Changes to BB101
Rules on school ventilation are changing under BB101 Guidelines on ventilation, thermal comfort and indoor air quality. The revised version of Building Bulletin is due to be published in late Spring or early Summer this year. The government is getting tough on air quality in classrooms with maximum CO2 limits being reduced significantly and minimum flow rates being established for science labs, halls and gyms.
To help prepare for the new revision we have put together a summary of the changes;
Minimum Flow Rates
- Classrooms should be capable of 8 l/s/p or 2 ACH for the design occupancy when occupied, whichever is greater;
- Halls and gyms should be capable of a minimum of 8 l/s/p or 2.5 ACH, whichever is greater;
- Corridors need a minimum of 2.5 l/s/p +0.3 l/s/m2 of floor area, or – if number of people is unkownn – 1.2 l/s/m2
- For science labs with an area >70m2, the minimum is 4 l/s/m2
Maximum CO2 Limits
Natural Ventilation
- CO2 can’t be greater than 2,000ppm for 20 consecutive minutes or more during occupied day;
- Average CO2 during occupied day must be less than 1,500ppm
Mechanical Ventilation
- CO2 can’t be greater than 1,500ppm for 20 consecutive minutes or more during occupied day;
- Average CO2 during occupied day must be less than 1,000ppm;
- In science labs, an alarm goes off when CO2 reaches 2,800ppm
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