25 June 2026

Update 25 June

Due to the persistent heat, a Red Code has been issued for Friday, including in the province of South Holland. According to Leiden University’s guidelines, university buildings would normally be closed under such conditions. However, as most buildings are equipped with adequate cooling and ventilation, (most) buildings will remain open for staff and students tomorrow.

What does this mean for our faculty’s buildings? 
For the buildings of our faculty, nothing changes compared to the message of Wednesday 24 June; we will follow the approach outlined in the message below. 

---

Over the next two days, temperatures will rise well above 30°C. This may lead to very warm conditions, particularly in older buildings. This can affect comfort, concentration and overall wellbeing. We therefore ask everyone to be mindful when working during this period of heat.

Workplace and working hours: flexibility comes first

• Choose the workplace that is most comfortable and coolest for you: if working from home is possible and preferable, please opt for that.
• If you work on campus, do so—where possible and in consultation with your supervisor—during the cooler morning hours and avoid the hottest part of the day.
• Seek out a cooler workspace and use a fan if available.

For colleagues in Sylvius and Van Steenis

Colleagues working in the Sylvius and Van Steenis buildings are welcome to use workspaces in the Gorlaeus Building, in addition to taking measures within their own buildings.
If you wish to make use of this:

• Report to reception with your LU card.
• You will be directed to the BE wing on the 1st floor and, if needed, also the CE wing on the ground floor.

For colleagues in the Huygens building

Colleagues based in the Huygens building can also use available workspaces in the Gorlaeus Building at Biophysics, FMD, ELD or IL. In addition, there are sufficiently cooler workspaces on the lower floors of the Huygens building.

Practical tips for a cooler working day

• Ventilate smartly: only open windows and doors when the outdoor temperature is lower than indoors—this will mainly be in the early morning. Close them once it becomes warmer outside.
• Use sun blinds/shading as soon as you arrive.
• Stay hydrated and do not skip breaks.
• During breaks, seek out shaded and cooler areas.
• Wear light, breathable clothing.
• Consider working temporarily in a room with climate control.

Building-specific considerations

• CML / Van Steenis: fans are available via office management; consider working from home or relocating to a cooler workspace.
• IBL / labs: if you experience issues due to the heat, please contact your lab manager or supervisor.

Teaching

Lecturers are asked to assess the suitability of teaching spaces during hot weather conditions. Where necessary and feasible, consider:

• Moving to a cooler room
• Delivering teaching online
• Shortening sessions or rescheduling them

Please ensure any changes are communicated to students in a timely manner via Brightspace.

Finally

Your health and wellbeing come first. Please take adequate rest, drink plenty of water and make use of the available flexibility.

Weather code orange

The KNMI issues weather warnings in different codes depending on the extent to which the weather poses a risk to people’s safety. Read in this news item what a weather code means for working and studying.