Building Bulletin 101, Ventilation Of School Buildings

Building Bulletin 101.

Guidelines on ventilation, thermal comfort and indoor air quality in schools Version 1

Building Bulletin 101 was updated in 2018 and is a 2nd tier regulatory document to the Building Regulations part F. This covers the ventilation in education buildings.

Within the document carbon dioxide (CO2) is used as an indicator of indoor air quality with exhaled air typically the principal source of CO2 in schools.
With levels inside classrooms affected by • the number of occupants in the room • the activity levels of occupants • the amount of time occupants spend in the room • the ventilation rate.

With ambient background CO2 levels typically between 400-450 ppm, without adequate ventilation, this level will rise considerably and quickly.

BB101 supports the Building Regulations Part F in laying out the requirements for ventilation in schools with the updated standard covering differences in natural, mechanical and hybrid ventilated spaces and states:

“Except where required for gas safety, ventilation should be provided to limit the concentration of CO2 as described in section 2.4. DfE performance standards for teaching and learning spaces

“The DfE has set the following performance standards for teaching and learning spaces which ensure compliance with Regulation 6 of the Workplace Regulations on Ventilation” as described “These standards must be followed if a school building is to comply with BB101. “

1. Where mechanical ventilation is used, or when hybrid systems are operating in mechanical mode in general teaching and learning spaces, sufficient outdoor air should be provided to achieve a daily average concentration of carbon dioxide (CO2) of less than 1000 ppm, during the occupied period22, when the number of room occupants is equal to, or less than the design occupancy. The maximum concentration should also not exceed 1500 ppm for more than 20 consecutive minutes each day when the number of room occupants is equal to, or less than the design occupancy.
2. In general teaching and learning spaces where natural ventilation is used or when hybrid systems are operating in natural mode the following standards apply:
   • a. Sufficient outdoor air should be provided to achieve a daily average concentration of CO2 of less than 1500 ppm, during the occupied period, when the number of room occupants is equal to, or less than the design occupancy.
   • b. The maximum concentration should also not exceed 2000 ppm for more than 20 consecutive minutes each day, when the number of room occupants is equal to, or less than the design occupancy.
   • c. The system should be designed to achieve a carbon dioxide level for the majority of the time of less than:
     • i.1200 ppm for a new building (800 ppm above the outside carbon dioxide level, taken as 400ppm) for the majority of the occupied time during the year – this is the criterion for a category II building 
     • ii. 1750ppm for a refurbished building (1350ppm above outside air level) for the majority of the occupied time during the year – this is the level for a category III building.23”

The Medem InAir v2 is designed to monitor for each of these described levels with a simple switch selector changing between alarm levels for the natural, mechanical or hybrid schemes.

Science, design and technology spaces

Higher ventilation rates are required for practical activities, such as science, design and technology and food technology.

In these practical spaces, higher levels of CO2 are acceptable for the periods of time when gas-fired appliances (Bunsen burners, cookers. Etc) are in use as they produce about double the amount of CO2 produced by a student or teacher.

In line with IGEM/UP/11 Edition 3 – Gas installations for educational establishments standards, these are fixed  alarm levels and gas interlocks by monitoring of CO2 should operate as follows:

• a. During practical activities, the appliances shall not cause the CO2 level to exceed 2800ppm, which will produce a signal warning of a high CO2 level
• b. An automatic gas shut down shall operate when the level of 5000ppm of CO2 is reached

Please see IGEM/UP/11 Edition 3 – Gas installations for educational establishments section for additional information and guidance on gas proving and interlock system for the safe use of gas within practical teaching spaces.

If you require any additional information on our systems to help meet these design standards or wish to discuss the standards further, please don’t hesitate to contact us.