Tag: energy usage

Energy Usage – Update

We’ve been tracking the energy draw of our various appliances since getting our geothermal system a few years ago. It was great to see the diminished usage with the geothermal system, but I’d like to reduce our usage farther. Not just to save money on our bill and reduce our impact, but reducing our draw will reduce the number of solar panels we’ll need to support our home.

The items we’ve audited so far account for 88.46% of our energy usage in the past year — the oven, cook-top, microwave, bathroom exhaust fan/heater, lighting (we installed LED bulbs several years ago), and misc small plug-in devices (tools, small appliances, laptops/tablets, phones) are 11.54% of our usage. While I’ll certainly make improvements wherever possible … I’ll see a bigger savings cutting the septic aerator usage in half than completely eliminating the untracked draw. The biggest savings comes from investigating the top of the list.

HVAC is still our biggest draw. We’ve dropped the temperature rather significantly in winter without seeing much decrease in usage, so just changing the thermostat isn’t a big win. I’ll be building a thermal imaging camera with a MLX90640 IR sensor — it’s a cool toy, and I’d be able to identify thermal leaks. Unfortunately, I picked a really bad time to look for thermal imaging bits. All of the temp checks we’re seeing to identify coronavirus infections? Thermal imaging everything is on backorder. I put my order in, so I’ve got a place in the queue.

The water heater … I’m going to spend more time investigating why our desuperheater doesn’t seem to do much. We’ve seen savings in the winter — when I’d expect to see the least benefit from the desuperheater — and nothing in the summer. I want to research insulating some of the water pipes and installing heat traps. And we’ll finally purchase the “smart” controller that hooks up to the WiFi and lets you drop the set-point on a schedule.

Next largest draw is an old refrigerator — that’s an easy change. We’ve got a newer unit that needs some repair. One year of energy savings will just about pay for the part, so it makes sense to retire the old fridge and bring the broken one back into service.

Those changes, plus fully shutting down the old server, should reduce our power consumption by about 4,500 kWh/year — a 450$ savings, and a significant reduction in solar system sizing.

Item kWh/year
HVAC 4932
Septic 4668
Water heater 2676
White refrigerator (1989) 2250
Car charging 1164
Black refrigerator 1134
New server 1103
Dryer 245
Family Room TV 144
Dishwasher 118
Bedroom air filter 61
Water pump 53
Washing Machine 30
Downstairs bedroom TV 12
Raven charging 7

And, hopefully, we’ll finally hit the ‘efficient neighbors’ line 🙂

Energy Usage

We’ve now been using our WaterFurnace geothermal system for a few months. This winter has been an odd combination of fifteen degree highs and seventy degree highs (yes, we went to the beach and played in the sand in February), but we’re starting to see significant energy savings v/s the Trane XV20i air exchange heat pump. Not only are we seeing lower electrical usage, but we keep the house at 72 degrees this year — almost too warm on occasion. With the air exchange heat pump, we were layering up, keeping the house at 68, and still feeling cold.

Energy use by the heat strips was my biggest concern with the system — that we’d still see the heat strips engaged in the middle of winter. Glad to report auxiliary heating system was not engaged since the earth loop was installed (December 2016, before the earth loop was hooked up, we used emergency mode to provide some heat from the coils – supplementing wood burned in our fireplace).

Our HVAC-related energy costs for the first three months of usage:

Jan 2017     131$ total, 75$ stage 1, 55$ stage 2
Feb 2017      93$ total, 55$ stage 1, 38$ stage 2
Mar 2017      81$ total, 43$ stage 1, 38$ stage 2

Comparing our kWh used year-to-year, our total consumption is significantly reduced during colder weather.

Our septic aerator used slightly less electricity than our HVAC did in March! As the temperatures warm up, I’m sure we’ll reach a point where the aerator is our high draw item (i.e. the thing that gets replaced next). We’re going to use our AeonLabs HEMs and some smart outlets that report energy usage to isolate other high-draw items and see what can be eliminated or upgraded … but we’ve certainly made progress in purchasing the geothermal system.