Doughnut of Kate Raworth into our assessment framework, with the main impact categories CO2, nitrogen, biodiversity, well-being, and affordability. The indicators required for each material are organized in a sunburst format diagram showing nested impact categories. There are three category levels: Impact category > Benefit Pathway > Assessment Indicator. This is to create layers of simplicity within the tool.

Our impact assessment model based on Doughnut Economics.

Assessment tool UI

In parallel to the data collection phase the team developed a web based application interface which allows for the selection and comparison of different building materials. This is a javascript based web app with access to the material database API. The prototype shows reactive data and the users can ‘build’ personalised models and print and save assessment results.

A prototype of the assessment user interface.

Material wiki

In this Sprint we also created a material wiki with product descriptions and additional technical data of all the different building materials in the tool. The images, descriptions and current pros of cons of each material will help visualize the benefits of bio-based materials. The data will be available inside the tool.

An overview and example of the building material wikis, which can be found in the tool.

Stakeholder consultations

During the developmental process we’ve been in contact with numerous knowledge partners, amongst others NIBE, NEN, The Green Village, Bloc, Nice Developers, Sawa, TNO, Platform M3 Architecten, ORGA architect, Stichting Nationale Koolstofmarkt, Dutch Green Building Council, ASN bank, gemeente Capelle aan den Ijssel, BouwN, EkoFlin and Strotec.

Next up in Sprint 3

  • User Testing on function, content, navigation, interaction and lay-out, especially with workshops etc.
  • Look at a real world test case scenario
  • Link back to Oncra transactions — possibly creating Carbon Certificates
  • Data Validation by third parties
  • Write-up assessment methodology
  • Delivery of the LifeLab website



Tijn Tjoelker
Climate Cleanup

A human mycelium network — weaving webs of synergy to catalyse regenerative transformation.