ventilation

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The consultation process for the new BB101 closed on the 25^th August 2016, Andy Williams from Jaga looks at what the proposals mean for the HVAC industry.

The means by which we ventilate our schools is one of the defining factors in creating and maintaining standards of health and comfort that allow students to thrive. But how we set about designing and regulating ventilation systems to best achieve optimum levels has been a slow evolving process. Now, however, a change for the better seems to creeping over the horizon.

The Department for Education (DfE) is currently in the process of updating the Building Bulleting 101 (BB101), which is being produced to fall in line with Education Funding Agency (EFA) Guideline Standards – in particular its ‘Facilities Output Specification’ (FOS). The proposed new name will be ‘BB101 – Guidelines for ventilation, thermal comfort and indoor air quality in schools’.

Whilst entirely subject to change, architects, building services engineers and education decision makers need to be aware of the direction the DfE wants to go with regards to ventilation in schools.

IAQ & Thermal Comfort – BB101’s Two Big Changes

Based on the draft BB101 proposal, there are two main factors that seem to be of the greatest importance when discussing Indoor Air Quality:

–        CO₂ levels

–        Thermal comfort.

Schools in the UK have traditionally been ventilated by means of either fix speed mechanical or natural ventilation. Natural ventilation often consists of a somewhat unsophisticated strategy – essentially, opening and closing a window, which is far from effective in measuring and maintaining sufficient Indoor Air Quality (IAQ). Similarly, fixed speed mechanical systems ventilate at a pre-determined rate, which has little regard for the actual requirements at any particular time.

Studies have suggested that the perfect conditions for an average classroom would be 1200 parts per million (ppm) of CO₂ in a room – a level not consistently achievable through natural ventilation, which has a maximum recommended limit of 2000ppm. As such, with a need for more accurate control of CO₂ levels, we are expecting a greater drive for more sophisticated methods: demand-controlled mechanical or hybrid ventilation.

Because demand-controlled mechanical ventilation is intelligent, it can react to the conditions within a room automatically, with CO₂ sensors constantly monitoring indoor air quality. That means that if it is programmed to control CO₂ levels to never exceed 1200ppm, by means of automatically introducing a fresh flow of air into the room when required and extracting the stale air, the perfect balance can be achieved without any manual input from staff.

In terms of thermal comfort, BB101 will seek to advise specifiers on how to prevent overheating, whilst becoming considerably more efficient via effective heat recovery – but will do so in a way that provides greater clarity in the quality of systems that should be used. Variabilities must be accounted for under greater scrutiny, be it the fluctuating radiant and air temperatures both inside and outside of the classroom, which can only be effectively managed by using an intelligent ventilation system.

Seeking Greater Control

(either full mechanical or hybrid) should be seen by all school construction stakeholders as the primary choice to adhere with new BB101 guidance. But it is not just a case of meeting compliance; it should be about exceeding the recommended standards to ensure that children have an optimal environment in which to make the most of their education.

Demand-controlled mechanical ventilation