Ozone Laundry System: Savings, Payback and How It Works

An ozone laundry system lets a commercial laundry wash in cold or much cooler water, which is where most of the savings come from: in a U.S. Department of Energy field demonstration, a hotel cut its laundry water-heating energy by 65 percent. The results are not automatic, though. The same study found a second site that saved energy but used more water and saw no payback. This article explains how ozone laundry works, what the independent data show, and how to judge whether it fits your operation.

An ozone laundry system is an add-on retrofit for commercial washers that generates ozone on site and injects it into the wash water, where it helps break down soils and sanitize linens so that wash cycles can run at lower temperatures with less detergent. It is used mainly by hotels, hospitals, care homes and other on-premises laundries running multi-load washers or washer-extractors.

How an ozone laundry system works

The best independent source on the topic is a 2014 report prepared for the U.S. Department of Energy by Pacific Northwest National Laboratory and Navigant Consulting: Demonstration of Advanced Technologies for Multi-Load Washers in Hospitality and Healthcare: Ozone Based Laundry Systems. It describes the system in four steps:

1. An ozone generator creates ozone from ambient air.
2. The ozone is injected into the wash water, where it dissolves.
3. Dissolved ozone reacts with insoluble soils, making them soluble, after which the mechanical action of the washer separates them from the fabric. Ozone also acts as a disinfectant.
4. After the wash cycle, the ozone is vented through a carbon tower.

The key point is that the ozone equipment itself does not save energy. As the DOE report puts it, adding ozone “enables the laundry facility to significantly reduce the wash water temperatures, which results in hot water energy savings.” Ozone stays dissolved more effectively in cold water, so wash temperatures can come down from the roughly 140°F (60°C) common in commercial laundries. The report notes that “in many cases, equivalent cleaning performance can be achieved using no hot water at all,” while some cycles using chlorine bleach may still need around 90°F (32°C) for effective stain removal.

What the benefits look like in practice

According to the DOE report, an ozone laundry retrofit can deliver:

• Lower water-heating energy, because washes run cold or cool.
• Possible water savings, because the rinse can sometimes be reduced from two cycles to one.
• Less detergent: at both demonstration sites, detergent quantities were reduced after installation to prevent over-sudsing.
• Shorter drying, since opening up the fibers makes linens easier to dry, which “can result in a decrease in drying time.”
• Retrofit compatibility: the report describes the technology as compatible with almost any multi-load washer, with minimal space requirements and little additional training.

The DOE field results: two very different outcomes

The DOE team metered two installations before and after ozone was added. The comparison is useful precisely because the outcomes differ.

Metric	Charleston Place Hotel (SC)	Rogerson House assisted living (MA)
Average laundry throughput	About 5,000 lb/day	About 500 lb/day
Approximate installed cost	$42,200	$12,000
Change in water-heating energy	65% reduction	63% reduction
Change in total water use	15% reduction	19% increase
Simple payback	2.8 years	No practical payback
Linen quality	Guest satisfaction remained high	Cleanliness remained consistent

Source: PNNL-23536, prepared for the U.S. Department of Energy, August 2014.

At the hotel, savings on natural gas and on water and sewer outweighed the small extra electricity used by the ozone generator. At the assisted living facility, energy savings were almost the same in percentage terms, but staff increased cold-water rinsing to keep cleaning performance satisfactory. That extra water, at high local water and sewer rates, cancelled out the gas savings. The report’s conclusion is worth quoting: “unlike energy savings, water savings is not assured by the installation of an ozone system.”

Is ozone laundry right for your facility?

The DOE results point to a few clear decision factors.

1. Throughput

Volume drives payback. Assuming water use can be kept neutral, the DOE team estimated that for a site with similar laundry and utility costs, “a minimum laundry throughput of around 1,500 pounds per day would be required” for the technology to be financially attractive. Smaller laundries may struggle to recover the investment.

2. What you pay to heat water

Savings scale with the cost of the energy you no longer spend heating water. The report notes that low energy prices, particularly for natural gas, make payback on energy savings alone difficult.

3. Water and sewer rates

If rinse programs are not tuned carefully, water use can rise. Where water and sewer are expensive, this can erase the benefit, as it did at Rogerson House.

4. Upfront cost

The DOE report estimates a minimum investment of about $10,000 for a relatively small system and over $40,000 for larger ones, and suggests checking utility incentive programs before purchasing.

5. Your chemical supplier

Wash programs are usually set by the detergent supplier. Because ozone reduces detergent use, the report identifies supplier resistance as a real barrier. Agree on who will reprogram and monitor the cycles before installation.

Implementation tips

• Meter before and after. Record hot water, cold water, gas, electricity and detergent use for several weeks before installation so you can prove the result.
• Reprogram carefully. The DOE report stresses that wash cycles must be adjusted so total water use does not rise. Re-check programs after the first weeks of operation.
• Check cleaning quality. Run the same linen types before and after, and track stains, rewash rates and complaints.
• Plan ozone delivery. Ozone must be dissolved efficiently into the wash water. Venturi injectors are a common method for mixing ozone gas into water; HSVN lists a venturi injector for ozone mixing from HSVN among its accessories.
• Build in safety. At one DOE site, staff initially worried about ozone leaking into the laundry room. An ozone safety monitor that shuts the generator down when it detects a threshold concentration eased those concerns. The workplace limit for ozone is 0.1 ppm, according to the NIOSH Pocket Guide.

Choosing the ozone equipment

The generator for a laundry retrofit is typically small compared with water treatment systems, but it must run reliably every cycle. Look for:

• adjustable output so ozone can be matched to washer size and load;
• clean, dry feed air, since moisture shortens generator life;
• ozone-resistant tubing, check valves and fittings;
• interlocks with the washer and an ambient ozone monitor in the laundry room;
• local service and spare parts.

Dr.Ozone’s air-fed industrial units start at small outputs. The Dr.Ozone D-10PRO industrial ozone generator, for example, is listed at 10 g/h with a stainless steel frame. HSVN describes its standard Dr.Ozone D and D-S series ozone generators as covering 1 g/h to 2 kg/h with knob control and timers. The right output for your laundry depends on washer capacity and cycle design, so treat any model as a starting point for a sizing discussion rather than a recommendation.

Ozone has other uses in hospitality too. Dr.Ozone has written about how a hotel deodorizes and disinfects rooms with ozone and about hotel wastewater treatment systems.

Frequently asked questions

Does ozone laundry really save energy?

Yes, when wash programs are switched to cold or cool water. In a U.S. Department of Energy demonstration, two sites cut water-heating energy by 65 and 63 percent. The ozone generator itself uses a little electricity; the saving comes from heating far less water, so it depends on how much hot water the laundry used before.

Is ozone laundry effective for hospitals and care homes?

The DOE demonstration included an assisted living facility, where linen cleanliness stayed consistent after switching to ozone. Ozone also acts as a disinfectant. However, some managers prefer traditional hot-water sanitization, and healthcare laundries should confirm that any change still meets their own infection-control requirements before adopting cold-water ozone cycles.

How much does an ozone laundry system cost?

The DOE report estimated about $10,000 as a minimum for a relatively small system and over $40,000 for larger ones. The two demonstration installations cost roughly $12,000 and $42,200. Actual cost depends on the number and size of washers, installation and local pricing, so request a site-specific quote.

Is ozone safe for laundry staff?

A properly functioning system with appropriate safety controls poses little additional risk to staff, according to the DOE report. Good practice includes an ambient ozone monitor that shuts the generator down at a set threshold and keeps exposure below the 0.1 ppm workplace limit, plus clear information for employees.

Thinking about adding ozone to your laundry? Send your washer list, daily throughput and current utility costs to our engineers through the Dr.Ozone contact page, or learn more about HSVN, the Vietnamese manufacturer of Dr.Ozone ozone equipment.