When it came to cooling options, some ideas were left in the dust, such as:
The viable options that remained were:
Cathy and I wanted to see what our cooling needs on the 1st floor really were. So we decided on a wait-and-see approach: “Let’s live a summer or two in our deep energy retrofit without system air conditioning and see how bad it gets.” That also bought me extra time to come up with some more cool ideas.
Our wait-and-see experiment over the past two years did not yield any surprises. There are summer days where air conditioning is essential, despite our thorough deep energy retrofit. And with climate change barreling down on us, it would be wise to assume that the number of those hot days will increase.
But we also found out that it doesn’t take much air conditioning to keep reasonably cool. We had used a portable 8,000 Btu Energy Star AC when it became unbearable, and it did a decent job, even in keeping the relative humidity down.
I used this time to follow the development on the “Magic Boxes” – energy or heat recovery ventilators (ERV or HRV) with an integrated air-to-air heat pump. I also put this question on the GreenBuildingAdvisor.com Q&A secion: Would the Magic Box be a good alternative to the minisplit in combination with our ERV?
The answer was an unambiguous no!
Dana Dorsett, a frequent contributor to the forums pointed out that “…ERV/HRV air volumes are too low, with temperature differences too small to make them useful for distributing heat/cool.”
Furthermore, Dana pointed to the difference in cooling efficiency. Where a Magic Box may deliver a mere Seasonal Energy Efficiency Ratio (SEER) of 11, an efficient minisplit could have an impressive SEER 33.
This finally pushed me over the edge and I felt comfortable going with the most frequent recommendation: Using a minisplit in combination with our ERV to provide the needed summer cooling and dehumidification.