Chapter 6: every rating needs a site visit by an IE-accredited assessor (delegable only to another IE assessor; supervised ratings must be done personally) confirming layouts, occupied floors and at least two-thirds occupancy of sampled tenanted space. Spot measurements may be subcontracted only to IE assessors or holders of listed qualifications (CAQP, CIE, certified occupational hygienist, National Engineering Register). Measurements are never reused, avoid holidays, maintenance closures, nearby construction, contamination and the five working days after HVAC chemical cleaning, extreme weather or water damage, run 9:00 to 17:00 on weekdays (occupant-influenced components 9:00 to 12:30 and 13:30 to 17:00), are completed within five working days, and start after HVAC has run normally for at least one hour with no early starts, overrides or flushes. For whole building and tenancy ratings they follow a valid survey within four weeks with no layout change. Missing data is never estimated; it is re-measured within five working days, or all data is re-measured. Equipment meets Appendix F, equilibrates 30 minutes, is placed 0.6 m to 1.1 m high and away from walls, sources, diffusers, doors and lifts, and carries current ISO 17025 calibration certificates (for rented kit, the lessor's pre-shipping checks).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.