Future cities - Building on energy efficiency

Energy consumption in buildings – including climate control, appliances, lighting and other installed equipment – represents nearly 40 % of the world’s total energy use.

But the lack of internationally agreed terms, definitions and procedures makes it very difficult to compare minimum energy performance requirements between countries, or to understand and compare data gathered on measured energy use of buildings.

This is why we urgently need a coherent set of International Standards for assessment and calculation, rating, labelling and best practices. Such standards would enable meaningful comparisons of actual energy use, and of the potential for novel energy savings and renewable energy technologies on a global scale. They would also facilitate the market for services related to energy use in buildings.

ISO technical committees ISO/TC 163, Thermal performance and energy use in the built environment, and ISO/TC 205, Building environment design, have established a joint working group (JWG) to respond to the need for improved building energy standards : ISO/TC 163/WG 4, Energy performance of buildings using the holistic approach.

The JWG’s task is to ensure maximum consistency among standards and new or existing work items from both committees concerning energy efficiency and energy performance of buildings, including technical systems.

In addition, the JWG is to prepare proposals for the development of an ISO vision on energy performance of buildings for discussion in relevant technical and higher-level ISO committees.

Experts from 17 countries are currently active in the JWG.

Performance requirements and classification

Two prime applications of these standards are :

• Judging compliance with building regulations expressed as a limitation on primary energy or a related quantity
• Transparency in commercial operations through the energy certification and/or display of a level of energy performance.

This requires transparent, verifiable, unambiguous, robust and reproducible procedures. Evidently, this should be formulated to allow handling national differences in climate, culture and building tradition, building typologies, occupant behaviour, and policy and legal frameworks, including building regulations.

Work programme

The JWG currently has three active work items in the top segments of the pyramid. The first is ISO 16344, Energy performance of buildings – Common terms, definitions and symbols for the overall energy performance rating and certification. Its aim is not to produce general terms and definitions used in building design, but to produce common terms, definitions and symbols that are essential for the unambiguous and transparent assessment of the energy performance, from top to bottom of the pyramid. Considering the use of terms, definitions and symbols in various standards under ISO/TC 163 and ISO/TC 205, the document will first be advanced as a technical report (TR). 1]

The second work item is ISO 16343, Energy performance of buildings – Methods for expressing energy performance and for energy certification of buildings. It covers Segment 2 of the pyramid. 2]

Last, but not least, ISO 16346, Energy performance of buildings – Assessment of overall energy performance, is the third work item and covers Segments 3, 4 and 5 of the pyramid. 3]

A spin off from these key energy performance items is the work item ISO 12655, Presentation of measured energy use of buildings. Its intent is to provide a methodology that will serve as a common basis to unify the collected data of measured building energy use and, in so doing, enable parallel analytical comparisons. Due to the obvious similarities, the work item ISO 12655 aims for a maximum of consistency with the above three items as another step toward harmonization.

The JWG has also recognized the urgent need for an overall framework for energy performance procedures that would link elements such as heating, cooling, lighting, fans, hot water and appliances, including their interactions. The framework would enable countries to adopt the procedures in a step-by-step fashion and help them make tailored choices, within the national or regional context and depending on the application.

In parallel, several working groups in ISO/TC 163 and ISO/TC 205 began work on new work items in the lower segments of the pyramid, covering a variety of subjects such as air flow and ventilation, heating systems and daylight in buildings.

A main challenge for the JWG is the coordination of these activities to ensure overall consistency. To this end, a strategic view working document has been prepared and is updated at regular intervals. This document comprises :

• An overview of standards and active, planned or missing work items on the assessment of the energy performance of buildings using the holistic approach
• Ground rules for the drafting of standards under the holistic approach, to ensure transparency and unambiguity
• Proposals on the links with closely related fields of international standardization.

The JWG has agreed upon ground rules and moved to translate these into detailed technical rules in close cooperation with all involved working groups. This comprises a common structure for each standard, with a clear separation of shared procedures and national choices, joint rules on making each standard “ software proof ”, including unambiguous input-output relations and rationalization of alternative options.

Cooperation for global standards

In early April 2011, CEN accepted a second mandate from the European Commission (M/480) for the development of a second generation of standards on energy performance of buildings. This move is seen as a major upgrade of CEN standards supporting the EU’s Energy Performance of Buildings Directive (EPBD), published in 2007-2008.

There is an extraordinary congruence in timing, goals, ambitions, work plan and personal liaisons between ISO and CEN activities. This calls for close collaboration, preferably under the Vienna Agreement, leading to truly global standards on the energy performance of buildings.

1] The relevant parts of the European Committee for Standardization (CEN) technical report EN/TR 15615 are used as starting point.
2] EN 15217 is used as a starting point.
3] EN 15603 is used as a starting point.