How this is calculated
Inspect the versioned inputs.
| Constant | Value | Scope & source |
|---|---|---|
| electricACH | 6 h⁻¹ | Electric sauna manufacturer guidance; Q[m³/h]=roomVolume[m³]×6. Not a fan-system pressure-drop calculation. harvia-ventilation ↗ Verified 2026-11-08 |
Input defaults that are not sourced measurements are illustrative planning assumptions. Exact unit definitions, the 52-week convention and algorithm details are in the shared methodology.
Worked example
An example you can inspect.
A 12 m³ electric sauna gives a manufacturer planning airflow of 72 m³/h, or 20 L/s. Duct resistance and fan performance are not calculated.
Choose the heating and ventilation systems first.
The four diagrams correspond to electric or wood-fired heating combined with mechanical or gravity ventilation. Select the pair that describes the actual proposed installation. A fan somewhere in the building does not by itself establish the pressure arrangement in the sauna. Likewise, a wood heater brings combustion and flue requirements that an electric-room airflow rule cannot size. The tool keeps those cases separate so a change in heater type cannot silently carry an electric airflow number into a combustion-air decision.
Distinguish a volume rate from a duct design.
For the electric case, the calculation multiplies measured room volume by the cited hourly air-change guidance. The same volume rate is then expressed in cubic metres per hour, litres per second and cubic feet per minute. These are equivalent units of flow. They do not specify duct diameter, fan static pressure, grille free area, noise, balancing or a route through the building. A fan's advertised maximum flow may not be the installed flow through the eventual system. Ask the ventilation designer how the required flow will be established and checked.
Treat positions as a conceptual air path.
The diagrams identify the intake, exhaust and relevant heater relationship described by the selected source. They are not a scaled plan of your building. Room-shape labels help frame the discussion but do not calculate short circuiting, pressure distribution or the effect of obstructions. Locate doors, benches, ceiling features and the actual duct route on a separate drawing. Compare that drawing with the exact heater manual, because manufacturer instructions may depend on sensor placement and installation configuration. Do not move a sensor or a vent solely to make this illustration resemble the room.
Verify the assembled installation.
Use the output to prepare a short list of questions: which source governs the chosen model, how air reaches and leaves the room, how adjacent spaces are affected, and what commissioning check is planned. For a wood-fired design, include the combustion-air supply, flue and relevant installation requirements in that review. For an electric design, retain the entered finished volume and the calculated flow alongside the professional's duct and fan specification. If the room dimensions or system type change, recalculate the conceptual example and revisit the detailed design rather than assuming the previous answer still applies.
Keep units on every design note.
A number without a unit is easy to misread during a supplier handoff. Copy the volume and flow units together and identify whether the example is electric or wood-fired. Include the selected mechanical or gravity arrangement as well. These labels make the calculation reproducible and help the professional identify where a separate detailed design or a manufacturer-specific instruction must replace the conceptual illustration.
Questions, considered
Questions about this tool
How should I interpret the ventilation planner result?
This is an air-path planning aid, not a fan selection, flue, combustion or code calculation. Room shape can identify a far wall but cannot establish adequate distribution. Choose an electric or wood-fired air-path diagram and inspect the manufacturer’s guidance before discussing the design with an installer.
Which assumptions matter in the ventilation planner?
For electric-heater guidance, airflow Q = volume × 6 air changes/hour. Convert m³/h to L/s or cfm by unit definitions. Mechanical and gravity layouts use different inlet positions. Keep supply air from cooling the heater sensor. Wood-fired diagrams do not inherit the electric six-change rate; combustion air and chimney pressure need separate design.
Primary sources
Follow the source.
- Harvia — Ventilation in the sauna ↗
Separate electric-heater and woodburning-heater sections; updated January 29, 2026
The six-change hourly rate is explicitly under electric heaters. Do not silently extend that rate to a wood-burning system; its combustion air, flue, depressurization and fire requirements need a qualified designer.
Checked 2026-11-08 - Harvia — Temperature sensor installation ↗
Minimum distance between supply air valve and temperature sensor; May 4, 2026
Sensor position remains model-specific. Cooling the sensor with supply air can defeat correct temperature measurement.
Checked 2026-11-08