Traditionally, in the building sector, local materials with low energy costs and low environmental impact were used. Nowadays, global materials such as cement, aluminium,concrete and PVC are used, increasing the energy costs and environmental impact. At present, the building sector contributes largely in the global environmental load of human activities: for instance, around 40% of the total energy consumption in Europe corresponds to this sector. It represents also a major potential for improvement, and is generally addressed by most environmental policies.
It’s necessary to highlight the interaction between all the stages of the life of a building: For example, if the investment in the construction phase is decreased (with a poor insulation), the investment in the use and maintenance will be increased. It’s estimated that 1 square meter built produce 1.5 tons of CO2 during its useful life span. So the question is: is better to invest in the construction rather than to invest in the use and maintenance? The application of a global methodology as the Life Cycle Assessment (LCA) will allow us to answer this question, since this methodology combined with Life Cycle Cost (LCC) can assess the global environmental impact and associated costs during the life span of a building.
1- Introduction
The Energy Performance of Buildings Directive includes environmental information in energy certificates, particularly CO2 emissions. Environmental performance is a major driving force to energy saving (climate change, exhaust of resources, nuclear waste, toxicity aspects etc.). Reducing environmental impacts in the building sector requires appropriate evaluation methods allowing:
{sidebar id=254 align=right} –environmental performance levels to be integrated in programmes (clients brief) by the demand side (e.g. requirements in municipal policy and building programmes),
–advice to be provided to designers, Architects and consultants, in order to reach such targets,
–guidance for efficient operation and management of buildings, so that actual performance corresponds to design performance,
–life cycle costing methods and tools do evaluate the most cost effective measures (actions) for energy savings and reduced environmental impacts over the whole life cycle.
Life cycle assessment (LCA) constitutes an important part of such evaluation methods. Previous studies allowed building LCA tools to be reviewed (e.g. International Energy Agency annex 31, European thematic network PRESCO, European projects REGENER and LENSE). Nevertheless there are some gaps regarding environmental indicators, easily understandable presentation of LCA results to users, simplification and adaptation of LCA to various purposes (e.g. early design phases). This paper presents a state of the art regarding the application of this method in the building sector and provides a list of existing tools, a description of environmental indicators and practice regarding application of LCA to building design.
LCA was mainly developed for designing low environmental impact products. As products, buildings are special since they have a comparatively long life, they undergo changes often (especially offices and other localities), they often have multiple functions, they contain many different components, they are locally produced, they are normally unique (seldom are many of the same kind), they cause local impacts, they are integrated with the infrastructure, system boundaries are not clear, etc. This implies that making a full LCA of a building is not a straight forward process like for many other consumer products.
{sidebar id=255 align=left} Life Cycle Costing gives information about most total costs over the whole life cycle. In combination with methods for environmental assessment and other assessment criteria, more support methods and tools are available for decision support during the design and construction process. Previous studies of existing LCC methods and tools, as well as the today’s use and future needs, are done in earlier projects as LCC Refurb, LCC-DATA, Task Group 4 (TG4) (2003) Report of Task Group 4: Life Cycle Costs in Construction, the European Commission, and EU Commission project Life Cycle Costing (LCC) as a contribution to sustainable construction: a common methodology.
2 – LCA methodology
SETAC1defines the Life Cycle Assessment as “an objective process to evaluate the environmental burdens associated with a product, process, or activity by identifying energy and materials used and wastes released to the environment, and to evaluate and implement opportunities to affect environmental improvements”.
At present, the LCA methodology is accepted as the basis on which to compare alternative materials, components and services. In addition, nowadays, the methodology is totally standardized through the following norms, ISO 14040-14043: The methodology of the LCA consists of 4 main phases:
– Definition of objectives and scope of application: The purpose of the study, the limits of the system, the necessary data, etc.
– Inventory Analysis: All inward and outward energy flows of the system during its entire useful life are quantified.
– Impact evaluation: A classification and evaluation of the results of the inventory analysis relating its results to observable environmental effects by using a collection of impact categories (acidification of soils, ozone layer depletion, toxicity, resource
depletion, etc.)
– Interpretation: The results of the preceding phase are evaluated together in accordance with the objectives defined in the study in order to be able to establish conclusions and final recommendations. Different techniques are used to do this including sensitivity analysis on the data, an analysis of the relevance of the different stages of the process and an analysis of alternative scenarios.
As can be observed in Figure 1, the LCA methodology has a dynamic character and the four phases are interrelated, so that as results are obtained, the original hypothesis can be considered or the data used can be refined in any one of the phases.
{sidebar id=256 align=right} Figure 2 presents the structure of the inventory analysis, which involves collecting data and calculation procedures in order to quantify all inputs and outputs of the system being studied. Quantified inputs for each stage of the building will include the use of energy and raw materials from nature: raw materials (water, sand, etc.) and crude fuel (carbon, natural gas, etc.); and from the technosphere: materials (glass, cardboard, etc.), fuels (propane, butane, etc.) and electricity. In the other hand, quantified outputs for each subsystem will include emissions to the air, water and soils, by-products and other wastes.
LCA studies the environmental aspects and potential impacts throughout a product’s life (i.e. cradle-to-grave) from raw material acquisition through production, use and disposal. The general categories of environmental impacts needing consideration include resource use, human health and ecological consequences. (ISO 14040). By doing a LCA you get quantitative information about the buildings contribution to for instance climate change and depletion of resources, which can be compared with the same information from other buildings.
The principle of LCA calculations is simple. For each life cycle phase you investigate the amounts of materials and energy used and the emissions associated with processes. The latter are combined it with emissions related to production, use, recycling, etc. and multiplied each emission with characterisation factors proportional to its power to give an environmental
impact.
One specific emission is chosen as the reference and the result is presented in equivalents with regard to the impact of a gram of the reference substance:
The number of equivalents summed up for each impact category can further be normalised and weighted to arrive at an aggregated result. The marked area is the core of each assessment method which differ between methods because for instance national differences in production processes, energy mixes or different choice of characterisation factors.
Further, use of different normalisation and weighting systems naturally causes different results. The possibility to easily acquire building data improves steadily with modern CAD-tools. For a simplified method it is possible to set up a database for a limited amount of building materials and energy carriers but preferably they should be in the form of EPDs (Environmental Product Declarations), which are Type III declarations (third party control, ISO 14025). More sophisticated LCA calculations need access to a larger international databases like Ecoinvent.
{sidebar id=257 align=right} 3 – Integrating LCA and LCC
Life Cycle Costing (LCC) is a tool for assessing the total cost performance of an asset over time, including the acquisition, operating, maintenance and disposal cost. Its primary use is in evaluating different options for achieving a client’s objectives, where those alternatives differ not only in their initial costs, but also in their subsequent operational cost.
LCC is central to the current international drive to achieve better value for money from the buildings and constructed assets we produce and use. The focus today has shifted to minimising both life cycle costs and the environmental impact. The inventory of building data for use in LCA can also be used in LCC but here you need complementary information on a database with €/MJ and € / kg.
The benefit with a LCC is that you can study the pay back time for the whole life cycle of different building products and design solutions. Since the future interest rate has to be anticipated different scenarios can be examined. Since both LCA and LCC is based on life cycle thinking assuming a certain life time for materials and the building they are suitable to combine giving simultaneously both potential life cycle costs and environmental impact for alternative designs. This combination may for nstance be used for:
— Choice of alternative technical solutions.
— Identifying the technical solution that meets an environmental target to the least cost.
— Recount environmental impact into costs.
— Evaluate a building investment.
It can be seen that LCC and LCA can either be used alongside each other in a broader revaluation process, or either process can form an input into the other.
4 – Potential users and purposes of LCA studies in the building sector
Table 2 presents the main target groups for applying LCA in the early design phases of a building. As can be observed in the table, the main potential users of LCA results are property developers, architects and urban planners.
{sidebar id=258 align=right}5 – Drivers and barriers for use LCA/LCC in the building sector
Both drivers and barriers might be real as cost offers or mental as a presumed high cost or complicated less useful result. Most barriers are probably of the latter kind.
Drivers may for instance be:
– Being environmentally progressive.
– Marketing benefit.
– European Energy Directive.
– The power of combining LCA and LCC.
– Simplified data acquisition.
– Environmental labelling of buildings.
– Environmental targets for buildings, the building sector, nations and Europe.
– Loans and subsidies for reduction of environmental impact.
Barriers to overcome might be:
– Prejudices about LCA complexity and arbitrary results.
– Poor knowledge about environmental impact and possibilities and to calculate them.
– Low demand for LCA/LCC.
– Too complicated calculations tools.
– Lacking of standardised interfaces to programmes used in the building sector (CAD, tendering, building physics).
– Poor cooperation between tool makers and potential customers.
– Too many tools displaying different results.
– Difficulties to understand and apply LCA/LCC results.
– Doubts about accuracy.
– Too high cost.
– Lack of legal demands.
– Low link with the energy certification tools.
– Poor incentives.
– Building sector is still driven by construction cost, operating and maintenance costs (not to speak of LCC) play a minor role.
6 – Building LCA tools
Due to the large amount of data required to perform a LCA it is recommended to avail of a software tool which facilitates the efficient undertaking of a study. At present various programs exist on the market and they allow the carrying out of LCA studies in different degrees of detail. In deciding which programs to use, it is necessary to consider several criteria.
The life cycle assessment of a building can be performed using general LCA software, but it requires much time to quantify building materials, energy use etc.
Therefore, specific tools have been developed to facilitate the use of LCA in the building sector: architects and engineers only have a few days to perform such a study, and appropriate interfaces are more convenient. Therefore this state of the art report focus on specific LCA tools for buildings.
{sidebar id=259 align=right}7 – ENSLIC BUILDING Project
Since 2007 the ENSLIC BUILDING Project 2 “ENERGY SAVING THROUGH PROMOTION OF LIFE CYCLE ANALYSIS IN BUILDING” is being developed. This project is co-financed by the European Commission (Intelligent Energy Programme Contract EIE/07/090/SI2.467609) and coordinated by CIRCE Foundation.
8 European partners participate
in this project: Ecofys (NL), SINTEF (NO), ARMINES (FR), CALCON Holding GmbH (DE), Royal Institute of Technology-KTH (SE), IFZ – Inter-University Research Centre for Technology, Work and Culture (AT), Non-profit Company for Quality Control and Innovation in Building (HU), y Sofia Energy Centre (BG). The aim of the project is to achieve energy saving in the construction and operation of buildings by promoting the use of life cycle assessment techniques in the design for new buildings and for retrofit and refurbishment of existing buildings. It will encourage and facilitate the use of LCA amongst architects, consultants and local authorities, providing them simple guides to perform LCA studies.
Within this research field, CIRCE is participating as a partner in the project LOW RESOURCE CONSUMPTION BUILDINGS AND CONSTRUCTIONS BY USE OF LCA IN DESIGN AND DECISION MAKING (LORE-LCA)” supported by the Seventh
Framework Programme for Research and Development and coordinated by SINTEF (Norway).
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Ignacio Zabalza, Sabina Scarpellini and Alfonso Aranda are at CIRCE -Centre of Research for Energy Resources and Consumption, University of Zaragoza, Zaragoza, Spain
Email: [email protected]
References
1 – International Energy Agency, Annex 31 : Energy related environmental impact of buildings, technical synthesis report, http://www.iisbe.org/annex31/index.html
2 – Åsa Jönsson, Tools and methods for environmental assessment of building products – methodological analysis of six selected approaches. Building and Environment, Volume 35, Issue 3, April 2000, Pages 223-238.
3 – Martin Erlandsson and Mathias Borg, Generic LCA-methodology applicable for buildings, constructions and operation services—today practice and development needs. Building and Environment, Volume 38, Issue 7, July 2003, Pages 919-938.
4 – Ding, Grace K.C. (2008). Sustainable construction – The role of environmental assessment tools. Journal of Environmental Management, 86, pp 451-464.
5 – Todd, Joel Ann, Crawley, Drury, Geissler, Susanne and Lindsey, Gail. (2001). Comparative assessment of environmental performance tools and the role of the Green Building Challenge. Building Research & Information, 29, 5, pp 324-335.
6 – ABDELGHANI-IDRISSI, M. A., BIROT, J.-J., SEGUIN, D., MILLER, A., IP, K. (2004), DURABUILD project, Environmental assessment tools report – http://www.durabuild.org/html/French/publications/EAT%20Report.pdf
7- Building environmental quality evaluation for sustainability through time (BEQUEST) (2000). Projet Européen. http://research.scpm.salford.ac.uk/bqpart/
8 – Department of Environment and Heritage. (2001). Projet Greening the building life cycle : Life cycle assessment tools in building and construction (Building LCA). Australian Government. Disponible en ligne. http://buildlca.rmit.edu.au/
