Although EPBD stated that minimum energy performance requirements shall take into account indoor climate conditions, many member states neglected indoor environmental issues while implementing energy conservation policies. As a result, nZEB rush pushed towards high insulated and airtight buildings, which resulted in an increased overheating risk during summer and shoulder seasons in both residential and non-residential buildings.
Concerns about overheating risk reawakened the interest in naturally ventilated buildings. However, the higher risk on performance prediction and the lack of design standards compared to mechanical systems, make natural ventilation systems still an extra building equipment rather than a complementary system or even an alternative to HVAC systems.
Last year the European Committee for Standardization (CEN) and the International Organization for Standardization (ISO) have approved new standardization projects on ventilative cooling and natural and hybrid ventilation systems within this framework.
The projects started last year under CEN/TC 156 (Ventilation for buildings) and ISO/TC 205 (Building environment design) and focus mainly on design aspects of natural and hybrid ventilation and ventilative cooling tackling both overheating and indoor air quality issues.
More specifically, working group 21 is dealing with a technical specification on “Ventilative cooling systems” which focuses on overheating prevention. Among other sources, background for integration of ventilative cooling in energy performance calculation, building design and standards is provided by the IEA Annex 62 project outcomes.
Beside the revision of EN 16798 part 3 and 4 on performance requirements for ventilation in non-residential buildings, working group 20 is dealing with a technical specification on “Natural and hybrid ventilation systems in non-residential buildings” which focuses on indoor air quality aspects.
ISO standard on “Design process of natural ventilation for reducing cooling demand in energy-efficient non-residential buildings” is under development within working group 2 in ISO/TC 205.
Projects are in the initial phase of setting up task forces, collecting background documents and redefining the scope in alignment with previous standards and other standards under development. First working drafts are expected in 1 to 2 years.