The concept realized in the ELAS Calculator is to evaluate the life cycle wide impact of a building or settlement as well as any planned changes to a building or a settlement (including radical changes such as demolition and construction at a different site with a different technological standard). That means that all impacts generated along the life cycles of all sevices and products necessary to build and sustain a settlement will be calculated and made transparent, not only in ecological but also in economic and social terms. This applies to current operation as well as all planned changes in to the existing structure as the status quo of buildings and infra-structure will not be rated according to their ecological, economic and social impacts. By this approach the users of the calculator can assess not only the direct impacts of their decisions but may also gain a comprehensive view on the consequences of their action on nature, economy and society.
The ELAS calculator operates in two modes, a „private mode” (that allows the evaluation of single buildings) and a municipal mode (that evaluates settlements and planning projects).
Besides the assessment of the impacts of housing under current conditions, the ELAS Calculator offers the option to calculate these impacts under future scenarios (with a time horizon of 2050):
Trend scenario: in this scenario total travelled distance for individual mobility increases by 25 %, 10 % of the fleet will be operated by biogas and 15 % by electricity, electricity demand itself increases at a rate of 2.2 % p.a.
Green Scenario: in this scenario energy demand of the settlement will decrease by 33 %, electricity will be provided entirely by renewable resources. Increase in traveled distance will again be 25 % however 70 % of cars will be operated on biogas and 30 % on electricity.
These scenarios enable the user to estimate the bandwidth of impacts of the settlement in future within reasonable boundaries.
In the ELAS Calculator the following ecological evaluation methods are implemented:
Cumulative energy demand: this measure was chosen to provide insight into the energy flows (grey energy from construction, renovation and infra-structure provision, energy for operation of the building or settlement, mobility of residents) caused by the life cycle network providing housing, accepting the fact that energy use is responsible for a considerable share of ecological pressures across many impact categories. This measure also provides clear indication of the consequences of energy efficiency measures.
Life cycle CO2 emissions: This measure corresponds to a particularly important ecological pressure, the emission of CO2 and the subsequent impact on global warming. This measure also captures the efficiency of the energy provision system regarding global warming and hence may be used to compare different alternatives for providing energy to the building or settlement.
The ecological footprint, calculated according to the Sustainable Process Index (SPI) method: this measure allows the inclusion of the impact of nuclear energy but also the evaluation of all relevant ecological pressures linked to provision of resources and the generation of emissions and wastes (also including greenhouse gases) from the life cycle network. This measure therefore can be used to compare different alternatives regarding their overall ecological impact.
The three methods are described in more detail below.
Life cycle wide energy demand
Energy is a major factor in the ecological pressure exerted by a building or settlement. The ELAS Calculator accounts for all energy flows generated by the whole life cycle network. This includes the energy to operate the buildings (heating, cooling, electricity demand of appliances), the necessary supporting infrastructure (energy to operate sewage systems, street lighting, road service, etc.) and mobility of residents. The calculator however also includes all “grey energy” that is necessary to provide the materials of construction for buildings and infrastructure or used in construction, renovation or demolition and disposal (when appropriate) for any planned changes to the current structure. This grey energy is calculated using the methodology of the “Kumulierter Energieaufwand – KEA” according to (Öko-Institut e.V., 1999). Grey energy input will be related to one year by taking lifetimes of buildings and infrastructures (66 years) into account.
Life cycle wide CO2 emissions
The calculation of CO2 emissions is directly coupled with the calculation of the ecological footprint (see below). All fossil carbon inputs across the whole life cycle network form the base of the calculation. This includes also CO2 emissions from synthetic materials used in construction of new buildings and infra-structure as well as in renovation, depreciated over the life time of the building and the renovation interval respectively.
Ecological footprint according to the Sustainable Process Index (SPI) method
The SPI is a method to calculate ecological footprints that emissions to air, water and soil besides resource provision into account (Krotscheck & Narodoslawsky, 1996). The method compares anthropogenic and natural flows according to the following sustainability critera (Narodoslawsky & Krotscheck, 2000):
Principle 1: Anthropogenic mass flows must not alter global material cycles;
Principle 2: Anthropogenic mass flows must not alter the quality of local environmental compartments.
The results of the footprint calculations are broken down into partial footprints for direct area consumption, fossil resource consumption, renewable resource consumption and emissions to air, water and soil.
Socio-economic impacts are calculated using the economic input-output analysis (Miller & Blair, 2009). This method calculates the impact of particular economic activities throughout the whole economic system by modelling the interaction of the sectors of the economy, using appropriate input-output coefficients linking the activities of different sectors. Activities evaluated with the ELAS Calculator are supposed to provide products summarised in building construction, building operation, municipal services construction and operation and external effects (mainly concerning transportation).
The ELAS Calculator will evaluate socio-economic impacts regarding the concrete region the settlement is located in. This requires regionalisation of the input-output coefficients, starting from national data provided by (Eurostat, 2007) and using regionalisation techniques according to (Clijsters et al., 2003, Baaske et al., 2004). This method counters the main drawback of mainstream regionalization techniques, i.e. the overestimation of multipliers and transformators.
Data base of the ELAS Calculator
The ELAS Calculator draws on a large and comprehensive built-in databank. Describing this data base in detail would exceed the scope of this text by far. The reader is therefore kindly asked to consult the extensive background material provided for this module.
It is the general approach of the ELAS Calculator to allow the user as much leeway as possible to individualize his/her data while at the same time reduce amount of data required from the user in order to increase user-friendliness of the program. Wherever possible the program will provide sensible default values.
Besides striking a delicate balance between individualization and generalization of data the ELAS Calculator strives for data coherence. This means that life cycle data are taken only from one source (Swiss Centre for Life Cycle Inventories, 2010) whenever possible, SPI-related data where taken only from the SPIonExcel homepage http://spionexcel.tugraz.at/. Statistical data underlying socio-economic evaluation are all taken from the material provided by Eurostat as already mentioned.
Specific data base of the ELAS Calculator
Many data required to evaluate the impact of the life cycle network underlying the ELAS assessment method are not available from existing statistics. This applies in particular for individual mobility of residents according to the levels of centrality that form the base of characterising the spatial interaction between settlements and services used by residents. As this aspect is a prominent factor for the sustainability of settlements great care has been applied during the development of the ELAS Calculator to come up with reliable and recent data for evaluating mobility of residents.
Mobility associated with a building or settlement is influenced by a complex set of factors. Besides distance to particular service providers (represented by the different levels of centrality and the distance from the settlement to the nearest cities associated with these levels) the demographic structure of the settlement has to be taken into account as residents within different age brackets show vastly differing mobility requirements and behaviours. The modal split used by residents to travel to service providers is in turn dependent on the centrality level of the settlement as the higher the centrality level is the larger is the fraction of public transport. Finally, the modal split also depends on the age bracket the individual resident belongs to.
In order to obtain a realistic data base for evaluation of crucial aspect of the sustainability of settlements as well as to verify statistical data from other sources a thorough analysis of ten Austrian settlements in seven municipalities, representing all levels of centrality, was undertaken. The settlements ranged in size from 20 to 428 households. Within this analysis all relevant parameters about buildings and infra-structure used in the ELAS Calculator were gathered. In particular this analysis encompassed a survey of households, inquiring about demographic set up of the household, consumer behaviour and technical building standard. Questionnaires inquired about mobility behaviour of individual residents regarding frequency of travels, leisure mobility and modal split for all categories of mobility. This analysis was coupled to a participatory evaluation process in all settlements, involving all residents as well as stakeholders and political representatives in the settlements, with public auditing events throughout the process. Local coaches distributed the questionnaires and helped with additional information. Due to this participatory nature of the analysis 37 % of the 1.585 household questionnaires could be recovered, on top of 1.047 individual questionnaires. This statistical material allowed the formulation of 75 different modal splits linked to all 5 levels of centrality and 5 age brackets.
User provided data
The user has to provide all data that define the building/settlement in sufficient detail to allow for reliable sustainability evaluation. The ELAS Calculator offers extensive help functions to guide the user through the evaluation exercise as well as realistic default values wherever possible. A thorough summary of the necessary data is found in the supportive material for this module.