Air conditioner ‘on’ or ‘off’ at night, which side of the debate are you on?

Sky-high electric bills are making central San Joaquin Valley residents break into a sweat.

The heat waves in late June and now this month, in which temperatures have climbed back into triple digits and remain there day after day, have sent electricity usage through the roof.

So how do you save kilowatts on a 108-degree day?

It all depends. Do you live alone? Work outside the home from 8-5? Keep a dog inside the house when you’re away?

Everyone’s energy consumption is different, and so tips for using less electricity have to match a consumer’s needs.

The Bee asked Pacific Gas and Electric Company, the supplier of electricity in Fresno, for cost-savings recommendations based on various household scenarios, including work patterns and family lifestyles.

And we asked the company to resolve some questions. For example: Do you save more money by turning an air conditioner off at nighttime or by leaving it on so it cools the house more quickly the next day? What do you think – on or off?

If you said shutting the air conditioner off at night saves more money, you’re right. But Denny Boyles, a PG&E spokesman, said if a spouse is uncomfortable with the heat, “I’d be careful celebrating that win.”

A compromise would be to set the thermostat to 80 degrees and use ceiling fans in your bedroom, Boyles said. A ceiling fan can make a room feel four or five degrees cooler and is cheaper to operate than central air conditioning.

Scenario 1

You and your spouse both work. You leave the house at 7:30 a.m. and get home at 5:30 p.m., Monday-Friday. You should set your thermostat to be at what temperature when you leave to save the most money?

A: PG&E recommends setting the thermostat at 85-88 degrees.

Scenario 2

You and your spouse both work. You leave the house at 7:30 a.m. and get home at 5:30 p.m., Monday-Friday, but you leave your dog inside. You should set your thermostat at what temperature to save money but keep the dog-panting to a minimum?

A: Boyles said that he sets his home thermostat to be at 85 degrees when he is at work. “And 85 is far more comfortable for my pets inside than the temperature outside.” But every pet is different, and if your pets have health conditions that require different temperatures, Boyles said check with your veterinarian for what is best.

Scenario 3

You work from home. You should set your thermostat at what temperature?

A: Every home is different, and comfort levels are different for everyone, but 78 degrees is generally comfortable, Boyles said. Keep this in mind, though: For every degree you raise your thermostat you will save 5 percent on your cooling bills.

Scenario 4

You and your spouse are going to be gone on a week’s vacation. You should set your thermostat at what temperature?

A: If you are going to be away for an extended period of time, you can save more by shutting off your air conditioner so that you are not cooling an empty home.

Scenario 5

You and your spouse and children are home all day on Saturday. You should set the thermostat at what temperature to be comfortable and save money?

A: A temperature of 78 degrees is usually comfortable. But consider closing blinds and windows during the day to keep radiant heat outside and to help your air-conditioning system work less to cool your home.

Scenario 6

You and your spouse and children are in-and-out all day on Saturday. You say the thermostat should be raised when you leave. Your spouse disagrees. Who is right?

A: You are right. It doesn’t make sense to cool an empty home. Try to limit the time that your door is open as you go in and out so that you aren’t releasing cooled air.

Scenario 7

You leave the house for an hour to go to the grocery store. It is in the middle of the day. You should set the thermostat at what temperature when you leave?

A: If you are going to be gone a short time, leave it at whatever setting you are comfortable with.

Scenario 8

You leave the house for three hours in the middle of the day to run errands and meet friends. You should set the thermostat at what temperature when you leave?

A: Setting the thermostat up to 10 degrees warmer than your usual at-home setting is fine, Boyles said. The system will cool the house when you return. Especially on a 105-degree day, even a 90-degree inside temperature will feel cooler.

Scenario 9

You have a pool. You should have the pump running how often – every day or every other day? At night only? During the day only?

A: PG&E recommends running pool pumps at night during periods of lower demand. If you are trying to save money, run the pump for fewer hours and do regular pool maintenance by skimming with a net and scrubbing the sides (hopefully not in the hottest part of the day for your own safety).

Also, pool pumps can account for up to 20 percent of your household energy use, and PG&E offers a $100 pool pump rebate to help customers save energy with a more energy-efficient pump.

Scenario 10

You have a big house with three on-the-roof units. You close off empty rooms and only use one unit to cool a guest room if someone visits. You say this saves money, are you right?

A: It doesn’t save to close off empty rooms, Boyles said. In fact, because the rooms aren’t airtight it can cost you more by unbalancing your system, making the system work harder to cool those rooms, he said. It would be better to block the windows completely with dark paper or heavy blinds and curtains but leave the vents open.

Scenario 11

You say running window air-conditioning units instead of a whole-house unit saves money. Are you right?

A: No. If you add up the cost of a series of window units it usually exceeds the cost of an efficient whole-house system, Boyles said.

Other good-to-know cost-saving facts

Here’s a handy idea: Devices called “kill-a-watts” that are available at home improvement stores and cost less than $20 can be programmed to tell you how much it costs to operate any device you plug in, Boyles said. Check with PG&E and the library near you, too. They sometimes have the devices to loan, he said. “I have one myself that I’ve used to help customers calculate their energy costs.”

Increasing the thermostat temperature by one degree

For every degree you boost the thermostat, you save about 5 percent on your cooling costs if you are trying to cool your house to 80 on a 100-degree day. The savings: $85 annually for each degree the temperature is increased in the summer.

Maintaining the air-conditioning unit

A properly maintained air conditioner can save you up to $50 each year. And replacing the filters once a month improves efficiency and can save you up to $45 a year.

Ceiling fans

Installing ceiling fans in rooms can cool a room by four to five degrees. They will make your house feel more comfortable so you may be able to raise the air-conditioner setting.

Closing blinds and drapes

Keeping the blinds and drapes drawn saves you money by reducing the radiant heat in the room and by helping your air conditioner work less to cool your home. Good window covering can save up to $60 a year.

Unplugging devices

Any electronic device that has a clock or display uses electricity even when in an idle mode. Each device alone doesn’t use much, but they can add up. Especially unplug cell or laptop chargers when not in use, PG&E recommends.

PG&E recommends setting your computer and monitor to go into “sleep” or “hibernate” after 20 minutes of inactivity. That can save the average household about $100 per year. Turning the computer off at night can save an additional $105 each year.

Lowering the hot water temperature

For each 10 degrees that you lower the temperature of your hot water heater, you get a 5 percent savings in water heating costs, or $20 each year for the average household, PG&E said. The utility offers a rebate of up to $500 for buying an energy-efficient electric water heater.

Replacing light bulbs

Replacing your five most-used lights with LED bulbs can save you up to $75 a year.

This story was originally published July 12, 2017 at 4:00 PM with the headline "Air conditioner ‘on’ or ‘off’ at night, which side of the debate are you on?."