How we reduce our cooling costs

One of the big recurring expenses in a household is cooling. The average temperature in the summer here is 80 F° and humidity hovers around 80%. There are around 2 months per year with highs above 90 F°. Our monthly cooling bill spikes to around $115 in the summer from early June to Late Sept.  It averages to $80 per month for a household of 4 living in an energy efficient 2000 square foot home. Today, I would like share a few tips that have helped us cut down our electric consumption considerably.

The screenshot above is our electricity consumption from Aug. 2018, which was a pretty hot month. Ours is the yellow one and the green one is the efficient homes of similar size in our community.

The screenshot above shows ours(yellow), the efficient homes(green) in our community and the national average(blue). So we consume only half as much as the national average. Do we feel uncomfortable?  No. I do not remember my family owned an AC when I was a little kid.

Air conditioning/Heat pump consumes the most electricity in a household. Typical consumption per hour is 15,000 watts and it costs 12 cents per kilowatt-hour here in North Carolina or $1.50.  Obviously, the less the AC runs, the more money we save. Here are the tips we use.

Open windows. The temperature here drops below 70 F° at night in the first half of June and the second half of Sept. Instead of running the AC , we open the windows at night and leave them open until the next morning. During the day, we close all our binds on the South facing windows.  As long as the temperature outside does not go over 85 F° , the inside temperature stays around 75 F° for the most part of the day and spike up to 78 F° in the afternoon. Our AC is mostly off during these days. This is a whole month of not using the AC.

To effectively cool down our house, we open windows on both the first floor and the second floor. This is a lot more effective or quick than just opening windows on one floor due to the stack effect. The stack effect or chimney effect is the movement of air into and out of your house. The taller your house , the more effective it is. Hot air rises because it is less dense then cold air. That is how a hot balloon rises. Without any help from breezes, our openings on the second floor basically sucks hot air out of the house and draws cold air from the first floor.

Use window fans. The above strategy works pretty well when the temperature difference between the inside and outside is more than 15 F°.  When the difference is around 10 F° and there is no wind, we rely on 2 window fans to bring in cool air and expel hot air.  We use one the first floor that draws in cold air and the other second floor to push hot air out.

Up the thermostat.  We set up our thermostat to 78 F° for the most part of a day when temperature outside can reach up to 95 F° in July , Aug. and early Sept. Studies found that each degree a thermostat is set above 75 F° could save 10% to 15% in electricity consumption.

Use fans. Fans do not actually cool the house or the air around you.They move the air around which makes sweat evaporation easier on your skin. As a result, you feel cooler because the evaporation dissipates heat. In addition to our ceiling fans, we have a few portable fans.I have this Lasko 3300 20″ Wind Machine in my small office during the day and take it with me to my bedroom at night. It is a great fan. The only down side is that it does not come with a remote. My wife and kids use this Holmes 12 Inch Blizzard with remote.

Block the sun. We close all our blinds on the south facing windows during the day. This is not negligible.  If we do not do that, the floors close to those windows could get pretty warm and heat up the house.

Insulate the house. Our house is relatively new. Its’ insulation is pretty good. But we still inspect it for leaky windows, doors and vents from time to time. For example, we do not have a dryer.  Its’ venting pipe has been plugged with my son’s old clothes.

Change Air Filters every three months.  We have a forced air system which means cold air is pumped into each room through ducts and filters. Clogged filters and ducts will dramatically reduce the efficiency of our heater. Normally ducts do not get clogged easily because of the filters. Filters, however, can be clogged up quickly if you live in a dusty area. If you hold up your used filter to light and compare it with a brand new one, the difference is obvious. We always buy the cheapest air filters that can last for 3 months because we do not have any furry pets.

Do not cook inside. We minimize our cooking inside as much as possible during the summer. Stove or Oven generates a huge amount of heat that your AC need to work hard to remove. We have a grill and a Camp Chef stove on the deck.  No only can we avoid the cooking heat, but also the cooking smell and grease. The cooking smell could linger around for quite a while because the home is well insulated.

Cool the space you need. It is a good method when you have a small home or do not have many people in your household. For example, my parents do not have central air. Instead, they have a wall mounted AC/Heat Pump  in their bedroom and another one in the family room where they spend most of their time. There is no AC/Heat in the kitchen or the bathrooms. These AC & Heat pump units are inexpensive, durable and powerful in a single room. This will be our set-up when our kids leave the nest and we downsize to a even smaller home.

How much electricity does your household consume in the summer? What are your strategies to keep it low?

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