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EnerBuiLCA: life cycle assessment for energy efficiency in

buildings

Speakers:

Isasa, M1; Gazulla, C1, Zabalza, I2; Oregi, X3; Partidário, P4; Duclos, L5.

1. ESCI-UPF (Cátedra UNESCO de Ciclo de Vida y Cambio Climático), Barcelona, Spain 2. CIRCE, Zaragoza, Spain 3. TECNALIA, Derio, Spain 4. LNEG, Lisboa, Portugal 5. NOBATEK, Anglet, France

Abstract: Reducing the huge environmental impacts caused by buildings- direct energy

consumption and embodied energy of materials- needs a broader application of LCA.

However this meodology is seen as too complex and time-consuming for being integrated in

their daily work. There is a need to bring this methodology closer to a broad public not

necessarily familiar with the LCA methodology.

The EnerBuiLCA project (funded by the ERDF through the Interreg IV B programme) has

developed a user friendly tool associated to an environmental information database of

construction products developed with available Environmental Product Declarations (EPD).

This tool has been tested on 20 pilot studies. It calculates the building´s primary energy

consumption and the Global Warming Potential measured in CO2 equivalents, allowing an

initial screening of the hotspots throughout the building´s life cycle. Tool´s limitations are

sought to be overcome in other research projects such as URBILCA.

Key words: Buildings, LCA, EPD, energy efficiency

Introduction

Two major global concerns have been identified: reducing energy consumption and the amount of associated Green House Gas emissions (GHG hereafter). In this context, the European Commission adopted a European Strategic Energy Technology Plan [1] in which a clean, efficient and low-carbon energy technology scenario for Europe is envisaged for 2020 by means of a triple 20% objective: GHG emissions reduction from 1990 level, increase of renewable energy sources in the energy mix and primary energy consumption reduction to improve energy efficiency. The European Union has also identified potential for reduction in energy consumption especially in energy intensive sectors such as construction, which will contribute to improving energy efficiency.

Buildings are responsible for 40% of energy consumption and 36% of CO2 emissions in the European Union [2]. The Directive on energy performance of buildings [3] and its recast dated May 2010 [4] is the main legislative instrument at EU level to achieve energy performance in buildings, and therefore achieve the EU´s climate and energy objectives. Under this Directive, the Member States must apply minimum requirements as regards the energy performance of new and existing buildings and ensure the certification of their energy performance.

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Measures to improve energy performance in buildings introduced through this Directive in member states legislation, focus in minimizing direct energy consumption to supply heating and cooling, hot water and lighting demands during the building’s use phase. However, energy consumption associated to other phases of the building´s life cycle such as the production of construction materials and other indirect impacts are still overlooked. In this regard, studies have shown that the amount of embodied energy in construction products can vary between 9 and 46% of the overall energy demand of the building´s service life in low energy consuming buildings and between 2 and 38% in conventional buildings [5]. A more global and realistic approach is therefore required to quantitatively evaluate the energy consumption and associated environmental impacts of buildings ‘from the cradle to the grave’, and effectively improve their life cycle energy efficiency.

According to the European Commission [6,7,8, 9], currently the Life Cycle Assessment (LCA) methodology constitutes the most appropriate framework to adequately assess the environmental impacts of any kind of activity, product or service throughout its life cycle. However, the application of this methodology to the construction sector is quite complex and needs to be adapted through appropriate tools to fit the particularities of the buildings and the relative lack of information throughout the sector. LCA is therefore considered as a versatile and useful tool for reducing the energy consumption and associated GHG emissions of the construction sector and establishing the most appropriate environmental improvement measures from a global perspective [10, 5].

The application of LCA to buildings, allows considering the environmental impact of all stages of their life cycle, including the product, construction process, use and end of life stages. At present, the current legislative framework is leading to the minimization of the environmental impacts associated to the use phase of the building, increasing therefore the relative weight of the remaining phases of the life cycle of the buildings.

The EnerbuiLCA project

The EnerBuiLCA European project, funded through the Interreg IV B programme aimed at fostering sustainability in the construction and refurbishment of buildings used either for housing or industrial uses. In so doing, a tool for the quantitative assessment of direct and indirect energy related impacts of buildings in Spain, the South of France and Portugal was developed based on the LCA methodology. The application of the tool allows the development of the appropriate strategies for reducing energy related impacts throughout the building´s life cycle, from materials production, building construction, use and maintenance to building refurbishment, thus promoting the development of the new `Life Cycle Zero Emission Buildings ´standard´[11].

Other project objectives included the training amongst the project beneficiaries- including any professionals related to the building sector- in the use and application of LCA for designing energy efficient buildings and raising awareness on the need for and opportunities to develop more sustainable buildings.

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The main results of the project, other than the EnerBuiLCA tool for the life cycle assessment of buildings, included the creation of a Thematic Network on LCA and energy efficiency in buildings, a database of representative construction systems for the SUDOE area and 20 pilot studies.

Methods

The EnerBuiLCA tool is accessible through the project website to all users registered within the Thematic Network, and is based on the LCA methodology as described in ISO 14040 and ISO 14044 standards [12, 13]. Technical specifications and calculation methods contained in EN 15643-1 [14], EN 15643-2[15], EN15804 [16] and FprEN 15978 [17] have also been considered in the development of the tool.

Life cycle assessment (LCA) addresses the environmental assessment of goods and services through their life cycle. The life cycle of a product is defined as the complete supply-chain of the product plus its use and end-of-life treatment. The standardized phases of an LCA include goal and scope definition, Life Cycle Inventory (LCI), Life Cycle Impact Assessment (LCIA), and the interpretation of results.

System boundaries

Taking into account the EnerBuiLCA’s objectives, the software tool considers the building’s product, construction and use stages, leaving the end-of-life stage out.

Database

Carrying out a LCA of complex products, such as buildings, is difficult and entails collecting a huge amount of quantitative data related to its individual life-cycle phases (LCI). The LCI of the production phase, due to the fact that hundreds of different products are used in the construction of a building, is foreseen as the most difficult and time-consuming to complete. Many databases have been developed by different commercial and industry data base providers in the last decades to facilitate this phase [18, 19]. However these databases offer a limited amount of construction-related datasets. The development of complete, up-to-date, flexible and free-cost LCI database was therefore considered necessary from the outset and is one of the main results of the EnerBuiLCA project.

The strategy followed for the development of this database involved the identification and the characterization of the main representative construction systems for Spain, France and Portugal and gathering information from available Environmental Product Declarations (EPD) of construction products under different ecolabelling schemes such as DAPc, Umwelt Deklaration, the International EPD System etc [20, 21, 22]. In doing so, three different standard databases were developed:

• 1 Construction products database including 72 different products;

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• 1 EPDs database including 169 entries with information on primary energy (MJ) and kg of CO2 equivalents;

• 3 Construction systems databases specific for each country including 18 representative systems for Spain, 20 for France and 11 for Portugal. These systems are defined by standard products which in turn are respectively related to an EPD.

A generic database including information on energy sources and transport has also been integrated into the tool.

To become part of the EPD database, EPDs had to be registered with a programme compliant with ISO 14025; declare primary energy and CO2 equivalents information and, as a minimum, declare the information from the product stage.

The environmental product database can include further information on products as its use increases. Only EPDs that have gone through a validation process integrated within the tool would be susceptible for becoming part of the standard database.

Pilot Studies

The tool was tested on 20 different pilot studies of real existing buildings in the three countries. These were selected following a multi-criteria analysis which included: geographical and climatic area, type of building and structure, construction systems used and data availability. The pilot studies were identified, characterized, and quantified in the framework of the project and the information gathered used as inputs to the tool. Energy simulations were developed to obtain information on final energy consumption. These results were also used as inputs to the tool and to obtain the energy certification according to each country´s relevant procedure. After the application of the tool to each pilot study, LCA results on Global Warming Potential (kg CO2 equivalents) and Primary Energy (MJ) indicators for the product, construction and use phases were obtained.

User´s interface and needs

In order to create and evaluate a project, the designer needs to (1) define the project and (2) the product stage followed by (3) the construction and (4) use stages in line with the system boundaries established for the project. Having done this, the designer will be able to calculate the results (5) and generate the associated excel spread sheet with environmental results and graphic information (6).

The designer in step (1) can choose to evaluate a building to be built or refurbished and following the selection of the Country in which the building is located- which will determine the construction systems and generic databases- continues defining the project with information such as: geographic and climate area, type of building, built and habitable floor space areas, service life etc.

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Having done this, the designer will be able to move on to (2) by defining the construction systems integrating the building, the categories of which include façades, roof, dividing walls, vertical and horizontal structures. The measuring unit for each of these categories is m2 except form the vertical structures which are defined by the units of the products integrating them. Each product forming each system is associated to an EPD. The tool is programmed to adapt the declared unit to the building´s functional equivalent in line with guidelines contained within EN 15978 [17].

Since the product and construction system databases currently contain limited amount of information, the designer at this stage will be able to select a system from the standard database and will also be able to modify the information associated to it to adapt it to the real scenario under study. Besides this, the user will also be able to create new products or construction systems.

Construction stage (3) implies the definition of some values relating to the construction of the building. The tool incorporates default values on electricity (24,23 MJ/m2 construction system) and diesel (23.4 MJ/ m2 construction system) consumption from on-site machinery, amount of waste generated on site (120 kg/ m2construction system) and its transport distance (50km) to the treatment facilities. The transport distances of the products included in the constructive systems from the factory gate to the building site (50km) are defined in step (2) when defining the construction systems. These default values were extracted from real data from a previous research project [23] and can be changed by the user if in possession of this information.

The user has to introduce the information on the energy consumption of the building during its use phase (4) which he would have previously obtained from a relevant simulation tool. The user can choose to introduce the information by type of use (heating, cooling, DHW and lighting) and source of energy associated to each use (renewable or non renewable including electricity, natural gas and diesel oil) or just by the source of the energy. The operation of the related equipment and services of the building has not been considered within the system boundaries neither have water demand, users’ mobility, consumable products, solid waste, etc. Building maintenance, repair, replacement and refurbishment processes are also considered at the use stage. Necessary maintenance during a product´s service life is extracted from the product EPD.

Having done this the user is able to obtain real-time information on energy consumption and the associated GHG emissions of the evaluated building to be built or refurbished (5 and 6) (Figure 1).

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Figure 1: Sample of impact and graphic information generated from the tool in an excel file

The needs of the potential users of the tool were taken into consideration through the analysis of the results of surveys undertaken to the users registered to the thematic network (currently 1,012) before and after publishing the tool. A survey amongst the 65 users that have created a project with the EnerBuiLCA tool since its publication has also been undertaken after project implementation.

Results of the application of the tool

This paper presents information on the 20 pilot studies and the results for the Primary Energy indicator after the application of the EnerBuiLCA tool. Besides it summarises the results of the survey undertaken to the 65 users that created a project with the tool.

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Table 1: Case studies information and Primary Energy Indicator results after the application of the EnerBuiLCA

tool

Notes: CA= Climatic area, ES Tool= Energy simulation tool, BA= Built area, HFA= Habitable Floor Space,

EC= Energy Certification

Wide heterogeneity amongst the Primary Energy Indicator results associated to each phase can be observed. According to the results, the amount of embodied energy in construction products can vary between 0.5% (lowest value for case study number 19) and 41% (highest value for case study number 11) of the overall energy demand of the building´s service life. Despite the fact that the building´s product phase normally represents a 30% of the overall energy demand, only 6 out of the 20 pilot studies evaluated, representing a 30% of the sample, showed results close to this value ranging from 21% to 41% (numbers 5, 6, 11, 13, 14 and 15). This is due to simplifications undertaken when characterizing the construction

nº Type of Building Country CA Materials assessed ES Tool EC Product Building Use Total

2,90E+01 3,02E+00 7,94E+02 8,26E+023,5% 0,4% 96,1% 100,0%

3,02E+01 4,78E-01 6,82E+02 7,13E+024,2% 0,1% 95,7% 100,0%

2,97E+01 3,95E+00 1,72E+0214,5% 1,9% 83,6% 100,0%

1,51E+02 6,50E+00 4,23E+02

26,0% 1,1% 72,9% 100,0%8,09E+01 2,90E+00 2,99E+02

21,2% 0,8% 78,1% 100,0%- - -

18,2% 0,5% 81,3% 100,0%- - -

0,9% 8,8% 90,3% 100,0%- - -

7,0% 0,4% 92,6% 100,0%1,55E+01 5,50E+00 5,14E+02 5,35E+02

2,9% 1,0% 96,1% 100,0%1,52E+02 1,50E+01 2,03E+02 3,70E+02

41,1% 4,1% 54,9% 100,0%3,79E+01 1,28E+01 7,30E+02 7,80E+02

4,9% 1,6% 93,5% 100,0%9,97E+01 2,90E+00 2,63E+02 3,65E+02

27,3% 0,8% 71,9% 100,0%1,67E+03 7,37E+00 2,80E+03 4,48E+03

37,3% 0,2% 62,5% 100,0%1,37E+02 3,43E+00 3,84E+02 5,24E+02

26,1% 0,7% 73,2% 100,0%9,31E+04 1,46E+04 2,40E+06 2,51E+06

3,7% 0,6% 95,7% 100,0%2,44E+05 1,96E+05 4,63E+07 4,67E+07

0,5% 0,4% 99,1% 100,0%1,35E+06 1,41E+05 7,41E+07 7,56E+07

1,8% 0,2% 98,0% 100,0%2,60E+04 1,94E+04 4,88E+06 4,93E+06

0,5% 0,4% 99,1% 100,0%2,58E+05 1,87E+05 5,68E+07 5,73E+07

0,5% 0,3% 99,2% 100,0%2,96E+01 7,20E+00 3,49E+02 3,86E+02

7,7% 1,9% 90,5% 100,0%

1,15E+03 1,15E+03

100,0% 100,0%

1,68E+00 2,37E-01 8,67E+02 8,69E+02

0,2% 0,0% 99,8% 100,0%

RCCTE A

LCA results

Primary energy (MJ/m2 climatized area*year)

Percentages

Building description

DesignBuilder D

21Single family house

(residential) Portugal I1, V2 Envelope

DesignBuilder C

20 Education centre

(services) Portugal I1 ; V2 -

DesignBuilder C

19 Nursery (services) Portugal I2 ; V2 Norte -

DesignBuilder A

18 Hotel (services) Portugal I2 ; V1 Norte -

DesignBuilder A+

17Offices and laboratories

(services) Portugal I1 ; V2 -

Alcyone + Pléiades Comfie

16Single family house

(residential) Portugal I1 ; V2 Norte -

Pléiades Comfie

15Housing block

(residential) France H2C Envelope+structure

CLIMAWIN

14Single family house

(residential) France H2C All except lighting

Autodesk Ecotect Analysis 2010 -

13Offices and laboratories

(services) France H2C Envelope+structure

Design Builder -

12 Offices (services) Spain C1 Envelope + geometry

Autodesk Ecotect Analysis 2010 -

11 Industrial Spain C1 Envelope+structure+geometry

CALENER VYP C

10Secondary school

(services) Spain C1 Envelope + geometry

CALENER VYP C

9Nursing home

(services) Spain C4 Envelope+structure

CALENER VYP D

8Health centre

(services) Spain A3 Envelope+structure

CALENER GT A

7Offices and laboratories

(services) Spain B4 Envelope+structure

CALENER VYP B

6Offices and laboratories

(services) Spain D3 Envelope

Housing block (residential) Spain C2 Envelope+structure Lider y CalenerVyP

CALENER VYP C

5Single family house

(residential) Spain D3 Envelope

Lider y CalenerVyP C

4Housing block (residential) Spain D3 Envelope+structure

24,78%

New Buildings built

Refurbishments

Housing block (residential+ offices)

Pre refurbishment Spain C2 - Lider y CalenerVyP EHousing block

(residential+ offices) Post refurbishment Spain C2 Envelope+structure Lider y CalenerVyP D

2

Refurbishment savings

C1

3Housing block

(residential) Spain C2 Envelope+structure

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systems in the product stage which mainly include those involved in the envelope of the building. Since the objective of this exercise was to test the tool, these simplifications were considered appropriate. These percentages of primary energy from the building´s product phase regardless of their contribution to the building´s final energy demand are not considered in the energy certification of the building.

Table 1 also shows the results of a refurbished building (number 2). When comparing the results prior and post refurbishment, it can be observed that the energy demand from the use phase reduces producing a 24% global energy savings.

Results obtained from the surveys undertaken to the users of the tool showed that 50% of the respondents came from an academic or research backgrounds linked to architecture whilst the remaining 50% were distributed amongst professional associations, construction products producers and engineering companies. 50% of the respondents had previously used the LCA methodology for the assessment of buildings, construction systems or products by means of the SimaPro software or other tools to develop EPDs. SimaPro users had made use of it in an academic context.

As for the limitations of the tool, 66% of the respondents reported the tool lacked environmental information to appropriately define the product phase and found the input to define the use phase limited. 88% found information limitations to define the construction phase, particularly relating to ground movements and excavation. The definition of the product phase is considered as very versatile, particularly the possibility of using different measuring units and the unit conversion calculations in place, although complex and time consuming. Limitations of the product database- linked to the lack of EPDs for building products- forces the designer to apply simplifications.

Despite the room for improvement, 66% of the users found the tool very useful (scoring 4 or 5 out of 5) and 16%gave it a fail under usefulness score.

Specific improvement suggestions to the tool included expanding the product and construction systems database, linking the tool to an energy simulation tool to obtain the inputs for the use phase directly without having to calculate them separately. Links to costing tools were also seen as an advantage. Expanding the systems boundaries to include the end of life phase is also considered necessary.

Discussion and conclusions

The EnerbuiLCA project provides a simplified and user friendly LCA tool and associated databases. The tool allows the incorporation of new elements to allow the assessment of real case studies in case this information was not available from the database. Despite its limitations, its application brings the LCA methodology closer to a broader public who is not necessarily familiar with it. This way, users have all the necessary information in their hands

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to be able to consider energy and environmental impacts when selecting materials, suppliers and more eco-efficient production processes.

Although the impact assessment in the EnerBuiLCA tool is based primarily on indicators of energy consumption and GHG emissions in line with the current environmental concerns, it would allow other environmental indicators (energy, water and financial), always from a life cycle perspective.

The URBILCA project- also presented in this congress- capitalizes the results of the EnerBuiLCA project, includes the end of life phase, further extends its spatial boundary to the urban scale and includes an indicator for water consumption. This will jointly contribute to an improvement in energy management in buildings and urban areas.

Acknowledgements

The authors would like to thank ASCAMM, CTCV and IAT for their contribution to the EnerBuiLCA project and the respondents to the user´s survey namely, Ignacio Zabalza (CIRCE), Joaquín Torres (UNAV), Josep Solé (URSA), Lluisa Hernandez (ECO-TEC), Xabat Oregi (TECNALIA) and a sixth unidentified respondent.

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[16] CEN. (2012). CEN/TC 350. EN 15804:2012. Sustainability of Construction Works – Environmental product declarations – Core rules for the product category of construction products.

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