Stoßlüften is one of those German words without a direct equivalent in English but it translates as ‘shock ventilation’. A new one on me. I first heard it last week when Angela Merkel used it when adding room ventilation to Germany’s hygiene advice to combat Covid-19. The five step advice now comprises social distancing, hand-washing, mask-wearing, using the coronavirus app and the airing of rooms.
Stoßlüften is apparently commonplace in Germany where many open their windows twice daily even in winter. Mrs Merkel described it as ‘one of the cheapest and most effective ways’ of containing the spread of the virus.
Compare the concept of Stoßlüften to the low energy practice of draught sealing, low ventilation rates and partial heat recovery / partial air recirculation systems used with the best of intentions in many modern ‘low carbon’ buildings. I have never been comfortable with the idea of high levels of air sealing, low ventilation rates and air recirculation especially in homes where stale air can be dangerous for babies. In the light of the Covid-19 pandemic air recirculation, which is intended to conserve heat, must be seen as fundamentally unhygienic and no air filters can block viruses (bear that in mind next time you fly). There is thankfully an alternative which is very high levels of building fabric insulation combined with 100% fresh air ventilation heated upon entry using a cross-flow heat exchanger capable of heat recovery from the outgoing air of up to 90%. Oh – and Stoßlüften!
Another of the many changes to the way we live being brought about by Covid-19.