17 Energy-Efficiency Measurements Every Homeowner Should Know

You don’t have to be a building scientist to know how to make your home more energy efficient. The information you need to keep your house comfortable, improve efficiency, and even get started with solar are available, if a little bit…scattered. To make things easier, we’ve compiled a handy rundown of acronyms, abbreviations, organizations, and standards to help you navigate your way to home energy efficiency and savings on your monthly bills.

Plus, identifying which energy-efficient products to purchase is easier than ever! Log in to Pearl’s free Green Door app to shop a curated list of high-performance, energy- and water-efficient products from our e-commerce partner Build with Ferguson. Green Door also enables you to build customized Home Investment Plans and filter products by category. Don’t forget to check out Green Door’s Rebates section to see if your purchases are eligible for cash back.

Insulation: R-Value

The “R” in R-Value stands for resistance, and according to ENERGY STAR^®, “It is the measure of insulation’s ability to resist heat traveling through it.” Simply put, the higher the R-Value, the better your insulation will do at keeping warm and cold air where you want it. R-Value requirements are determined by local building codes and have changed over the years. Older homes generally have less insulation than newer homes.

ENERGY STAR divides the country into eight different insulation zones and provides R-Value recommendations for each. But in general, adhere to the following recommendations:

Don’t worry about knowing how the R-Value is calculated; the important thing to remember is that all appliances, windows, fixtures, and insulation should be ENERGY STAR-rated. When in doubt, check data from Uncle Sam.

Related Post: Step-by-Step Guide to a High-performing Home: The Ins and Outs of Insulation

Air Sealing: Air Changes by Hour

Even the best HVAC system can’t make your home comfortable if your building shell leaks air. To identify the gaps in your home’s armor, consider a blower door test. “During a blower door test, an energy auditor will set up a big, calibrated fan in the front door, run the fan, and get a reading as to how leaky the home is,” says Casey Murphy, Pearl Certification SVP Business Incubation. Blower door tests reveal air flow measured by air changes per hour (ACH), a calculation of the number of times the total air volume in a room or space is completely removed and replaced in an hour. The test is the best way to figure out how well your home is sealed.

The minimum air sealing requirements for high-Performing homes include:

Related Post: First Step to a High-Performing Home: The Blower Door Test

Faucets and Showerheads: Gallons Per Minute

In the kitchen and bathroom, it’s all about the flow. In addition to ENERGY STAR, the U.S. Environmental Protection Agency (EPA) also launched WaterSense, a set of standards that measures water efficiency.

Water use is measured in gallons per minute (GPM). Modern faucets come equipped with an aerator — a metal screen that adds air to the water stream and slows the flow. Standard faucets have a max flow rate of 2.2 GPM. WaterSense bathroom faucets can get as low as 1.5 GPM, reducing water flow by 30% or more without affecting performance.

It's the same story with showerheads. Traditional flow is pegged at 2.5 GPM, which can add up as most families use about 40 gallons per day, just on showers. WaterSense-approved showerheads max out at 2.0 GPM. With bathrooms accounting for 50% of a home’s total water usage, WaterSense faucets and showerheads could mean substantial savings.

Toilets: Gallons Per Flush

Toilets are rated by gallons per flush (GPF), and fixtures that are older than 25 years are known water wasters. A newer WaterSense-rated unit can help reduce GPF by as much as 60%. Selecting a toilet with 1.28 gallons per flush is a worthy goal. Also take note that some older low-flow toilets sold during the 1990s had design flaws that required a double flush, which negates any water savings. Today’s toilets work correctly and efficiently.

Lighting: Watts and Lumens

Lighting is important to every room in the house, even closets. Incandescent lighting fixtures are on their way out and are being replaced by light emitting diodes (LEDs). LEDs are 75% more efficient than incandescent. ENERGY STAR has a guide to help you make the switch.

Watts measure how much power a light bulb consumes; the higher the wattage, the more energy it consumes. Lumens, on the other hand, measure how much visible light is emitted; the higher the lumen, the brighter the bulb.

To measure a light bulb’s efficiency, simply divide the number of lumens by the number of watts. For example, a 40W bulb that produces 490 lumens has an efficiency of 12.75 lumens per watt, whereas a 60W bulb that produces 800 lumens has an efficiency rating of 13.33 lumens per watt, making the 40W bulb slightly more efficient. Just look at the packaging of the light bulb to begin making your own calculations.

Ventilation: Cubic Feet Per Minute

Bathroom ventilation is key to keeping the air moving to help eliminate mold, mildew, and odors. Ventilation efficiency is measured by airflow and is expressed in cubic feet per minute (CFM). Bathroom exhaust fans should be rated at 80-110 CFM. Modern range hoods in the kitchen are sized at 100 CFM per linear cooking space.

Major Appliances

When purchasing an appliance, never settle for anything without the ENERGY STAR label. However, just because an appliance has earned the coveted label does not mean it’s the most efficient in its category. Check out ENERGY STAR’s robust search engine to easily compare different models by size, cost, features, and of course, efficiency. At a minimum, appliances must meet the below qualifications to earn an energy-efficiency rating.

HVAC: SEER, EER2, BTU, and AFUE

Efficiency scores for heating, ventilation, and air conditioning (HVAC) systems are a bit more complicated and expressed by four different acronyms. The seasonal energy-efficiency rating (SEER) measures cooling output divided by watt hours.

In 2022 and prior, air conditioners had to meet the energy-efficiency ratio (EER), but as of January 1, 2023, air conditioners must now meet the EER2 standard. EER2 measures the efficiency of the unit when it operates with an outdoor temperature of 95°F, an indoor temperature of 80°F, and at 50% humidity. Minimum standards vary by region of the country and system capacity.

British Thermal Units (BTUs) measure the amount of heat needed to raise a pound of water by one degree. BTUs have been around since 1846 and are used to calculate everything from kilowatt hours to the heating capacity of wood.

Picking the most efficient HVAC system means weighing how much energy it uses against how much it costs to operate. A heat pump system combines heating, air conditioning, and ventilation and is generally considered to be the most fuel-efficient system.

Boilers, furnaces, air conditioners, and heat pumps all come with several ratings. For tracking pure efficiency in furnaces and boilers, the most useful tool is the Annual Fuel Utilization Efficiency (AFUE) rating — a number mandated by the Federal Trade Commission. Keep in mind that high efficiency may not be the lowest cost as electric resistance furnaces have efficiencies of 95%-100% but may be the most expensive way to heat a home based on the price of electricity.

The simplest way to get the big picture is to read the EnergyGuide label, which is attached to all new appliances. When making big decisions about the most efficient way to heat and cool your home, you also need to factor in the price of electricity and the availability of other fuels, including natural gas.

Related Post: Heat Pump Versus Furnace: How do they stack up?

Water Heaters: Uniform Energy Factor

Hot water heaters can be fueled by natural gas, propane, electricity, or solar. Most people use a traditional storage tank system, while others are going tankless. The U.S. Department of Energy (DOE) estimates that 20% of your home’s energy usage is spent heating water. Like other major appliances, hot water heaters come standard with a whole sheet of statistics, including an EnergyGuide label.

The DOE also rates hot water heaters using a uniform energy factor (UEF) measurement. UEF measures overall energy efficiency based on the amount of hot water produced per unit of fuel consumed over a typical day. The number accounts for:

• Recovery efficiency: A measurement of how efficiently the heat from the energy source is transferred to the water

• Standby losses: The percentage of heat loss per hour from the stored water compared to the heat content of the water

• Cycling losses: The loss of heat as the water circulates through the tank

The higher the UEF value is, the more efficient the water heater. Compare the numbers, factor in your fuel, and you’re well on your way to the soaking tub. 

Related Post: Water Heaters: Do You Know Your Options?

Solar System: Efficiency Rating

Roof-mounted solar power systems have gone from science fiction to common sense, especially when electric rates are high. Solar power systems use photovoltaic cells (PV) to filter electrons out of sunlight to power the home. Before making the big decision, talk to a Pearl Network Contractor, who can use the Pearl Solar Equity Calculator^® to calculate discounted cash flow over time and the efficiency rating, which is the percentage of the sun’s energy falling on the panels that is converted into usable electric energy.

Related Post: Solar Energy: How to Get Started, Confidently

Collectively, these measurements and standards illuminate how efficiently your home performs and can be especially helpful when upgrading an appliance or system. Waiting for a system or appliance to break before upgrading it can lead to a rushed decision. Instead, plan ahead by logging in to the free Green Door app to create a Home Investment Plan to formulate your custom approach to a more resilient and high-performing home.