At last! Environmental sustainability is starting to resonate with a significant number of hotel guests, and leading hoteliers are now starting to build this into their offer to the business and leisure markets. They have quickly learned the need, first to ‘talk the talk’ and then, even more importantly, to ‘walk the walk’!
The surprise has come when they found that in parallel to their actions on environmental sustainability, they achieved lower operating costs, better quality and greater productivity!
This month we look at how they are achieving this.
1. Minimising the carbon footprint
Only about 10% of laundry energy use goes on electricity for light and motor drives, but the cost of this per unit is about three times that of heat energy from natural gas, so it makes up around one quarter of the laundry’s energy bill. In the most energy efficient laundries this cost is minimised in two ways:
- New equipment is always based on gas heating. This applies to washer extractors, tumble dryers and ironers. For washer extractors this might mean the purchase of a small steam generator or in-line gas water heater, which is usually worthwhile for the substantial saving obtained over the life of the laundry equipment.
- The electricity consumed in powering part loads is almost the same as for full loads, so it is essential to manage the laundry so that every machine is always filled to capacity. Running a half-loaded machine doubles the electricity charge per item washed for that load! This often requires small monthly injections of linen stock to make up for inevitable losses, but this is normal and essential.
There is one machine design which tackles electrical energy demand head on and that is the Hydrofinity washing machine. The entire design is based around low temperature laundering and it uses XOrbsTM to displace around half of the water volume, which produces similar reductions in chemical demand and heating costs. As a result, the lifetime primary energy demand (heat and power) is about two thirds lower than the average for comparable sized washer-extractors. This is a startlingly good outcome for this novel design and the saving has been independently verified.
Minimising carbon footprint also requires other no-cost changes which are not always obvious, but which can have startling results. One important factor is hydro-extraction after the rinse, because it is vital to reduce the residual moisture to the minimum. This is because drying and finishing uses around twice as much heat energy as washing, per kg of dry textile. Squeezing the water out in the spin (in a washer extractor) or in the membrane press (after tunnel washing) uses only a fifth of the energy needed for ironing and only one-fifteenth of the that used in tumble drying! This means trialling increases in spin times, increasing these in half-minute steps until there is no improvement in moisture retention. Old, 24-bar membrane presses need at least 60 seconds at full pressure; newer 40-bar presses at least 30 seconds. (There is side benefit to this: in hard water areas, this will reduce alkali carryover to the ironer, resulting in an improvement in the life of calender clothing.)
Once you have optimised the moisture retention, you should be able to reduce tumble dryer cycle times and improve calender productivity. You will obtain even more benefit if you fit automatic drying cycle terminators to the dryers, eliminating over-drying completely. There is a modest investment for these, but the energy saving alone gives a relatively short payback. Some operators have found the improvement in dryer productivity to be even more valuable, as guests demand ever heavier towels. A side benefit is the reduction in towel greying, which usually accompanies over-drying.
Another no-cost improvement in carbon footprint can be achieved by minimising (and in many cases eliminating) conditioning of flatwork in the dryer. Work from the washer extractor should be taken directly to the ironer, saving both energy and double handling. The thermal efficiency of the ironer is probably 90 – 95% whereas that of the dryer is rarely much above 50%. Any drop in ironer productivity from the slightly higher moisture retention can be countered by maximising the number of lanes and the bed coverage (by edge-to edge-feeding).
2. Achieving ecologically sustainable water consumption
Heating of wash water uses typically 30% of the total heat energy involved in day-to-day laundering, so it makes sense to tune the wash dips down to established minimum levels (125mm for pre-wash and 75mm for main wash) for each programme on each washer extractor. This reduces both heat energy and water demand. This can be a time-consuming chore, but it is a basic and essential one and the only cost is in the time needed by the Laundry Engineer and Laundry Manager. (There is no need to do this with the HydrofinityTM machine, because the minimum water required is precisely metered into the drum whereas most other designs rely on level controls).
Launderers who have undertaken this task have often been surprised at the immediate benefits it brings. Reduced fill times reduce overall cycle times, increasing productivity. Chemical additions can be reduced in direct proportion to the lower water requirements. The biggest benefit is often found to come with the reduction in rinse water levels, especially in areas where the local water quality is good. If this is low in dissolved alkali, then less is needed to rinse out the detergent chemistry.
The basic design of the Hydrofinity machine, because it uses XOrbs to displace water demand and because of its precise metering system, results in a halving of water consumption when rated against other comparable machines, even when the latter have been correctly set up. This claim has also been independently certified.
3. Minimising chemical discharges
The chemistry of washing relies on the concentration of each wash chemical in the wash liquor. This means that, in order to reduce the quantity of chemical discharged to drain, it is necessary first to minimise the volume of water in the pre-wash and main wash. If you can reduce the volume of the pre-wash demand by say 15%, then you can immediately reduce the amount of each pre-wash chemical addition by the same percentage.
Work by the British Launderers Research Association many years ago established optimum pre-wash dips for a 50kg machine at 125mm, in order to allow sluicing of loose debris (such vomit or faeces) to drain. If you have relatively clean work and you can classify the occasional heavy soiled item separately, then you might be able to convert to a ‘stepped wash’. This involves shortening the drain stage at the end of the pre-wash, so that you only reduce the dip down to say 75mm, which is the ideal dip for the main wash. You will also be able to reduce your chemical additions for the main wash, because you will have much more carryover from the pre-wash than you did before. This gives you significant savings in water and time, because you do not need to run in water to make the main wash dip, in addition to the chemical savings already described.
Many launderers still rate the attractiveness of the detergent by the price and buy the cheapest. This is rarely the best way, because to minimise chemical additions (at the same time as reducing the wash temperatures to reduce your carbon footprint) may require a modern formulation which is more expensive per kilo. However, when you weigh in the advantages of less chemical and very low heating costs, the net benefit is significant. If you also get better productivity and much longer textile life, the gains become even greater. Cheap detergents are often built around low-cost ‘fillers’, whereas modern laundering requires pure, concentrated power.
Do the suggestions made here actually work in practice or is this just fancy theory? If you look in the UK government guide to energy saving in laundering, you will find typical energy consumption ratios for ten years ago. Most large laundries are members of the UK Textile Services Association, which negotiated an agreement with the UK government for waiver of the climate change levy in return for quantified, year-on-year reductions in unit energy consumption. This resulted in an industry-wide reduction of 25% in energy demand over a five-year period for this group (which includes most of the large laundries in the UK). This was achieved by a variety of methods, but some of the most successful have been refined and are presented in this blog. They do not apply just to large laundries – they are now available for even the tiniest operations - both commercial and in-house. The wide range of performance data for sustainability in small and medium sized laundries is testament to the opportunities which still exist.
Building on these opportunities will yield not only sustainability benefits, but it will open up quality improvements, better productivity and improved textile life. Most do not need much investment, but they each need dedicated management time. As the sectors open up after the pandemic, now is the time to seize these chances and reap the rewards so readily available! Good luck!