Few hotel laundry facilities achieve peak efficiency. They are often overlooked by large margins. This presents significant opportunities for cost-savings and improvements.
There are many definitions of optimal efficiency. They could include minimal operating costs, maximal utilisation of small spaces, minimum energy consumption, maximising labor productivity to offset under-staffing, and maximising machine productivity to delay capital investment. It is often a combination of all these elements.
We will be looking at the first opportunities in energy and water management, and how to address them in your own setup. We will be writing a blog about the future of labour productivity and how to get more from your pint pot.
Set your target
First, you need to clearly state what you want or the current problems that you wish to solve. These are some improvements you might consider:
Overall cleanliness: measured by whiteness, or simply by referring to a white napkin or handkerchief kept in the manager’s drawer.
Stain Removal: Less than 1% of items remain stained after a normal washing, without reducing textile life.
Water efficiency: Most washer-extractors can only produce less than 20 litres/kg dry textiles. However, some machine designs can reach 10 litres/kg.
Energy efficiency, cost and cost: The best hotel laundries now target textiles below 1.5 kWh/kg. However, many still use more than 2.5 kWh/kg! Some machines are better than others.
Process design (if your current quality is satisfactory, you can skip this section).
Optimizing your washing process is an important first step. You will likely return to it again and again. You can use the expertise of your detergent supplier to identify which classifications you should process. Pillowcases are more difficult than hotel sheets, and spa towels can be more challenging than guest room towels.
You need to fix each classification:
- There are many stages
- Each stage’s duration and temperature
- Dosage of chemicals for each stage
- Each stage has its own water level
- Final extract time.
To create your process manual, your chemicals supplier should be able tabulate the details of each classification. This should include the rewash process. It is not a good idea to wash stains in the same way every time. You have already proven that the normal washing process doesn’t work for them. It is necessary to have specialized rewashing processes that will result in a high percentage recovery and useable items from one rewash. Not the same items going around the system with the same results – stains!
You are now ready to get started on efficiency improvements.
It is often worth reducing water consumption first. This affects the wash heat energy, fill time, chemical consumption, wash quality, and water cost. All water levels are measured in ‘running dips’. This is the average dip when the cage rotates normally.
If you have to clean up food or other debris, the pre-wash should be approximately 125mm (5″) in length. If you don’t expect to find any solids soiling, you can use a lower pre-wash dip (around 75mm (3″)), and then skip the drain. The main wash will still be performed with the same water. This is called a “stepped wash” and saves time, energy, and chemicals. Pre-wash should be performed at a temperature below 40C (38C ideal). This will soften the skin and remove any protein-based substances (e.g. food, blood, and other body fluids).
For a machine weighing 23kg, the optimal main wash dip should be 75mm (3″) in diameter. This will give you a lift and drop action that effectively removes soiling and stains. Main wash time may vary between 7 and 8 minutes. For hotel sheets lasting one night, it can take up to 15 minutes. For heavily stained kitchen cloths. It is not necessary to leave the cloths for more than 15 minutes. Because the suspending agents that keep the soiling and staining from being removed in suspension only work for a short time, they are not recommended to be used more than 15 minutes. Graying will become more severe over time.
There are many opportunities to optimize rinse dips, as most washers have factory settings that can handle the lowest quality water in the country. A wash dip that yields a final rinse water with an alkalinity less than 2% is considered safe. Most water supplies in the country are more reliable than those of the poorest, so almost every rinse dip can safely be reduced. For maximum efficiency, reduce the rinse dips by 1 cm each. Keep each rinse dip the exact same. Once you have established the safe minimum, adjust the detergent dosage in proportion to keep the wash liquor at the same concentration. This is the key to dip management’s other benefits, such as a reduced time frame and lower chemical costs.
Once you’ve mastered the water, you can now focus on energy consumption and cost. You will have already made energy savings by tuning your wash dips. You can now extend your savings by setting the final extract speed or time. Because of the possibility of creases being ironed or removed by the tumble dryer, cotton flatwork can generally be spun at the highest extraction speed. If the garments are to be steam-pressed, such as on a steam-air former or rotary press, cotton requires more care. The best way to control residual creasing in cotton garments that will be tumble dried or tunnel finished is to use a combination of washing technology as well as final spin speed. This topic will be addressed in the Hydrofinity.
To minimize energy consumption in drying and finishing, the length of the final extract is crucial. To dry one litre of moisture in an electric tumble dryer, it takes fifteen times more energy than to do the same thing in a washer extractor. Even an efficient ironer takes five times the energy. To make the most of this, you need to adjust the spin duration so that the final moisture content does not drop by half a minute. This is especially important for towelling as it reduces drying time and can improve the machine productivity over the course of the day.
Once you have set the spin times correctly, it is time to only dry towels and bathrobes in the dryers. The ironer should finish the sheets and pillowcases, without any intermediate conditioning in the tumbler. The ironer’s thermal efficiency is up to three times greater than the dryer. It’s more efficient to use the ironer slowly, with maximum coverage on the heated bed, rather than to load wet textiles into the tumbler for a quick pre-dry.
The same logic applies to pillowcases that are twice stuffed into an ironer, even if they dry unevenly the second time. One person can run the ironer at half speed and feed two lanes. This will produce perfect results at the lower speed with no reduction in the amount of pillowcases produced.
Although there are slight differences in the water, energy, and chemicals consumed by washer-extractor models, one design stands out.
Xeros enabled washing machines use less water than traditional washing machines, which gives it a world-class economy in water and energy. This innovative design requires half the water required by others and only half the chemicals needed to reach the desired concentrations. This could explain why washer-extractors at some laundries use over 25 litres of water per kg textiles while others can handle half that! This could explain why certain laundries use 2.5kWh of energy per kg textiles while others only use 1.0kWh/kg.
Many small changes can make a big difference in your water and energy consumption. This makes a huge difference in operating costs and carbon footprint, but it is not well understood. Each laundry can benefit from these simple principles. The least efficient laundry will have the most to lose. Although this requires some management effort, most laundry operations require little to no investment. Good hunting!