|Aspect||B-31 (Buildings) / B-11 (Products) Distinction between Modules B2, B3, B4 and B5|
||Modules B2 to B5 cover the impacts related to the service life of building and building parts, whether it is a light modification, such as a small maintenance operation or an important retrofit (rehabilitation).It is sometimes difficult to determine which module a specific operation should be attributed to. The present aspect proposes a common definition of these modules, plus recommendations on how to use them at the product and building scale.|
related study objective
|☒ stand-alone LCA||☒ comparative assertion|
related study phase
|goal and scope definition||inventory analysis (LCI)||impact assessment (LCIA)||interpretation||reporting|
|new buildings||existing buildings||construction products||screening LCA||simplified LCA||complete LCA|
|Provisions||Standards EN 15804 and EN 15978 provide definitions and examples of aspects B2 to B5. The LCA practitioner should refer to these standards.B2 – Maintenance encompasses all actions related to maintaining a product or building part – i.e. replacement or reparation of a used, damaged or worn part of the product (a part, but not the entire functional unit) in a state in which it can perform its functions [EN 15978]. According to EN 15978, this applies to planned actions, and should include:
Maintenance actions are part of the ‘intended use’ definition that should be provided with a product’s reference service life (see EN 15804, annex A and 126.96.36.199 Reference service life). The reference service life (RSL) is valid under a specific set of conditions, notably the in-use environment (e.g. UV, heat, humidity, etc.), and proper implementation and maintenance that comply with the producer’s recommendations and with state-of-the-art practices. The RSL should be used to calculate the number of replacements. See the aspects: ‘Definition of the service life of a building product’ and ‘replacement frequency’ for additional information.
B3 – Repair encompasses all actions related to returning a product or building part to an acceptable condition in which it can perform its required functional and technical performances [EN 15804], including:
The example given in EN 15978 and EN 15804 is a window with a broken pane.
–> Although the distinction between the maintenance and repair modules is not straightforward, the example given for repair falls outside the scope of the intended use that defines reference service life.
B4 – Replacement covers the replacement of a whole construction element [EN 15804], including the production and installation of a new (and identical) construction element. Examples given in EN 15978 include replacement of a partition wall, and replacement of a boiler or heating system.
–> The replacement module is distinguished from the maintenance and repair modules by the fact that a complete component or part is replaced (maintenance include the replacement of subcomponents, and repair the replacement of damaged parts). Although this ultimately depends on the breakdown of the building into subcomponents, it seems reasonable to understand it as the replacement of a complete functional unit such as defined in the EPD.
B5 – Refurbishment covers concerted programmes of maintenance, repair and/or replacement activity across a significant part or whole section of the building [EN 15804]. Examples provided include: ‘a major change of the internal layout (partitioning)’, a ‘change of the technical system related to heating’ and ‘modification for the purpose of a […] change of use’ [EN 15978].
–> The refurbishment module addresses important modifications that would impact on several building components, and modify building performances and/or functions.
All these aspects are related to the notions of durability and service life planning, as described in the ISO 15686 series. Relations between the type of operations and performance of a given product or building part could be represented as follows:
Figure 18: Example of performance over time relation depending on operations [EN 15804]
This figure is shown only for explanation purpose, and many other cases are possible, such as:
Furthermore, “service life planning can only address foreseeable changes. Since service life planning is concerned with foreseeable risks, it is not applicable to the estimation of obsolescence […] or to defective performance resulting from unforeseeable events or processes” [ISO 15686-1, part B.8.2.].
In the case of sound statistical feedback on the replacement rate of a specific product for a given country or region, it is unlikely that a clear distinction between the causes of replacement could be easily made. In that specific case, replacement causes would naturally encompass all cases: i.e. premature failure, failure due to foreseeable ageing (i.e. RSL) and obsolescence. The figure below presents a hypothetical distribution of replacement rate according to the main causes of replacement (including building deconstruction).
Figure 19: Replacement rate [EN15804]
||As the distinction between Modules B2 to B5 is not straightforward, it is recommended that the following principles be applied when developing product and building LCA. These principles are based solely on the distinction between the causes of end of life:–> For end of life related to performance decrease over time (e.g. aging, decay, degradations, etc.):
–> For end of life related to modification of expectations regarding the building’s performance level or functionalities (e.g. obsolescence, such as modification of activities inside the building, modification of regulation, etc.):
B2 – Maintenance:
For product LCA, this module should cover all operations necessary to maintain the performance of products, or to return them to their original level, including scheduled replacement of parts and subcomponents. Example include: scheduled replacement of boiler parts; scheduled replacement of light bulbs from luminaires; repainting of a wall, door or window frame; replacement of small elements of roofing, such as tiles (e.g. a certain number of tile per 10 years per square metre), etc.
For building LCA, maintenance should take into account maintenance modules as provided within EPD, as well as additional information if needed (e.g. current or state-of-the-art practices, recommendations, etc.).
–> Maintenance should be understood as the set of operations performed under normal conditions. This applies in a given context (e.g. maintenance of a product could change, depending on the climate). Product modification and operations caused by accidents, improper installation or handling, unforeseeable events (such as flood), etc. should be covered by the repair module (see below).
–> Maintenance scenarios at the building scale should be consistent with the building’s physical structure: maintenance of a given component should take into account the influence of neighbouring components (e.g. accessibility).
B3 – Repair:
For product LCA, the repair module should not be included in the baseline scenario.
For building LCA, the repair module should not be included in the baseline scenario. The repair module may cover all operations related to product modification outside the scope of the maintenance module – that is, outside the scope of normal conditions, including improper use of a product, unforeseeable events such as flood or vandalism, etc.
–> For existing buildings, repair scenarios could be based on the history of the building (i.e. examples based on previous reparation);
–> For new buildings, repair scenarios could be used to assess the environmental impacts of a specific risk (e.g. the impact of reparation due to flood, the impact of improper installation that causes damage, etc.).
B4 – Replacement:
Replacement is necessarily related to the reference service life. Replacement occurs at the end of life of a product: that is, when it does not meet its initial performance requirements (modification of the requirements after product installation should be considered as obsolescence, and be covered by a specific scenario: see below). The number of replacements is further described in the aspect ‘Replacement frequency’.
–> It is recommended that replacement caused by events that are outside the scope of condition defined by the reference service life be treated as repair.
For product LCA, replacement covers the replacement of the whole functional unit by a new one after RSL. The boundaries of replacement include [EN 15978]:
Most of these may be similar to other modules for cradle-to-grave product LCA, for instance:
–> If no differences arises from a comparison between a replacement scenario and an installation scenario (including related production, transport, end of life, etc.) then a replacement scenario is not necessary. In any case, it should be clearly stated whether or not the assumptions regarding B4 modules are similar to those used for other modules (e.g. the replacement process is different from the initial implementation because of the building structure, etc.).
For building LCA, replacement should include:
–> Replacement scenarios at the building scale should be consistent with the building physical structure. Replacement of a given component should take into account the influence of neighbouring components (e.g. accessibility, possible replacement of other components, etc.).
B5 – Refurbishment
For product LCA, no refurbishment module need be included in the baseline scenario, as this is highly dependent on information at the product scale.
For building LCA, the refurbishment module should not be included in the baseline scenario if the building service life is equivalent to the reference study period. Additional refurbishment scenarios may be developed. For example:
–> A refurbishment(or deconstruction/new construction) scenario should be developed if the service life of the building is less than the reference study period.
It is recommended that a refurbishment scenario be developed when long reference study periods (>100 years) are being considered, as modification of the building use is expected over such a period of time. Refurbishment scenarios could also be developed if the reference study period is longer than the reference service life of the load-bearing components and structural elements.
The progressive loss of performance of some components will have an impact on the overall performance of the building (e.g. loss of performance of insulation may lead to an increase of energy demand for heating). If sufficient data are available, these aspects should be addressed using a sensitivity analysis.
According to NEN 15804 (Annex A), Reference service life “could be based on empirical, probabilistic or statistical data and shall always taking into account the intended use (description of use) as described in ISO 15686-1, -2, -7 and -8” [EN 15804, Annex A].