Building with a positive ecological footprint

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International HISER Conference on Advances in Recycling and Management of Construction and Demolition Waste

21-23 June 2017, Delft University of Technology, Delft, The Netherlands

238

Building with a positive ecological footprint

Development and evaluation of a Cradle to Cradle ®-inspired energy-plus house Salfner S.1 and Lang W.2

1

Hochschule Ansbach/Campus Feuchtwangen, Sustainability in the Building Sector, Ansbacher Str. 20, 91555 Feuchtwangen, Phone (+49) 1522 1866110;

E-mail: simone.salfner@hs-ansbach.de 2

Technical University of Munich, Institute of Energy Efficient and Sustainable Design and Building, Arcisstr. 21, 80333 Munich

Abstract

Energy-plus houses have been taking on particular significance in future-oriented residential construction. Therefore, it should be possible to build CO2-neutral buildings that can meet their own energy demand and in fact supply energy for additional consumers, e.g. electromobility. Based on the example of Cradle to Cradle® (C2C), the aim is moreover to demonstrate how buildings can already be constructed with an essentially positive ecological footprint today.

This research project analyzed and described how the fundamental C2C principles: “Waste equals food,” “Use current solar income” and “Celebrate Diversity” can be transferred to and implemented in the “nexushaus,” designed and built for the Solar Decathlon competition 2015.

Material. Technical and biological nutrient cycles of the “nexushaus” were defined and

described in the list of materials along with the specified environmental indicators. A healthy residential environment achieved by pollutant-free materials is discussed. This is followed by a detailed discussion of the recyclability of the nexushaus.

Water. The water footprint of the building structure is analyzed. Potential measures to enable

eco-sufficient use of water as a resource are described. Gray-water recycling saves drinking water and can be used for the irrigation of green spaces. The use of accumulating

condensation water supports self-sufficient food production (e.g. aquaponics). If rainwater is harvested, its use for drinking water or garden irrigation should also be considered.

Diversity. The architectural design of the house offers cultural benefits: barrier-free access

and diverse qualities of stay in the indoor and outdoor space by outlooks and partial insights that accommodate places of retreat. Additional habitats for animals and plants can be provided in the form of green roofs and façades.

Keywords: Cradle to Cradle®, Material, Energy, Water, Diversity Introduction

In order to enable a fundamentally positive approach to the earth’s ecosystem, further aspects over and above energy efficiency must be considered when planning and constructing buildings. This includes taking into account closed biological and technical nutrient cycles when using materials and resources. Sufficiency concepts and efficiency measures can help reduce the construction and operation costs.

In addition, health aspects, aspects related to meeting the needs of all generations, as well as sustainable use of water must be included, taking low-tech solutions into consideration.

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Creating habitats for flora and fauna enhances the microclimate and has a positive impact on the well-being of residents and users. For instance, green areas in interior spaces can improve room acoustics and air quality.

Use of resources

We currently distinguish between two overarching recycling scenarios. The linear recycling process, whereby a product is bought, used and disposed of, without asking what eventually happens with it still prevails. The optimized and future-proof goal is cycle-oriented product recycling. A product is purchased, used or consumed, and returned to the manufacturer or to nature to create a new product. To enable unrestricted recyclability in the technical or biological nutrient cycle, it is crucial to disassemble all system components into their individual parts. To achieve this, it is necessary to embrace the Design for Disassembly (DfD) strategy as early as the initial planning phases (Fig. 1).

Where selective disassembly requires only a few steps, this helps achieve cost reductions compared to disposing of materials and components [1].

The following aspects should already be considered in the initial planning phases to enable transformation of the building and reuse of its elements:

Useful life of materials and building components; accessibility; choice of connecting means; structural protective measures, material wear and maintenance

Digital planning tools applied in Building Information Modeling (BIM) help implement the transformation of the building. Assembly and disassembly sequences are presented, avoiding collisions in the manufacturing process and achieving substantial time savings. Appropriate material management saves storage space on the construction site.

Water footprint

Water is a vital resource for humans, animals and plants. Consequently, water pollution may cause substantial damage. For example, humans may contract diseases from waterborne viruses or the diversity of aquatic life may be minimized by excessive algae formation. Due to rising population numbers and increasing consumption, there are no prospects for reduced resource consumption in the near future. Therefore, there is a major need for immediate action. Cradle to Cradle hence advocates careful use of water when manufacturing products [2].

Fig. 1. Technical and biological nutrient cycles of the case-study house

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The water footprint of the nexushaus was calculated on the basis of the Ökobau.dat data for 2016 (Fig. 2). The manufacturing, maintenance and disposal of products consume freshwater resources, or they are transformed into another physical state (for example from liquid to gaseous by evaporation) after use. Water is used for cooling purposes particularly in the context of energy supply. This is confirmed by the sector-specific water extraction rates. According to Statista, 20.3 billion m3 of water are withdrawn by thermal power plants, which corresponds to 61.6%. This is followed by the mining and manufacturing industries, accounting for 20.2% (6.8 billion m³) and public water supply for households and small businesses (17.6%, 5.9 billion m³). Agricultural irrigation accounts for 0.2 billion m³ or 0.6% of total water extracted [3].

The water used for the energy-intensive production of wood-based materials as well as the cooling water required for thermal utilization place the highest strains on fresh water resources. Approx. 166 m² of Oriented Strand Boards (OSB) are needed when constructing the nexushaus, this corresponds to a volume of 4.44 m³. The panels are used for wall mounting and stiffening as well as for the raw flooring of the modules. When the life-cycle assessment is based on a building life of 50 years, this results in 105,016 m³ of water. Only recycling the material (D) can credit a few resources to the product. The dataset from Ökobau.dat (2016-I) refers to 1 m³ and contains the following parameters for describing the use of freshwater resources [4]:

A1 Supply of raw materials: 12,500.00 m³; A2 Transport: 1.27 m³; A3 Production: 7,030.00

m³; C2 Transport (disposal): 0.15 m³; C3 Waste treatment: 49.90 m³;

D Recycling potential (thermal) 4,230.00 m³; D Recycling potential (material): -242.00 m³

The total water footprint caused by the building structure of the nexushaus amounts to 123,315 m³. Given a maximum number of 3 residents, each resident carries an additional ecological water rucksack of 2,252 l per day up to the end of the building’s life (50 a). This does not include domestic drinking water.

Conclusion

Any building task should encompass far-sighted planning that covers the entire life cycle of a building (cf. lean construction/management). The abovementioned C2C principles help achieve this. The research report presents the implementation with regard to material, water, energy and diversity in the construction sector, in which the cycle concept plays the central role.

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241 References

[1] E. Durmisevic, Green design and assembly of buildings and systems: Design for Disassembly a key to Life Cycle Design of buildings and building products. Saarbrücken: VDM Verlag Dr. Müller, 2010

[2] Cradle to Cradle Products Innovation Institute. (2016). Cradle to Cradle CertifiedTM: Product Standard, Version 3.1. [Online]. Last downloaded 21/04/2017:

http://www.c2ccertified.org/resources/detail/cradle_to_cradle_certified_product_standard [3] statista.(2016). Wassernutzung – Entnommene Menge nach Sektoren in Deutschland

2010. [Online]. Last downloaded 21/04/2017:

https://de.statista.com/statistik/daten/studie/12358/umfrage/wasserressourcen-in-deutschland-nach-nutzung/

[4] Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit (Hrsg.). (2016). Prozess-Datensatz: Oriented Strand Board (Durchschnitt DE). [Online]. Last downloaded 21/04/2017:

http://www.oekobaudat.de/datenbank/altbrowseroekobaudat/daten/db1/3.2.04/Holz/Holzwerk stoffe/OSB-Platte.html