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Eco-index OI3

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Eco-index OI3

The OI3 eco-index provides a simplified quantitative assessment method for building materials, constructions and buildings based on eco-indicators and life cycle assessments. In recent years, the OI3 has found its way into various housing subsidy models. The OI3 comprises the eco-indicators global warming potential, acidification potential and the demand for non-renewable primary energy, and can be calculated for building materials, structures and entire buildings. As a single figure, the indicator makes a quantitative statement about the potential to warm the climate, acidify the environment (acid rain) and consume non-renewable energy resources.

Objectives:

Creating awareness of ecological connections Reduction of environmental impact and building construction and maintenance.

The following OI3 basic indicators are defined:


ΔOI3BS (pronounced Delta OI3) Eco-indicator of a building material layer

ΔOI3KON Eco-indicator of one square metre of construction

Eco-indicator OI3 for buildings
Basics of the OI3 assessment:
Point System:
The OI3 comprises the three indicators global warming potential, acidification potential and the demand for non-renewable energy. The absolute values of the indicators are converted into a points system. The higher the score achieved, the more serious the impact of the construction or building on the environment. Detailed information on the various OI3 indicators and precise calculation rules are presented in the current OI3 calculation guide.
∆OI3BS Indicator for Component Layers:
The ∆OI3 BS of a building material layer within a component indicates by how many OI3 points this building material layer increases or decreases the ΔOI3KON value of the construction. In other words, if a component layer is deleted from a construction, the ΔOI3KON of the construction is reduced by ∆OI3 BS points. This ∆OI3 BS indicator is very helpful in construction optimisation, as the ‘ecological heavyweights’ of a construction can be easily identified by the highest ∆OI3 BS points.
OI3 KON Indicator for Components:
The ecological quality of common constructions is represented by the eco-indicator ΔOI3 KON.
Spatial and Temporal Balance Sheet Limits:
In order to assess the environmental impact of buildings, all components of all constructions would have to be recorded and included in the assessment. As this would lead to a disproportionately high calculation effort, a flexible balance boundary concept is used. This specifies which components or component layers are taken into account and whether the service life of structures must be included.
Reference to the OI3 Building Indicators:
The OI3 building indicators can be related to the gross floor area ‘GFA’, reference area ‘BZF’ (corresponds to the GFA and half the floor area of buffer rooms such as conservatories) and the characteristic length lc.
OI3 optimisation strategy in the planning process
The calculation of the OI3 indicators for constructions and/or buildings in different balance limits is carried out using the eco2soft online software (http://www.baubook.info/eco2soft/).

Two methods are available for the ecological optimisation of buildings:
1. minimisation of the surface area of constructions with high ΔOI3KON values
2. avoid constructions with high ΔOI3 values

If the following principles are taken into account when selecting building materials, the impact on the environment is generally reduced and the OI3 is optimised: 

• Building materials from renewable or regenerative raw materials
• Building materials made from recycled materials
• Regional products
• Materials with low manufacturing costs
• No products with hazardous ingredients
• No products with harmful emissions
• Durable products
• Easily disposable (recyclable) products

Advantages of the OI3 eco-index:

There is no additional work involved in calculating the key figures. The required eco-indicators can be determined automatically using the same data that was collected or calculated for the energy performance certificate.
This is an aggregated ‘single-payment model’ as it is not reasonable to expect applicants to draw up an ‘eco-key figure profile’.
Environmental impacts are recorded. In particular, the most significant and meaningful values.
Direct comparability is guaranteed. The calculated results of the OI3 indicator for the thermal building envelope are in the same range as the numerical values for the heating requirement.
Simple evaluation and judgement: The lower the calculation results, the lower the impact on the environment.
These advantages have led to the acceptance of eco-indicators in the context of subsidy models. The eco-indicators of building materials and constructions (IBO guideline value table) required for the calculation of the OI3 indicator are provided free of charge by the IBO, the building physics software manufacturers and the baubook internet database and are updated on an ongoing basis.

Further information: