ISO 16818:2008

Overview

ISO 16818:2008 - Building environment design - Energy efficiency - Terminology is an ISO standard that defines terms and definitions used in the design of energy‑efficient buildings. Published in 2008 and prepared by ISO/TC 205, it is applicable to both new buildings and retrofitted existing buildings. The document provides a common vocabulary for designers, engineers, regulators and energy assessors to ensure consistent communication across energy modelling, specification and compliance activities.

Key Topics

This terminology standard covers a broad set of technical concepts relevant to building energy efficiency, including:

• Building envelope and envelope subtypes (exterior, semi‑exterior sheltered) - definitions that clarify what elements require insulation and weather‑stripping.
• Conditioned space / air‑conditioned floor area - how spaces served by HVAC are classified and measured.
• HVAC components and performance metrics - terms such as air handling unit, boiler, coefficient of performance (COP) for cooling and heat pump heating mode, and cooling design temperature (noting the 2.5 % exceedance definition for sizing).
• Lighting terminology - definitions for connected lighting power, adjusted lighting power, ballast factor, area factor, and daylit area (horizontal and vertical).
• Controls and metering - terms for automatic control devices, control loop, check metering and control points used in energy management.
• Insulation and thermal terms - continuous insulation, thermal transmittance concepts, and related vocabulary for heat transfer and hygrothermal performance.
• Energy accounting and modelling - definitions such as building energy cost, budget building design, and metrics used for energy performance calculations.

Applications

ISO 16818:2008 is practical for professionals and organizations that need a consistent terminology foundation when specifying, designing, modelling, verifying or regulating energy performance:

• Architects and building services engineers using energy modelling tools and preparing specifications.
• Energy assessors and auditors producing energy performance reports or compliance documentation.
• Building code developers and authorities having jurisdiction who adopt standardized definitions to align regulations.
• Facility managers and retrofit planners coordinating upgrades across disciplines.
• Manufacturers and consultants referencing consistent terms in product data, commissioning and control strategies.

By harmonizing vocabulary for HVAC, lighting, enclosure and control concepts, ISO 16818 improves clarity in contracts, design documentation, energy simulations and compliance checks.

Related Standards

ISO 16818 references and complements several ISO documents focused on building performance and environmental design, including:

• ISO 6707‑1 (building vocabulary)
• ISO 13790 (energy performance - calculation of energy use)
• ISO 16813 (building environment design - indoor environment principles)
• Standards on thermal insulation, thermal comfort and hygrothermal properties (e.g., ISO 7345, ISO 7730, ISO 9288, ISO 9346)

Using ISO 16818 alongside these standards ensures consistent terminology when implementing energy‑efficient building design and assessment practices.