March 26, 2020
So, why do we overcomplicate it? According to BB101, designers of ventilation for schools need to take account of indoor air quality (pollution, CO₂ levels), thermal comfort (draught, overheating) and noise.
With a wide range of equipment on the market, there seems to be a penchant for technology that needs a lot of design and integration to produce classroom ventilation. Smart mechanical ventilation (SMV) is the simple solution to this.
In this brief article, I’d like to tackle each of these criteria individually and explain why SMVs make solving the challenges of BB101 simple for you.
SMVs are equipped with filtration, typically from ePM10 75% to ePM1 80%, arresting a substantial proportion of those particulates which are so damaging to lung development.
In using an exchanger for heat recovery, the benefits are threefold: energy savings, comfortable air temperatures and separation between intake and the exhaust pathways. This pathway segregation means that stale room air is evacuated and not recirculated, resulting in superior control of room CO₂. Significantly, students in classrooms equipped with SMVs benefit from compliance with the strict CO₂ limitations imposed by BB101 on mechanical ventilation. Having minimal concerns over intake pollutants, SMV ventilated classrooms guarantee better learning environments as well as being healthier places.
Draught has two components – velocity and temperature. BB101 overlooks any velocity component for natural systems, possibly because this element lies outside of their control. Due to their integral heat exchangers, SMVs can use recovered energy to temper fresh air before it enters the room. Furthermore, modulating fans ensure that the speed of incoming air is closely controlled. Most SMVs harness the Coanda effect, which makes use of entrainment of room air to reduce velocity, ensuring thorough air distribution throughout the room and optimising the supply air temperature. This is how draught is eliminated.
To deal with potential overheating issues, BB101 generally recommends passive methods for the cooling of rooms. The main intention here is to prevent rooms from heating up in the first place and therefore the use of solar shading, thermal mass and reflective glazing are important. However, if rooms continue to be at risk of overheating, then night-time cooling is critical to success. Night-time cooling is triggered by a high temperature recorded during the preceding day, cooling the room in advance of occupancy to reduce the potential number of overheating hours.
SMVs deal successfully with noise arriving from outside as well as casing breakout. High quality acoustic insulation and non-linear internal pathway design keep a tight grip on casing breakout, whist fan speed limiters ensure that the 35 dB(A) target for normal classrooms is never exceeded.
In combination with good filtration, SMVs mitigate some of the biggest issues faced by classrooms in built-up areas. In AirMaster’s case, external noise is attenuated by up to 49 dB, whilst casing breakout of 35 dB(A) is measured at 1 metre!
In terms of installation, SMVs are straightforward; they’re basically plug and play with minimal commissioning in most instances. With duct-free air distribution by the Coanda effect, suspended ceilings can be a thing of the past.
Bizarrely, BB101 takes no notice of energy consumption or expresses any preference for lower carbon technologies, arguably encouraging the use of inefficient equipment. Any claim by natural ventilation suppliers that their offers are more energy efficient than heat recovery units are contentious at least. On average, SMVs could save 55% in energy costs in comparison to their natural counterparts.
Why should our children have to compromise? For a simple solution, choose AirMaster SMVs.
Article by: Jonathon Hunter Hill
Sector Manger – Education, SAV Systems