For the majority of Kentuckians, a programmable thermostat is not the efficiency tool we were sold. Instead, it can lead to higher humidity and widely fluctuating temperatures in our homes. This makes us feel less comfortable, and ultimately costs us more money. Why is this?
Here in Kentucky–and in the rest of the humid south–your air-conditioner is your home’s dehumidifier. For most of us, the summer is about dehumidification, not just cooling.
By programming your thermostat to a higher temperature when you’re away, your A/C will have to work harder to get you back to a comfortable temperature and humidity.
Every 5% humidity will make you feel 2-4 degrees warmer – by leaving your A/C off for 8 hours during the day, humidity can easily increase 10% or more. This can make your house feel 4-8° hotter than your thermostat displays.
Rather than programming higher temperatures while you’re away, simply maintain a proper, comfortable temperature and humidity. Your home’s comfort is more than just temperature. It’s humidity, air movement, sound, and temperature. Setting your thermostat back can cause excess humidity, extra sound from your system working hard to catch up, and a shortened life span from overworking your equipment. If your house stayed comfortable all the time, you would likely keep your normal temperature a few degrees higher, saving you way more than the programmable thermostat!
A heat pump will call on auxiliary heat any time it gets more than 2° away from its setpoint, which uses a ton of electricity. If you let your house cool off all day to save money, and the use auxiliary power to heat your home back up, you will:
The 1% of people who have old, leaky houses with a gas furnace, plus an incredibly fixed schedule.
Gas heat is a lot hotter and more forgiving; it changes temperature in the house much more quickly and can save you money on your gas bill if you have a fixed schedule. But, if your gas furnace is paired with an air-conditioner, remember this will only increase efficiency with heating. The rest of the article still applies when you are using your unit to cool your house.
In a climate like Kentucky’s, where the temperature changes dramatically from day to day, the learning features of a programmable thermostat are not accurate. You might be asking yourself why you would get a programmable thermostat if it’s not going to save you any money. Here’s why:
If you like different temperatures for different times of the day, then this will allow the thermostat to adjust accordingly. Do you like your bedroom cold when you sleep? Me too! The programmable thermostat allows you to schedule the temperature to drop a few degrees around the time you go to bed, and warm up a bit before you wake up.
This article is written to address the lack of energy efficiency of programmable thermostats. However, if you are setting your thermostats at different temperatures during different times of the day for the purpose of comfort, then this might be the accessory for you.
Utility companies make money based on consistency, and they lose money when utility usage peaks. As an example, commercial companies in the Lexington, KY area pay 3 times the electric rate between 2:00 and 6:00pm April-August. Why? That’s when everyone’s air-conditioner is working the hardest and the electric grid is peaking. If your programmable thermostat has your air-conditioner off during this time, it saves the utility company from peak load, and it saves them a lot of money.
Kentucky Utilities (KU Electric) offers a program to get a small rebate in exchange for allowing them to turn off your air-conditioning during peak times during the summer. If you are in the central Kentucky area, see if you qualify!