Posted on

Methods and instruments for measuring indoor climate

Published 2022-12-09

Methods and instruments for measuring indoor climate

Nordtec Indoor Climate

What exactly is a good indoor climate? On the one hand, people may have different perceptions of what is acceptable in terms of temperature and draughts. What we call thermal comfort. On the other hand, there are physical measurable quantities such as air temperature, radiant temperature from surfaces, air movement, humidity and so on.

In this article, we explain what an occupancy zone is and give examples of some common measurements used in indoor climate assessments. In case of a complaint, the first step is normally to check some of the above mentioned quantities. A more detailed investigation is then carried out if the measured values are above or below certain limits.

Residence zone

The occupied zone is the part of a room where thermal comfort is required for human well-being. The occupied zone is bounded by two horizontal planes 0.1 meters and 2.0 meters above the floor. On the sides, the occupied zone is limited by vertical planes 0.6 meters from the outer walls. However, in front of windows and doors, the distance is 1 meter.

Measurement points
The air temperature and the operating temperature are measured in at least two places in the room in question: 1 meter in front of a window 0.6 meters above the floor, and in a corner 0.6 meters from each wall and 0.6 meters above the floor.

thermal climate section bbr 46
The picture shows a living zone in a room seen from the side with the given dimensions. Source:
thermal climate plan bbr 47
The picture shows an occupied zone in a room seen from above with specified dimensions. Source:

Initial control

To get a first idea of the thermal indoor climate, an initial check of the air temperature in the room is carried out. Depending on the complaint, the check can be complemented by a simple measurement of humidity.

pop air temperature

Air temperature
The air temperature can be measured with a standard air thermometer, but it may also be a good idea to use a data logger as it records readings over a longer period of time.


Heating elements
Too low or too high a room temperature can have simple causes. A quick check of the heating elements will show if the hydronic heating system needs an overhaul.

air humidity

Air humidity
A humidity sensor can be used to determine if the air is too dry. Moreover, these sensors are often combined with a sensor for simultaneous measurement of the air temperature.

Detailed control

A more detailed investigation may include measurement and assessment of the operational temperature and how much the operational temperature differs between different measurement points, floor temperature and also air movements due to draughts or cold draughts.

Operational temperature
The operational temperature is the average of the air temperature and the average radiant temperature from surrounding surfaces. By calculating the operational temperature, you can describe how the temperature is perceived.

The operating temperature is often measured with a globe sensor. It is a practical and simple method that provides a good enough measure of the combined effect of air temperature and radiant heat. A globe sensor consists of a temperature sensor inside an air-filled black painted sphere.

testo 925 surface temperature

Floor temperature
For floor surfaces there are often both lower and upper temperature limits. According to Boverket’s building regulations, the floor temperature in the occupied zone should be at least 16 ºC (in hygiene rooms at least 18 ºC and in premises intended for children at least 20 ºC) and can be limited to a maximum of 26 ºC.

According to FoHMFS*, the floor temperature is measured by taking the average of four measurements within a square of 30×30 cm at the same measuring points where the other measurements are taken.

* The Public Health Agency’s general advice on indoor temperature

Air movements
A draft sensor can be used to quickly determine whether there is air movement or cold drafts in the occupied zone. It is also possible to use indicator smoke to see if there is any air movement.

According to Boverket’s building regulations, the air speed in a room’s occupied zone should not be calculated to exceed 0.15 m/s during the heating season and the air speed in the occupied zone from the ventilation system should not exceed 0.25 m/s during the rest of the year.

Examples of some of our measuring instruments

Measurement set with testo 440 dP and globe transducer and strain gauge

Measurement kit with testo 440
Comprehensive thermal comfort checks often require measurements of operational temperature and draught. This measurement set can do both of these tasks.

Read more

IR thermometer testo 830-T2 kit

Measurement kit with IR thermometer
Contains testo 830-T2. For all types of temperature measurements, such as on walls, windows, radiators and floors. Mini sensor and air and liquid sensors are included.

Read more

testo 925 perspective

Temperature meter testo 925
A true basic instrument for temperature measurement – robust, flexible and accurate. All type K temperature sensors can be connected and also wireless radio sensors.

Read more

testo 440 CO2 mätset - 0563 4405 - Miljö 3

Occupancy zone and thermal comfort

Application: Air temperature – floor temperature – operating temperature – humidity – air movement

Measurement solution: testo 400, testo 440, IR thermometer testo 830-T2, testo 925

Related application pages

Building climate

With an optimal climate, you can finish the building on time.

See all customer stories

Contact persons

Mats Landin


Mats Landin

Area of responsibility: Construction, HVAC, Indoor climate control
031-704 10 85
031-704 10 70