Eye popping electric bills, monitoring and reducing electrical consumption
Have Another Day is currently in Fort Myers on the Caloosahatchee River. It’s quite warm here with daily highs in the low to mid 90s. As a result, the water in the marina is also quite warm at nearly 90 degrees. Last month Have Another Day sucked down over $300 in electricity, that’s more than she uses in an entire season in Chicago. During the day, with the thermostat set to 76 degrees the salon air conditioner runs nearly continuously from about 11 am until sunset. So, I figured my biggest culprit is likely the 48,000 BTU split gas Salon AC unit. I’ve verified it’s properly charged, strainer clean, condensers flushed, etc. I had previously put an amp clamp meter and knew it draws about 16 amps once started.
The marina power is billed at $0.12/kWh which means that running the unit costs about $0.44 / hour (230v*16a=3,680 watts or 3.68kw * $0.12 = $0.44). If it runs for 12 hours a day (which seems like it might be low) that’s $5.28 per day from just that one AC unit. There’s still the other AC unit, the fridges, chargers and everything else on the boat. So, it’s not so hard to figure out how I got to $300 in a month.
I think we’ve already done most things we can easily do to reduce the cooling needs. We’ve added heat rejecting film to the inside of the pilothouse windows, we keep the wood blinds closed on the salon windows, and we keep the curtain drawn on the aft sliding door, we turn the stateroom AC units above 80 degrees every morning.
I’m a data-driven person and I love to know the impact of changes quickly. So, I’ve been wondering, how much would I save if I set the thermostat a degree or two warmer. To get an idea I installed a Blue Sea Systems 1838 OLED AC Multimeter. It does a nice job of displaying real-time info but it doesn’t count kWh consumed nor can I display it remotely and opening the engine room hatch each time isn’t super convenient.
At my dirt home I’ve gone nuts with branch circuit monitoring. Each of the roughly 60 breakers in my panel has an individual current transform (CT) connected to a BrulTech GreenEye Monitor (GEM). From there I run the data through a number of data visualization services. While I love this level of information I’m not sure it’s viable on the boat. My AC panel is very full and cramped and I don’t believe I’d have much luck jamming all the CTs in plus I’d then have to find a space for the GEM which is pretty big. But, I’d still love at least some of the information like what I can get at home.
So, I’m curious if others have ideas both about measurement and potential ways to reduce energy consumption? I’ve considered trying to add insulation to the boat, but I’m not sure I can get enough in to make a meaningful difference. I’ve already added the foil and bubble insulation above to hatches and other areas I can feel heat coming in. I’d also love to get better control of the thermostats. I really wish I could get Nest like functionality with occupancy sensors that adjusted the set-point based on our occupancy. I’m all ears for any ideas.