Single zone and Multiple Zones

EN ISO 52016 — Multi-zone Calculation and Adjacent Zones

EN ISO 52016 defines that:
The calculation now allows the definition of several thermal and non-thermal zones adjacent to the considered zone.

External Adjacent – Unheated Zone: It is possible to define an unheated adjacent zone in contact with the considered thermal zone.
The length of the separating wall may be entirely or partially connected to the considered zone.

The calculation involves: 1. Determining the internal temperature of the non-thermal zone. 2. Evaluating the heat exchange with the thermal zone.

External Adjacent – Heated Zone: In this case, the wall between the two zones is considered adiabatic (no heat exchange). Adjusted Coefficient: To account for the different temperatures between zones (e.g., thermal and non-thermal), an adjusted coefficient is calculated.

Assumptions and Simplifications

The standard defines various assumptions specified in section 6.5.3 — Assumptions and specific conditions.
In general, it aims to simplify the zoning approach by reducing the number of zones to a minimum (ISO EN 52016-2:2018).

It also emphasizes that:

A multi-zone calculation with interactions between the zones requires significant and often arbitrary input data (on transmission properties and air flow direction and size).
It can also lead to other technical and procedural complications that add uncertainties to the results.
A further complication can be the involvement of different heating, cooling and ventilation systems for different zones, which adds to the complexity and arbitrariness of the input and modelling.

Key Remark: Therefore, the benefits of calculations with thermally coupled zones can be smaller than the drawbacks.