New standardization projects relevant to ventilative cooling applications (an air system that cools a building taking ventilation air from outside at its actual temperature and humidity and shall not have any mechanical pre-cooling based on refrigeration process) have officially been initiated under Technical Committees (TC) in the European Committee for Standardization (CEN/TC 156) and the International Organization for Standardization (ISO/TC 205) since 2017. The scope of this work is to make technical documents focusing on design aspects and setting criteria for ventilative cooling, and natural & hybrid ventilation systems in residential and non-residential buildings. The aim is to help designers designing these ventilation systems in order to fulfil the set criteria for indoor air quality (IAQ) and thermal comfort.

The projects are progressing well and content has started to emerge into actual drafts. Some of the projects are further in the process than others, e.g. item #1 and #2 below where the 1^st working drafts has been sent to CEN/TC 156 for information and final draft is due by June 2019. Subsequently a voting-procedure is performed by CEN-members. The initiated projects are planned as CEN Technical Specifications, an EN standard under CEN/TC 156, and as an ISO standard under ISO/TC 205.

More specifically, four projects relevant to ventilative cooling applications, have already started:

1. Ventilative cooling systems

• Main focus: Thermal comfort (reduce cooling loads and prevent overheating)
• Document type: A CEN Technical Specification
• Work initiated: In CEN/TC 156, WG/21

2. Natural and hybrid ventilation systems in non-residential buildings

• Main focus: Indoor air quality
• Document type: CEN Technical Specification
• Work initiated: In CEN/TC 156, WG/20

3. “Revision of EN 15665:2009 and CEN/TR 14788:2006” (focus to expand information on Natural and Hybrid ventilation in residential buildings)

• Main focus: Indoor air quality
• Document type: Aim is one EN Standard
• Work initiated: In CEN/TC 156, WG/2

4. Design process of natural ventilation for reducing cooling demand in energy-efficient non-residential buildings

• Main focus: Thermal comfort (design process to prevent overheating)
• Document type: ISO standard
• Work initiated: In ISO/TC 205, WG/2

In this work is it important to make clear which inputs are needed to make the performance calculations for the ventilation systems. Further it is important to give the designer different options without pointing to only one solution or value by providing a classification of different categories. More specifically in e.g. item #1 the aim is to split the document into natural, hybrid and mechanical ventilative cooling, where each system should be designed with following steps:

• Find your criteria
• Conceptual design (simple evaluations, e.g. simple equations)
• Detailed design (detailed evaluations, e.g. simulations)
• Design validation

Many of these technical documents are entering a new territory and will be the first of its kind, as no documents are currently available at CEN level describing natural and hybrid systems as well as ventilative cooling.

Furthermore, this is a good opportunity to define the design and calculation methods to achieve the given criteria for ventilative cooling, and natural & hybrid ventilation systems in buildings on the European and International scene. Content for this work may be found from international projects e.g. by applying findings from the recent IEA EBC Annex 62 publications on ventilative cooling found here.

Article be Christoffer Plesner, VELUX A/S, Denmark & Jannick Roth, WindowMaster International A/S, Denmark