Choosing Your System Boundary and Scope

Introduction to life cycle modules

When it comes to assessing the environmental performance of the built form, there’s a number of conflicting assessment system boundaries (broadly defined scopes). The standard EN15978 Sustainability of construction works – Assessment of environmental performance of buildings is a great reference as it’s scope is very comprehensive.  See below for a summary of the eTool and EN15978 system boundary.

How to rating systems compare?

See the below table to understand how the ratings system credits compare against EN15978:

Rating System Object of Assessment A1-3 A4 A5 B1-B2 B3-B4
B6 B6+ B7 C1-4 D
eTool Buildings or Infrastructure YES YES YES YES YES YES YES YES YES YES YES
Green Star – Buildings Offices, Education etc (Following NABERS Tenancy) YES YES YES YES YES YES YES* NO YES YES YES
Residential, Hospitals, Hotels etc YES YES YES YES YES YES YES YES YES YES YES
Green Star – Interiors Following NABERS Tenancy YES YES YES YES YES YES PARTIAL** YES YES YES YES
BREEAM UK – New Construction 2011/2014 Fully Fitted / Shell & Core Only  YES  YES  YES  YES NO YES OPTIONAL OPTIONAL  OPTIONAL YES*** NO
BREEAM UK – Refurbishment & Fit-Out (RFO) 2014 Part 3 & 4 Fit-out / Parts 2, 3 & 4 Fit-out^  YES  YES  YES YES  NO YES  OPTIONAL OPTIONAL  OPTIONAL YES*** NO
BREEAM UK – New Construction 2018# Fully Fitted / Shell & Core Only YES YES YES YES NO YES NO NO NO YES*** NO
BREEAM UK – New Construction 2018# Shell Only YES YES YES YES NO YES NO NO NO YES*** NO
BREEAM International – New Construction 2016 (Non-Residential) Fully Fitted / Shell Only / Shell & Core Only YES YES YES YES NO
BREEAM International – New Construction 2016 (Residential) Fully Fitted / Partially Fitted YES YES YES  YES NO
BREEAM International -Refurbishment & Fit-Out (Non-Residential) 2015 Part 3 & 4 Fit-out / Parts 2, 3 & 4 Fit-out^ YES
LEED – New Construction v4 Buildings YES YES NO YES YES YES NO NO NO YES NO
ISCA Materials Calculator Infrastructure YES YES NO YES YES YES NO NO NO NO NO
ISCA Energy Credits Infrastructure NO NO NO NO NO
ISCA Water Credits Infrastructure NO NO NO NO NO

* Green Star projects using NABERS base building energy calculations generally excludes tenancy lighting which is required to be in-scope according to EN 15978. At eTool, we strongly encourage users to align include this input to gain more value from your LCA studies. Fortunately we already have multiple easy-to-add templates in the library to account for tenancy lighting for your project.

** Green Star Interiors projects using NABERS tenancy energy calculations will exclude much of the base building’s integrated energy inputs (HVAC, lifts, common lighting etc) which does not align with EN 15978

*** When using the BRE IMPACT dataset, only modules C4 are in scope.

# For more detailed breakdown on what areas are in- or out- of scope for BREEAM 2018, please visit this page.

^Part 1 – Fabric and structure: external envelope including walls, roof, windows and floor
^Part 2 – Core services: centralised mechanical and electrical plant including heating, cooling and ventilation
^Part 3 – Local services: localised services including lighting, local heating, cooling and ventilation
^Part 4 – Interior design: interior finishes, furniture, fittings and equipment.

Which scope is right for you?

We generally recommend complying with EN15978 wherever possible and including the optional scope items (B6+ in particular).  The advantage of this approach is that regardless of the limitations of rating system credits, you and the design team get the whole picture and can see where genuine effort should be placed to maximise environmental performance improvement. Furthermore, EN15978 is a rigorous standard and it’s a personal professional milestone to write a compliant report (albeit eTool makes this easy).

To decide how to report our LCA results we’ve put together the following guidance. The decision points (questions we have to ask ourselves when deciding what scope to use) are in the first column. The deliverables (including scope) are in the subsequent columns. The general principal is to:

  • Try to align where possible
  • Provide as much feedback on the whole building as we can
  • Limit confusion for jobs with lesser scope by providing a custom cover sheet that summarises rating scheme points etc
  • Only provide the “out of the box” eTool marketing information when we are comparing to an eTool international benchmark.

Specific guidance and exceptions

Here’s some example guidance for certain rating systems which may help you decide on the scope of your assessment.

Green Star buildings

When entering energy use information, be careful to include tenancy lighting in commercial buildings (in fact all integrated energy use must be included) to comply with EN15978.  This is the main pitfall with Green Star buildings, providing this is resolved the scopes align well (EN15978 is referenced in the Green Star credits).

Green Star interiors

There’s arguably a conflict in the requirements of the interiors LCA credit.  It requires compliance with the EN15978 scope (whole building) but also states that the scope is the interiors construction contract scope.  We think users have flexibility here and could take either direction (model the whole buildings or limit it to just the construction contract scope).  Modelling the whole building (and hence properly complying with EN15978 for modules A1-3, A4, A5 etc) is hard to swallow when you’re just trying to pick up interiors points and the design team for the interiors project don’t necessarily have influence over the way the building is constructed.  In this case the scope can be constrained by excluding the main structure of the building and just limiting the structural scope to the actual construction scope of the interiors project (some times this will include glazing etc, it really depends on the scope of the project).  In this instance, it’s important to call out what is and isn’t in scope in your eTool model by using the scope section on the structure page.

Here is a list of common elements is scope for the fitout contract and operation that form part of an LCA model:

  • Energy tenancy loads as Used in GGE calculator (HVAC supplementary, lighting, plug load and IT, domestic hot water)
  • Water supply and treatment as used in Water calculator (taps and showers)
  • Integrated systems and fittings (HVAC, ducting, lighting)
  • Internal finishes (floor, ceiling and walls)
  • Partition walls, Doors
  • Fixed cabinetry
  • Bathroom and kitchen fittings
  • Staircase, balustrade
  • Office maintenance (cleaning)
  • Optional (depend on data availability for both reference and proposed design) and needs to be reported separately:
    • Mobile cabinetry (desks, chairs, lockers, storage) .
    • IT infra (servers, desktop computers and monitors, projectors, tv screens)

The scope of EN 15978 in relation to operational energy excludes in-use appliances IT and other often tenant installed uses, the methodology may be changed to require these energy uses are accounted for in the LCA in addition to the scope of EN 15978 in certain circumstances.

EN15978 Part
If the energy use of appliances that are not building-related (plug in appliances, e.g. computers, washing machines, refrigerators, audio, TV and production or process-related energy in the use of the building) is included within the energy calculation, then this shall be documented and reported and communicated separately.

eTool allows for this by categorising energy use as B6+ (Non integrated energy use) rather than B6 (hence reporting and communicating separately). Operational energy benchmarks as used in the Green Star Greenhouse Gas Emission Calculator for the project shall be used.

EN15978 Part
The assessment shall include impacts and aspects of the building-integrated technical system and building related furniture, fixtures and fittings. The system boundary for the assessment shall exclude impacts and aspects of the appliances and furniture, fixtures and fittings that are not building integrated.  The impacts and aspects of appliances and furniture, fixtures and fittings that are not building-related may be assessed separately. Where this is the case, these impacts and aspects shall be recorded and reported and communicated separately.

eTool allows for this by creating a separate design and recording changes as recommendations. Depend on data availability for both reference and proposed design. Product warranty periods will make the most difference.


EN15643 includes a module B8 – Users Utilisation which accounts for the use of the infrastructure and associated impacts.  For example, if the object of the assessment is a road, module B8 would include the tailpipe emissions of the cars using the road over the life of the asset.  eTool will likely include this module at some point in the future (exciting!).  For now we still recommend trying to quantify this on the back of an envelope (contact us if you want help) because it can shine a light on that big picture and perhaps direct effort in a more rewarding direction in terms of design improvements.


ISCA verifiers have very limited time to certify projects.  For this reason you need to very specifically address the credit as it’s written in the ISCA manual or it’s likely that despite all the hard work you’ve done in compiling a full scale LCA, you won’t get credit (at least ISCA credits anyway).  Our experience is that design teams LOVE the insight that a full LCA in eTool gives them, but to satisfy the certifiers we need to be very specific about the credit requirements and directly address that which typically means taking to the LCA with a scalpel to split the results and/or inputs back out into a language and format they are familiar with.

Living Building Challenge

Under the Living Building Challenge (administered by the International Living Futures Institute – ILFI) embodied impacts must be offset. Projects must also demonstrate a 20% reduction in embodied impacts compared to an equivalent baseline. At this stage only modules A1 – A5 are compulsory for the embodied carbon assessment, though including the other embodied carbon modules is encouraged. Likewise, only “primary” and “interior” materials are compulsory to include in the assessment – this includes foundations, structure and enclosure, and internal floor, wall and ceiling coverings – though including other elements such as building services, and landscaping items is also encouraged.

Leave A Comment?

You must be logged in to post a comment.