10.3 Subprojects, Clustering & Non-Typical Projects

10.3 Subprojects, Clustering & Non-Typical Projects

Exam Focus: This material spans sub-topic 2.2 and the certification-process rules in Domain 6.0. Expect scenario questions in which a described development must be structured correctly before any modelling begins.

The structural decision — what counts as one building, what becomes a subproject, what gets its own certificate — precedes every technical input. Getting it wrong means re-modelling after the Auditor rejects the structure.

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What Counts as One Building

EDGE defines a single building as a physically separate structure. The important qualification: if two buildings are connected by a conditioned space, they can be considered a single building. An unconditioned link — an open colonnade, a covered but unconditioned walkway — does not merge two structures.

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The Clustering Thresholds

Where one project with a single owner consists of several buildings:

• Buildings of less than 10% of the project floor area, up to a maximum of 1,000 m², with the same use, may be clustered together as a single building.
• Buildings larger than 10% of the project floor area, or more than 1,000 m², must be considered separate buildings.

Note that both conditions must hold for clustering: under 10% and under 1,000 m² and the same use. A 900 m² ancillary block in a 50,000 m² development qualifies on both numeric tests; a 1,200 m² block does not, even though it is well under 10%.

The equivalent rule for mixed use in EDGE v2

Projects still running under EDGE v2 follow a parallel rule for secondary uses: if a building has more than one use and the secondary use occupies less than 10% of the floor area up to a maximum of 1,000 m², the entire building may be certified under the primary use. Above either limit, that portion must be certified separately. GBCI's worked example: a 10,000 m² residential building with a 1,200 m² ground-floor retail portion exceeds both tests, so the areas must be certified separately under the Homes and Retail typologies.

EDGE v3 replaces this with the Mixed Use typology route described in Section 10.1, but the v2 rule remains examinable and still governs legacy projects.

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Residential Certification Is Per Unit

This surprises candidates who assume a certificate attaches to a building:

• In residential projects, each individual unit receives an EDGE Certificate — not the overall building.
• Where multiple unit types are present, each unit type in the project is assessed separately.

The commercial logic is straightforward: a homebuyer buys a unit, not a tower, so the certificate that supports a green mortgage must describe the unit.

The v3 trade-off you must disclose

Mixed-use or multiple-unit-type residential projects modelled in a single EDGE v3 subproject receive certificates showing the range of savings across the project, rather than the more exact savings for a specific unit type or building use. That is a real commercial decision, not a technicality. A developer marketing a premium unit type may want the precise figure for that type and should therefore accept the extra modelling effort of separate subprojects. An Expert who silently takes the faster single-subproject route and then hands the client a range has under-served them.

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Structuring a Multi-Building Development

A workable sequence:

1. Identify physically separate structures, merging any that are connected by conditioned space.
2. Apply the clustering test to each small ancillary structure: under 10% of project floor area, under 1,000 m², same use.
3. Assign a typology to each remaining building and check which category it falls in.
4. Split subprojects at category boundaries — Residential, Guest Accommodation and Non-Residential cannot be merged, and industrial uses cannot join Mixed Use at all.
5. Split further where the client needs unit-type-specific certificates.
6. Check height and use differences — a mixed-use development with substantially different building heights should be modelled in at least two subprojects, and guest accommodation sections must be separated from commercial ones.

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Existing Buildings and Major Renovations

EDGE is not a new-construction-only system. Certification is available for existing buildings and major renovations, with these rules:

• The EDGE Standard is unchanged: at least 20% predicted savings in energy, water and embodied energy in materials, benchmarked against the same base case conditions.
• Certification of existing buildings attests to the building's features, not its measured performance — EDGE is an asset rating instrument.
• Materials in buildings more than five years old are considered embodied-energy neutral, indicated as "re-use of existing materials" within the EDGE App. This is the single biggest modelling difference and it usually makes the materials threshold straightforward for an older asset.
• Existing buildings skip the Design Audit and proceed directly to the post-construction stage. Buildings undergoing major renovations (greater than 25% of major elements) may opt to undertake a Design Audit.
• Where documents normally required are unavailable for an existing building, other evidence of construction details — existing building drawings or photographs — may be submitted.

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Where Registration Sits in All This

Registration with GBCI is a flat fee for any number of buildings located at a single project site, as long as they are all registered at the same time. That single sentence has a real planning consequence: fragmenting registration across dates multiplies registration fees unnecessarily. Establish the full building list before registering. Fees are covered in Section 14.1.