The objectives of this project were to showcase an innovative application of an available technology that has great potential for energy savings in hospitality facilities with on-premise laundry OPL operations in the PG&E service territory. Energy savings would commence immediately upon installation and would continue at the same rate of savings over the life of the equipment. A favorable demonstration of the ozone technology might warrant PG&E involvement to accelerate the adoption of this technology through promotional programs.
This report describes the results of an assessment of the energy impacts resulting from use of ozone in an on-premise hotel laundry facility. While the use of ozone in on-premise laundry (OPL) operations is becoming more common, most of the available data on the energy impacts of ozone are from the equipment manufacturers themselves, which calls into question the objectivity of the values. The Pacific Gas and Electric (PG&E) market segment and product teams thought they needed data collected and analyzed by an impartial third-party to objectively promote the technology among their hospitality customers and to quantify the appropriate incentive level for the technology.
Technical Potential for Ozone in Hospitality On-Premise Laundry Operations in PG&E’s Service Area
There are approximately 2,136 hotel properties possessing about 179,000 guest rooms in PG&E’s service area.1 Due to the size of PG&E’s service area and the large number of hotel and motel rooms it contains, there is a significant opportunity for ozone in hospitality OPL operations. Secondly, the current trend towards “green” business is providing a fertile environment for technologies such as ozone; businesses can embrace and promote it among their customers.
The estimated electricity savings at the host facility due to the ozone system was 44 kWh per occupied guest room per year. Therefore, the annual electric technical potential for all the hotels in PG&E’s service territory hotels is 5,230,204 kWh. The estimated natural-gas savings at the host facility due to the ozone system was 58 therms per year, per occupied room. Therefore, the annual natural gas technical potential for all the hotels in PG&E’s service territory hotels is 7,455,051 therms.
Table ES-1 Maximum Technical Potential Electricity Savings from Ozone in Hotel Laundry Operations
|Annualized savings per occupied room at host facility||40||58|
|Annual technical potential for all hotels in PG&E service territory||5,230,204||7,455,051|
What is Ozone?
Ozone is a form of oxygen found naturally in the Earth’s atmosphere. In its most stable form, oxygen exists as a gaseous diatomic molecule (O2). Ozone is formed by the breakdown of diatomic oxygen and the recombination of a percentage of the oxygen atoms into a gaseous triatomic molecule (O3).
How Ozone Cleans
Being a powerful oxidizer, ozone cleans fabrics by chemically reacting with soils. Ozone removes electrons from the soils, causing the soils to break into smaller molecules; these become water-soluble and are released from the linen by ordinary agitation.
How Ozone is Produced
The most-common method of producing ozone for laundry applications is via corona discharge. Simply put, dry air is passed through an electrical field. The electric field causes some of the oxygen molecules to split into separate oxygen atoms. Individual oxygen atoms are unstable and attach to other oxygen molecules, forming ozone molecules.
The Benefits of Ozone in Laundry Operations
The quantifiable benefits of ozone in laundry operations are well-documented and include:
The host for this demonstration was the 278-room Hilton Garden Inn–Emeryville (Figure ES-1).
The hotel is 13-stories high and features a full-service restaurant, lounge, pool, exercise facility, and meeting and banquet space. Owing to these amenities, the linens used and laundered on-premise include: sheets, blankets, bedspreads, towels, tablecloths, table skirts, napkins, and kitchen and cleaning rags.
The Hilton Garden Inn–Emeryville installed the ozone generator and associated plumbing at a cost of $14,000, including labor. The installation required minimal modifications to existing plumbing, which kept labor costs down.
Figure ES-1 Façade of 278-Room Hilton Garden Inn-Emeryville
Table ES-2 summarizes the savings due to the installed ozone system at the Hilton Garden Inn–Emeryville. As expected, the value of the natural gas saved due to the replacement of hot water with cold was the leading component of total savings. The value of the electricity savings were minor, also as expected. The value of the water and sewer savings were larger than expected, which is significant since the ozone system vendor did not include that value in the pre-installation savings estimates upon which hotel management based their decision to install the ozone system.
Considering all the quantifiable savings resulting from the installation of the ozone system, the ozone system at the hotel has a simple payback of 7.5 months. With available rebates and incentives, the pay back would be significantly shorter.
Table ES-2 Summary of Savings Resulting from Ozone in Laundry Operations
|Cost Point||Value of Each Unit Saved||Unit Saved per Year||Savings per Year||Percent of Total Savings|
|Water & Sewer||$5.92/ccf||1,154.5 ccf||$6,835||30.6%|
|Electricity (washer-extractors)||$0.0900/kWh||7,488 kWh||$674||3.0%|
|Electricity (dryers)||$0.0900/kWh||1.163 kWh||$105||0.5%|
|Natural gas (hot water)||$1.1940/therm||10,383 therms||$12,397||55.5%|
|Natural gas (dryer)||$1.1940/therm||1,948 therms||$2,326||10.4%|
|Total Quantifiable Savings||—-||—-||$22,337||—-|
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