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In the office building market, there is increasing interest in offices where people feel comfortable. The WELL standard is a certification that focuses on human health. Air quality is an important factor. This requires the measurement of a number of gases. Which measuring instrument is the best to use for this purpose? And when do your measurements meet WELL's requirements?


The quality of the air we breathe affects all our bodily functions. To obtain a Well certificate, the air inside the office must contain as few harmful substances as possible.
With the Dutch government's Energy Label, but also with BREEAM and LEED certification, the real estate world has been putting a lot of effort into demonstrating the energy efficiency and sustainability of buildings in recent years. Under the influence of these requirements, for example, the energy consumption as well as the air permeability of façades, roofs and floors have been greatly reduced. However, these measures also have a clear impact on the indoor environment.

WELL looks at factors in the environment that are harmful to the user of a building. Such as toxic substances, insufficient daylight and too little exercise. Air is one of the most extensive categories of the Well standard.

Kantoor luchtkwaliteit


The WELL standard has 3 levels - Silver, Gold and Platinum. The standard consists of 100 requirements, divided into 7 categories (Air, Water, Food, Light, Vitality, Comfort, Mind). In order to be certified, a building does not have to meet all 100 requirements, but the air quality requirements are mandatory.
Certification is still in its early stages - some 152 buildings worldwide are currently (early 2019) certified, two of which are in the Netherlands. There are 55 projects in the Netherlands and 32 people are accredited by WELL.
For many companies, the motive for certification is increased productivity, in addition to employee welfare. In addition, real estate owners expect to be able to distinguish themselves with WELL and to achieve greater returns.

WELL standaard


To become Well certified, there is a set of conditions that must be met (the "Pre-conditions") and a set of conditions that must be met between 40%-80%.

Air quality is one of the elements that must be met in all cases.
For this purpose, these gases must be measured:

  • Total VOC < 500 µg/m3
  • CO < 9 ppm
  • PM2,5 < 15 µg/m3
  • PM10 < 50 µg/m3
  • O3 < 51 ppb
  • Radon < 0.148 Bq/L
  • CO2 < 800 ppm (spaces larger than 46.5m2)

The WELL standard also describes how to measure and the accuracy of the measuring equipment. In general, we describe it below, but you can find the complete information in the pdf's that we have attached.


The standard therefore includes the gases that must remain below certain maximum values. The measurements must take place both inside and outside the building.

1. Measurements outside the building

Gases to be measured:
CO, PM2,5, PM10, O3

Location measurement point:
Measurements must be made at an air inlet for the air handling equipment.
If this is not available, the measurements should be made at 8,3m from the main entrance, at a height between 0,9 - 1,8m.
The measurements must be repeated 3 times within 1 day.

2. Measurements inside the building

Gases to be measured:
CO, PM2,5, PM10, O3, formaldehyde, VOC’s

Measurements should be taken in all areas of high traffic or of a certain size and at a height between 0.9-1.8m. At least one measurement location per floor.

WELL kit

Photo; Aeroqual's WELL kit

WELL to complicated?

In terms of costs, WELL certification may not be available to everyone, despite the fact that it is sometimes possible to draw up an ROI. But the intention is good to strive for; moreover, BREEAM and LEED also say something about air quality.
If you don't want a WELL certificate, but you do want to promote health within the building, then the WELL Building Standard offers the right tools. The WELL Building Standard describes exactly which aspects you need to think about in order to achieve a healthy working environment. Based on this, you can extract the relevant points for your own working environment and set your own performance requirements.

WELL table


The standard has extensive requirements for accuracy, so it is recommended that you go through the document below.
Here is a summary:
Formaldehyde: ISO 16000-4-2011.
VOC’s: ISO 16000-6 of EPA TO-1, TO-17, EPA Compendium Method IP-1, of OSHA Validation Guidelines.

Carbon monoxide and Ozone:
There are good handheld meters, which can measure these kinds of gases very accurately. The difference between the different types is mainly the gases that can be measured, the accuracy and whether there is a method to read the meter from a distance.

Handheld meters

  • Special kit for WELL measurements
  • Favourable price
  • Can be used in other locations
  • Flexible and expandable system thanks to separate measuring heads
  • About 20 different heads: each gas can be measured
  • Supplied with calibration certificate



  • Simultaneous measurement of several gases
  • Standard GSM and WiFi connectivity
  • Measurements can be viewed and used immediately
  • Robust and accurate
  • Internal calibration unit as an option
  • Supplied with calibration certificates

Because this equipment can be read remotely, it is also attractive for many parties to make stationary measuring systems part of the office. The current measurements can then be made visible to users and visitors on screens in the building. Happy Energy, for example, is a company that focuses on this.

More information?

Please contact our Sales Engineers:

Teesing Sales Engineers
NL: Tel.   +31 70 413 07 50
CN: Tel.   +86-(0)10-60576210
USA: Tel.   +(1) 973 383 0691
TW: Tel.   +886-(0)3-5600560
Mail: sales@teesing.com

OR RENT? As the validity of a WELL certificate is 3 years, the measurement takes place occasionally. This is one of the reasons why it is also possible to rent measuring equipment from us.

Teesing Sales Engineers

Tel.   +31 70 413 07 50
Mail  sales@teesing.com