Simon Jarman outlines considerations that FMs should make when dealing with ventilation and extraction, the importance of getting it right, and the toll it will take on your energy bills if you don't.
5 June 2014
Increasing energy prices are becoming a real concern for business owners, as research shows that prices in the UK are rising faster than in other countries.
Add to this the prospect of ever more green taxes, which look set to add as much as 50 per cent to the electricity prices paid by 2020, and it is clear that companies must explore the viable energy-saving strategies available to them if they wish to cut their bills.
One area that should not be ignored is the commercial kitchen, whether that is preparing food for your staff, your customers or the general public. Our belief at Quintex is that the energy use in a commercial kitchen is exceptionally significant as a percentage of a typical business's usage. If you take into account all the things that a kitchen does - air handling, lighting, cooking, refrigeration, hot storage, ware-washing - these are a lot of high-energy consuming activities and so it is vital to research methods for minimising use - and costs.
Measure what you use
One of the biggest issues that kitchen operators face in terms of energy use is staff behaviour. By encouraging behavioural changes, significant amounts of energy can be saved. For instance, ensure that the gas on the cooking appliance isn't switched on until required and that lights are switched off when the kitchen closes, rather than being left on overnight. Proper maintenance of appliances can also make a significant difference. I'm a big advocate of energy monitoring - you can't manage what you don't measure and if you invest in monitoring systems you know how much energy your appliances and kitchens are using, which gives you much more opportunity to do something about it.
It is also well worth looking at the area of ventilation in the commercial kitchen, as this is one space where we know efficiency can be significantly improved.
It is quite common in a commercial kitchen for the chef to come in first thing in the morning and put the gas on straight away - often just to warm up the kitchen. As a legal requirement, the gas has to be linked to the ventilation system, which means that the ventilation fans will automatically switch on to avoid the build-up of noxious gases in the area. What tends to happen is that the fans run at full speed all day, even when there's little or no cooking taking place.
Indeed, a traditional kitchen hood and extractor system in a commercial kitchen is designed with a capacity sufficient to remove 100 per cent of the heat, steam and smoke produced when cooking levels are at maximum and all appliances switched on and running at maximum operating levels. Under normal operating conditions, however, it is highly unlikely that cooking will be constantly at maximum levels and all appliances under the hood will be running at 100 per cent for an extended period of time. This means the ventilation system is often running in excess of the level needed to successfully remove the heat, steam and smoke produced.
This clearly identifies an area of energy use that can be reduced if there is a suitable method to do so. Another area facilities managers should look into is that of demand controlled ventilation.
Demand Controlled Ventilation (DCV) is an exceptionally effective and underused means of saving energy in a commercial kitchen; it has the ability to achieve savings of up to 80 per cent in fan energy use.
DCV uses sensor technology to detect cooking activity levels and reduce ventilation fan speeds so that extract rates are matched to cooking demands, so optimising energy use.
A fan running at 50 per cent of its normal operating speed will only consume 12.5 per cent of the energy required to run the fan at 100 per cent of its operating capacity, resulting in significant carbon emission reductions. This is obviously a huge reduction in fan energy use for businesses and will result in significant financial benefits.
In addition, there will normally be two fans in a kitchen, an extractor fan taking away waste air and a supply fan bringing in fresh air and replacing that waste air at the same rate as it is being lost to the atmosphere. In many cases, the fresh air that is being brought in from outside is conditioned before being brought into the kitchen, so it is heated or cooled, depending on the season.
Air in, air out
Conditioning the outdoor air to replace air exhausted from a commercial kitchen imposes a significant energy burden - typically more than half of the total HVAC load in a commercial food-service facility. By using DCV, less air is extracted from the kitchen when fan speeds are reduced so, in turn, the requirement for conditioned supply air is also reduced. As a result of this, further savings are achieved through the use of DCV because less hot or cold air is required from the building's heating or air conditioning plant. The savings from reducing conditioned air losses are also very large. In addition, the life of the ventilation system is also extended as a consequence of lower operating loads, leading to reduced costs.
To sum up, while rising energy costs will affect businesses, there are methods available to reduce use and bills, and ventilation represents a real opportunity for savings. When you look to cut costs and increase efficiency facilities managers would find it is certainly worth considering the energy use of any commercial kitchens you operate.
Simon Jarman, CEO, Quintex