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Blower door tests are measured in a few different ways, but the most popular are air changes per hour (ACH) and cubic feet of air (CFM) moving through the house per hour. A good ACH score is less than 2ACH, but 1ACH is better. This means the house experiences a total air change within 60 minutes (for 1ACH). For 2ACH, there’s a complete change every 30 minutes, and so on. CFM scores are similar in that a lower score means less air change, and therefore less leakage.

A small sump pump running infrequently uses an average of 10 kilowatt-hours (kWh) of electricity per month. The average cost for electricity is $0.171 per kWh. The size and use frequency affect how much electricity it uses. Sump pumps average one-third to one horsepower (hp) motors. One hp is equal to 745.7 watts. Watts multiplied by the time your pump is running divided by 1,000 equals your average kWh. Multiply kWh by your average cost of electricity. In areas with high rain or a marsh basin, the average cost can be as high as $15-$25 a month.

Home power is measured in kilowatt-hours, commonly expressed as kWh. The average home uses between 800 and 1,000 kWh per month. Peak usage (and highest bills) occurs in the middle of summer and the depths of winter. Keeping on top of your usage during these crucial months will lower your annual average usage considerably. 

To determine the right size generator for your house, you should calculate the total wattage of the appliances and devices you want to power during an outage. List all essential items, note their start-up wattages, and add them together.

Here are some typical wattage requirements for common appliances:

• Refrigerator: 600 watts

• Large dehumidifier: 700 watts

• Large window air conditioner: 1,400 watts

• Water heater: 3,000 to 4,500 watts

• Electric furnace: 5,000 to 25,000 watts

A 7,500-watt generator might be sufficient for essentials like a refrigerator, freezer, well pump, and lighting circuits. However, for high-demand items like a water heater or furnace, a whole-home generator is a better choice. A portable generator may be enough if you only need to power a few critical items.

While home square footage can offer a rough estimate, it is not always a reliable indicator. For reference, here are some typical generator sizes based on square footage:

• 1,000 sq ft: 6–9 kW

• 1,500 sq ft: 7–10 kW

• 2,000 sq ft: 10–14 kW

• 2,500 sq ft: 12–16 kW

• 3,000 sq ft: 16–20 kW+

For the most accurate sizing, consult a professional who can calculate your home's peak and average power consumption and recommend the optimal generator.