THE RELATIONS BETWEEN BUILDING PERFORMANCE AND EMBEDDED ENERGY – A NEW FOCUS ON BUILDING
ENERGY SOURCES, EMBEDDED ENERGY AND MATERIAL SCARCITY Energy mix and material energy profile
From 1990 and onwards there has been a steady increase of the renewable energy in Danish public energy supply. The energy-mix of renewable energies and fossil fuels has risen from approximately 6%
renewables of the total production in 1990 to more than 23% in 2012. The political ambition was to reach an energy-mix with 30% renewable energy by 2020, which has already been accomplished.8 The future aim is to phase out fossil fuels by 2050, where the energy production is to be based completely on renewable resources.9 As the renewable energy becomes a larger part of the energy-mix the performance energy of buildings is becoming more sustainable ensuring geopolitical energy independence and posing as a lesser environmental threat.
Renewable energy is also becoming a part of production of building materials and components. To a varying extent the public energy supply also influences the material production. In addition to the development in public energy supply, the political ambition and the increasing attention to sustainability will arguably give manufacturers of building materials the incitement to restructure production toward renewable energy. But for now renewable energy generally occupies a minor percentage of the total energy use in the production industry. As an example, the energy used in the production of mineral wool and gypsum boards includes less renewable energy in production than what is represented in the local public energy-mix.10 Many existing materials were produced with a lesser amount of renewable energy.
Hereby, materials represent a constant energy-profile linked to the time and place they were produced.
This profile is unaffected by contemporary development in energy-mix i.e. energy-profile of existing materials represent a greater environmental impact than future versions of the same materials. This leads to the question: Is it reasonable to continue focusing on performance energy of buildings without addressing the necessity of limiting the impacts tied to building materials?
Materials embedded energy and building lifetime environmental impact
As indicated in the previous paragraph an increasing amount of materials are being used in achieving a more energy efficient building stock. A study of 7 Danish office buildings showed that the embedded emission counts for 21%-75% of the total impact in a lifespan period of 50 years. The highest performing office building had a material-to-operation impact ratio of 9.1 kg to 3.0 kg CO-equivalent/ (m2 x year) resulting in 75% embedded emissions, whereas the lowest performing building had a material-to-operation impact ratio of 5.5 kg to 21.1 kg CO-equivalent/ (m2 x year) resulting in 21% embedded emissions.11 Furthermore, a Norwegian study of national office buildings shows that the embedded emission is becoming a substantial part of the environmental impact with a total impact of 66% over a
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60 years’ life span tied to its materials.12 Despite the fact that Denmark has less renewables in its energy-mix than Norway, both cases show that the bulk of energy increasingly is tied to the materials of the building instead of its performance. Especially, in high performance buildings it demonstrates that the impact is shifting from lifetime performance energy use and emissions to energy embedded in the materials.
In a Danish perspective, a primary means to achieve high performance buildings, such as nearly-zero energy buildings, is highly insulated building envelopes. The relations between embedded energy of mineral wool and its impact on operational energy over time was analysed in the fall of 2016. The analysis shows that the optimal point, where the total environmental impact of insulation is at its lowest (operational plus material impact within the building's lifetime), does not correlate with an increasing amount of insulation.
Figure 4: The optimal level of insulation showed by relating total lifetime impact tied to the insulation material to the attained benefits on heating requirements.13
The performance effect of the insulation material decreases as quantity increases. This indicates that performance energy cannot stand alone when assessing the environmental impact of a building. To get a realistic picture of the total lifetime impact of a building the material impact and a dynamic view on energy-mix must be part of the assessment. The latest LCA-assessment software14 is addressing the need for looking upon energy-mix in a dynamic way. It is possible to weigh material choices for buildings against a static and dynamic setting. In the included example of an average office building in Denmark the static view on energy-mix (2015 levels) suggests approximately 38% of total lifetime impacts are tied to materials and in a dynamic setting the impacts tied to materials go up to approximately 68%. This indicates that as long as material impacts and development in energy-mix are not addressed in the Danish Building Regulations it is impossible to substantiate the CO2 impact of Danish buildings.
A holistic view on material environmental impacts
As the building industry is beginning to look more closely at building materials and their environmental impact other related challenges are beginning to emerge. The Danish building industry causes approximately 1/3 of the total waste production. Although, 87% of the waste is recycled only a marginal percentage is reused.15 In the Danish context, the definition of recycling means that most building
AMPS, Architecture MPS; London South Bank University, UK on 9-10, February, 2017
materials are grained and used for road fill.16 As a result, a down cycling of materials at the buildings end-of-life happens and the need for virgin materials remains high.
During the last decade, the demands on virgin materials have influenced the prices of scarce raw materials.17 The scarcity of raw materials influences the building industry on many levels. Amongst others, the demand for concrete has increased in the last 20 years creating a request for useful sand types.
Sand mining has lead to damages in biodiversity and land erosions in river basins, coastal areas and inland areas across the globe - as well as it is creating economical uncertainty in impoverished communities.1819 As a consequence, the need for better, more efficient, and larger quantities of reused materials within the building industry is part of the agenda in Denmark both within the building industry and at political level.2021
DISUCUSSION
Since the 1970’s the Danish Building Regulations and National Legislations have enforced an understanding of high performance buildings being the optimal solution for providing answers to the energy crisis and sustainability. But, the legislation comes across with a one-sided focus that has not adjusted to new knowledge and challenges, and it does not include a broad approach to environmental issues such as, materials environmental impacts, waste production and material scarcity. When considering the sustainable development in the mix, the discussion on buildings energy-performance will become a question of supply capacity and finances whereas the environmental aspects increasingly will be tied to the impact of the building materials. Combined with the waste production of the industry and the risk of material scarcity a focus on material use in architecture is re-emerging.
The focus on energy performance has led to new markets of energy efficient products. The result has been an escalation in the number of building materials and components on the market.22 High-tech composite materials are common in buildings today and their environmental impact is difficult to assess.
Layered construction methods ad to this complexity and can be hard to decipher. Together, these aspects make a complex and expert based building culture that is difficult to maintain and deconstruct. This makes re-use of building materials challenging and expensive, and as a result; destructive demolition is often chosen at end-of-life. Questioning the overall environmental impact of buildings and especially materials used in a performance based building culture could potentially lead to a new understanding of the role of architecture when aiming for a sustainable future.
The role of the architect has changed with the performance based architecture and has resulted in a breach between ‘traditional’ craftsmanship and material understanding as governed by the pre-1970’s Danish Building Regulations. Although, the increasing industrialisation of building constructions, the development of technology and material complexity of the 21th Century have revolutionized construction practices, simultaneously traditional crafts have been wiped away without regards to its empirically developed circumstances.23 One could argue, that contemporary construction, older industrialised construction and historical construction methods build upon different tectonic visions, which not necessarily work together with the construction methods developed as part of contemporary energy performance based building culture. With a re-discovered focus on materials - a return to an architectural understanding/ethos as perceived in the pre-crisis Building Regulations could occur;
resulting in a new tectonic vision based both on contemporary energy performance, as well as material energy-profiles. Ideas based on material circular economy can introduce an architecture where buildings are approached as; ‘temporary storages of materials’, which opens the door for flexible and reversible architectural designs. Although, the premises of material use are changing and becoming a part of an
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1 World Commission on Environment and Development, Our Common Future (Oxford: Oxford University Press, 1987).
2 Jørn Lund, ed., Den Store Danske Encyklopædi (Copenhagen: Danmarks Nationalleksikon, 1994).
3 Erik Kjersgaard, Kjersgaards Danmarkshistorie ([Kbh.]: Aschehoug Fakta, 1998).
4 Danmarks Radio, “Tidslinje: Krisen Måned for Måned,” DR, 2017, http://www.dr.dk/skole/historie/tidslinje-krisen-maaned-maaned.
5 Christian Larsen, “Da Danskerne Skruede Ned for Varmen,” Rigsarkivet, november, 29, 2014, https://www.sa.dk/danmarkshistorien/nyt-i-arkivet/oliekrisen.
6 Rob Marsh, Arkitektur og Energi: Mod En 2020-Lavenergistrategi (Hørsholm: SBI forlag, 2011).
7 European Parliament, Council of the European Union, “Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the Energy Performance of Buildings” (2010), http://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32010L0031.
8 Energi-, Forsynings-, og Klimaministeriet, “Vedvarende energi dækker nu 30 Pct. af energiforbruget i Danmark,”
www.edkm.dk, December 1, 2016, http://efkm.dk/aktuelt/nyheder/nyheder-2016/december/vedvarende-energi-daekker-nu-30-pct-af-energiforbruget-i-danmark/.
9 Klima og energiministeriet and Regeringen, Energistrategi 2050: fra kul, olie og gas til grøn energi:
sammenfatning (Kbh.: Regeringen: [eksp.] www.ens.dk, 2011).
10 This data is based on Environmental Product Declarations (EPD) of insulation materials, production stage (A1-A3) from Institut Bauen und Umwelt e.V. (IBU) in accordance with ISO 14025 and EN 15804
11 Harpa Birgisdóttir and Statens Byggeforskningsinstitut, Kortlægning af bæredygtigt byggeri (Statens Byggeforskningsinstitut, 2013).
12 Tor Helge Dokka, Torhildur Kristjansdottir, Berit Time, Sofie Mellegård, Matthias Haase and Jens Tønnesen,
“ZEB Project Report No 8, A Zero Emission Concept Analysis of an Office Building” (NTNU, 2013).
13 Illustration from: Sohn, J.L., et al., “Life-Cycle Based Dynamic Assessment of Mineral Wool Insulation in a Danish Residential Building Application, Journal of Cleaner Production,” 2016,
http://dx.doi.org/10.1016/j.jclepro.2016.10.145.
14LCA-byg SBI 31/1 2017, software for LCA assessment in a Danish context.
15 Miljøstyrelsen, Rasmus Toft, Christian Fischer, Nanna Aasted Bøjesen, “Affaldsstatestik 2014,” September 2016.
16 Genbrug af byggevarer: forprojekt om identifikation af barrierer (Statens Byggeforskningsinstitut, 2015).
17 Lucia Mancini et al., Security of Supply and Scarcity of Raw Materials towards a Methodological Framework for Sustainability Assessment. (Luxembourg: Publications Office, 2013),
http://dx.publications.europa.eu/10.2788/94926.
18 Global Environmental Alert Service (GEAS), “Sand, Rarer than One Thinks” (UNEP, March 2014).
19 Laura Höflinger, “World’s Beaches Becomes Victims of Construction Boom,” February 10, 2014,
hbp://www.spiegel.de/internaQonal/world/global-sand-stocks-disappear-as-it-becomeshighly- sought-resource-a-994851.html.
20 Miljøstyrelsen, Danmark uden affald: Ressourceplan for affaldshåndtering 2013-2018, Vejledning fra Miljøstyrelsen nr. 4, 2014.
21 Miljøstyrelsen, Danmark uden affald II: strategi for affaldsforebyggelse (Regeringen, 2015).
22 Stephen Kieran, Refabricating Architecture, How Manufacturing Methodologies Are Poised to Transform Building Construction (New York: McGraw-Hill, 2004).
23 Anne Beim, Royal Danish Academy of Fine Arts, School of Architecture, “Tectonic Visions in Architecture:
Investigations into Practices and Theories of Building Construction; Six Case Studies from the 20th Century.”
(Royal Danish Academy of Fine Arts, School of Architecture Publishers, 1999).
AMPS, Architecture MPS; London South Bank University, UK on 9-10, February, 2017
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