DfES Building Bulletin 101, often referred to as simply BB101, provides strict performance standards to be met concerning thermal comfort in summertime and ventilation rates to be achieved for all teaching space in new educational buildings. BB101 first came into play in 2006 and was updated in 2018 to form the present guidelines.
BB101 States for Overheating:
CIBSE published criteria in TM52 to assess overheating in free-running buildings, based on the adaptive comfort model. BB101 requirements are based on these criteria.
The criteria are based on a variable temperature threshold that is related to the outside running-mean dry-bulb temperature.
Three criteria have been developed which indicate when overheating is likely to be problematic. These criteria should be applied outside the heating season and for the hours of 09:00 to 16:00, Monday to Friday, from 1st May to 30th September, including the summer holiday period as if the school was occupied normally through the summer. A lunchbreak 12pm to 1pm with no internal heat gains during this period may be allowed for in classrooms. The three criteria are:
the number of hours for which an adaptive thermal comfort threshold temperature is exceeded (total hours of exceedance).
the degree to which the operative temperature exceeds the adaptive thermal comfort threshold temperature (daily weighted exceedance).
the maximum temperature experienced at any occupied time (upper limit temperature).
BB101 States for Ventilation:
A school building will comply with BB101 when.
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 period, 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.
In general teaching and learning spaces where natural ventilation is used or when hybrid systems are operating in natural mode the following standards apply:
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.
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.
the system should be designed to achieve a carbon dioxide level for the majority of the time of less than:
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.
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.
At L2 Energy Consulting we can help to demonstrate these requirements through dynamic simulation modelling software. Please call us on the number above to discuss your BB101 Compliance, or ask for a quote electronically.