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1. WHY TOTEM ?

2. METHODOLOGY OF TOTEM

2.1 Basic principles of the methodology used in the TOTEM tool

2.2 Level of analysis: from material to building

2.3 Functional unit

2.4 Life span

2.5 Taking energy aspects into account

3. Generic database and specific data

3.1 Generic TOTEM components

3.2 Specific components (Environmental Product Declarations or EPDs)

4. RESULTS OF TOTEM

4.1 Environmental profile in the TOTEM tool

4.2 Choice of environmental indicators and the corresponding impact analysis methods

4.3 Individual environmental impact scores

4.4 Aggregated score in millipoints

 

1. WHY TOTEM ?

Driven by European regulations on the energy performance of buildings (EPB), the construction sector has been working intensively to reduce the energy consumption of buildings in the past years. As a result, the performance has greatly improved. But buildings with the best energy performance require more (insulation) materials and have more complex technical installations. More and more insulation materials, solar panels, ventilation systems, ... and other necessary elements are added to the classic construction elements to make buildings energy efficient.

The environmental impact linked to the energy consumption during the life span of a recent building is significantly lower compared to old, poorly insulated buildings. In that case, the building materials are responsible for the largest share of a building's environmental impact (up to more than 50% of its overall impact).

At each stage of its life cycle, a building consumes resources (inputs) and generates emissions (outputs) that often have a dangerous impact on the environment (grey water, exhaust fumes, hazardous auxiliary products, CO2, ...). This can result in the pollution of water, air and soil and can even destroy ecosystems, thus contributing to the loss of biodiversity. Last but not least, it can also damage the health of humans and other living beings.

All these effects with environmental impact must be identified, inventoried and classified so that an evaluation can be carried out in a scientifically sound manner.

TOTEM's main objective is to disseminate knowledge and understanding of the environmental performance of buildings and to facilitate dialogue within the construction sector. The tool enables to calculate and communicate the environmental performance of building elements and buildings in a uniform and neutral way, adapted to the Belgian context.

Objectivity and transparency are central values of the TOTEM tool. This enables actors from the Belgian construction sector (architects, engineering firms, contractors, developers, public authorities, etc.) to identify and limit the environmental impact of buildings from the start of the design phase.

The evaluation method has been developed in consultation with the sector. The OVAM (Public Waste Agency of Flanders) launched the project in 2011 and organised consultations with experts from the construction sector and consultations with Flemish, Walloon and Brussels public administrations throughout the development process. In addition, there was close collaboration with several scientific partners such as VITO, BBRI and KU Leuven.

 

2. METHODOLOGY OF TOTEM

2.1 Basic principles of the methodology used in the TOTEM tool

The TOTEM tool has been developed in a methodological framework in accordance with current European standards (EN15804+A2, EN 15978, EN 15643 and TR 15941).

Life cycle analysis is applied worldwide. The modalities are described and standardized in the ISO 14040 standards. For construction products and buildings, the standards EN15804+A2 and EN15978 more specifically describe the general calculation rules for achieving a qualitative LCA.

2.2 Level of analysis: from material to building

A building is the collection of all building elements (for example: floors, walls, roof, ...), which are themselves composed of components (for example: masonry, insulation, paint). And these components are themselves composed of different materials (for example: bricks, mortar, glue, insulation material, ...).

With the TOTEM tool, it is not possible to make analyses on the level of a component (or lower); the intention is to make analyses on the level of the building elements or of buildings as a whole. This level of analysis makes it possible to take into account the effects of the choices made in one element and that have an influence on other elements (for example: if heavier load-bearing elements are chosen, this requires a more solid foundation). In addition, it is only possible to make a correct comparison when two elements pursue the same level of performance (e.g. equivalent U-value, etc.).

2.3 Functional unit

The functional unit (FU) is the unit of measurement used to evaluate a building element. Like two (different) types of fruit can be compared via the price per kilo, the environmental impact of two elements can be compared via a common unit of measurement. The choice of the FU is therefore important, because it enables a complete and objective comparison.

To evaluate the environmental impact of a building element, for example a “wall” m² is chosen as the FU of the element (1 m² of exterior or interior wall, 1m² of floor, ...). Structural elements are compared in running meters, doors are compared per piece, ...

In the TOTEM tool, the predefined elements in the library are classified according to their common functional unit (m² / running m / piece /...).

2.4 Life span

The methodology of the TOTEM tool fixes the average life span of buildings at 60 years. This applies to all possible uses of buildings (housing, office, school, stores, ...).

The starting point is that all load-bearing structures and the main original elements last 60 years, provided that normal maintenance is carried out during their life span. If the building is retained after this period, it is assumed that most of the materials used will be replaced by others.

The life span of (non-load bearing) interior elements is often shorter (e.g. 30 years for non-load bearing interior walls), which takes into account the fact that these elements are replaced more often during renovation works.

2.5 Taking energy aspects into account

For the analysis at the building element level and at building level, the tool also takes into account the energy consumption for heating during the use phase. For this purpose, the energy losses via transmission through the building elements are calculated, taking into account the thermal transmission coefficient (U) and the average duration of a heating season (1200 equivalent degree days). The average efficiency of a heating installation (at the distribution, emission, control and heat production level) equipped with a modulating and condensing gas boiler (less than 100 kW) is also taken into account. At building level, ventilation losses can also be taken into account. This concerns an estimate of the ventilation losses due to controlled ventilation and ventilation losses due to infiltration; these estimates are made on the basis of the heat loss area, the heated volume of the building and a number of fixed parameters (e.g. ventilation rate, leakage rate, ...).

It is important to take this energy consumption into account to be able to compare building elements that are more or less insulated. If this were not taken into account, the least insulated wall would be favoured, as it contains less (insulating) materials and therefore has a lower environmental impact caused by its materials.

In a future version of TOTEM, links between the energy calculation software and the TOTEM tool will be strengthened to facilitate data encoding.

 

3. GENERIC DATABASE AND SPECIFIC DATA

The TOTEM library contains two types of components: generic TOTEM components and specific components based on Environmental Product Declarations (EPDs).

3.1 Generic TOTEM components

Generic TOTEM components are based on the Swiss Ecoinvent database. These data are widely accepted in scientific studies.

The Swiss Ecoinvent database provides the necessary data for the calculations in the tool. These data are generated by bringing together (available) data from various manufacturers and provide an indication of the 'average' impactof a building material. There are several reason for the  use of these data: completeness, transparency, adaptability (e.g. the possibility to adapt certain details to the Belgian context, such as the energy mix or waste treatment), reliability, regular updating, representativeness of the data for Western Europe and Belgium, availability of information on the uncertainty of the data, ....

The generic data were chosen to be representative of Western Europe. The data are - as far as possible - adapted to the context of the Belgian construction (e.g. energy mix for electricity production, transport scenarios for import of raw materials, transport distances, ...). In case of missing data, representative data from other parts of the world is used and adjusted to take into account as much as possible the European energy mix and the Belgian context

These generic components currently included in TOTEM are, to the extent possible, representative of the components used in Belgium to build residential and office buildings.

3.2 Specific components (Environmental Product Declarations or EPDs)

In addition to generic components, the library also contains environmental data for specific components made directly available by material producers. These are brand specific data from Belgian building material manufacturers that have been objectively declared in the form of a B-EPD in the Federal Public Service (SPF) EPD database (see www.b-epd.be for more information). The integration of these data offers great added value for the tool as they provide an even more accurate picture of Belgian construction practice.

 

4. RESULTS OF TOTEM

4.1 Environmental profile in the TOTEM tool

In this phase of LCA, the results of the Life Cycle Inventory Analysis (LCI) are translated into a specific impact. Each inventoried data (for example: fuel consumption for transporting materials to the site) is assigned to a specific environmental impact (for example, kg equivalent CO2 for the category of impact on global warming). This way, an environmental profile of the analysed building (element) is obtained.

4.2 Choice of environmental indicators and the corresponding impact analysis methods

For the evaluation of the environmental profile, it is necessary to select the environmental indicators and the corresponding methods of analysis. The indicators selected for TOTEM are the ones recommended by the European norm EN 1804+A2 (including both the reference and additional environmental impacts).

4.3 Individual environmental impact scores

The environmental impact of the various indicators is calculated based on the inventory. This way, a score is determined for each of the indicators, each with its specific unit (example: kg CO2 equivalents for the global warming indicator).

The 19 scores obtained enable to obtain a detailed overview of the environmental profile of materials, components, building elements and buildings.

Although these results are quite detailed and complete, it is still quite difficult to interpret them correctly and no global comparison can be made with them (due to the different units of the indicators).

4.4 Aggregated score in millipoints

In order to facilitate the comparison between variants, the different environmental impacts considered in TOTEM are aggregated into a single score, expressed in millipoints per functional unit (m², m or piece for an element, m² of floor for a building).

This environmental score is obtained by summing up the scores of each indicator (x Kg CO2 equivalent for global warming) multiplied by a specific aggregation factor based on the European PEF (Product Environmental Footprint) weighting method.

The aggregated score is calculated in two steps. First, the environmental indicators are normalised by comparing them with the impact of a reference (global impact per person). Then, the normalised scores are weighted and summed to obtain the aggregated score. The weighting factors are derived from stakeholder consultation, factual criteria and expert’s opinions. An additional correction for the robustness of the indicators is also applied to all weighting factors.

Obviously, these environmental impact indicators should be considered as additional information to the other selection criteria, such as the technical, financial and regulatory aspects. The architect or contractor is thus given the opportunity to evaluate his material choices on a well-founded basis, based on various parameters, including environmental impact.

 

For more details about the methodology, the following document is available: Environmental profile of building elements [update 2020]

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