We have sent email too all staff and lunchtime MSA to be mindful and proactive in keep doors closed at lunch and breaktimes. We have lowered the heating to avoid classrooms getting to hot which results in windows being opened. We have a huge problem with doors being left wide open during break and lunch and are proactively reminding staff to ensure these are closed to reduce heat loss. EMails have been sent and site manager is monitoring doors during these periods. We have aslo added a reminder to our staff daily briefing.