Air Infiltration
The uncontrolled flow of outdoor air into a home through gaps, cracks, and openings in the building shell — around doors, windows, electrical outlets, and pipe penetrations. It forces heating and cooling systems to work harder because conditioned air escapes at the same time unconditioned outside air enters. The EIA estimates air infiltration accounts for 25–40 percent of a typical home's heating and cooling energy use.
Common fixes include weatherstripping on exterior doors and caulking around window frames, both of which cost under $50 per opening and can be done without a contractor.
All-Electric Home
A residence that uses electricity as the sole energy source for every major end use — space heating, cooling, water heating, and cooking — with no natural gas or propane appliances. Because electricity carries loads that gas-supplied homes split across two fuel sources, all-electric homes show higher average monthly kWh consumption and are more sensitive to electricity rate changes.
Ampere A
An ampere, or amp, measures how much electric current is flowing through a wire. It's the volume of electricity moving, where voltage is the pressure behind it. Your home's breaker panel is rated in amps, often 100 or 200.
Each breaker in your panel trips at a set amperage to keep a circuit from overheating. Volts times amps gives you watts, the actual power being used.
Related: Volt , Watt
Average Monthly Usage
The average Texas home uses roughly 1,000 kilowatt-hours a month, though summer cooling can push it well past 2,000. This number matters because electricity plans advertise their rate at 500, 1,000, and 2,000 kWh, and the price can change a lot depending on which usage level you actually hit.
A plan that looks cheap at 1,000 kWh can cost much more at 500 kWh because of hidden minimum-usage fees or bill credits. Check your past 12 months of bills to find your real average before you compare.
Related: Electricity Usage , Kilowatt-Hour , Electricity Facts Label
Source: Power to Choose (PUCT)
Baseload
Baseload is the steady, around-the-clock level of electricity demand that never goes away, even at 3 a.m. when most of Texas is asleep. Power plants that run constantly, like nuclear and large natural gas units, cover this baseline, while other sources ramp up to meet the daytime peaks.
Picture a chart of daily electricity use: baseload is the flat floor everything sits on top of, and peak demand is the tall spike in the afternoon.
Related: Peak Demand , Load , Megawatt
Source: ERCOT
Building Envelope
The set of physical components that separate a home's conditioned interior from the outdoors, including walls, roof, windows, doors, and foundation slab or crawl space. A tighter, well-insulated envelope reduces the temperature difference the HVAC system must overcome, directly cutting the cooling and heating electricity a home requires.
Older homes with minimal attic insulation and single-pane windows can have envelope losses severe enough to double electricity use compared to a same-size newer home — making envelope quality as important as square footage when estimating expected bills.
Source: U.S. Department of Energy
Carbon Monoxide Poisoning CO Poisoning
A life-threatening medical emergency caused by inhaling carbon monoxide gas, which is produced by burning fuel — such as gas, charcoal, or propane — in an enclosed or poorly ventilated space. During power outages, CO poisoning risk rises sharply when people use gas ovens, grills, or portable generators indoors as improvised heat sources.
Source: Texas Department of State Health Services
Coefficient of Performance (COP) COP
A measure of how efficiently a heat pump converts electricity into usable heat, expressed as the ratio of heat energy delivered to electrical energy consumed. A COP of 2.5 means the system delivers 2.5 units of heat for every 1 unit of electricity used, making it far more efficient than resistance heating, which has a COP of exactly 1.
Cooling Load
The amount of heat energy an air conditioning system must remove from a building to maintain a desired indoor temperature. Cooling load increases as outdoor temperatures rise, as more heat enters through windows and walls, or as internal sources like appliances and occupants add heat. It is typically measured in British Thermal Units (BTUs) per hour or in tons of cooling capacity.
Cooling Setpoint
The target indoor temperature at which an air conditioning system is programmed to activate. When the indoor temperature rises above the setpoint, the AC compressor turns on to bring the temperature back down. Raising the setpoint reduces how often the compressor runs and directly lowers electricity consumption.
Duct Leakage
The unintended escape of conditioned air from holes, gaps, or poorly connected joints in a home's heating and cooling ductwork before that air reaches the intended room. ENERGY STAR estimates duct leakage accounts for 20–30 percent of cooling energy loss in many homes. Sealing ducts is a utility-rebated improvement offered by several Texas TDUs.
Source: ENERGY STAR
Electric Strip Heat
A heating method that converts electricity directly into heat using resistance coils — the same principle as a toaster or space heater scaled to a whole home. Strip heat consumes roughly two to three times more electricity per unit of heat delivered than a heat pump, making it the primary driver of high winter electricity bills in all-electric homes.
A home relying on strip heat may see its January kWh total rival or exceed its July air-conditioning bill.
Electricity Usage
Your electricity usage is the total amount of energy your home consumed during the billing period, measured in kilowatt-hours. It's the single biggest factor in what you pay, and it's the number you plug in when comparing plans on a site like Power to Choose.
Your smart meter records usage and sends it to your TDU, who passes it to your retail provider for billing. Heating and cooling drive most of the swing from month to month in Texas.
Related: Kilowatt-Hour , Average Monthly Usage , Load , Smart Meter
Source: Power to Choose (PUCT)
ENERGY STAR
A voluntary certification program run by the U.S. Environmental Protection Agency (EPA) that identifies appliances, electronics, and building products meeting defined energy-efficiency thresholds. Products carrying the ENERGY STAR label have been independently tested and use meaningfully less electricity than standard models for the same function.
Source: U.S. EPA ENERGY STAR
Heat Pump
A vapor-compression system that moves heat rather than generating it: in winter it extracts warmth from outdoor air to heat the home; in summer it reverses to act as an air conditioner. A heat pump delivers two to four units of heating or cooling for every unit of electricity consumed, making it far more efficient than electric strip heat and a significant factor in comparing winter electricity usage across home types.
Heat-Pump Water Heater HPWH
A water heater that uses a refrigerant cycle to move heat from surrounding air into the water tank rather than generating heat directly from electric resistance coils. Heat-pump water heaters typically use 60 to 70 percent less electricity than a conventional electric storage water heater for equivalent hot-water output. They require adequate space with ambient temperatures above roughly 40°F to operate efficiently.
A Texas household replacing a standard 4,500-watt electric storage water heater with a heat-pump model can reduce water-heating consumption from roughly 270 kWh per month to under 100 kWh.
Home Energy Audit
A systematic inspection of a home to identify where energy is being wasted and which improvements would reduce consumption. Auditors typically examine insulation, air sealing, appliances, HVAC equipment, and windows, and may use tools such as a blower door test or thermal camera.
In Texas, some utilities and assistance programs offer subsidized or free audits; a professional audit typically costs $200–$400 when paid out of pocket.
Source: U.S. Department of Energy
HVAC HVAC
Acronym for Heating, Ventilation, and Air Conditioning — the equipment systems that control a building's indoor temperature, humidity, and air quality. In Texas, the air conditioning component dominates residential electricity use, typically accounting for 60–70 percent of a home's total consumption during peak summer months.
IECC Climate Zone
A geographic classification defined by the International Energy Conservation Code (IECC) that groups regions with similar heating and cooling demands together. Most of Texas falls in zones 2 and 3, which are warm and mixed-humid climates. The classification determines the minimum insulation levels, window performance, and air-sealing standards required by building codes for new and renovated homes.
Source: U.S. Department of Energy — Energy Codes
Kilowatt kW
A kilowatt is 1,000 watts. It measures how fast you're using electricity at a given moment, not how much you use over time. Think of it like speed: kilowatts are the speedometer, kilowatt-hours are the miles.
A central air conditioner might pull 3 to 5 kilowatts while it's running. Run 5 kW for two hours and you've used 10 kilowatt-hours.
Related: Kilowatt-Hour , Watt , Load , Peak Demand
Kilowatt-Hour kWh
A kilowatt-hour is the unit your electricity is measured and priced in. It's how much energy you use by running 1,000 watts for one hour. Every charge on your Texas electric bill traces back to how many kilowatt-hours you used that month.
Ten 100-watt bulbs left on for an hour burn one kilowatt-hour. A typical Texas home uses around 1,000 kWh a month, and your energy rate is quoted in cents per kWh.
Related: Kilowatt , Watt , Average Monthly Usage , Electricity Usage
Source: Public Utility Commission of Texas
Level 2 EV Charging
A method of charging a plug-in electric vehicle using a 240-volt circuit — the same voltage as a large home appliance — that delivers roughly 7 to 11 kilowatts per hour of charge, significantly faster than a standard 120-volt outlet. Because a Level 2 session draws substantial power for several hours, scheduling it during off-peak electricity hours can produce notable savings on a time-of-use plan.
Load
Load is the amount of electricity a home, building, or the whole grid is drawing at a given moment, measured in kilowatts or megawatts. The more devices running at once, the higher the load. It's the demand side of the equation that ERCOT has to keep matched with supply, second by second.
Your home's load spikes when the AC, oven, and dryer all run together. Across Texas, total load climbs every summer afternoon as millions of air conditioners kick on at the same time.
Related: Peak Demand , Kilowatt , Megawatt , Baseload
Source: ERCOT
Load Shape
The pattern of a household's or facility's electricity consumption over time, typically shown as usage plotted hour by hour or day by day. Load shape reveals when consumption is highest and lowest, which determines how well different rate plan structures — such as time-of-use or flat-rate plans — will fit a given customer.
A household that concentrates most of its usage on weekend mornings has a very different load shape from one that runs appliances in the late afternoon, and the two households may pay very different amounts under the same time-of-use plan.
Megawatt MW
A megawatt is one million watts, or 1,000 kilowatts. It's the unit used to measure big power, like a power plant's output or how much electricity all of Texas is using at once. You won't see it on your bill, but you'll hear it whenever ERCOT talks about the grid.
One megawatt powers roughly 200 Texas homes during a summer afternoon. ERCOT set its all-time peak demand record on August 20, 2024, when statewide demand topped 85,500 megawatts.
Related: Kilowatt , Watt , Peak Demand , Baseload
Source: ERCOT
Megawatt-Hour MWh
A unit of electrical energy equal to 1,000 kilowatt-hours. Wholesale electricity is priced and traded in megawatt-hours, while retail bills report household consumption in kilowatt-hours.
A household that uses 1,000 kWh in a month has consumed exactly 1 MWh; a provider paying $50 per MWh wholesale translates that to roughly 5 cents per kWh before adding delivery charges and margin.
Mini-Split
A ductless heating and cooling system pairing an outdoor compressor with one or more indoor air handlers to condition individual rooms or zones, with no central ductwork required. Mini-splits are common in apartments, home additions, and older homes that lack duct systems, and their per-zone operation can significantly affect monthly kWh totals compared to a whole-home central system.
Peak Demand
Peak demand is the highest amount of electricity being used across the grid at one time, usually a hot summer afternoon between 3 and 7 p.m. when air conditioners run hardest. ERCOT watches peak demand closely because that's when the grid is stretched thinnest and prices climb.
Texas hits its yearly peak in July or August. The state's all-time record was about 85,500 megawatts, set August 20, 2024. Some time-of-use plans charge more during these peak hours to nudge you to shift usage to cheaper times.
Related: Load , Baseload , Megawatt
Source: ERCOT
Phantom Load
Electricity consumed by appliances and devices when they are switched off or in standby mode but still plugged in. Common sources include older refrigerators, pool pumps, and electric water heaters running on incorrect schedules. Phantom loads appear as a baseline of consumption during hours when no one is actively using anything in the home.
On a Smart Meter Texas interval chart, a consistently elevated reading between midnight and 5 a.m. is a practical indicator that phantom loads may be significant.
Power Outage
An interruption in electrical service caused by a fault, equipment failure, or physical damage on the TDU's distribution or transmission network. In Texas's deregulated market, outages are always reported to and resolved by the TDU—not the retail electric provider—because the TDU owns and operates the physical wires regardless of which REP is billing the customer.
Switching providers does not change the outage reporting process; the same TDU emergency number applies before and after a switch.
Pre-Cooling
A demand-shifting strategy in which a home's air conditioning system is run more intensively before an on-peak pricing window begins, cooling the indoor space to a lower temperature so the system can run less — or not at all — during the more expensive peak hours. Pre-cooling works best when paired with a programmable or smart thermostat and a well-insulated building envelope.
A household on a TOU plan might pre-cool to 70°F before 3 p.m. and allow the temperature to drift to 76°F by 8 p.m., reducing expensive on-peak air-conditioning runtime.
Programmable Thermostat
A thermostat that lets you set different temperature targets for different times of day or days of the week, so heating and cooling adjustments happen automatically without manual changes. Unlike a basic thermostat, it follows a schedule you program once — for example, raising the cooling setpoint while you are at work and lowering it before you return home.
A smart thermostat is a type of programmable thermostat that also connects to Wi-Fi, learns your preferences, and can receive signals from a utility or retail electric provider during demand response events.
R-Value
A measure of how well a building material resists heat flow — the higher the number, the better the insulation. In Texas, the recommended attic insulation level is R-38 to R-60 depending on climate zone. Homes built before 1990 often have R-11 or less, meaning a significant amount of heat moves through the ceiling and into the living space during summer.
Adding blown-in insulation to bring an attic from R-11 to R-38 typically costs $1,500–$2,500 for a 1,500-square-foot attic and can cut cooling costs by 15–20 percent.
Source: ENERGY STAR
Refrigerant
A chemical fluid that circulates through an air conditioner or heat pump, absorbing heat indoors and releasing it outside. When the refrigerant level is low — often due to a leak — the system must run longer to cool a space, increasing electricity consumption significantly.
A technician who finds a low refrigerant charge will typically locate and repair the leak before recharging the system, since simply topping it off without fixing the leak is both wasteful and, for many modern refrigerants, regulated.
Residential Energy Consumption Survey RECS
A periodic national survey conducted by the U.S. Energy Information Administration (EIA) that collects data on how American households use energy. It covers appliance ownership, home characteristics, fuel types, and energy expenditures, and is widely cited as the authoritative source for residential electricity consumption patterns.
Source: U.S. Energy Information Administration
Resistance Heating
A method of generating heat by passing electricity through a resistive element, which converts electrical energy to heat at a 1-to-1 ratio. Unlike a heat pump, it does not move heat from outside air but creates it directly, making it significantly less efficient and more expensive to operate per unit of heat delivered.
Resistance heating is common in older Texas homes and many apartments, and it is often the backup heating mode on heat-pump systems during very cold weather — a key reason winter electricity bills can spike sharply.
SEER Rating SEER
A standardized measure of air conditioner efficiency, calculated as total cooling output over a typical season divided by total electrical energy consumed. Higher SEER values mean less electricity is used to move the same amount of heat — a 20-SEER unit costs less to run than a 14-SEER unit doing identical work. Federal minimum standards require 14 SEER for new central air conditioners installed in the South.
A system below SEER 14 consumes noticeably more electricity per degree of cooling, which shows up directly in summer bills even if usage habits and rates stay constant.
Source: U.S. Department of Energy
Single-Speed Pool Pump
A pool circulation pump that runs at one fixed motor speed, typically full power, regardless of the filtration task at hand. Because it cannot slow down for lighter-duty cycles, it consumes substantially more electricity than variable-speed alternatives and is a notable contributor to high summer bills in Texas homes with pools.
Replacing a single-speed pump with a variable-speed model is one of the higher-return efficiency upgrades available to Texas pool owners, often saving 70–80% of the pump's prior energy use.
Smart Thermostat
A thermostat that connects to a home network and can automatically adjust heating and cooling setpoints based on a programmed schedule, occupancy sensors, or remote commands from a smartphone app. Unlike a basic programmable thermostat, a smart thermostat can learn household patterns and respond to utility demand-response signals. Studies by device manufacturers report average cooling savings of 10–15 percent compared to homes without scheduled setbacks.
Many smart thermostats qualify for a federal tax credit and utility rebates, reducing the effective upfront cost of a $150–$250 device.
Temperature Setback
A deliberate increase in the cooling setpoint — or decrease in the heating setpoint — during periods when full comfort conditioning is not needed, such as when occupants are away or asleep. Each degree of setback reduces the runtime of the heating or cooling equipment and lowers the associated electricity use.
For example, raising a thermostat from 78°F to 85°F while the house is unoccupied is a 7-degree cooling setback.
Thermal Mass
The ability of a building's materials — walls, floors, furniture, and contents — to absorb, store, and slowly release heat. A home with high thermal mass stays warmer longer after the heating system stops running, which is relevant during power outages in cold weather.
Pre-warming a home to 70–72°F before a forecasted outage takes advantage of thermal mass, potentially keeping interior temperatures above dangerous thresholds for several hours without any active heating.
Ton (Cooling Capacity)
A unit expressing the cooling output of an air conditioner or heat pump; one ton equals 12,000 British thermal units (BTUs) of heat removed per hour. Residential central AC systems in Texas are commonly sized between 2 and 5 tons. A higher ton rating generally means greater electricity draw, which is why central AC is the largest single contributor to monthly kWh consumption in most Texas households.
A 3-ton central air conditioner removes 36,000 BTUs of heat per hour and typically draws 3,000 to 3,600 watts of electricity while running.
Vampire Load
Electricity consumed by devices that remain plugged in but are not actively in use — such as televisions, game consoles, cable boxes, and phone chargers in standby mode. The Lawrence Berkeley National Laboratory estimates vampire loads account for 5–10 percent of a typical home's electricity use. Smart power strips can eliminate most of this waste automatically.
Volt V
A volt measures the electrical pressure that pushes current through your wires. Standard outlets in Texas homes run at about 120 volts; large appliances like a dryer or electric range use 240 volts.
Voltage is the push, current (measured in amps) is the flow, and power (watts) is what you get when you multiply them together.
Related: Watt , Ampere
Watt W
A watt is the basic unit of electric power. It tells you how much electricity a device draws while it's on. The higher the wattage, the more energy a device burns and the more it adds to your bill.
An LED bulb might use 9 watts; an old incandescent used 60. A thousand watts equals one kilowatt, the size used to price your electricity.
Related: Kilowatt , Kilowatt-Hour , Electricity Usage
Weatherstripping
Flexible sealing material applied around the edges of doors and windows to block drafts and prevent conditioned air from escaping. Reducing air infiltration lowers the amount of work a heating or cooling system must do, directly cutting electricity consumption.
Weatherstripping an exterior door typically costs $10–$30 in materials and is one of the highest-return, lowest-cost efficiency upgrades available to renters and homeowners alike.