Let Us Help You Calculate the Savings
Because they use less water and energy, compact front load washers and ventless dryers cost significantly less to operate. Some of the biggest savings come from ventless dryers eliminating the need to reheat or re-condition the apartmentful of make-up air that a conventional vented dryer exhausts to the outside with every load.
Here are some simple formulas and rules of thumb to help you compute the savings.
Computing Water and Sewer Cost Savings
Here in the Washington, D.C. area, the combined W-SSC water and sewer cost is $6 per 1,000 gallons, or 0.6 cents per gallon.
A 24-inch front-load washer uses approximately 20 gallons less per cycle than a comparable top-load washer.
That produces a savings in water and sewer of 12 cents per cycle.
A machine used just three times per week saves $20 per year. In a 200-unit community, that’s a savings of nearly $4,000 per year.
Computing the Savings in the Cost of Hot Water
In a perfect system, 1 kWh of electricity will heat 4.1 gallons, 100 degrees. But there are no perfect systems. System efficiencies range from 60% to 85% depending on the location of the water heater, circulation pumps, ambient water temperature, and other factors.
This means that in the real world, 1kwh of electricity will heat only 2.5 to 3.5 gallons.
A 24-inch front-load washer uses 10 gallons less hot water during a hot wash and 5 gallons less during a warm wash. This means it can save roughly 3 to 4 kWh per hot wash and 1.4 to 2 kWh per hot wash.
That’s a savings of up to 624 kWh per year.
Cost of Reheating Air Exhausted to the Outside by a Conventional Vented Dryer
A typical vented dryer exhausts 200 cubic feet per minute, or 10,000 cubic feet during a 50 minute dry. All of this air is pulled out of the apartment and must be replaced with unheated or unconditioned air drawn from the outside air. In fact, the amount exhausted is more than the total amount of air in a 1,000-square-foot apartment.
It takes .75 kWh to heat 10,000 cubic feet of air 10 degrees. If the inside temperature is 75 degrees and the outside temperature is 35 degrees, then it will take 3 kWh of energy to reheat the air being exhausted.
In the summer, the problem is reversed, as additional energy is consumed to re-cool the hot air drawn into the apartment to replace the already conditioned air the dry sucked out.
These figures do not include the continuous convection losses through the 4-inch hole in the wall for the dryer vent, or losses through central ducts in mid and high-rise buildings.