From 2021, a new energy performance of buildings regulation, the so-called NTA8800, comes into force in the Netherlands. 4 indicators are used: BENG1 represents the energy demand, BENG2 the fossil primary energy consumption, BENG3 the fraction of renewable energy production and TO_july is an overheating indicator (only in residential sector).

Instead of the designed ventilation system, a fixed standard ventilation system is supposed when calculating BENG1. In that way, the regulation stays technologically neutral by focusing on the envelope characteristics in BENG1. Energy efficient ventilation systems using sensor based demand control or heat recovery can be valorized via the BENG2 indicator.  

Electricity driven HVAC installations are stimulated due to a low primary energy factor (PEF) of 1.45 to calculate the BENG2 indicator.

Passive as well as active cooling measures are taken into account. Active cooling is stimulated by the low PEF value and the absence of an overheating risk (TO_july = 0) in houses when using active cooling. This means that passive cooling based on ventilative cooling or solar shading has theoretically no impact on the overheating risk in houses, in case of active cooling. When no active cooling is applied, passive cooling measures can considerably reduce the overheating risk.

When a cooling demand is present, summer night ventilation based on operable windows has a positive effect on the following 2 indicators: the fossil primary energy consumption (BENG2) when active cooling is present and the overheating risk when no active cooling is present (TO_july = 0). Several requirements are set on the devices for summer night ventilation: rain tight, insect proof and no risk on burglary. The application of louvres or the right location and design of operable windows is of importance to guarantee the correct use of night cooling and to maximize its effect on the indicators.  

Ivan Pollet, Renson, Belgium