Building Bulletin 101 - Summer Overheating

The Department for Education and Skills (DfES) Building Bulletin 101 stipulates the performance standards for learning spaces with regards to overheating during the summer months and for the occupied period of 09:00 to 15:00, Monday to Friday, from 1st May to 30th September.

Summer Overheating Indicators

There are three parameters in the standards that provide an indication when overheating is likely to occur. These parameters include:

1. the number of hours for which a threshold temperature is exceeded;
2. the degree to which the internal temperature exceeds the external temperature;
3. the maximum temperature experienced at any occupied time.

The use of the three performance parameters will ensure that the design of future schools is dictated by a combination of factors which will allow a degree of flexibility in the design of the school. They will also take account of the use of the school, for example, a school's choice of term dates.

Compliance Measures

The performance standards for summertime overheating compliance are:

a) There should be no more than 120 hours when the air temperature in the classroom rises above 28°C;
b) The average internal to external temperature difference should not exceed 5°C (i.e. the internal air temperature should be no more than 5°C above the external air temperature on average);
c) The internal air temperature when the space is occupied should not exceed 32°C.

Compliance Requirements

In order to show that the proposed school will not suffer overheating two of these three criteria must be met.

How can we help you?

We can assist you to determine potential overheating in classrooms as indicated by these performance parameters and suggest remedial actions. The results of our calculations can be used to demonstrate compliance with the performance standards.

To discuss your requirements, please contact us on:


11 Caithness Crescent
Manor Kingsway
Derby DE22 3XS


01332 492082


0788 6277 818