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Temperature and humidity

Our world-leading expertise and research enables innovative improvements in practical and traceable measurement, and is underpinned by realising and disseminating the International Temperature Scale of 1990 (ITS-90)

Helping organisations to understand the impact of reliable temperature and humidity measurement on their processes, and solve their challenging measurement problems

We realise and disseminate the UK National Standards for temperature (between approximately -196 °C and 3000 °C) and humidity (dew-point temperatures from -90 °C to +95 °C) the uncertainties of which are demonstrated through international comparisons. NPL is making world-leading contributions to the realisation of the redefined kelvin.

We have a growing portfolio of temperature, humidity and moisture calibration services. These UKAS-accredited services offer very low calibration uncertainties, wide measurement ranges and flexibility in the operating parameters used. We use the International Temperature Scale of 1990 (ITS-90) which defines procedures for realising temperature in kelvin and degrees Celsius. All quoted uncertainties are expanded uncertainties, based on a standard uncertainty multiplied by a coverage factor k = 2, providing a coverage probability of approximately 95 %.

We have leading expertise and novel techniques for solving real-world temperature and humidity measurement problems, including those in challenging or harsh environments. We provide cost-effective, impartial, quality-assured solutions to organisations looking to understand the impact of temperature and humidity measurement on their infrastructure, products, research and development. This is not limited to a particular sector or technology, but is both wide (from construction to space) and deep (from practical applications to theoretical knowledge and modelling).

We engage with users in a variety of ways, including long-term research, industrial partnerships, consultancies, calibration services, instrument sale and installation, good practice guides and tailored training.

Contact us

Our research

Our experienced team conducts cutting-edge research into the development of innovative temperature and humidity measurement techniques, from concept to complete instruments. In particular, we have expertise and ongoing research in:

Contact thermometry

We are developing generic and bespoke solutions to contact temperature measurement challenges, including reliable traceable thermometry in harsh environments.

Humidity and moisture measurement

We are broadening our humidity and moisture calibration techniques to cover a growing range including non-air gases, high pressures and moisture content in solids and liquids.

Non-contact thermometry

We are developing low uncertainty, thermodynamic temperature capabilities to complement our existing temperature calibration services, especially at higher temperatures

Primary thermometry

Our world-leading research into a range of primary thermometry techniques directly links temperature measurement to thermodynamic temperature.

Quantitative thermal imaging

We are designing world-leading instruments for robust and traceable temperature measurements using thermal imaging in 2D and 3D in the laboratory and harsh environments.

Reliable harsh environment thermometry

We are improving techniques for reliable temperature measurement in harsh environments, including using thermographic phosphors and fibre-optics

Our services

Our state-of-the-art equipment supply and our highly accurate calibration services give organisations improved performance, reliability and understanding of temperature and humidity measurements.  

Case study

Quantifying moisture in failed spent AGR fuel pins


Case study

Monitoring the temperature of nuclear waste


Case study

Long-term reliable surface thermometry for nuclear material


Our resources

We have published extensively in this area, have a number of good practice guides and e-learning or training modules. Search our comprehensive list of resources.


Our team

We have over 20 internationally recognised researchers focused on temperature and humidity measurement.
View our team