Robert Gammon wrote:

Canada says all new houses there should be equipped with an air to air
heat exchanger...

Do "they" also say that all new houses "should" be painted white? :-)

http://r2000.chba.ca/What_is_R2000/R2000_standard.php

YOU pointed the spec to us, NOW READ THIS PAGE

No thanks.

Note that this is not a MANDATORY construction method, it is a voluntary
program designed to influence both builders and consumers.

Aha. That kind of "should," as in "All men should be named Dave."

And Canada is far more than just Ontario, and Ontario is far more than
the southeastern region that lies just across the lake. Toronto
winters are very different than Chicoutimi, or Calgary, or even
locations in Ontario in the north and west regions. R-2000 addresses the
needs of the ENTIRE country.

From the mountains, to the prairies,
to the oceans, white with foam...

Nick