We have been living in our new house just over a year now, so it seems fitting to offer some thoughts and insight into how everything is working out. The answer, thankfully, is that all is good.
From a design and function standpoint, everything works great. We use every room in the house, so we didn’t overbuild. Energy use is low, as expected. The only issue we run into is controlling humidity, a common problem with low-load homes in mixed humid climates.
The house is comfortable almost all the time, although we are still figuring out the best way to manage temperature and humidity in the shoulder seasons. The Atlanta area can have fairly large temperature and relative humidity swings on a daily basis.
Recently the temperature was in the 60s at night and almost 90 by midday. I prefer to open windows when the weather is moderate, and do so as often as I can; however, the process of turning HVAC equipment on or off and opening or closing windows twice or more per day sometimes falls by the wayside when I am busy, and makes me (just slightly) more tolerant of people who just keep their homes closed up and manage comfort exclusively with HVAC.
As summer approaches, I expect that we will rely on AC more than I would like. Earlier this spring we ran into a situation that I find common with high performance homes: the house was colder than the outside air, as it was holding its temperature so well. My wife was cold and was about to turn on the heat when I suggested she open a couple of windows. That did the trick, as it was in the mid 70s outside.
Last fall, we had our first issue with humidity. There were a few days in the mid 70s with high humidity. To keep the house comfortable, as well as avoid potential mold and mildew, I had to turn on the AC for a few days just to dehumidify.
As I noted in an earlier post, in retrospect, I would have used a venting dehumidifier instead of an ERV to help control indoor humidity when it is cool but humid. To better manage humidity, I recently installed an Ultra-Aire 98H dehumidifier in my mechanical room. I considered tying it into the existing ducts to and from the ERV, but the complexity of this installation wasn’t worth the effort. I ended up installing an intake and exhaust for the dehumidifier in my hallway, and it runs as needed to keep the RH in the 50% range, while the ERV provides the whole-house ventilation.
Having tried to use minisplits to dehumidify in the past, only to have them overcool the space, I understand that dehumidifiers need to take advantage of the reheat capacity of their compressors to control the outgoing air temperature. What I didn’t realize is that the exhaust air can be quite warm. Running the dehumidifier will end up adding slightly to the cooling load on the house, but so far it looks like the impact is minimal. Another option would be to install a that doesn’t reheat the dehumidified air — but that’s not going to happen at this house.
Bored with my apps
I tried out several iPhone apps for various systems in the house, only to lose interest in them fairly quickly.
I had a energy monitoring system installed; it provided real-time energy use for most circuits in the house. After a few weeks, it wasn’t providing me with enough useful information to continue watching it.
Similarly, I can access my thermostats and alarm systems through , and while I have used them, I don’t find them useful enough to bother with them. Perhaps when I am out of town and want to make an adjustment to temperature or disarm the house so someone can enter, I will use them again.
I bought a to try out, and watched those reports on my phone for a while, only to lose interest in that as well.
Finally, we installed a with our low-voltage package. For some reason, the video was very slow to show up on my phone, so we didn’t find it that useful. Then it stopped working altogether, so I finally got rid of it.
I find that my simple indoor/outdoor temperature and humidity sensor gives me most of the information I need. I may be a bit of a Luddite, but I’m OK with that.
I have been watching our electric use closely and tracking our Site Energy Use Intensity (EUI). Through the first year, we are averaging 920 kWh per month for this all-electric house, which includes two full-time home offices and charging one electric and one plug-in hybrid car.
Our EUI (kbtu/sf/yr) is 14.25 — well below the average for the southern U.S. of 41.5, and about 65% of the 2030 Challenge target. Without renewables on the house, this is about as efficient as a house with HVAC can be.
A “stealth” green home
I’ve come to think of this project as a “stealth” green home, primarily because it doesn’t have the touchstone “green” features people think about: solar panels, ground-source heat pumps, a heat-pump water heater or tankless water heaters, and maybe that key one, spray foam insulation.
It’s also a very traditional design which doesn’t seem to get as much attention as contemporary architecture these days. But I don’t care what people think about it. We are enjoying the house, the porch, and even the carport and driveway which, it ends up, is an awesome party space.