Friday, 9 September 2016

Can't read the air

Building culture changes around the world. People talk about "vernacular architecture" as if buildings are all having conversations with each other, but often the languages seem to be mutually unintelligible. 

Heat recovery ventilation is one area where a lot seems to be lost in translation. And there was plenty of hot air to start with.

In Japan, ventilation systems are usually called 24時間換気 niju-yo-jikan kanki  i.e. 24-hour ventilation. It seems like a strange name, as if you would call your refrigerator a 24-hour refrigerator, or your roof a 24-hour roof! They have been mandated in new buildings since 2003, but a lot of people switch them off. So they are not really 24-hour after all. There are plenty of reports of people who have switched off their ventilation because it makes the house cold, but if you do that, as Last resort blog (in Japanese) warns, you're going to get condensation.

顕熱交換 ken netsu koukan  is heat recovery ventilation (HRV), while 全熱交換 zen netsu koukan is energy recovery ventilation (ERV) which also recovers moisture, and is probably the more common choice in Japan when any kind of heat is being recovered. Translation aside, this may be a shock for those who read the first law of thermodynamics and thought heat and energy were the same thing. My dictionary gives Ken netsu as "sensible heat". And that's not a very sensible expression in English where "sensible" usually has a different meaning. The opposite of "sensible heat" is not "foolish heat" but is "latent heat".

The Japanese language often uses abbreviations of English words that are not commonly used in English. For example PA is used for parking area, and IC for interchange, and you will find these driving on the expressways. KY is an abbreviation of kuuki yomenai, ie cannot read the air. Reading the air means reading a situation, so KY refers to someone who is out of touch with the rest of the room.

Japanese building plans with ventilation systems will show SA for supply air, RA for return air, EA for exhaust air and OA for outside air. These abbreviations are occasionally used in English.

There is a page here that:

proposes a housing environment that has a "Flow of healthy air" and is "Clean and safe".

It should be pointed out that inverted commas are used in Japanese for emphasis, so the inverted commas around "flow of healthy air" and "clean and safe" do not mean that somebody said it was healthy, clean and safe, but they're actually being sarcastic.