Explain: Does turning the AC off when not at home save energy?

Summer heat can lead to huge energy expenses. The majority of people want to remain comfortable and not waste the energy or money. Perhaps your family has fought over the best method for cooling your living space. What is better? keeping the air conditioner on all summer long with no break or turning it off in the morning when you’re not around to be enjoying it?

We are an team of architects and construction systems technicians that use energies models to model heat flow and system performance to solve this recurring issue: Will you have to eliminate more heat from your home through continuous removal of warmth throughout the day, or taking out excess heat only at the at the end of the day?

The answer is boiled down to how energy-intensive it is to take heat out of your home. The amount of energy required is determined by a variety of aspects, including the degree to which your home is constructed in addition to the size and model of your air conditioner and the outdoor temperature and humidity.

According to our calculations that aren’t published, the possibility of letting your home get heated when you’re at work and then cooling it down at home consume lesser energy than keeping the house cool, however it’s dependent on.

Keep your air conditioner running all day, even when you’re not?

Consider first the way that heat builds up at the beginning. The heat is absorbed into your home when it is able to store less heat than the exterior. When the quantity of energy that flows through your residence is determined at a percentage that is “1 unit per hour,” your AC will always contain 1 amount of warmth to be removed each hour. If you shut off your air conditioner and let the heat build up it could be able to provide as much as to eight hours of heat by the end of the day.

The majority of homes are less but homes do are limited to the amount of heat they can hold. Also, the amount of heat that can enter your home will depend on how warm the building was to start with. For instance, if your home is able to store the energy of five thermal units prior to getting to equilibrium outside temperature when it is the time of day, you’ll only need to eliminate 5 units.

In addition, as your home gets warmer the process of transfer of heat is slowed down until it is at a point of no heat transfer when the inside temperature is the similar to that outside. The A/C cools less efficiently in extreme heat, therefore keeping it off during most hot times of the day will increase the effectiveness of the system. The results of these effects suggest that there’s not single solution to whether to blast the air conditioner all day long or wait until you’re back in the evening to return home.

The energy used in different A/C strategies

Think about a test case for tiny homes with standard insulation that is insulated in two warm climates Dry (Arizona) in humid (Georgia). Utilizing the energy modeling software developed in the U.S. National Renewable Energy Laboratory for the purpose of analyzing energy use in residential structures We looked at a variety of examples of energy use for this hypothetical 1,200-square-foot (110-square-meter) house.

We looked at three different temperature strategies. The first has the temperature in the room set to the same level of at 76 degrees F (24.4 degree Celsius). The second allows the temperature to fluctuate between to 90 F (31.6 C) during the course of an eight-hour day – known as a “setback.” The last sets the temperature back to an 89 F (31.6 C) for the duration of a four-hour working day.

Within these three scenarios we have looked at three different A/C systems which include A single-stage central air conditioner and an air source heat pump (ASHP), a central air source heat pump (ASHP), and mini-split heat pumps. Central air conditioners are a common feature of modern residential structures as heat pumps are getting more and more popular due to their increased efficiency. Central ASHPs can be used as single replacements for central A/C units. Mini-splits are better than central air conditioning but are more expensive to put up.

We were interested to determine how much energy usage from the A/C system varied between these instances. We were aware that no matter the HVAC technology employed the A/C system would increase its power as the temperature setpoint was returned to the temperature of 76 F (24.4 C) and in all three cases during the late afternoon hours which is when outdoor temperatures tend to be the most extreme. In the case of setback we set the A/C to begin cooling the room when the resident returns to ensure that they are comfortable when they arrive home.