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--- planning:non-residential_passive_house_buildings:passive_house_schools:passive_house_schools_requirements [2014/11/28 15:04] – christine
+++ planning:non-residential_passive_house_buildings:passive_house_schools:passive_house_schools_requirements [2021/10/08 13:42] (current) – yaling.hsiao@passiv.de
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-====== Passive House schools – Requirements ======
+======Passive House Schools - Boundary Conditions ======
+Research for building Passive House schools has been conducted in the [[https://passipedia.org/phi_publications/research_group_for_cost-effective_passive_houses_proceedings|Research Group for Cost-effective Passive Houses]] Vol. 33
-The criteria for building Passive House schools were developed by the [[http://passiv.de/en/06_training/01_akkp/01_akkp.htm|Research Group for Cost-effective Passive Houses]] on the topic of “Passive House schools”:\\
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 **1. Each modern school should have __controlled ventilation__ which meets the criteria for acceptable indoor air quality.**\\
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-This was shown in a contribution by Rainer Pfluger in the relevant Protocol Volume [[planning:non-residential_passive_house_buildings:passive_house_schools:passive_house_schools_requirements#Literature|[AkkP 33] ]].This is nothing new; these findings had often been made during measurements of the air quality in schools, but were repeatedly ignored.  In the long term however, one can't get around this fact.
+This was shown in a contribution by Rainer Pfluger in the relevant Protocol Volume [[planning:non-residential_passive_house_buildings:passive_house_schools:passive_house_schools_requirements#Literature|[AkkP 33] ]].This is nothing new; these findings had often been made during measurements of the air quality in schools, but were repeatedly ignored.  In the long term however, one can't get around this fact. In 2020 this became appearent again with the COVID-19-pandemic: The virus floats for quite a time (up to 3 hours) in the air. The infection risk is higher, the higher the concentration. Therefor, providing a decent amount of fresh air (which is around some 15 to 30 m³/h per person in schools depending on the age) will dilute the aerosol particles and reduce the infection risk. If you calculate the fresh air requirement in a classroom, you will often end up with 3 ore even more airchanges per hour; this is difficult to provide, unless you keep windows fully open or you have a working mechanical fresh air supply. The first alternative is not realistic in typical Central European winter condition. It is the second path to go - and that will also reduce all the other indoor air pullutants to secure levels (for example the particulate matter).
 [{{ :picopen:bremen_gruppenraum_lueftung_passivhausschule.jpg?direct&300|A group room in the Passive House school in Bremen: The supply air vents in the suspended ceiling are clearly visible – like the heater on the left near the door.}}]
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 With these reference values, the result is **a significant improvement in the air quality** in comparison with the values usually obtained in Germany, Austria and Switzerland today. Experience with the Passive Houses already built also shows that the designed values should not be reduced even further.  For increased air quantities attention would have to be paid to the resulting reduction in the relative air humidity in winter, however – this raises a number of questions (hygiene of any possible moisture recovery or supply air humidification, more equipment for corresponding air conditioning systems), which were not dealt with in the Research Group.  If the per person air flow rates are projected as 15 to  20 m³/(h pers) in the given interval, the primary objectives of indoor air quality will certainly be achieved and the problem of low relative humidity does not even arise.\\
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+If we go for even higher fresh air flows, what is desirable in case of infection risks, we will have to take care for keeping the indoor relative humidity above ~30%. An air humidifier will have to be used if external temperatures are low (lower than ~14°C). It is important in this case that the humidifier is kept clean all the time.
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 In comparison with residential buildings and office buildings, the overall air flow rates and air change rates which have to be planned are considerably higher during use due to the increased number of persons present in schools.
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 A direct result of the designed high air change rates is that the operating times of the ventilation system have to be restricted to the periods of use or the air quantities should at least be greatly reduced outside of these times, because otherwise there will be very high electricity consumption values even for efficient systems – this differs fundamentally from home ventilation in which the designed air quantities are near those required for basic ventilation needed on a permanent basis (with 0.25 h<sup>-1</sup>).\\
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-In schools, for basic ventilation planned with 2 h<sup>-1</sup>, there are several possibilities, the most efficient being a **one-hour preliminary purge phase with designed volumetric air flows**, with which the necessary **”double” exchange of the air volume** can be achieved. After that, regulation of the air quantities according to demand should be strived for, on which the occupancy density, the CO<sub>2</sub> content of the air or other representative **air quality indicator** can be based.
+In schools, for basic ventilation planned with 2 h<sup>-1</sup> or even more, there are several possibilities, the most efficient being a **one-hour preliminary purge phase with designed volumetric air flows**, with which the necessary **”double” exchange of the air volume** can be achieved. After that, regulation of the air quantities according to demand should be strived for, on which the occupancy density, the CO<sub>2</sub> content of the air or other representative **air quality indicator** can be based.
 [{{ :picopen:co2_radon_messung_fenster_lueftung.png?direct&300|Without any ventilation, the air quality is poor. The CO<sub>2</sub> concentration can be easily measured; and is correlated to other indoor pollution substances e.g. Radon. With a ventilation system, all pollution is reduced to a hygienically satisfactory level (subjectively, visitors note that "it doesn't smell like a school here at all").}}]