Sharing Transparency for a More Efficient Future

Glossary of Building Rating Terms

Click a term to see its definition.

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The ratio of path pressure drop, including fully open control damper pressure drop, to the pressure drop across the fully open damper at design flow. [Source: ASHRAE]

Abatment Potential

In the context of climate change mitigation, the abatement potential is the amount of mitigation that could be reduced over time. [Source: IPCC]

Absolute Energy Saving Target

This target is set based on the energy consumption after the renovation and this needs to be below a certain threshold (i.e. reduction in energy consumed). All buildings will have the same standard after the renovation. Targets would be given in kWh / m2/yr (EU) and KBtu/ft2/yr (US) after renovation. [Source: GBPN, 2012]

Active House

Active House, as a building that combines energy efficiency with specific attention to the indoor climate and focus on user’s health and well-being. [Source:]

Air Changes

Expression of the amount of air movement or air leakage into or out of a building in terms of the number of building volumes or room volumes exchanged. [Source: ASHRAE]

Air Circulation

Motion of air, either natural or induced. [Source: ASHRAE]

Air Conditioning

To provide a form of indoor air treatment, by which temperature is controlled or can be lowered. [Source: EPBD Recast]

Air Conditioning System

Assembly of equipment for air treatment to simultaneously control its temperature, humidity, cleanliness, and distribution to meet the requirements of a conditioned space. [Source: ASHRAE]

Air Infiltration

The uncontrolled inward airflow through openings in the building envelope caused by the pressure effects of wind, the effect of differences in indoor and outdoor air density, or both (cfm) [m[sup]3[/sup]/s]. (US) [Source: ASHRAE]

Air Leakage

Uncontrolled or unwanted infiltration or exfiltration of air into or out of a building. [Source: ASHRAE]

Air Tightness

Qualitative term describing the integrity of the building envelope relative to air permeation; the resistance of the building envelope to the flow of air and entrained moisture. [Source: ASHRAE]

ASHRAE Standard 90.1 - 2010

This standard provides the minimum requirements for the energy-efficient design of most buildings and offers, in detail, the minimum energy-efficient requirements for the design and construction of new buildings and their systems, new portions of buildings and their systems, and new systems and equipment in existing buildings as well as the criteria for determining compliance with these requirements. [Source: ASHRAE]

Assessment Systems

The overarching framework that governs the evaluation, comparison and labeling of a buildings energy efficiency. [Source: Institute for Market Transformation]


Accredited energy professional who evaluates building energy performance in accordance with certified standards and methodologies. In the EU, assessors are certified in accordance with national EPBD policies.[Source: Institute for Market Transformation]

Asset Rating

An energy rating based on calculations of the weighted net delivered energy used annually by a building for heating, cooling, ventilation, domestic hot water and lighting. [Source: CEN standard - EN 15217 Energy Performance of Buildings - Methods for expressing energy performance and for the energy certification of buildings]