Most English schools are ventilated quite simply.  They have extensive window areas that can be opened either by the occupants of the room or with electric motors.  In general windows are not connected to a Building Automation System (BAS).  Heating for these buildings is generally supplied by radiant water systems, usually from a wall radiator and occasionally from a radiant floor. 

I heard a case study from a recently completed Scottish school project that had achieved a very high score on their BREEAM sustainability rating system.  This particular building relied entirely on window ventilation with radiant floors.  I inquired about typical winter low temperatures and was told about -4 C.  The architect told me that the occupants open windows even on such cold days and that the radiant heating is able to keep up with the heat loss.  He also maintained that this school has very satisfied occupants and good indoor air quality.

I can’t imagine one of our mechanical engineers in the U.S. accepting this type of design.  We would worry that the radiant heating could not keep up with the heat loss from too many open windows, or we would worry that closed windows would result in compromised indoor air quality.  Frankly, nearly every one of the schools that we visited on our tour seemed to have indoor air quality problems based on odors we detected.  So, although we in the U.S. need to re-examine our over-reliance on mechanical ventilation for schools, I would suggest that U.K. architects look more closely at indoor air quality in their natural ventilation only school buildings.  Hopefully there is a happy medium.  Perhaps the Passivhaus approach with energy recovery ventilation is an option.

Advertisements