Historically, kitchen ventilation equipment has been an intensive energy user, but over recent years systems have been developed that have reduced these requirements. Clare Nicholls investigates how foodservice operators can keep their kitchen air clean without being stung in the pocket.
Kitchen canopies are essential to ensuring a safe and comfortable working environment in a commercial kitchen, but until recently they have been seen as the ‘energy vampires’ of the catering equipment world. So how can operators ensure that the system they specify isn’t a power-sucker?
According to HVAC Ltd’s head of kitchen ventilation, Ian Levin, the manufacturer ensures all of its systems are tailored to each application. “We design as much efficiency into each system as is practicable within the space and budget constraints of each project,” he says. “This may include basic decisions such as selecting the correct type of fan motor and impeller. The careful positioning and sizing of the canopy and integral components is critical to achieving effective collection and containment.”
HVAC has developed several canopy configurations that are said to use intelligent design features to maximise efficiency, allowing the firm to select smaller plant motors, size smaller ductwork and decrease the cost of downstream air treatment components.
Levin explains: “The question of energy efficiency goes much further than purely ‘how much does it cost to run a fan?’ or ‘how much treated air is being sent straight back to atmosphere?’ It is more relevant to talk about through-life costs. For instance, a system with poor up-front filtration in the canopy will require higher maintenance and cleaning. One of three call-outs could easily be saved each year by utilising more efficient canopy filtration methods. It is unfortunate that so many of these relatively simple energy- and cost-saving ideas fall prey to capital-budget constraints — or the dreaded ‘value engineering’ — on too many projects.”
With regards to demand-controlled systems, he claims that the default document for the design and installation of kitchen ventilation systems, the Building & Engineering Services Association’s publication DW172, does not effectively accommodate the efficient use of these systems.
“Since the writing of DW172 (first published in 2005), technology has moved on and it is well-recognised within B&ES and the industry as whole, that there needs to be an update incorporating such developments,” he argues. “I am fully behind utilising new technology including demand-based controls but there needs to be more consideration of all effects that the controls have on the rest of the ventilation processes.”
He cautions that when demand control is used, factors such as grease or ultraviolet filtration efficiency should be considered, as well as the type of fans used, accurate proportional supply-air fan speed matching, collection of the thermal plume from the cooking process and the effect upon carbon dioxide and carbon monoxide build-up within the kitchen.
“In practice, demand-based controls rarely meet some of the grand claims of savings made by some of the organisations selling and designing them, and so there is a degree of cynicism surrounding their use. Often they are too complex and costly to pay-back in the ways described and the projections can be based on idealistic scenarios. Having said that, I also believe that simple effective systems are viable and can be developed with little extra effort from the industry.”
Ultimately, operators are advised to stick to the principles that ventilation design depends on the equipment it is going to serve. The choice of a particular piece of kit can potentially double or triple the air movement otherwise required. Solid fuel appliances require massive air movements, for instance, while induction technology is comparatively innocuous.
Likewise, the location of individual pieces of equipment in relation to each other can heavily affect the air movement and sizing requirements of a ventilation system and canopy. Sparsely arranged equipment with work surfaces in between, positioned in the middle of a room, require high air movements. The same kit, closely positioned against a wall, requires significantly less air movement.
Over at Canopy UK, director John Ellingham takes a different stance on demand-controlled ventilation than Levin. He thinks that demand-based systems are the way forward. “Commercial kitchen facilities have high energy consumption, with equipment and commercial ventilation being the primary energy consumers,” he says. “Demand-controlled ventilation will help to further reduce exhaust airflow when cooking is not taking place under the hood.”
Andrew Galeckyj, commercial director at Britannia Kitchen Ventilation, has similar thoughts on demand-controlled extraction. “Operational, users will turn on the ventilation extraction in the morning and leave it on all day,” he says. “Based on this practice, the system is running consuming energy. A system that monitors cooking activity that reduces the speed of the extract and supply fan to match these conditions must be a benefit, as long as it complies within the current DW172 guidelines.”
Canopy UK incorporates a number of features within its installation of ventilation systems to drive energy reduction: “By careful extraction fan selection, from manufacturers who are continuously striving to improve the energy efficiency of their products, we use odour control companies to help with smoke capture, grease extraction and disposal. We maintain acceptable air quality in the kitchen and temperatures with the control of external emissions and heat recovery.”
Ellingham also points out that kitchen ventilation units can become more energy efficient through regular maintenance, while simple habit-forming steps such as setting mechanical controls correctly and ensuring fans are turned off when not required can help bring bills down, too.
Cooking equipment and restaurant HVAC systems are the primary energy consumers, both of these systems contribute up to 80% of the total restaurant energy consumption”
Elsewhere, Halton has invested much research into developing two main forms of kitchen ventilation energy saving: its Capture Jet and MARVEL (Model-based Automated Regulation (of), Ventilation, Exhaust Levels) technologies.
The Capture Jet hood is said to be highly efficient, with Halton’s customer services manager, Craig Gould, reporting: “We have introduced a mechanically-controlled air curtain that increases the containment efficiency and reduces contaminated air spilling into the kitchen. Our biggest energy-saving innovation to date is MARVEL, which enables full control of the extract and supply fans and offers the potential for huge energy savings.”
MARVEL is designed to provide a proactive individual management system through the use of infrared and temperature sensors on every canopy installed in a kitchen. “It offers the unique possibility of changing the exhaust and supply air flow rates according to the equipment’s activity in real time. It reacts to the cooking,” comments Gould.
He feels it is a logical step to try and match the ventilation performance with the cooking activity. “Restaurants have, probably, the highest energy consumption per square metre of a typical commercial building. Cooking equipment and restaurant HVAC systems are the primary energy consumers. Both of these systems contribute up to 80% of the total restaurant energy consumption.”
While he advises that the first course of action should be to specify high efficiency catering equipment from the outset, he comments: “The Holy Grail of commercial kitchen ventilation is to develop a safe and efficient method of ‘recirculating’ the exhaust air, for all types of cooking including gas and solid fuel, as this will eliminate the need to condition large quantities of incoming fresh air.”
Elsewhere, other energy-saving techniques are getting results for operators. Mansfield Pollard utilises high efficiency LED downlight fittings across its commercial canopy range to achieve optimal performance without consuming excessive power. “LED lights use significantly less energy, give off less heat and have a much longer life than traditional fluorescent bulbs and these benefits drive significant reductions in operating costs,” says sales and marketing director, Andrew Glen.
Mansfield Pollard can also provide an Eco-Sense proactive fan management system, which automatically adjusts the ventilation rates relative to increases or decreases in cooking activity. “Matching the ventilation to the cooking activities delivers energy savings, which results in a relatively quick payback period,” Glen says.
The manufacturer also offers a range of heat recovery options which use heat generated during the cooking process. The adoption of heat recovery technology represents one of the biggest opportunities for energy reduction within kitchen ventilation systems, according to Glen. “Once the whole life cost of a system that includes heat recovery is considered, the economics are compelling. Incorporating heat recovery technology will result in a larger initial capital cost for the system but the savings will very quickly deliver a payback on that additional capital expenditure and then drive lower operating costs for the life time of the system.”
Over at Corsair Engineering, the company offers bespoke solutions including upgrading standard fluorescent lighting to LED tubes or supplying heat recovery coils within the kitchen ventilation system.
“Energy efficient EC fans are just one of our more common offerings for ventilation systems which offer (over a typical AC fan) up to 50% energy savings,” remarks operations director, Adrian Levin. “There is no escaping that the purchasing cost is higher but the possible energy savings should also be factored in when purchasing a new ventilation system. Customers need to understand that it is a viable investment and not only just helps sustain the environment.”
One of the manufacturer’s products is the Airstream canopy range, which can be manufactured to house heat recovery filters, and has double skinned extract chambers with thermal insulation, which is said to maximise heat recovery efficiency. “More subtle changes to the canopy design, such as bell-mouthed extract spigots, also reduce air turbulence,” Levin adds.
It is unfortunate that so many relatively simple energy- and cost-saving ideas fall prey to capital-budget constraints — or the dreaded ‘value engineering’ — on too many projects”
He believes that demand-controlled ventilation (DCV) should definitely be considered when specifying a kitchen, but cautions: “DCV shouldn’t be mistaken as a process to solely limit energy consumption — it also ensures that operators are working in a safe and comfortable environment. There is a significant investment for DCV and routine maintenance costs to take into account. Therefore, this usually tends to be favoured by the high-end market sector. The challenge now is how to make this a necessary and economical product,” he adds.
Levin argues that there are limiting factors that need to be addressed in kitchen extract, as the efficiency of the baffle filters are compromised when under control of a DCV. “Limiting fans and dampers to suit the operation of the cooking equipment impacts the effective efficiency of the filters. At lower speeds, effluent from the cooking process will potentially not have the optimum velocity passing through filters and may ultimately lead to more grease in the system. Therefore secondary filtration in the extract chamber should be considered when implementing a DCV.”
The final word goes to Britannia Kitchen Ventilation, which feels that methods determining and controlling airflows pose the greatest opportunity for energy to be saved. To ensure cooking fumes are adequately contained, a traditional configured canopy requires a high capture velocity to draw the plume to the centre or rear, but Britannia’s Andrew Galeckyj says its Econex system operates in a different way.
“Grease filters are positioned at the periphery of the canopy, where they are able to extract and filter the fumes from the cooking process before they manage to escape. This can reduce extract volumes by up to 40%, in turn leading to smaller plant and energy loads.”
Galeckyj points out that ventless cooking has grown substantially, with many sites restricted with plant location, planning restrictions and neighbourly issues. Applications such as airports, stadia, arenas, basement cooking and many more instances have increased challenges. Energy savings are even being found in this category of the market, with Britannia developing a range of self-contained, ‘Refresh Ultima’ recirculation units, suitable for electrically-powered equipment. “This is available in various sizes to accommodate multiple pieces of equipment of up to 3600mm wide. The system has been designed with an efficient fume capture giving low air duty, with the combination of an internal fan tower designed with energy efficient fan motors.”
Whatever your preferred system, the gains that are now being made in modern-day ventilation are changing the game for foodservice operators and helping to ensure kitchen profits don’t disappear into thin air.
Pizza boom drives business for extraction specialist
A specialist kitchen extraction supplier is seeing a sharp spike in demand for its services off the back of Britain’s pizza chain boom. Andover-based Chimflue, which designs and fabricates bespoke flue systems, has bagged dozens of contracts with restaurant chains that use authentic wood-fired cooking equipment in their kitchens. Over the past year it has completed projects with Rossopomodoro, Franco Manca and Home Slice, which between them operate more than 30 branches and are looking at further expansion in 2016.
Other pizzerias it has carried out work for include Sacroe Cuore, Santa Maria, Pizza Union and Pizzeria Apollo, which all have branches throughout the London area, as well as Craft London, which is based on the Greenwich Peninsula. “We have been installing specially-designed flues and water-based filtration systems on pizza ovens for many of these customers to ensure they have the correct extraction in place — keeping them cooking day and night,” explains managing director Sam Ford.
Ford says that while much of its work with pizza chains was done in London, an appetite for nationwide growth means it is increasingly carrying out installations in cities such as Newcastle, Manchester and Liverpool.
So, what are the main factors that operators need to bear in mind when it comes to extraction for equipment such as wood-fired ovens? “Ensuring that they install a system capable of the high temperatures and soot produced by the ovens as well as an ability to easily clean the system,” replies Ford. “They also need to ensure that they are in compliance with local regulations and guidance for installation of such appliances.”
‘Method of flow rate calculation is archaic’
Ventilation is dictated by the air volumes needed, based on the cooking appliances used. Induction cooking appliances, for example, require considerably less air volume. A reduced volume will mean smaller energy efficient fan motors making the system more efficient.
But according to Andrew Galeckyj, commercial director at Britannia Kitchen Ventilation, the current method of flow rate calculation (DW/172 Method 1 –SEFR) is “archaic” as this method of calculation was devised for cooking appliances available at the time of the first publication of the industry standard (DW/171) back in 1999.
“Little consideration was given to the appliances’ input loads, whether it be gas or electric,” he argues. “It would also be fair to comment on the fact the cooking appliances in use in new restaurant cooking styles in the current market place, are not even listed in DW/172. In a nutshell, the flow rate requirements are generic, based on plan area of appliances and do not reflect true requirements of the appliances being served. This will hopefully be taken into consideration on the revised version of the specification (DW/173).”