Meet the Jury Gert-Jan Steeneveld on Indoor overheating in homes: from citizen science observations to early warning

Arenberg Doctoral School is proud to invite you to Meet The Jury!

When internationally renowned experts visit KU Leuven as a member of a PhD Examination Committee, we like to seize this opportunity to give this expert a forum to a large audience. All members of Science, Engineering & Technology are most welcome to the Meet The Jury Lectures.

Prof. Gert-Jan Steeneveld (Wageningen University, Netherlands) will give a lecture on “Indoor overheating in homes: from citizen science observations to early warning”.

Cities are typically warmer than the countryside, i.e. the urban heat island effect is a well known phenomenon. Warm weather episodes pose challenges to human health and urban infrastructure. However, citizens spend about 80-90% of their time indoors, and as such the heat load indoors is as relevant as the outdoor heat. This presentation will discuss bed room and living room temperatures recorded in 100 homes in Amsterdam in the period between 2022-2026. These observations are complemented by 24 outdoor weather stations across the city. First we analyse indoor temperatures during a heatwave in sept 2023 and compare with citizen science observations. Median room temperatures reach 28.0 °C on the warmest day, while outdoor mean minimum and maximum temperatures reached 20.6 °C and 31.1 °C respectively. We find that the crowdsourcing approach reports temperatures that are significantly higher (biased) than the professional approach, which supports the need for professional indoor networks. Second we test to what extent the pool of homes in the dataset comply with the Dutch housing legislation for heat (weighted temperature over threshold, GTO). Surprisingly we find that the majority of the studied homes comply well with the current legislation. However, the results appear very sensitive to the assumed ventilation velocity in the GTO protocol. Next, we develop a straightforward room temperature model that takes into account the energy flows towards the room. The model is validated against long term observations in 7 homes across the Netherlands (for which some contain 27 years of data). Subsequently this room temperature model is forced by the European Center for Medium Range Weather Forecasts outdoor weather forecast, to produce room temperature forecast 5 days ahead for a full summer. Forecasts for living room temperatures outperform those for bedrooms (median MedAE: 0.30 K vs. 0.36 K), and performance degrades gradually with lead time (median MedAE: 0.30 K day one; 0.80 K day five).

Following the lecture, there will be opportunity for young researchers to interact with him.

• Venue: Room 01.267 at the Geo-Institute, Celestijnenlaan 200E, 3001 Heverlee
• Date: 3 September 2026 – 13:30-14:30
• Prof. Gert-Jan Steeneveld is visiting KU Leuven on the occasion of the PhD defence of Fien Serras