Gate 4 — QCRT Optimisation

Gate 4 is the quality assurance gate. It runs the selected design option through four lenses — Quality, Cost, Regulatory, and Technical — and produces a structured assessment of risks, failures, and optimisation opportunities before the design is committed to the graph.

The four lenses

Quality (Q)

Assesses how well the design meets architectural quality standards:

• Room quality: aspect, daylight, natural ventilation, outlook
• Circulation quality: legibility, wayfinding, threshold experience
• External quality: street presence, public realm, massing articulation
• Sustainability quality: orientation, passive solar, natural light penetration

Cost (C)

Estimates the indicative construction cost of the selected option:

• Elemental cost breakdown (substructure, superstructure, MEP, finishes, external works)
• Cost per m² against benchmarks for building type and location
• Cost risks: complex massing, deep plan, basement, high-rise penalties
• Value engineering opportunities: where cost savings can be made without quality loss

Regulatory (R)

Checks the design against applicable building regulations and planning policy:

• Building Regulations Part A (structure), B (fire), K (protection from falling), L (energy), M (accessibility)
• Local planning policy: height, massing, density, affordable housing, car parking
• National standards: NDSS (residential), BB103 (schools), HBN (healthcare)
• Heritage and conservation constraints (if applicable from Gate 1)

Technical (T)

Assesses structural and services feasibility:

• Structural grid coordination: does the chosen massing work with a rational structural grid?
• Core and riser placement: are cores efficiently located for MEP distribution?
• Vertical transportation: adequate lift provision for occupancy and floor count?
• Plant and service space adequacy: enough room for plant rooms, risers, and roof plant

The QCRT Report

Each lens produces a scorecard with:

• An overall rating: 🟢 Good / 🟡 Marginal / 🔴 Risk
• A list of findings — specific issues with severity (info / warning / critical)
• Optimisation suggestions — concrete changes that would improve the score

Example findings

Lens	Severity	Finding
Quality	⚠️ Warning	6 of 24 north-facing apartments have no direct sunlight year-round
Cost	⚠️ Warning	Deep plan (22m) will require mechanical ventilation — budget uplift of ~£45/m²
Regulatory	🔴 Critical	Travel distance from northernmost unit to stair exceeds 9m (Part B max for residential)
Technical	ℹ️ Info	Structural grid of 7.2m is efficient for the residential floor plate

Responding to Gate 4

For each critical or warning finding, you can:

• Accept — acknowledge the risk and proceed (recorded in the project graph)
• Resolve — type a correction and Gate 4 re-evaluates that finding
• Defer — flag it for resolution in the next design stage

Only critical findings block progression to Gate 5. Warnings and info items are advisory.

Resolve the travel distance issue — move the northern stair 4m further north
so it is within 9m of all units on that wing

Gate 4 re-evaluates the travel distance finding. If it passes, it turns 🟢 and you can proceed.

Proceeding to Gate 5

Once all critical findings are resolved (or accepted with documented rationale):

• Click Proceed to Gate 5
• The QCRT Report is saved to the project graph as a set of Requirement and Compliance nodes
• All accepted risks are recorded with timestamps and user attribution