Coming: Energy regs for vacuum cleaners

Indications are that the European Commission Ecodesign Directive, the entity that releases the EU's equivalent to US Energy Star regs, could release draft regulations for a variety of product categories by the end of the year. One in particular that is worth noting is residential vacuum cleaners.

The European regulations are of interest to manufacturers in other countries because there is an effort to harmonize regulations of this sort so product designers can focus on meeting similar goals regardless of where their products are used.

Interestingly, the Europeans mandate not just energy efficiency, but also set minimum performance levels for cleaning. For example, they define a parameter called dust pickup on carpet that has to be greater than or equal to 65%; similarly, dust pick up on a hard floor must be greater than or equal to 95%; dust re-emission must be no more than 2%;and the vacuum's sound power level (weighted average level) must be less than or equal to 77 dB (re 1pW). “Dust pick up” is the ratio of the mass of the artificial dust removed after a number of double strokes of the cleaning head to the mass of artificial dust initially applied to a test area. The definition is similar for hard floor dust pick up.

The Europeans also say the most efficient vacuum cleaner they've found was an upright vacuum cleaner of 650 W with a specific energy consumption of 1.29 W-hr/m2. Battery-driven professional dry vacuum cleaners, they say, can be found at a nominal power 400 W with a specific energy consumption of around 0.75 W-hr/m2.

Not surprisingly, The EPA's Energy Star program has also studied vacuum cleaner efficiency. In a report issued late last year, the agency noted that historically, vacuum cleaners have employed centrifugal fans to create suction power in a manner that leads to relatively inefficient energy conversion. The report cited an EU Eco-Design preparatory study which found that maximum efficiency can be as low as 15% and has seldom been greater than 50%.

When the leaks and inefficiencies of the vacuum cleaner and its connecting tubes and filters are taken in to account, says EPA, the overall energy conversion capability can be anything between 10% and 33%. This energy conversion efficiency has no relationship with cleaning efficiency or ability to pick up dirt where absolute levels of suction, airflow and suction power are more critical.

The Agency also noted that though manufacturers have historically promoted the amperage of the vacuum motor as an indication of vacuum cleaning ability, there is minimal correlation between power and cleaning performance. Cleaning head design, brush mechanisms, a sealed system, and other overall design are often more important factors for cleaning performance than input power, EPA says.

EPA notes there is more correlation between suction power and cleaning performance than input power alone. The maximum suction power divided by the input power at the same point determines the maximum airflow efficiency (energy conversion efficiency) of the vacuum cleaner. This value, which is not related to cleaning efficiency, is normally quite low, rarely above 50% and often around 30%, indicating that input power goes mostly to heat. This heat is primarily the result of resistance in the copper windings on the motor armature and field as current flows through them.

Air flow travels through both the suction fans and the motor to cool the system. In addition to the resistance within the power unit, there is resistance caused by air turbulence in the hose and tubing, restriction where the cleaning nozzle contacts the floor, as well as a rising resistance within the filtering system as the unit fills with dirt. EPA explains that the largest potential for energy savings is in the improvement in the efficiency of the motor/fan. For current vacuum cleaners, the Agency says, energy losses are between 60 and 75%. The energy losses are manifested as heat via the exhaust air.

The Agency says that with application of best available technology, a target energy loss of 45% is achievable through improvements in design to the fan case and fan blades.

The Agency has also weighed in on vacuum cleaner airflow. To remove soil, airflow must meet a threshold of typically 18 ft3 per minute. It thinks improvements can be made to the design of vacuum cleaner airways. Currently their energy losses are at best 5% and at worst 10%. Best available technology suggests that energy loss of around 5% is the achievable target.

Nozzle design is another critical area for efficiency. Current energy losses exhibited here are at best around 15% and at worst around 25%. EPA thinks with efficient nozzle design, a target energy loss of 10% is achievable. Leakage between the vacuum generator and nozzle can lead to energy losses as well, currently around 20% at worst. EPA thinks losses due to leakage could be reduced to a target energy loss of about 5%.

Currently, total overall energy losses are at best 75% and at worst as high as 89%. Through greater emphasis on energy efficiency in the design process, EPA says the data currently available suggests that an overall target energy loss of 60% could be achieved.

But more efficient vacuums won't benefit their owners much. EPA estimates the per-unit annual savings for residential vacuums are on the order of 10-19 kW-hr/yr, which would offer lifetime savings of $7 to 15 over an assumed 7-year lifetime.

However, the savings look more impressive when considering that the totality of vacuums sold in the U.S. each year is 28 million, giving a national energy savings opportunity on the order of 67,000 to 135,000 MW-hr per year if 25% of products sold were replaced with energy efficient models. Energy savings for commercial vacuums look better because they are used more often ($46-91 over a 2.5 year lifetime of the product). But fewer of them are sold, so the national energy savings are estimated at 24,000 to 48,000 MW-hr/yr.

A draft of the European vacuum cleaner standard can be found here:

The EPA ENERGY STAR Market & Industry Scoping Report on vacuum cleaners is here:

Vacuum cleaner maker Dyson has also weighed in on the proposed European regs. Interestingly, Dyson thinks they aren't stringent enough in their testing regimens:

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