<story><title>Air-to-Air Heat Exchangers for Healthier Energy-Efficient Homes</title><url>https://www.ndsu.edu/agriculture/extension/publications/air-air-heat-exchangers-healthier-energy-efficient-homes</url></story><parent_chain></parent_chain><comment><author>throw0101c</author><text>These is more generally known as &amp;quot;heat recovery ventilation&amp;quot;, HRV (the term is first used about half-way down the article):&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Heat_recovery_ventilation&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Heat_recovery_ventilation&lt;/a&gt;&lt;p&gt;There are also energy recovery ventilators, ERV, which in addition to tempering the temperature of incoming air, also temper the humidity:&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Energy_recovery_ventilation&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Energy_recovery_ventilation&lt;/a&gt;&lt;p&gt;In the past HRVs were mostly used in colder climates, as the humidity exchange would cause frosting of the exchange core, but modern core membrane materials have improved in recent years, and some units can operate frost-free down to -10C &amp;#x2F; 14F: colder than that and you may need a have pre-heater running on the intake, or the unit may have a defroster.&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.broan-nutone.com&amp;#x2F;getmedia&amp;#x2F;d7230185-8067-4256-a1a2-32127fe9328a&amp;#x2F;Owners-Manual-ERV100S-ERV100SP.pdf?ext=.pdf&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.broan-nutone.com&amp;#x2F;getmedia&amp;#x2F;d7230185-8067-4256-a1a...&lt;/a&gt;&lt;p&gt;Some units have defrost modes so that they can run even in -27C (though it will probably be defrosting a lot):&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.broan-nutone.com&amp;#x2F;getmedia&amp;#x2F;3ec22979-19c4-4f1e-94fd-1388d9e66583&amp;#x2F;Spec-Sheet-B160H65.pdf?ext=.pdf&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.broan-nutone.com&amp;#x2F;getmedia&amp;#x2F;3ec22979-19c4-4f1e-94f...&lt;/a&gt;</text></comment>
<story><title>Air-to-Air Heat Exchangers for Healthier Energy-Efficient Homes</title><url>https://www.ndsu.edu/agriculture/extension/publications/air-air-heat-exchangers-healthier-energy-efficient-homes</url></story><parent_chain></parent_chain><comment><author>olivermuty</author><text>This required building code in all homes in Norway since 2017.&lt;p&gt;It is good when the building is designed to have the system easily serviced, bad when the unit is in a hard to get loft.&lt;p&gt;You need to change filters at least once a year to keep your indoor climate good.&lt;p&gt;I just bought an old house, sealing all the vents and installing balanced ventilation with one of these is on my list for summer of 2024. Adding 5cm of insulation (up to modern codes, from 10 to 5cm of glass wool) to keep the house even less energy demanding in winter.</text></comment>