A turning point in the development of sustainable housing

Editie: 31 - Global vs. Local

Published on: 07 juli 2024

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Nowadays the construction sector is responsible for 38% of the carbon dioxide emissions (CO₂) (United Nations, 2020). In line with the UN Climate Change Conference in Paris 2015, the Dutch climate plan was set up and states a necessary reduction of 95% of CO₂ emission in 2050 in relation to 1990 (DGBC, 2023). Besides this, the Netherlands is dealing with a housing crisis. There is a challenge for the residential construction sector to develop 900.000 houses by 2030 (Actieagenda Wonen, 2021). The question is whether these goals are compatible and whether the development sector can address both challenges at the same time?

 

Building Emissions

Looking at the life cycle of a building, three types of emissions can be established. First, there are emissions accountable to the materials used in construction. Material-related emissions of buildings are those produced during the production and construction process stage of a building its life cycle (Sobota, Driessen, & Holländer, 2022). Emissions from maintenance, replacement, the end-of-life stage and when possible, the recycle/reuse stage are also defined as material-related emissions. The second type of emissions are those produced during the use stage of the life cycle and are defined as energy-related emissions. These are the emissions produced by energy consumption, water, heating, and climate systems. The last category of emissions is user-related emissions produced by energy consumption due to cooking, household appliances, and other electrical appliances used by the user (Blom, Itard, & Meijer, 2011). User-related emissions are not further included in this article, as they are beyond the direct control and influence of project developers and the construction sector.

 

Sustainable Transition

Since the mid-90s and the early 2000s, “sustainable development” became a rising theme in the construction sector (Zhou & Lowe, 2003). More focus was paid by designers and project developers to the decrease of the environmental impact of houses, with the main focus to decrease the energy-related emissions. Improving the energy performance coefficient by increasing insulation and the efficiency of installation has drastically decreased the energy-related emissions. Besides, the introduction of the energy label as the required certificate at the sale or rental of a house, stimulated the improvement of the energy performance of one’s house. So the total energy-related emissions of a house have decreased, but this has resulted in more material use. Ramesh et al. concluded in 2010 that approximately 10-20% of the total building emissions is accountable to material-related emissions, emitted during the production, construction, and reuse stage. However, since effort has been put into improving the energy performance of houses, more building materials are used, which can result in the role of material-related emissions in low-energy houses up to 50% (Sartori & Hestnes, 2007; Cabeza et al., 2014). The same conclusion is drawn by a recent research conducted in the Netherlands. This study concluded that a newly constructed house in the Netherlands emits 5 kg of CO₂ per square meter per year of energy-related emissions (W/E Adviseurs, 2023). The material-related emissions of the same newly constructed house at the start of the use stage are 340 kg CO₂ per square meter. Meaning that after 68 years the energy-related emissions are equal to the material-related emissions at the start of the use stage. In comparison, the life span of a building is often set at 75 to 100 years (Birgisdottir & Rasmussen, 2016). Renewal and renovation are not considered in these calculations, meaning that the share of material-related emissions is even larger. The material-related emissions emitted during the renewal and renovation process can take up to 35% of the total material-related emissions, mainly related to the replacement and maintenance of building elements and installations (Sobota et al., 2022). Due to the addition of material, the material-related emissions can count up to 50% of the total building emissions (Sartori & Hestnes, 2007; Cabeza, Rincón, Vilariño, Pérez, & Castell, 2014). This means a significant increase in material-related emissions in comparison to the 10-20% share that was accountable for material-related emissions before the additional energy performance measures (Ramesh, Prakash, & Shukla, 2010).

 

This effect is illustrated in Figure 1, showing the life cycle assessment (LCA) of the environmental impact translated into the generalized global warming potential (GWP)[1] for three types of buildings. The Traditional building reflects a house constructed to the minimal requirements as stated in the building regulations. The Energy efficient building including energy efficiency measures to become energy neutral. And the Material efficient building which reflects a house where focus has been paid on material-related emissions without significant retrogression of the energy-efficiency. Comparing the energy efficient bar to the traditional bar, the GWP at the product stage increases due to the inclusion of large more installations (e.g. solar panels) and more material (e.g. more insulation). The amount of material and the increase in pollution per material result in more emissions at the start of the life cycle. Due to the energy performance measures, the use stage decreases drastically. When also implementing sustainable materials, as shown in the material efficiency bar, the GWP of the product stage decreases drastically when combined with the reuse stage. In combination with energy efficiency measures and sustainable materials, the total GWP decreases.

 

This underlines the need for construction with sustainable materials. Instead of building with CO₂ intensive materials like concrete and cement, in this article referred to as ‘traditional materials’, a transition is starting to take place to materials with significantly lower or even positive effect on CO₂ concentrations in the atmosphere (Bronsvoort, Veldboer, Slaa, & Kaptein, 2020). Two primary sustainable material alternative groups can be distinguished, namely circular materials and biobased materials (e.g. Oorschot, et al., 2023; Arnoldussen, et al., 2020). Circular construction materials can be based on the principle of demounting and reusing materials without degradation of the quality (e.g. modular systems, façades, and window frames), this principle is referred to as circular design (C2C Products Innovation Institute, 2023). Another option is circular sourcing, which means using construction and demolition waste in new materials (e.g. fragmented glasses and wood in insulation). The use of circular materials aims to effectively repurpose resources, resulting in a decrease in the reliance on new materials and minimizing environmental consequences. Biobased materials are a class of materials derived partially or entirely from biomass sources (Yadav & Agarwal, 2021). Biobased materials are manufactured from plant-based sources, such as wood, paper, hemp and bamboo. Examples of commonly used construction materials include wooden façade cladding, fiber boards, and wooden window frames (Oorschot, et al., 2023). Biobased materials represent a natural and renewable resource, reducing dependence on non-renewable sources. In order to achieve sustainability objectives, the construction sector must transition towards greater utilization of circular and biobased materials. However, the full implementation of biobased and circular construction materials presents both technical and financial challenges.

 

Adapting to Sustainable Material Use

Within the construction sector, innovation is leading to the development of new, more environmentally friendly materials for construction. However, at this point, these materials are predominantly more expensive than their traditional alternatives. The study concluded that circular and biobased material alternatives result in most cases in additional material costs ranging from +10% to +20% (VORM, 2023). Increased material costs result in an increased risk for a project developer when revenues do not increase. So the question is, is there willingness by consumers to adopt sustainable materials and therefore also willingness to pay for sustainable material use in housing?

 

The willingness to pay for sustainable material use is mainly determined by whether consumers perceive a certain material to have added value. Examples of added value include reduced environmental impact, improved aesthetics, or enhanced living conditions. From literature, it can be concluded that people perceive sustainable materials differently, such as wood. On one hand, people perceive wood as a construction material with less durability, longevity, and low fire resistance (Gold & Rubik, 2009). However, wood as a construction material is positively associated with aesthetics, well-being, and eco-friendliness (Lähtinen, Harju, & Toppinen, 2019). Circular materials (either recycled or reused) are generally associated with lower quality and being second-hand (Pretner, Darnall, Testa, & Iraldo, 2021). However, the same literature also indicates that the willingness to pay for circular materials increases when labeled as environmentally friendly.

 

Assessing the choice probability of the material alternatives using a mixed logit model indicated significant heterogeneity within the choice probability for several biobased, mostly wooden, material alternatives. This aligns with the literature mentioned, which suggests a divergence in how people perceive wood as a construction material. Another notable result from the data analysis reflects on the disparity between perceived sustainability and actual sustainability. Among the circular and biobased material alternatives, the highest choice probability was determined for the biobased roof covering. The biobased alternative for the traditional material (i.e., grit ballast roof) was a green sedum roof. The green roof was the only material alternative that showed a higher environmental impact than the traditional level. Due to additional materials, such as drainage and filtration systems, the green roof includes more material and thus has a higher environmental impact (GPR Software, 2023b). The results of the experiment indicate that individuals did not base their choice on the real environmental performance but rather on the perception and experience of a certain material. The sedum roof looks green, and people tend to associate greenery with sustainability (Ferraz, Petroni, & Santos, 2023), leading to a higher choice probability for a green roof as a preferred sustainable alternative. This effect, wherein a product or service is presented as more environmentally friendly than it truly is, is called “greenwashing” (United Nations, 2023).

 

In the study, the choice probability was transformed into willingness to pay for the circular and biobased material alternatives in relation to the traditional material of a specific building component. Taking a broader look at these results, the conclusion can be drawn that the willingness to pay for sustainable materials by consumers is not necessarily related to the additional costs of these materials. For the circular material alternatives, there was a shortfall of 2.3% between the additional material costs and the willingness to pay for these materials in relation to the traditional level. The biobased materials generally showed similar results. However, the large variation in preference for biobased materials resulted in different outcomes, indicating that people who perceive wood as a construction material show a significant positive willingness to pay for wooden building structures.

 

Conclusion

The study emphasizes the complexity of individual preferences and perception with sustainable materials. Revealing that, while people express a willingness to invest in sustainable alternatives, this inclination is dependent upon direct experiences or perceptions with the perceived sustainability of the materials. The study concludes that, overall, the willingness to pay for sustainable materials does not outweigh the additional material costs associated with circular and biobased material alternatives. The study emphasizes that individuals tend to exhibit increased willingness to pay for materials they associate with sustainability. Notably, materials with a “sustainable appearance”, such as the green roof, tend to have a positive choice probability. Designers and project developers should take note of the findings when designing and constructing new houses. However, it should be controlled due to the potential effect of “greenwashing”. This practice is undesirable as it fails to reduce emissions, whilst it is thought by individuals that they behave more sustainably. Awareness should be created under consumers about the performance, characteristics, and quality of sustainable material alternatives, encouraging them to make sustainable choices.

 

It is crucial to raise awareness about the need to enhance the use of sustainable materials in construction of houses. Instead of primarily concentrating on reducing energy-related emissions, there is a need to find a balance that also addresses material-related emissions. By raising awareness and underscoring the need of finding a balance between these two factors, the construction of houses can happen in a more sustainable manner. Only a full transition to a sustainable built environment is not possible without societal understanding and need. Emphasis should be paid on improving environmental awareness. This can be achieved through targeted efforts in marketing sustainability in housing, coupled with initiatives to increase public knowledge about the incentives associated with purchasing a sustainable home. This aligns with the fact that individuals are more willing to pay for a material or product labelled with a certificate which they are familiar with or when they have knowledge about the advantages of the product.

 

On the author: Joep Dirx

Joep Dirx graduated from Eindhoven University of Technology in January 2024, completing his Master’s in Architecture, Building, and Planning with a specialization track in Urban Systems & Real Estate. Currently, Joep is working as a junior project manager at the housing corporation Stichting Trudo. There, he is part of the team responsible for development projects in Eindhoven.

 

References

Actieagenda Wonen. (2021). Samen werken aan goed wonen. Actieagenda Wonen.

Arnoldussen, J., Errami, S., Semenov, R., Roemers, G., Blok, M., Kamps, M., & Faes, K. (2020). Matiaalstromen, milieu-impact en energieverbruik in de woning- en utiliteitsbouw: Uitgangssituatie en doorkijk naar 2030. Amsterdam: Stichting Economisch Instituut voor de Bouw & Metabolic.

Birgisdottir, H., & Rasmussen, F. (2016). Introduction to LCA of Buildings. Aalborg University. Aalborg: Trafik-og Byggestyrelsen.

Blom, I., Itard, L., & Meijer, A. (2011). Environmental impact of building-related and user-related energy consumption in dwellings. Building and Environment, 46(8), 1657-1669. doi:10.1016/j.buildenv.2011.02.002

Bronsvoort, E., Veldboer, T., Slaa, A. t., & Kaptein, T. (2020). Bouwen aan een houten toekomst. Amsterdam: Circle Economy.

C2C Products Innovation Institute. (2023). Circular Economy. Retrieved September 18, 2023, from c2ccertified: https://c2ccertified.org/topics/circular-economy

Cabeza, L., Rincón, L., Vilariño, V., Pérez, G., & Castell, A. (2014). Life cycle assessment (LCA) and life cycle energy analysis (LCEA) of buildings and the building sector: A review. Renewable and Sustainable Energy Reviews, 29, 394-416. doi:10.1016/j.rser.2013.08.037

DGBC. (2023). Meten: Sturen op werkelijk gebruik. Retrieved March 8, 2023, from Dutch Green Building Council: https://www.dgbc.nl/meten-sturen-op-werkelijk-gebruik-235

EPA. (2023, April 18). Understanding Global Warming Potentials. Retrieved June 5, 2023, from United States Environmental Protection Agency: https://www.epa.gov/ghgemissions/understanding-global-warming-potentials

Ferraz, L., Petroni, L. M., & Santos, E. d. (2023). How urban green areas influence different dimensions of sustainable behaviour. Revista De Administração Da UFSM, 16(1). doi:10.5902/1983465969508

Gold, S., & Rubik, F. (2009). Consumer attitudes towards timber as a construction material and towards timber frame houses – selected findings of a representative survey among the German population. Journal of Cleaner Production, 17(2), 303-309. doi:10.1016/j.jclepro.2008.07.001

GPR Software. (2023, June 7). GPR Materiaal. Retrieved June 7, 2023, from GPR Software: https://materiaal.gprportaal.nl/5397ed2a-89d0-4642-8a34-eea13011bac9/component

GPR Software. (2023b, June 7). GPR Materiaal. Retrieved June 7, 2023, from GPR Software: https://materiaal.gprportaal.nl/5397ed2a-89d0-4642-8a34-eea13011bac9/component

Kollmuss, A., & Agyeman, J. (2010, July 1). Mind the Gap: Why do people act environmentally and what are the barriers to pro-environmental behavior? Environmental Education Research, 8(3), 239-260. doi:10.1080/13504620220145401

Lähtinen, K., Harju, C., & Toppinen, A. (2019). Consumers’perceptions on the properties of wood affecting their willingness tolive in and prejudices against houses made of timber. Wood Material Science and Engineering, 14(5), 325-331. doi:10.1080/17480272.2019.1615548

Oorschot, J. v., Sprechter, B., Rijken, B., Witteveen, P., Blok , M., Schouten, N., & Voet, E. v. (2023). Toward a low-carbon and circular building sector: Building strategies and urbanization pathways for the Netherlands. Journal of Industrial Ecology, 27(2), 535-547. doi:10.1111/jiec.13375

Pretner, G., Darnall, N., Testa, F., & Iraldo, F. (2021). Are consumers willing to pay for circular products? The role of recycled and second-hand attributes, messaging, and third party certification. Resources, Conservation and Recycling, 175. doi:10.1016/j.resconrec.2021.105888

Ramesh, T., Prakash, R., & Shukla, K. (2010). Life cycle energy analysis of buildings: An overview. Energy and Buildings, 42, 1592-1600. doi:10.1016/j.enbuild.2010.05.007

Sartori, I., & Hestnes, A. (2007). Energy use in the life cycle of conventional and low-energy buildings: A review article. Energy and Buildings, 39, 249-257. doi:10.1016/j.enbuild.2006.07.001

Sobota, M., Driessen, I., & Holländer, M. (2022). Carbonbased Design. Rijksdienst voor Ondernemend Nederland. Den Haag: Transitieteam Circulaire Bouweconomie.

United Nations. (2020). Emissions Gap Report 2020. Nairobi: United Nations Environment Programme.

United Nations. (2023). Greenwashing – the deceptive tactics behind environmental claims. Retrieved December 6, 2023, from United Nations: https://www.un.org/en/climatechange/science/climate-issues/greenwashing

VORM. (2023). Bouwdeelbegroting: MBP11, Moederbegroting Bouw Plus Jaargang 1 Versie 1. Rotterdam: VORM Bouw B.V.

W/E Adviseurs. (2023, April 15). Zo bouwen we binnen ons CO2-budget. Retrieved June 6, 2023, from W/E: https://www.w-e.nl/kennisbank/zo-bouwen-we-binnen-ons-co2-budget/

Yadav, M., & Agarwal, M. (2021). Biobased building materials for sustainable future: An overview. Materialstoday: proceedings, 43(5), 2895-2902. doi:10.1016/j.matpr.2021.01.165

Zhou, L., & Lowe, D. (2003). Economic Challenge of Sustainable Construction. In D. Proverbs (Ed.), RICS Construction and Building Research Conference, School of Engineering and the Built Environment, University of Wolverhampton (pp. 113-126). Wolverhampton: RICS Foundation.

 

Full study

https://research.tue.nl/en/studentTheses/the-willingness-to-pay-for-sustainable-material-use-in-the-dutch-

 

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