Overview
ISO 12567-2:2005 - Thermal performance of windows and doors - Determination of thermal transmittance by hot box method - Part 2: Roof windows and other projecting windows - specifies a standardized laboratory method to measure the thermal transmittance (U-value) of roof windows and other projecting windows using a calibrated and guarded hot box method. It is intended to produce repeatable, comparable thermal performance data for product comparison and declaration.
The standard covers mounting and calibration procedures for projecting glazed products installed flush to the cold side of the surround panel (insert‑ or kerb/curb‑mounted). It clarifies test orientation (vertical mounting is acceptable for comparison purposes) and lists exclusions: edge effects outside the specimen perimeter, solar radiation effects, and air leakage through the specimen are not included.
Key Topics
- Test principle: Measurement of steady‑state heat flow through roof and projecting windows using the hot box technique.
- Specimen mounting: Install in a surround panel flush with the cold face; include flashings and kerb when representative of normal installation.
- Calibration: Use calibration panels or CTS mounted flush with the cold face; calibration and specimen tests must be at the same orientation.
- Environmental temperature: Determination of combined radiant and air temperatures (convective fraction derived from calibration measurements).
- Edge zone treatment: Heat flow through the edge zone is accounted for using linear thermal transmittance (ψ) values (tables provided in the standard).
- Apparatus requirements: Comply with ISO 8990 and ISO 12567‑1 where applicable; special provisions for baffle distance (cold side baffle ≥ 80 mm from glazing).
- Reporting: Test report must include inclination, installation details, and specimen aperture area used to calculate U-value.
Applications
ISO 12567-2:2005 is used by:
- Test laboratories performing hot box thermal measurements on roof windows and projecting windows.
- Window and rooflight manufacturers for product thermal performance declaration and quality control.
- Certification bodies and regulators requiring standardized U‑value data for product compliance and labeling.
- Energy modelers, architects and façade engineers who require validated laboratory U‑values for building energy and thermal comfort calculations (values may be adjusted using national procedures for in‑situ orientation).
- R&D teams optimizing glazing, frames, kerbs and flashings to reduce thermal transmittance.
Relevant SEO keywords: ISO 12567-2:2005, thermal transmittance, hot box method, roof windows, projecting windows, U-value, window thermal performance, calibration panels, linear thermal transmittance (ψ).
Related Standards
Open preview (PDF)Thermal performance of windows and doors — Determination of thermal transmittance by hot box method — Part 2: Roof windows and other projecting windows
