Choose the right size air conditioner to cool your home. Buying the right size of air conditioner is in your best interest; only the right size of unit or system will efficiently and effectively keep you and your family comfortable. Air conditioners that are too big use more electricity and leave the air in your house with excess humidity. Air conditioners that are too small do not cool your home to a comfortable temperature. Choosing the right size air conditioner requires some basic math and just a few minutes of your time. Measure the square footage of the room that you'll air condition. Use a tape measure to measure the length and width of the room. Write these measurements on your paper. If the room is not square or rectangular, divide the room into sections composed of squares and triangles and take those measurements. Calculate the square footage of the room. For a square or rectangular room, multiply the length by the width. If your room is some other shape, find the square footage of the triangular sections by multiplying 0.5 x length x width and sum each of the square and triangular sections to determine the total square footage of the room.

Determine the square footage of each room of your home if you are purchasing a central air conditioning system. how to make an air conditioner screenReviewing your property tax statement or contacting your county auditor's office is another way to find out the total square footage of your home. how does an air conditioning unit worksDon't include areas, like the basement, that won't be cooled. water in window air conditionerDetermine the cooling capacity needed for the room or your home. Cooling capacity for room air conditioners and central air conditioning systems is measured in British Thermal Units (BTUs) per hour. The United States Department of Energy Energy Star website offers these guidelines for BTUs per square footage: 100 up to 300 sq. feet: 5,000 to 7,000 BTU 300 up to 550 sq. feet: 8,000 to 12,000 BTU 550 up to 1,000 sq. feet: 14,000 to 18,000 BTU 1,000 up to 1,200 sq. feet: 21,000 to 24,000 BTU 1,500 up to 2,000 sq. feet

: 30,000 BTU 2,000 up to 2,500 sq. feet: 34,000 BTU Things You Will Need Steel measuring tape Paper Pencil Tip References Energy Star: Properly Sized Room Air Conditioners Photo Credits Jupiterimages/Comstock/Getty Images Suggest a CorrectionCool the rooms that need it the most by choosing the right amount of air conditioner BTUs Need to cool off? Cooling just one or two of your most frequently used rooms can reduce the load on your whole house unit, which may lead to lower power bills. This guide will tell you which type of air conditioner is best for your home. Tip: Take note of the voltage of your new unit. UL requires that only 115-volt models using more than 7.5 amps be connected to a standard single outlet. Models that are 208/230 volt require one of three branch circuit power supplies. Keep your home safe and do not exceed the recommended voltage or amps for your electrical circuit. Window, Freestanding, and Built-In Units Air conditioners perform three basic functions: lowering the air temperature, removing air moisture, and filtering the air.

Window units are the most popular because they are affordable and easy to install. Some models can also double as a heater. Most can be installed in either a single- or double-hung window and typically come with accordion panels to ensure a secure fit. Models designed for sliding windows require a support that can be attached to the exterior of your home. Freestanding portable air conditioners can be moved between rooms. They have a standard window venting kit for the exhaust, much like a clothes dryer is vented. Most portable units have reservoirs that need to be emptied periodically, although some come with optional hookups for a drainage hose. Other models evaporate much of the moisture as exhaust, greatly reducing the number of times you need to empty the container. Portable units can be heavy and are less efficient than newer window units. Built-in air conditioners can be installed in your wall for permanent placement and can provide both cold and hot air. They are ideal for areas of your house that may not be connected to the central heating and air system, such as a garage.

Built-in wall units are more expensive than window units and they require opening a hole in an exterior wall, but they don’t take up window space and allow for a more airtight and secure fit. Larger units may require professional installation. If you’re considering a home remodeling project or room addition, mini-split heating and cooling systems can save you the expense of installing ducts, which are necessary for most traditional HVAC systems. Mini-splits are becoming increasingly popular and are a great solution for homes without ductwork. Cooling Capacity & BTUs Choosing the right BTU, or British thermal unit, for your room size will make sure get the most energy-efficient cooling system for your home. The BTU rating is a number that essentially tells you how quickly and effectively a unit can cool a room. Ratings generally range from 5,000 BTUs to more than 20,000. A unit with too few BTUs may not be able to cool a large space efficiently, while an oversized air conditioner in a small space will cycle on and off, wasting energy and decreasing the unit's ability to adequately dehumidify the room.

It’s important to consider factors such as ceiling height, room insulation, sun exposure, location and your area’s climate when choosing a unit with the right BTU rating. All air conditioning units are labeled with their EER (Energy Efficiency Rating). Units with higher ratings offer lower greenhouse emissions and monthly electric bills. EERs range from 8 to 11.5. The Home Depot carries several models that are Energy Star rated. Check the yellow Energy Guide label on new air conditioners for more information. Before You Buy Checklist 1. Calculate your room size 2. Check your connections 3. Measure to fit Multiply the room length by the room width (in feet) to get the square footage of the area to be cooled. Check out your power source (nearby outlet) and make sure to match the unit to that outlet. Measure the height and width of the opening and check the dimensions of the AC unit you select to be sure it will fit.There is no need to suffer through summer heat when inexpensive, energy-efficient air conditioners are widely available.

Since October 26, 2015, all ENERGY STAR rated room air conditioners have been required to meet a new standard, ENERGY STAR 4.0, that sets maximum power use at 10% less than older models following the 2014 guidelines. And, when used to provide cooling only where they're needed, room air conditioners are less expensive to operate than central units. This guide will help you find the model that is right for you. A room air conditioner's efficiency is measured by the energy efficiency ratio (EER). The EER is the ratio of the cooling capacity (in British thermal units [Btu] per hour) to the power input (in watts). The higher the EER rating, the more efficient the air conditioner. Each increase of 1.0 on the EER scale represents a 10% increase in energy efficiency. When buying a new room air conditioner, information about the EER can be found on the EnergyGuide label for the unit. Look for an EER of at least 12 and the ENERGY STAR label. Earning the ENERGY STAR means a product meets strict energy efficiency guidelines set by the U.S. Environmental Protection Agency and the U.S. Department of Energy.

The required cooling capacity for a room air conditioner depends on the size of the room being cooled. Room air conditioners generally have cooling capacities that range from 5,500 Btu per hour to 14,000 Btu per hour. Many people buy an air conditioner that is too large, thinking it will provide better cooling. However, an over-sized air conditioner is actually less effective — and wastes energy at the same time. Air conditioners remove both heat and humidity from the air. A properly sized unit will remove humidity effectively as it cools.To figure out which size unit is best for your cooling needs, see the Air Conditioner Cooling Needs Calculator below. Verify that your home's electrical system can meet the unit's power requirements. Room units operate on 115-volt or 230-volt circuits. The standard household receptacle is a connection for a 115-volt branch circuit. Large room units rated at 115 volts may require a dedicated circuit and room units rated at 230 volts may require a special circuit.

If you are mounting your air conditioner near the corner of a room, look for a unit that can direct its airflow in the desired direction for your room layout. If you need to mount the air conditioner at the narrow end of a long room, look for models that have a “turbo” fan mode that can drive air further into the room. Other features to look for: For those that keep to a regular schedule and don't have smart home devices installed in their home, a timer will help save money (about $100 on the air conditioner itself and your energy bill) and save you from coming home to a hot, stuffy home. For many, though, the ability to control a room air conditioner from anywhere can be a huge help and cost savings, especially if you don't stick to a schedule. And, you can connect them to other smart home devices so they fit seamlessly into your daily routine. The Frigidaire FFRE0533S1 ($167.99 on Amazon), rated at 5,000BTU, gets high marks for its cooling and dehumidification capabilities of up to 1.1 pints per hour.

The unit, which has an EER of 12.2, two cooling and two fan speeds, a 24-hour programmable timer, built-in thermostat with digital temperature readout, remote control and a four-way adjustable vent to direct air flow. The Wi-Fi connected Frigidaire FGRC0844S1 Cool Connect ($296.99 on Amazon) delivers 8,000 BTUs, enough to cool a room up to 350 square feet, with an EER of 12.0. The unit has 3 fan speeds and 2-way slanted louvers that direct airflow in an upward, circular motion for even cooling. You can create a custom 24-hour schedule or control the unit remotely with the Frigidaire app for iOS and Android or dedicated remote control. If the power goes out, the unit will automatically restart when power is restored.  It has an air ionizer to help remove allergens, like pollen, and other impurities from the air and the magnetic front grill, which has an antibacterial filter, easily detaches for cleaning. A little planning before installing your air conditioner will save you money and energy.

The unit should be level when installed, so that the inside drainage system and other mechanisms operate efficiently. If possible, install the unit in a shaded spot on your home's north or east side. Direct sunshine on the unit's outdoor heat exchanger decreases efficiency by as much as 10%. You can plant trees and shrubs to shade the air conditioner, but do not block the airflow. Don't place lamps or televisions near your air-conditioner's thermostat. The thermostat senses heat from these appliances, which can cause the air conditioner to run longer than necessary. Set your air conditioner's thermostat as high as is comfortably possible in the summer. The less difference between the indoor and outdoor temperatures, the lower your overall cooling bill will be. Don't set your thermostat at a colder setting than normal when you turn on your air conditioner; it will not cool your home any faster and could result in excessive cooling and unnecessary expense. Set the fan speed on high, except on very humid days.